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Old 07-17-2012, 04:54 PM   #1
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Default Project: Basher Buggy Build from a Racer's Perspective

I have posted this thread on a couple other forums, but I felt like it would be a good addition to RCTech as well. I see this build not only as a resource for those of us who use our RC's for both racing and bashing, but as a kit building resource in general, with basic info about shimming, trimming mold flashing from parts, use of cap head screws in critical areas, etc. For most on this forum, this may seem like basic knowledge, but I have seen so many poorly assembled cars over the years with linkages that would bind, tons of stripped screws, and arms that would flop forward and back when turning, and I thought this would be useful for people who don't really know the basics of kit building for racing and bashing. And being a budget minded build, this build started out with a used buggy purchased from a user right here on RCTech. I also hope that this build can persuade more people to buy used RC's, it seems that many people think buying a used RC is a huge risk and it's better to buy new, which in some cases it is, but in my opinion its always good to look into buying a used RC car instead, especially if one is on a budget, they can afford a nicer RC just by buying a used RC. I also wanted to prove with this build that high end 1/8 buggies are not just for the racing crowd, they make excellent weekend bashers and they are so much tougher, better handling, and longer lasting than a vast majority of vehicles out there marketed to the bashing crowd. So on that note, here it goes....


So as a racer and basher, I demand quite a bit from my RCís. They need to be tough, but they need to handle well at the same time. Many of us know that this really isnít easy to achieve with alot of the current offerings for RCís out there unless you want to drop a ton of money on a high end 1/8 kit. Well I decided I wanted a high end 1/8 kit but didnít want to pay the price, so Iíve stuck with older cars, like the Mugen MBX5 series. My race truck is a Mugen MBX5T that Iíve built up to be lightweight (weighs in at around 9 pounds 5 ounces ready to go without fuel, only a little heavier than many of the newest generation truggies), and Iíve got it setup to where it handles good and matches my driving style. Problem is, itís tough, and I end up bashing it too, which tends to making it sloppy or break something and then my race truck is down, so I needed something elseÖÖ

After watching some youtube videos of 1/8 buggies bashing, I figured what better platform for a super tough, great handling bash car than a 1/8 buggy. The short arms of a buggy still have the same beef as the truggy counterpart but alot less leverage on them in a crash, and lighter overall, which adds up to a tougher car. I browsed the RCTech for sale section for a while and came across a deal for a Mugen MBX5R converted to electric with some extras for $125 shipped, so I jumped on it. Didnít really know what to expect because the pictures werenít very detailed, but when I got the box my jaw hit the floor, it weighed in at 34 pounds and cost the guy almost $40 to ship. Opened it up and it looked like I had been sent his entire Mugen buggy collection, easily over $1500 worth of stuff (and probably $200+ of that just in spare suspension arms, tons of Mugen Prospec parts and King Headz parts NIP and enough spares to build 3 more complete buggies with plenty of spares to cover breakage). The buggy itself that came with all of this stuff was in need of some TLC, and I wanted it to be nitro (I love brushless but always have better luck with nitro, so donít hassle me to convert it again or ask why I didnít run brushless!), so I figured the best plan of attack would be to rob some parts off the current buggy and build up another one from all the brand new parts that I got with the deal.

This buggy will be built with lightweight parts (lots of CF) and aluminum strength upgrades from King Headz, Fioroni, and Reckward Tuning. The reason? Reduce the weight to help increase the strength. Get rid of excessive beef where it isnít needed (like the servo tray and steering top plate and center diff top plate, which come stock as aluminum and I am replacing them with CF) and replace with light weight parts and keep the beef/add more where it is needed (like lower hinge pin supports and such), and still have a fuse to prevent worse damage in a bad crash in all the needed areas (like some plastic parts). Everything will be built like the buggy will be raced, meaning shimming everything that needs to be shimmed, de-burring the plastic parts where they break away from the mold tree, properly shimming the diffs, getting the linkages setup to be as efficient and smooth as possible, and get the handling dialed in. For the setup (like link positions and such) I am going off of a combination of Mugenís stock setup sheet for the MBX5 and MBX5R Prospec (the MBX5R does have some slightly different parts and this is a 5R so thats why I am using both setup sheets to get 1 baseline setup). There is nothing extraordinary here that the average guy with a 1/8 buggy canít do, as I am not going to have any custom made parts on this buggy, everything can be purchased for this particular buggy, and really the same applies for most 1/8 buggies out there because of similar design.

Here are the details for what running gear it will be gettingÖ.

Engine Ė Werks B5 (was planning on using my old Picco P3-28 but youíll see why that changed in the pics below)
Servos Ė ACE/XP DS1015′s on throttle/brake and steering
Radio System Ė Futaba 3PM 2.4GHz FASST
Rx Battery Ė Protek 1700mAh LiFe
Fuel Ė Byrons 30%

Now for the picturesÖ.

The MBX5R that I bought next to my MBX5T (5T has a broken front lower arm, donít mind that),


And of course, the mandatory nude picture!


Previous owner of this MBX5R must have been an amateur machinist like myself as the chassis that it was on had been pretty heavily machined and didnít seem like it was machined in the right places for use with a nitro setup, so that chassis went into my aluminum scrap. This picture shows some of that, along with the Elite RC MBX6 motor mount and Tekno battery tray


Here is why plans changed on using the Picco P3-28, and I just want to note that it was still running, and I thought I better check it out just in case before I put it in the buggy and Iím glad I did. Must have been a factory fluke or something, but the rear bearing failed and was letting the crank slop up/down/side to side, exactly what it shouldnít be doing, and it was enough to allow the piston to come into contact with the head button. Amazingly though it was still running, but I think itís just going to be used for mock up purposes now, no sense in going through the trouble of putting it in the buggy if eventually itís just going to grenade.


Tear down of the (filthy) MBX5T. Took the Picco out, and removed the servos from the MBX5Tís servo tray and put them in one of the brand new CF trays that came with the MBX5R.


MBX5R chassis torn down. front and rear assemblies removed, center diff and motor mount removed. You can see the parts from the completely disassembled Picco in the upper right corner. Also note the machine work done to the chassis by the previous owner, definitely not up to my standards and it looks kind of hack and I thought the chassis felt way too flexible when the buggy was still together, so itís getting a lightly used factory replacement.


Just wanted to show these off, a brand new unused set of aluminum center diff mounts, I believe they are Mugen Option parts, as Iíve never seen a set before, but I am wondering if they are aftermarket because the anodizing color isnít the same as any of the rest of the Mugen parts. I am not using these for this buggy build because they are a little too nice to throw in a basher and I plan on machining them to make them lighter and use them in another build eventually. But they are really nice so I figured theyíd make some good eye candy for the build thread. Anyone out there happen to know what brand these are?




Then I started putting things back togetherÖ got the front bulkhead put together with the diff (brand new diff, filled with 4K weight fluid) and got the diff shimmed up. Put it together with the Mugen stock #0 front hinge pin support (optional ones include a # -1 plate which drops the front kick-up angle of the arm down, also known as anti-dive). For the front lower block (the one in the picture below) I started with a King Headz 1į, but I think their machining must be off, as you can see in the picture below it made the bulkhead sit off of the chassis. I compared this chassis to a couple others I had and it is not bent, so I swapped the King Headz front lower block for a Fioroni 1į block and everything sat down on the chassis like it was supposed to -


Here it is now with a brand new front shock tower on, and the Fioroni 1į front lower block, which let everything sit like it was supposed to down on the chassis.
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Old 07-17-2012, 04:54 PM   #2
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And againÖ. (notice the use of cap head screws, see my note below!)





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NOTE/TIP: One thing I like to do whenever possible is replace those stupid 2mm hex button head screws with equivalent length cap head screws with a 2.5mm hex. They practically never strip the head out compared to the button head screws which strip regularly, and the weight difference, especially for a basher, is extremely minimal, and a food scale can barely pick it up. I would say the weight difference between 10 cap head screws with the 2.5mm hex and 10 button head screws with the 2mm hex is probably only a couple grams, definitely a worth while upgrade. Also, save yourself some money if you do alot of projects, buy your hardware from McMaster, you can buy boxes of 100 of these screws for like $4 to $8 each depending on the length, and thatís for black oxide coated M3 (thread) metric grade 12.9 screws, and all of the boxes I have ordered from them say Made In The USA and they are Cam-Car brand (which are great IMO). Canít beat that.

One thing to keep in mind is if you live someplace humid and you typically store your cars in your garage or your home has a swamp cooler rather than AC, invest in some cans of WD40. I made the mistake of leaving this car in my garage for about a week now and already the shafts are rusty, diff outdrives are rusty, and the screw heads are rusty. Donít be turned off from buying black oxide coated steel screws just because they rust, they are stronger than stainless screws (and cheaper), and a little WD40 will keep the rust away. Donít make my mistake, as I am going to have to take alot of this car apart again to clean the rust off. USE WD40 FOLKS!

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Continuing on, I put the steering together using a Fioroni ackerman plate, it is lighter than the Mugen Prospec ackerman plate, however it is not quite as beefy, if it ends up bending I will be going back to the Prospec part, but I doubt it will. Also something to note here is that the MBX5R uses a different ackerman plate than the MBX5 buggy and the MBX5T truggy. The MBX5Rís ackerman plate actually has the holes set back by about half of their diameter, so when comparing the two the holes are half on/half off each other, I guess this was because Mugen figured something out with the steering geometry and added that change in with the MBX5R, but itís minimal so I doubt Iíll notice a handling difference. While typing this up I did notice some slop in the steering though, namely the bell cranks moving up and down on the posts, so that needs to be shimmed, and the ackerman plate is a bit sloppy on the bellcrank arms and will need shims under it, I suspect because the threaded inserts that go into the bellcrank arms and rotate as they move left and right are a bit long and letting the ackerman plate move around a little too much for my liking. I also will be changing the ball studs to these ones Mugen makes that have a fatter washer side to them to help correct some of the bump steer than MBX5 series cars are known for having. Anyway, here is a pic of the steering mostly put together with the upper and lower arms on and the CF steering top plate. Also noting the upper arm position, I have it in the lowest position with the Mugen C & D lettered upper arm hing pin holders.


And againÖ.


Here is a good picture showing how I shim the upper arms. Those aluminum countersunk washers, in this case ones meant for M4 screws, work excellent as shims and look good too. I used 1 aluminum countersunk washer and 2 regular flat shims in this case, but using the countersunk washer looks alot better in many cases because it takes up more room that normally youíd have some ugly thick shim pack in there. You can also see a clear anodized M4 aluminum countersunk washer used as a shim on the lower arm, its the perfect thickness and only needs 1 per side. Also not that I am using a mix of new and old parts on the steering. The plastic bell cranks and aluminum servo saver bellcrank tube and the Fioroni ackerman plate are brand new, and the spring and nut and bellcrank posts are used but in good condition.


Here you can see alot more progress, I installed the King Headz aluminum servo tray post/mounts, the servo tray with servos, the radio box, and the center diff and front chassis brace. Nothing too special here, this picture shows it all really. I did modify both the front and rear chassis braces to use a beefy M4 screw where they bolt to the chassis. Got an Irwin M4 tap and the corresponding drill bit (I donít remember what size it was, google it if you are interested) and drilled out the lower hole on the braces and ran the tap through them to get them to M4 thread, then used a countersinking bit to get the hole in the chassis prepped to accept an M4 countersunk screw. The reason for M4 screws on the chassis braces is because I did the same thing to the Mugen Prospec braces on my MBX5T with good results, as the stock M3 screws were always loosening up during a race and then the braces were essentially useless since the screws were loose and letting them move around. The M4 screws can be tightened down alot more without the risk of stripping the hex head of the screw, and they wont loosen up. I used what I believe are Reckward Tuning chassis braces, couldnít find them on Amain but I am assuming they are Reckward Tuning because the color of anodizing on them matches some other Reckward Tuning stuff that I own. They are also lighter than the Mugen Prospec braces by like a few grams each, they look cool, and actually are a little beefier with more contact area on the chassis to reduce flexing. Have them for both the front and rear braces.

Also on the center diff I am running fiberglass brake rotors of unknown brand, a brand new bearings throughout the whole car. Center diff is filled with 7k weight fluid. Also running a brand new brake cam and linkage setup with brand new calipers/pads (technically no glued on pads, just the steel pieces since im running fiber brake discs). Also using a Mugen Prospec CF center diff top plate, and drilled out to use flanged bearings on the brake cams as opposed to the factory setup of bushings. They donít get sloppy and they last a very long time. They are HB flanged bearings, and can be bought here, a worthy upgrade for any 1/8 buggy or truggy IMO - http://www.amainhobbies.com/product_...ghtning-Series


Then I got the rear end assembly put together and finished up the front. I rebuilt all of the shafts front and rear (and had a set of brand new center shafts that I put in it) with new cross pins and such to eliminate any slop in the shafts. Front end got brand new pillows balls and brand new knuckles and bearings and stub shafts. Also installed the freshly rebuilt (by previous owner) shocks up front. Put a brand new diff with new ring and pinion in the rear just like the front, shimmed it up properly and the diff is filled with 3k weight fluid. Using a pair of used Mugen Prospec aluminum rear upgrights, and brand new bearings throughout just like the rest of the car. The rear anti-squat plate is a brand new 3į King Headz anti-squat plate, and the rear toe block is a new plastic unit with 2.75į of toe in and no additional anti-squat. Went with plastic for the toe block because I didnít have an aluminum one for 2.75į toe in and Iíve never broken a plastic one anyway on the truggy so it should be good enough for the buggy. Also installed a brand new rear shock tower, brand new wing mounts and hardware for it along with new aluminum posts/spacers for the wing mount. Did a little filing on the edges of the King Headz rear aluminum chassis brace bracket to make it look a little more like the Fioroni parts on the car. All hinge pins are Mugen Option hinge pins that have a hex head on 1 end and threaded on the other for a nut, beats captured pins and e-clip pins any day! Also something to note, if your rear uprights, toe blocks/anti-squat blocks, front lower blocks, etc. have a location for a set screw, that is there for a reason and use it, especially if any of those parts listed are aluminum! It keeps the hinge pin from turning in those aluminum parts which will wear them out. You want the pin to remain stationary and the arm to pivot on it. Itís alot cheap to replace worn out sloppy arms than it is to replace aluminum anti-squat blocks, toe blocks, etc.


King Headz 3į aluminum Anti-Squat Block


Rear view of the rear end of the car, note the aluminum uprights, brand new rear shock tower, all brand new arms for the front and rear, and the cool scalloped and vented fiber brake rotors.


Rear chassis brace installed (and just like the front itís been re-threaded for an M4 screw at the chassis and the hole in the chassis has been countersunk for the M4 screw), along with the rear freshly rebuilt (by previous owner) shocks, sway bar, hex hubs, and a plain factory new Mugen wing. Also running AKA wheels with AKA Cityblock tires. Itís officially a roller now! Note the chassis too, no strange millwork done on this one by the previous owner, and itís only lightly used. Also running a DE rear skid plate.


And with one of the included bodies. Talk about an old school body though, the "drivers compartment" of it is huge compared to today's cab forward buggy bodies!
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Old 07-17-2012, 04:55 PM   #3
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Continuing on, showing the little details that can matter, making the difference between a well built (and properly built) car and a thrown together car. I took the time to de-bur all of the plastic parts where they break away from the mold tree. It really doesnít save any noticeable weight or do anything for the performance, but it looks better and itís just something that should be done IMO. Picture shows an example of this, one arm has had the burrs from where it breaks from the mold tree cleaned up, the other hasnít.


Now on to the throttle/brake linkage. This is something that alot of people overlook and donít put much though into it, but with a nitro car it can make the difference between everything working like it is supposed or your engineís carb slide sticking and causing a runaway or wearing weird and causing an air leak. When a throttle linkage pulls crooked or in an extreme arc, the servo is literally pulling on that carb slide and it can make it wear unevenly which can cause sticking and air leaks. To avoid this one must setup the throttle linkage to keep as straight of a pull as possible. At idle the linkage is aimed slightly diagonally from front left to right rear, from a little past idle to about 7/8 throttle, the linkage straightens out and pulls almost perfectly straight, and then from about 7/8 throttle to full throttle the linkage only slightly angles diagonally from left rear to right front. There is no way to make it pull 100% straight when your servo uses rotational motion, so the arm is traveling in an arc, but setup right you can minimize the arc that the throttle linkage follows and maintain a pretty straight travel. While this is not as critical with the brake linkage, I have it setup to where the brake linkage also follows a very straight path and engages both brake cam levers while the linkage is fairly straight, which helps eliminate oddball brake bias characteristics that you can get from not having your linkage pull in minimal arc. Also notice in the pictures the use of those small rubber inserts that come in the box with servos these days. Don't throw those out, always use them (especially in nitro cars for the throttle servo), they isolate vibrations from your servos, which is important if you want your servos to last a long time!

At idle -


At full throttle -


And just a side view showing how Iíve got the brake linkages setup so that they remain flat and arenít trying to pull up or down on the brake cam levers either -


Yesterday I ordered my Werks Racing B5 engineÖ.. http://www.amainhobbies.com/product_...=Product-Feeds

Ö.along with some glow plugs, another Protek 2S LiFe 1700mAh receiver pack, and an aluminum servo arm for the steering linkage. So stay tuned for more progress! Up next will be the steering linkage setup, additional shimming of steering components and trying to fix the bump steer issues of this car, fuel tank installation, and engine installation later in the week.

Continuing on though, I just wanted to show off a small fraction of some of the parts I got with this buggy when I bought it, this is probably about 2/3 of the aluminum and CF goodies that came with the car. Alot of brand new King Headz and Mugen Prospec parts in there along with quite a few used King Headz and Mugen Prospec parts, although lightly used. All of those CF servo trays are brand new also.


Now on to more of the build, next up is the steering linkage, this can be a problem area for cars with a lay down steering servo as the linkage moves up and down at 1 end through the servo armís arc, which can give the effect of some weird steering exponential if not setup properly (and when not setup where it moves exactly the same in both directions). This is a very easy fix though, just make sure that your turnbuckles are exactly the same length on both sides so the wheels will turn the same amount in both directions and get the servo so that the arm is pointed straight up with wheels centered. To do this, I just adjusted the link from servo arm to bell crank until wheels centered had the arm straight up and down. The 3 pictures below will show the arm at center, full lock and full lock, and notice that the link has about the same incline in both directions, so there is no strange exponential effect when turning.

So here is wheels straight and arm centered and pointing straight up, note the link angle has a normal amount of incline to it -


Then at full lock steering to the left, the link is level -


Then at full lock steering to the right, the link is level -


And just a quick shot of it with the body one, a JConcepts Punisher for the MBX6
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Old 07-17-2012, 04:55 PM   #4
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Now for the good part, the new engine! Got my Werks B5 in from Amain, here are all the vital stats on itÖ

Specifications:
Stroke: 16.50mm
Bore: 16.30mm
RPM Range: 3,000 to 39,000
Output: 2.6ps at 33,000 rpm
Sleeve: Five Port, Chrome Plated Brass
Piston: CNC Machined High-Silicon Aluminum Alloy
Connecting Rod: Double bushed made with special 7075 T6 aluminum alloy
Carburetor: Aluminum 2 needle with adjustable venturi (7mm stock).
Cooling Head: CNC Machined, lightened, low CG design

Using a Dynamite 086 pipe and a Mugen 34mm aluminum fly wheel (3 shoes clutch setup) with OFNA aluminum shoes (7075) with two 1.0mm springs and one 1.1mm spring, and an OFNA non vented 13t clutch bell (stock tooth count, will be gearing it up 1 more tooth to 14t, this thing has some crazy bottom end, could use the speed benefit of 1 more tooth on the clutch bell!).

First thing I did before installing this engine was to take it apart and inspect it and remove any shavings that might be left over in it (which there were a couple of them!). This engine has a billet cooling head and billet piston, an aluminum carb (which I am not a huge fan of but it does have a very thick insulator around the carb base neck), comes with a 7.0mm venturi insert, and itís a turbo head engine (and I donít believe they have a standard plug option unfortunately, so you have to bite the bullet on the cost of plugs!).







And this is why I take my engines apart before break in, that is a little metal shaving stuck to the side of the sleeve with oil -


Sleeve has nice machining, itís a 5+2 port design


Check out that crank with the smooth cuts, dimples machined in it to balance it, and that beefy con-rod!


I think the Werks B5 conrod looks a little beefier than a Picco P3-28 con-rod, what do you think?


I then put the engine all back together and only had to use a very minimal amount of RTV sealant (the nitro proof kind of course, I use Racerís Edge brand) as the back plate, carb base and pinch bolt all had fat o-rings on them, but I did use sealant on the pinch bolt anyway to seal the threads, and I applied sealant to the washers and fuel inlet and HSN between all of those parts to prevent any air leaks there, no real detailed pictures of this because it should be fairly self explanatory.

Same thing goes for the clutch, itís just a plain 3 shoe clutch using a Mugen 34mm fly wheel, OFNA aluminum shoes (7075 ones), and I used two 1.0mm springs and one 1.1mm spring, and a 13 tooth OFNA clutch bell. Nothing special here so I wonít take up a bunch of space with pictures of the clutch, most people know what they look like.

Here is the engine re-assembled and and installed in the buggy with the mesh set. I use a plastic bag that parts typically come in because its thicker than paper and I feel it gives the proper mesh for mod1 pitch gears like this.


One very important thing to keep in mind with any nitro is shimming the clutch bell and/or flywheel to put the clutch bell in the proper location, which would be where the spur gear and clutch bell teeth are centered on each other. This keeps the load even between the two clutch bearings which ensures longer bearing life.


Now those who saw my previous pictures of the throttle linkage know I got it all setup to work with my Picco P3-28 just as a mock up, but I know that the Werks would be a bit different and in fact it was, so I had to change up my throttle linkage a bit. I couldnít get the pull as exact as I would have liked it with the carb perfectly straight, so I angled it with the slide pointing to the front right slightly, and the pull is about as straight as it gets, no weird binding or slop either. I just moved the linkage attachment point out 1 hole on the servo arm and it seems to have done the trick.



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NOTE/TIP:Something you should really use to your advantage here is the EPA settings on your transmitter! A properly setup throttle linkage is only half of the equation, and especially if you use powerful or fast servos. Without adjusting the EPA your servo will be trying to pull on the carb slide beyond its maximum open point, which puts alot of stress on the carb and the servo and your whole throttle linkage. Set your EPA so that full throttle is right where the servo stops, and when adjusting this make sure you have the trigger all the way down, but not mashed down, just a normal relaxed full throttle position, and adjust so the servo stops just where the carb slide stops. If you canít get it exact, adjust the throttle linkage a bit by threading the main linkage rod in or out of the ball cup slightly. One obvious way to tell if your EPA on the throttle side is not set right is if things move around (like the servo tray flexes, things of that nature) when you give it full throttle (bench testing kind of full throttle obviously), if anything moves besides the carb slide and servo arm at full throttle then the servo is trying to pull beyond the carb slideís maximum open point.

The same thing goes for your brakes, while it may seem cool that your servo can completely mash that fuel tubing on your brake linkage, itís not good for the brakes or the servo. Remember, the calipers can only squeeze on the rotors so hard, if your servo is trying to pull on the brakes beyond where the fuel tubing (or springs, depends on your setup) compress then itís pulling too far and the EPA needs to be adjusted so that it stops before it does this. A bit of flexing of the radio tray or movement of the center diff assembly can be alright if you like your brakes set really strong, but this still should be minimal, so set it up similar to how you set up the throttle side EPA. Apply full brake with the trigger (while in the EPA menu of your transmitter) and start turning down the EPA until the fuel tubing looks like it isnít completely compressed. Set the car on the ground and apply full brake and try to push the car (do this on a really high traction surface too), if you canít make the wheels roll at all or its very very difficult then turn the EPA down some more on the brake side, as you do not need brakes capable of locking up all 4′s on a very high traction surface. It should be tough to make the wheel roll with full brake applied on a high traction surface but it shouldnít require Arnold to do it, again this should be self explanatory and if you play around with it for a while you will see how it should be set.

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Old 07-17-2012, 04:56 PM   #5
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Continuing on, I went ahead and installed the receiver since the radio box was good to go. I added some velcro in the radio box and on the bottom of the receiver, and while it isnít really needed because the receiver should stay put in the radio box it does help cushion it a bit, no sense in letting your $70 2.4GHz receiver bounce around in there when it doesnít need to. Also note the on/off switch block of plate, I have had so many on/off switch failures over the years that have caused runaways that I got fed up with them and just plug the battery directly into the receiver. If you can remember to use an on/off switch then you can remember to pull the receiver box lid and unplug the battery, its cheap insurance and only takes a little longer to do that than turn off an on/off switch. Another thing to note in the below picture is the small rubber grommet where the receiver antenna goes through the box. While this is 2.4GHz and you really donít need to even use an antenna, I like to anyway just to be on the safe side, but the rubber grommet is important here. I have had to replace the antenna on some receivers in years past because the insulation rubbed off where they went through the radio box and eventually it cut through the wire, itís rare but it can happen, putting in a small rubber grommet like the one pictured is cheap insurance against that. I believe that grommet is actually for use with a servo (on the mounting ears), but those things for servos so work good for that too, so use then when you can!


Just a recommendation, the switch to lithium batteries is quiet popular for powering the receiver and servos, especially with the new high voltage servos. Problem is, if you donít have HV servos and you want the runtimes of LiPo you have to run a voltage regulator. If you want to get the runtimes of LiPo without the voltage regulator, you can use a LiFe receiver pack. Their fully charged voltage is 7.20 volts, the same as a NiMH 5 cell receiver pack, and even with the same mAh rating, the LiFe rx pack I run gives me like 3 times the runtime that the NiMH packs ever did, the reason behind it is because they can handle the amp draw alot better and donít drop off in such a steep discharge curve like NiMH packs do. I use a Protek LiFe 2S 1700mAh pack, only $35 from A-MainHobbies, same cost as alot of the NiMH packs out there, if you have a LiFe capable charger I would seriously consider picking one of these up. http://www.amainhobbies.com/product_...=Product-Feeds

Next up was some other basic stuff, like getting the fuel tank installed, fuel lines routed, air filter installed, fuel splash guard installed, getting the pipe cleaned up and installed, etc.

First up was the fuel tank, lines, splash guard, and air filter. I had to modify the splash guard a bit to clear the brake linkage when at full throttle, just a simple cut and clean up with the Dremel. For the fuel tank I also added an addition o-ring between the tank and the posts, so there is that o-ring and a rubber bushing on the tank mounting ears to reduce tank vibration that causes fuel foaming (not pictured).


For the fuel tube routing I really love the little double line clips that you can get from OFNA and various other companies. Alot of 1/8′s these days have these already molded into the side of the tank but older buggies like this MBX5R did not, so I CA glued 2 of them to the side of the tank, and used additional ones to keep the lines together where they were all in 1 place. I also kept the fuel line itself on the highest portion of the clips to keep the fuel away from the pipe to keep it cooler. I also donít run a fuel filter because I feel the stone filter in the tank is good enough and in the past when I have run fuel filters, when I took them apart to clean them I never found any debris in them, so they just seem pointless to me, just another place for an air bubble in the lines to cause a random lean condition. I also installed the pipe, pipe support spring and support spring post. Pipe is a Dynamite 086 with smooth flow round header.
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Old 07-17-2012, 04:56 PM   #6
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And here it is! Pretty much done and ready to go! I started breaking in the engine yesterday, these pictures were taken right before then, itís all dirty now. EnjoyÖ.



















And just a quick teaser shot of it running, was driving 1 handed and trying to take a halfway decent picture, but the exhaust and tire tracks proves it lives!
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Old 07-17-2012, 04:57 PM   #7
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Here is a quick FAQ & A that I hope will answer some of the basic questions the bashers out there will have about this build.

Q: Why did you go with a buggy instead of a truggy or MT?
A: I decided a buggy would fit my needs best because I wanted something super tough that could handle big jumps. A buggy has short arms with small, light weight wheels and tires, so bad landings don't put nearly as much force on the arms as a bad landing with a MT or truggy. It's the basic principle of leverage at work.


Q: Wouldn't a buggy get stuck more often than an MT? They have much lower ground clearance right?
A: Other than tire size, overall ground clearance isn't that much different than an MT. Think about it, the lowest part of an MT is right below the diffs, that's where it will get hung up on obstacles the most. The lowest part of a buggy is also right below the diffs, but the chassis doesn't rise up in the middle, so it doesn't create a "hook" in front of the rear diff. I feel a flat chassis is superior for bashing because it will slide over things that an MT's rear diff hangs up on. And honestly, if I wanted to go rock crawling, I wouldn't do it with an MT anyway, and how many people really go mud bogging with their RC's? The ground clearance argument is pointless.


Q: Why did you go with those boring dish wheels? And I thought wheels with spokes were stronger anyway because they have more ribbing?
A: Dish wheels are lighter and still have ribbing inside of the wheel like any spoked wheel has. But because they don't have holes (spokes), dish wheels can be made of thinner material and still be just as strong, the side benefit of this is they are also lighter. Yeah they might be a little bit boring, but I'll probably never break one of my dish wheels. I've cracked a few spoked wheels on other cars over the years.


Q: I see you used a .21 engine, why not use a big gnarly .28 for more power and awesomeness?
A: Today's .21's are nothing like yesterday's .28's and .21's. They easily put out as much power, they get better fuel economy which translates to more time bashing and having fun. 21's also spool up quicker than 28's, which means you can build more speed quicker and get more air from that jump with a short run up. And at close to $30 a gallon for 30% nitro fuel, I'll stick to the fuel sipping 21's instead of the fuel guzzling 28's.


Q: Doesn't carbon fiber crack and splinter easier? And why don't you have RPM arms on that thing?
A: Carbon fiber will crack and splinter, but I'm sure I would have worse problems if I manage to wreck the buggy bad enough to damage the CF radio tray, diff plate, or upper arm plate. And RPM doesn't make arms for high end 1/8 cars like Mugen, Kyosho, Losi, Xray, Serpent, or even OFNA/Jammin for that matter. They aren't needed on 1/8 cars because their parts are beefy from the factory and their plastics are of a higher grade than the plastics on cars typically marketed toward the bashing crowd.


Q: Why would you build up a race buggy for bashing, isn't bashing so much harder on an RC than racing?
A: Ever race a quad or dirtbike? Ever ride trails with a quad or dirtbike? Do both, and tell me which one makes you more sore, racing on a track or riding trails. Most of you who have experienced that will say racing, because just like racing an RC, its constant and consistent pounding lap after lap, where as trail riding, just like bashing an RC, is a bump here, jump there, a rock or two here and there. Take a car that was designed to race and put it in a lower stress environment and it's going to last longer than if you were racing it every weekend. Remember folks, there is a reason why 1/8 cars are built like they are.


A short video will be in the next post, followed by an engine review!
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Old 07-17-2012, 05:32 PM   #8
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Initial engine review after running about 15 tanks through it.

And a 15 tank report card on the Werks B5....
(Rating system of 1 through 10, 10 being the best)

Initial Impressions/Packaging - 8.5
-This engine comes out of the box looking like a champ, and the massive billet cooling head is the first thing that caught my eye. It is well packaged, but the engine DOES NOT include an instruction manual, and there is a reason for this... According to the Werks B5 thread on RCTech, Werks believes that 4 different racers will give you 4 different answers on tuning, needle settings, etc, so to prevent confusion and risk of engine damage by providing needle settings that even as a baseline may be completely wrong for one person's application, Werks does not include this information. They preset the carb to a rough baseline, then it's up to you as the nitro RC hobbyist to do the rest. This is not an engine for beginner tuners, even though it is extremely easy to tune and break in, the lack of baseline settings could be bad news for newbies. If you know how to tune a nitro, and know the general stuff like how your air to fuel ratio is really what you should be tuning in conjunction with your LSN and idle speed and that the HSN controls the main flow of fuel to the carb and whatnot and have owned a few nitro engine, you should be fine with this engine. But at $200, for some this is a steal deal and for others it could be alot of money, if you are not 100% confident in your tuning abilities, I wouldn't recommend this engine. If you are 100% confident in your tuning abilities, by all means get a Werks B5, best bang for your buck power for the intermediate to advanced nitro enthusiast!

Pre-break in tear down and rebuild/Impressions of engine internals - 7 & 9
-As with any nitro engine you should always pull it apart before break in to make sure there are no shavings inside from the manufacturing process. Even super high end engines are not immune to metal shavings, it's better to be safe than sorry, and I probably had a chance of being sorry if I didn't take this engine apart, as I did find one rather large metal shaving stuck to the cylinder wall, as well as a loose casting bur in the exhaust port. They may not have harmed the engine a bit, or they may have, but $200 is a good bit of money, so why risk it when it only costs maybe 30 minutes of your time to do a tear down and inspection. Other than those two shavings/burs, I found no other debris in the engine. The tear down went very smooth, no screws stripped and I was very impressed with the quality of this engine. As shown in the pictures a few posts up, the conrod of this Werks is as big if not bigger than a Picco P3-28 conrod, talk about beef! The crank looks nicely machined, as does the piston and sleeve. The carb is aluminum with a thick composite insulator around the base neck. 8 out of 10 for Initial Quality Impressions of the internals.

Break in and beyond - 10
-The Werks B5 .21 does not have a ton of mechanical pinch from the factory, but that shouldn't scare you away, it's actually a good thing, less mechanical pinch means less stress on the crank/conrod/wrist pin/piston/bearings. After break in (currently sitting at around tank 15), I cannot turn the flywheel much past where the piston goes above the exhaust port (where your compression ratio measurement would start from), and from how it feels, I would say that I can't turn the engine over farther by hand because the compression is so high, not because of insane mechanical pinch, as the piston does not stick or feel like it's dragging along in the sleeve like it does in an engine with lots of mechanical pinch. Anyway, to put that in a shorter form, this engine has lots of compression, so much so that I cannot turn it over with it in the buggy. Break in was easy with this engine once I figured out my rough idle gap and LSN. I had to preheat it with a heat gun to get my starter box to even crank it over (4S LiPo powered twin 550 motor OFNA box at that!), but it fired just a few bumps after it was primed. For a plug I used O'Donnell hot plug (This is a turbo head engine, unfortunately I don't think there is a standard plug head button option out there), and the hot plug was only for break in to get the temps up, but I couldn't get it much past 150* so I had to use aluminum foil and a sock around the head to get it up to 230/240* (my personal temp preference for break in). Too low of temps during break in will cause an engine to lose compression because it's not expanding enough and wearing too much off the piston/sleeve wall, so break in this engine on a hot day and put a sock of the head to get it up to temp. For the first tank I was after a smooth steady idle but still on the rich side at the LSN, and once I achieved that I let the engine idle on the box for 2 tanks, shutting it down when it got up to temp. For tank 3 and 4, I started doing figure 8's and started leaning the tune a little more (still with a sock over the head) to keep the temps up and so it wouldn't stall out, and still repeating the shut down when up to temp, let it cool completely, then repeat. I did this for tanks 3 through 7 (probably a bit much but that's just my personal preference). After that I started giving the engine more throttle, but not winding it out just yet, so tanks 8 through 12 were with a tune very close to a normal race tune, but with a low smooth and steady idle. Tanks 13 through 15 are at a full race tune but I am not going quite all out with this engine yet, any full throttle is in short bursts.

I am using the stock 7.5mm carb insert/venturi, a Dynamite 086 pipe with a smooth flow round header, Byrons Race 3000 30% nitro, factory head shims (and it's shimmed tall! 2 thick aluminum shims and 2 thin copper/steel shims), Hot glow plug up until tank 8, then switched to a medium plug and adjusted the tune accordingly, and stock gearing for this MBX5R buggy. My clutch setup is a standard Mugen 3 shoe with an aluminum fly wheel, OFNA 7075 aluminum shoes, non vented 13t OFNA clutch bell, two 1.0mm springs and one 1.1mm spring. This engine is a torque monster though, it throws this buggy around like a rag doll and the short bursts of WOT I've done so far show that it's insanely fast, and could be even faster without adverse side effects by going up 1 tooth on the clutch bell, this engine easily has the torque to handle that. The runtimes with the stock 7.5mm venturi are also very impressive given the power that this engine has, I am averaging around 12 to 13 minutes just bashing it around the yard but remember that is with a fairly large venturi and it's not the same kind of continuous driving like racing, so the track runtimes will probably be a bit shorter.


Overall rating with this engine thus far, factoring in ease of tuning, quality of components, initial impressions, and comparing it to all of like 3 other .21's that I have owned, I rate it a 9 out of 10 as a budget racers engine and 7 out of 10 as a basher buggy engine (lower rating as a bash engine due to not being nitro newbie friendly).



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~




I now have about 2.25 to 2.5 (I lost track, lol) gallons through this engine. This "mid-term" review will be short because, in my opinion, results (being a good engine) speak for themselves. I still have ALL of the factory shims under the head, which would be 2 thick aluminum shims and 2 thin copper shims, not sure exactly how thick the shims are but again, its the same as how it was when I first pulled it out of the box.

Compression has of course gone down, but when the engine is primed I can not turn it over with 1 finger in the buggy. At the engine of a run after it has cooled down and doesn't have much fuel in the engine, it can be turned over with 1 finger with a bit of effort.

Run times have remained consistent throughout the engines life thus far, and I am still hitting about the 12 to 13 minute mark. I still run O'Donnell medium turbo plugs, and have been through maybe 4 plugs with this engine so far. Keep in mind that the elevation where I live is around 4500 feet above sea level, so I have to run a leaner tune than a majority of people reading this.

My #1 complaint about this engine, and it may just be due to my glow plug choice, climate, and tune, is that is can be a bit finicky to start. I have it tuned for when the chassis is heat soaked and everything is up to normal operating temp, and that tune is rather rich for start-up. I have to "lean start" the engine by priming it, putting the glow driver on the plug for about 15 seconds, pinching the fuel line, then bumping it. It starts reliably like that, but to me it's just strange, as I've never had an engine that requires such a starting procedure. Once it's up to temp it usually starts much easier though.

As far as power goes, this engine is an animal. Very aggressive power band. Tons of torque on the bottom end with a wicked fast top end. Only pipe I've used with this engine so far is a Dynamite 086 pipe with a smooth flow header, but with as good as it runs, I don't see any reason to change it. Same goes for fuel, I only run Byron Race 3000 30% nitro with 11% oil content, the engine runs strong on it and I see no reason to switch to anything else.

I recently swapped this Werks B5 into my Mugen MBX5T Prospec truggy to do some racing, and a quick test run around the yard really impressed me. It throws my truggy around just as easily as it did with the buggy, although I feel I can coax a bit more top speed out of the truck and smooth the take off (which is ridiculous by the way, it throws a massive roost) with some clutch tuning and jumping up 1 tooth on the clutch bell, but it seems just right for a tight and technical track. The midrange power of this engine is a bit iffy, and I believe that is partly because of the pipe I use, but I blip a lot when I drive anyway so the tendency of this engine to bog a bit in the midrange is almost never noticeable unless I drive the car with a smooth trigger finger. The throttle response is so snappy that it jumps in RPM quickly and seems to just rip clean through the midrange like most nitro engines do when driven with the "blipping/off-on" trigger finger.

I have no complaints about tuning this engine, it holds a tune and the only reason I have to mess with it this time of year is because of Southern Arizona's wild monsoon season where temperature and humidity and pressure can change in all of an hour and drastically affect the tune required. Over the winter this engine was a piece of cake to tune, it was a case of "Set it and forget it" and I rarely had to adjust the needles.


I still give this engine an overall rating of 9 out of 10 thus far, but I feel that it could be an intimidating engine for a nitro newbie. Anyone with decent tuning skills would have no problem with this engine. It's not hard to tune, its just the lack of a baseline setting (no instructions or tuning guide with this engine) and the requirement of really thinking your adjustments through is why I feel its not a newbie friendly engine.
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Old 07-17-2012, 05:34 PM   #9
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And here is a quick youtube video of the buggy doing some big jumps off of a truck rack, as well as a slide show, in February.

+ YouTube Video
ERROR: If you can see this, then YouTube is down or you don't have Flash installed.
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