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John Stranahan 05-20-2008 01:23 PM

CRC Battle Axe, GenXPro 10, 1/10th pan, Brushless, Lipo,4c, Road, Oval,TipsandTricks
 
1 Attachment(s)
CRC Battle Axe, GenXPro 10, 1/10th pan, Brushless, 4 cell, Lipo, Road, Oval, Tips and Tricks

I have been running touring cars, wide pan cars, and racing oval pan cars lately on a large 280 x 70 foot 1/8 scale outdoor track. There is one of each in my fleet. We use a small portion of this on-road track for a paved asphalt oval. Under construction is an indoor carpet track that may become an oval or small road course

Although this thread has 1/10 pan car in the title it is not meant to replace the good on-road pan car thread that seems to be misplaced in the oval car forums. It also will be quite different from the CRC 1/10 pan thread. There has been a small resurgence in pan car activity as a result of normal market forces and possibly my previous pan car thread.

Pantoura, 1/10 pan car, 2S LiPo, tips and tricks.

This thread was quite popular. It was getting 200 views for each of my posts later in its life. I suggest that racers, new to pan cars, read the Pantoura thread up to the first narrow pan car video, about 10 pages. I was a complete pan car rookie at the beginning and got lots of good setup help and general tips. I have a couple of years of pan car experience now as well as years of RC experience with various other cars. My oval experience is increasing as we speak.

This thread is meant to thoroughly explore CRC’s new Battle Axe Oval car and possibly their new GenXPro 10 as well as any 1/10 pan car topics that readers would like to discuss in depth. The thread will be tech heavy as befits RCtech.net. There will be plenty of good quality photos of the test object at hand.

I will continue my reports of testing with brushless and hopefully soon LiPo batteries on the oval. I started these discussion on The Losi LCD Thread.

Also note I had a well read touring car thread that ran simultaneously with the last part of the Pantoura thread.

Associated Factory Team TC5 Tips and tricks

Here are some Pan car suppliers that I have found. If you have additions or corrections to the lists below please send me a Private Message or e-mail and I will edit the new information into this post. This will keep this info condensed.

Cars: Road Cars and Oval Cars

CRC
Calandra Racing Concepts (CRC)
(Makers of the Carpet Knife and Bloody Carpet Knife)

Battle Axe 200 mm
Oval Pan Car

GenX Pro 10 200mm (or convertible to 235 mm)
Road Pan Car

Custom Works
Aggressor Oval Slider Car Kit

KSG
Oval Car Kit

Leading Edge
Oval conversion slider kit

KSKT racing products
SK spec conversion

Wide Pan Conversion for the Pantoura or RC10L3T
Powell Racing Components
New graphite chassis, bottom and top pod plates available.
"The top pod plate is one that I offer for the 10L2 to convert to a tri-shock setup." Picture.

BMI Racing
DB10R 200 mm- Road Pan Car

Hyperdrive
Pro 1/10 on-Road
Hyperdrive Pro 3 team slider kit oval

Team SpeedMerchant
Street Spec (solid front end)

DarkSide Motorsports
I-force. 1/10 on road pan narrow, (wide), adjustable
large photo

Corally
Corally CCT
1/10 Narrow (190-200mm wide) Entry Level Pan Car

Corally C10 X
Top level wide pan car

Associated
RC10-L4O oval car

Associated
RC10 L, RC10 LS (wide), RC10LSS, RC10L2 (wide, 220mm), RC10 L3T (narrow) Various Associated 1/10 Pan Cars are still popular on the used market. These include both early wide 235 mm 1/10 pan cars and later model narrow 1/10 pan cars 190-200mm. Some parts are still available from Associated. Some of these kits and possible conversions are described at the link above.

MLP
Models to be announced July 2008

Foams

GRP Gandini tires
Great tire. Hard to find in the states now.

Trinity
These tires are made by Jaco now. Older TRC tires on a yellow wheel were made by GRP

Jaco
1/10 pan. Four hole mount on rear tire. Black wheel. The pink compound has slightly less grip than a GRP or RC4less tire.

RC4Less Tires
I have tested these tires on orange wheels and they work great on road. I am told they are the same compound as GRP tires on an orange wheel.

BSR tires
These tires come on a black wheel. The pink compound has more grip than the pink GRP or RC4 less tire.

Axles Hubs Bearings, Ride Height Adjusters, Springs
Irrgang Racing Service (IRS)

RC4less.com

Lefhander-RC.com

Niftech

Murdoch Racing
Wind Tunnel, Long travel front suspension, Progressive rate Springs, Heavy duty front axles.

Silva Concepts

Associated Electronics
Very good drawings and manuals for the discontinued cars are available online.

Bodies
VansInvent.com
A nice broad selection of GTP (open and closed cockpit) and F1 bodies with front and rear wing that will fit both narrow and wide pan cars.
a couple of examples are posted in this thread

200 mm Bodies
These also fit 200 mm Nitro Cars

Pro-Line Protoform
Lola T 530 Body

HPI

Peugeot 1/10 GTP body

This is a wide body for 10 L or C10X. It's back in stock. Get the .030 body for outdoors. Very nice looking body with a proper pan car wing with side dams.

McAllister Nissan
Here is a wide pan body I found in stock at Stormerhobbies.com. Works really well on my Wide Pan

Spur Gears (Associated Diff Gears), Servo Saver
Kimbrough
RC10 L2 parts at TowerHobbies.com

Use the associated part number and search tower or stormer for parts for old associated cars.

Shore chart Compliments of Trinity the harder the tire, the bigger the shore hardness, the less the grip.

John Stranahan 05-20-2008 01:31 PM

The car is in the mail should be here later in the week. Exciting times.
The car is on a couple of months loan from Rick Sieboldt. Thanks for getting this started.

jla8874 05-20-2008 01:43 PM

You are very thorough sir. Nice job!

John Stranahan 05-20-2008 02:55 PM

Thanks

Building the pan car diff
There are all sorts of complicated ways of building the rear diff which include sanding, flattening the rings, etc. In my experience the pan car diff can be built just like the one on a touring car with the use of carbide balls.

Use Carbide or Ceramic Balls, Assembly order
First get a set of carbide diff balls if the diff does not come with them. I have used the same set for two years of hard use. They are still very smooth. If you are running stock or superstock, the lightened diff rings that are (inverted) star shaped from either IRS or lefhander-rc.com are a nice touch to remove rotating mass. (I use these on my 3.5 powered wide pan car as well) Put only a dot of diff grease on each ball. Any excess will be thrown out so don't worry about this. Put a dot of grease on the back side of each point of the star to hold the diff rings in place on the diff flange and hub flange. I assemble the parts like this.
Axle diff side up stick on the first ring.
Next gear bearing flange down (or flangeless on the Battle Axe)
(I put an optional thin associated shim next to take out some of the gear wobble.)
Next inner hub bearing flange down.
Then hub with ring stuck to it with diff lube.
Next the outer hub bearing flange out.
Next Thrust cone with pointy side in followed by 3 Bellville (curved spring washers) pointy side out.

My Preffered Diff Nut
Then an 8 x32 Nylon nut, or if you want your diff settings to stay put use an Associated blue Aluminum Axle Nylock nut from the TC3 or TC4.
The plastic nut threads will always flow away from the constant pressure and require constant adjustment. The Aluminum nut is slightly heavier but well worth it by holding the diff setting perfect. If you overtighten you ruin your axle by pulling out that little threaded stud. This is not much of a problem with our current graphite axles but was with the fiberglass Pantoura axle.

Breakin
Now Adjust the nut untill holding the left tire and spur with one hand the other tire is hard to turn. This locks the diff gear and prevents diff slip. Now run the car 30 seconds holding one wheel stationary. This makes the groove that the balls will ride in. You can easily imagine that cutting this groove with the carbide balls is going to remove any surface treatment you gave the diff rings. So don't bother sanding them.

Final Adjustment
Hold the left tire and spur and rotate that right tire again and make sure the diff is still tight. The diff will not require further adjustment until it gets gritty feeling from wear. It holds up quite a while even on our dusty outdoor track.

When I redo the diff I just wipe it off and reuse the same side of the rings if they are not pitted. Regrease. Turn the rings over if pitted. The carbide balls crush any remaining fine dirt. The diff is very smooth again. Check the outer hub bearing bearing that carries thrust, the first one under your nut often. It will get brinneled from crashes (impact pits evenly spaced), and worn from the thrust loads. Spin it on a pencil point before every race. I don't believe an aftermarket thrust bearing is neccesary as our caged radial bearings are designed to carry a side load.

Axle Bearing
The axle bearing closest to the spur takes the worst abuse. I actually replace this one before each race. When it fails you loose forward drive. This is especially important for mod 3.5 use.
Here is a very light left hand hub from KSG. I just cut mine to look the same but it is not near as nice looking. You may require a custom axle spacer to be able to use it though.


Opposing views are always welcome. Boomer if you still have that large diff schematic we could post it again here.

John Stranahan 05-20-2008 03:37 PM

Choice of tires for Asphalt
GRP or RC4less tires
Mod Pan- Purple fronts, Pink Rears (my choice), (magenta rears, Pro-ten's choice)

Stock or superstock (4 cell)
After you get good at driving the beast you will be able to add more steering to this type with a softer front tire. With a 3.5 motor the front pink just does not last very long. With a 13.5 and four cell wear is acceptable on the front pink tires.
Pink front, Pink rears.

On the oval you can tinker with slightly harder tires on the right side of the car. Since you always turn left some guys like pink all around except a purple on the right front.

BSR tires-The pinks were a little grippy on our sugar water treated asphalt oval on my homebuilt car, but very good on Joshs more traditional LE executioner oval car. I am going to try BSR Magentas front and back next.

Guys at the carpet oval nats were using similar tires that we use on asphalt. Few exotics to be found. Plenty of pinks and purple.

If the car is bogging down in the corner go harder. If it is wearing the tire too fast go harder. If you have insufficient forward traction or cornering traction go softer. Generally pink is the limit with mod. White may work with four cell. A foam hardness chart is in the first post.

lidebt2 05-20-2008 07:11 PM

Coming to you John
 
Here are some photos of the car coming to you by this weekend. The caps under the blue tape are for the speed controller. I didn't have time to solder them in. The rest of the body parts are in the bag.

Have fun!!!!!!!!!!!!!!!

John Stranahan 05-20-2008 08:09 PM

Thanks Rick

I thought I would post this tip that I got by private message from Jason at BMI
"In addition to what you posted, I sand my diff rings so they are real flat and parallel. I do this with 220 grit and then finish with 600 grit. This makes it so you dont need to tighten the diff as much and also takes a ton of load off of the hub bearing."

protc3 05-21-2008 04:24 AM

This is a nice thread you started John.

To explain a little as to why we sand them is because the diff rings are stamped and the material tends to cup or become concave(potato chip shape). When we tighten our diffs, we need to tighten them until they do not slip and in order to have the diff work the most efficiently, all 12 balls need to be in contact with the rings for manximum holding force. Sanding the concave shape out of them will allow for all 12 balls to touch easily with minimum clamping force which will take alot of load off of the hub bearing. Otherwise we need to destort the ring with added pressure to get all the balls in contact with the rings. I hope this makes sense. If not i can try to explain it a little better.:cool:

jla8874 05-21-2008 05:17 AM

Right here halfway down the page is step by step article about sanding the CRC diff rings.

ta_man 05-21-2008 06:38 AM


Originally Posted by John Stranahan (Post 4462776)
Thanks

Building the pan car diff
There are all sorts of complicated ways of building the rear diff which include sanding, flattening the rings, etc. In my experience the pan car diff can be built just like the one on a touring car with the use of carbide balls.

Use Carbide or Ceramic Balls, Assembly order
First get a set of carbide diff balls if the diff does not come with them. I have used the same set for two years of hard use. They are still very smooth. If you are running stock or superstock, the lightened diff rings that are star shaped from either IRS or lefhander-rc.com are a nice touch to remove rotating mass. (I use these on my 3.5 powered wide pan car as well) Put only a dot of diff grease on each ball. Any excess will be thrown out so don't worry about this. Put a dot of grease on the back side of each point of the star to hold the diff rings in place on the diff flange and hub flange. I assemble the parts like this.
Axle diff side up stick on the first ring.
Next gear bearing flange down.
(I put an optional thin associated shim next to take out some of the gear wobble.)
Next inner hub bearing flange down.
Then hub with ring stuck to it with diff lube.
Next the outer hub bearing flange out.
Next Thrust cone with pointy side in followed by 3 Bellville (curved spring washers).

My Preffered Diff Nut
Then an 8 x32 Nylon nut, or if you want your diff settings to stay put use an Associated blue Aluminum Axle Nylock nut from the TC3 or TC4.
The plastic nut threads will always flow away from the constant pressure and require constant adjustment. The Aluminum nut is slightly heavier but well worth it by holding the diff setting perfect. If you overtighten you ruin your axle by pulling out that little threaded stud. This is not much of a problem with our current graphite axles but was with the fiberglass Pantoura axle.

Breakin
Now Adjust the nut untill holding the left tire and spur with one hand the other tire is hard to turn. This locks the diff gear and prevents diff slip. Now run the car 30 seconds holding one wheel stationary. This makes the groove that the balls will ride in. You can easily imagine that cutting this groove with the carbide balls is going to remove any surface treatment you gave the diff rings. So don't bother sanding them.

Final Adjustment
Hold the left tire and spur and rotate that right tire again and make sure the diff is still tight. The diff will not require further adjustment until it gets gritty feeling from wear. It holds up quite a while even on our dusty outdoor track.

When I redo the diff I just wipe it off and reuse the same side of the rings if they are not pitted. Regrease. Turn the rings over if pitted. The carbide balls crush any remaining fine dirt. The diff is very smooth again. Check the thrust bearing, the first one under your nut often. It will get brinneled from crashes (impact pits evenly spaced), and worn from the thrust loads. Spin it on a pencil point before every race. I don't believe an aftermarket thrust bearing is neccesary as our caged radial bearings are designed to carry a side load.

Axle Bearing
The axle bearing closest to the spur takes the worst abuse. I actually replace this one before each race. When it fails you loose forward drive. This is especially important for mod 3.5 use.
Here is a very light left hand hub from KSG. I just cut mine to look the same but it is not near as nice looking. You may require a custom axle spacer to be able to use it though.


Opposing views are always welcome. Boomer if you still have that large diff schematic we could post it again here.

I wonder if you are mixing text from different procedures in the above. On the one hand you mention the thrust code and bellville washers, and then a little later, under "Final Adjustment", you mention the caged thrust bearing. The thrust bearing is mont mentioned in the "Assembly" section. Here is a link to an articvle that describes building a pan car diff with a thrust bearing. These thrust bearings can last for years.

http://www.rc-oval.com/?p=77

John Stranahan 05-21-2008 08:49 AM

Things that I write are not really mixed text. It is original writing out of my head. I'll edit the text a little bit to this "Check the outer hub bearing that carries thrust,"

I call it a thrust bearing because that is the primary way that it is used. It is the same 1/4 inch flanged caged radial ball bearing that we use on the axle. My point is that this type of bearing is designed to carry side loads (thrust). A separate thrust bearing is not really needed. (A full compliment radial ball bearing has no cage. Full compliment means as many balls as will fill the race. Because of this it has a cut in the race to insert the balls. It cannot carry much side load.) A caged ball bearing is assembled by moving the center to the side inserting all the balls and then spreading the balls out and putting on a cage. There are gaps or space between the balls occupied by the cage. For this reason the race is not partly cut away and it does just fine carrying a side load.

What neither caged radial or thrust bearings do well is carry an impact load when you hit the boards. This is the primary reason for failure. If you don't hit the boards either one last quite a while.

Now if you read the quoted text you also know my opinion on sanding the rings. This may help if you use steel balls by preventing flat spotting the balls on breakin. No way you are going to flat spot a carbide ball on breakin. I see a set of ceramic diff balls in the latest tower catalog at $8. That is money well spent. The diff will be ultra smooth as a result without sanding. The carbide balls cut a groove. Even if the diff ring is not perfectly flat, the bottom of the groove is perfectly flat after that very brief breakin. If you like to sand the rings I am fine with that as well. Evidence that you would need to sand the rings is a groove that is not the same width all the way around. I never see this.
John

lidebt2 05-21-2008 09:38 AM

you have a PM
 
You have a PM and check you links. Some aren't working correctly.

Rick

John Stranahan 05-21-2008 09:59 AM

Done. All fixed or deleted except the MLP site is down quite a bit.
John

Boomer 05-21-2008 10:47 AM

oh great - ANOTHER thread I absolutely have to read! :D

GreaseMonkey 05-21-2008 10:58 AM

I was thinking the same thing.

@ Jason: Didn't you make some diff rings that were almost perfectly flat? if so, do you still make them?

John Stranahan 05-21-2008 11:32 AM

1 Attachment(s)
Boomer-I am continuing the Pantoura thread here. It will fade back into archives not too long from now.

Here is a pic of the lightened diff ring I use. I put a very thin layer of red grease on the granite surface plate. I pressed the ring onto the plate. The surface is uniformly covered indicating little cupping (less than .0001 inch). This Track Attack ring is new from lefthander-RC.com. The surface plate is flat to .000001 inch or so. Sanding this ring will only make it a little convex shaped.

Notice the pic is in best light to show the grease. It is a very thin barely visible coat of red to the eye.
John

energyracing 05-21-2008 12:23 PM

Good thread, lots of good content.

protc3 05-21-2008 01:11 PM

I have seen diff rings be up to .005 out of flat. This is using a dial indicator and the placing the diff ring on a magnetic surface grinding plate. They will flaten out when the diff is tightened. The diff just wont need to be as tight with flat rings. I did make surface ground diff rings but they were a big pain in the butt.:lol:

John Stranahan 05-21-2008 03:44 PM

Jason-Thanks for your comments and the extra detail.
All-Thanks for the kudos.

When the Battle Axe comes I will give a thorough evaluation of the parts that are new and different like the rear pod and the Pro strut front end and the adjustable servo plate. I will make some photos of all these parts. I have been studying the manual for the GenX10 to get a head start. I will revisit Ackerman as this seems to be adjustable on the Battle Axe. That was the single most helpful adjustment I made to my home built oval car.

Corner Exit Hooking
I thought I would start with some tuning advice. When I first started running pan cars with powerful motors this seemed to be the hardest problem to tune out. One reason is it is hard to understand what is happening. When we got on the oval, I noticed 3 other drivers having trouble with the same problem. So here are some clues as to what is going on and then a suggestion to fix the problem. Here is what you notice, the front dives suddenly for the inside board on corner exit.

Corner exit is the time just before the wheels are straight at the end of a corner.

1 The main cure was to delay your throttle roll on a few milliseconds until the wheels straighten out. If you are able to drive from ground level you notice you have better control of this problem because you can see your front wheels and can pause until they are straight.

2 The problem gets worse the harder the front tire.

3 The problem gets worse the more punchy the bottom end of the mod motor. Thats why I like the 3.5 instead of a 4.5 on the road car.

4. The problem gets worse the less traction on the track.

I can now look back on the sum of these observations and realize that the front end is losing traction. You are not spinning out in the typical sense. You are spinning in. The rear is still planted.


So the cure or partial cure is a little softer front springing. Maybe a touch more droop. A full coverage of traction compound on the front tire rather than just on the inside. In other words more front grip.


So this is what happens. The car is rotating in the turn at a certain yaw rate or a certain number of degrees per minute on its vertical axis. When it reaches the end of the turn the outside rear tires is still loaded high. It is applying torque steer (ouside tire is now pulling harder than the inside rear tire from extra load) which helps keep the car rotating. When you apply more throttle the car rotates faster from the torque steer and spins in. The front tires which were at the limit of traction let go. Anyway that is what I think happens at this point in time.

Now there are other times like at mid corner where a pan car likes to spin out from loss of rear traction. Solve this separately. Maybe more wing is needed.

I welcome opposing views.

John

protc3 05-21-2008 03:55 PM

Is this spinning out to both left and right side on your road car? I know the one thing i noticed when going to low wind mod motor was static balance had to be spot on or the car would want to loop in 1 direction on lower bite tracks. I will reread what you posted to make sure i absorbed it all. Interesting discussion though.:cool:

John Stranahan 05-21-2008 03:59 PM

Spining in was to both sides on the road car. My side to side balance is usually perfect. I will note that that is why we want it so, to prevent that torque steer. Note I don't do that any more from experience. Most new guys will do it quite a bit.

Spinning in on the oval car was of course always to the left as we only turn left. Huge 12 ounce preload on this car to the left side but we are cornering hard on the oval. No doubt from tire wear that the right rear still carries an excess load on corner exit.
John

protc3 05-21-2008 04:24 PM

Yeah, I see what you are saying. I havent run oval much but i do plan on it. I have an oval kit ready to go in my cad/cam for when i am ready to try it out. It is based off of my DB10R with quite a few changes(same suspension to an extent). I hope to try it out at my next carpet race at minnreg. :cool:

John Stranahan 05-22-2008 11:10 AM

3 Attachment(s)
Battle Axe First Pics and First Impressions

Well the Battle Axe is in. Thanks Rick! I have ordered up a bunch of tuning parts for it. I'll have more pics as I go along.

The first pic shows the entire car. The shape shows why the car is called the battle axe. Notice the narrow waist of the car. This is going to allow good chassis flex to keep the car hooked up. The car has a traditional for oval 3 shock rear setup, but a very non traditional pod with several improvements that I will discuss next. The foam bumper is unique. It is slit down the middle and the bottom extends below the chassis line to scrape every possible bit of air up over the car. The center shock front mount has many adjustment holes. It also has a tidy means to hold that tiny receiver antenna. The transponder fits down through a hole in the bumper to keep the center of gravity as low as possible. This one is mounted flush with the bottom of the bumper which sits on top of the chassis plate.

Rear Pod Top Plate Support Post
The second pic shows the top plate and center post detail. Notice the top plate by itself is a cantilevered beam and in most pictures looks like it hangs out into space near the shocks. Instead it has a center post that is attached to the bottom plate right through the center pivot ball. The end of the beam is thus very rigidly held. That is some clever engineering. The minimized top plate allows plenty of room for the multitude of wires that come out of our brushless motors.

X braced rear pod
The third pic shows the pod by itself. This is truly a work of art. Very pleasing to the eye. Note the cut down left side plate and minimized top plate for a low center of gravity and easy brushless install. Stiffness is returned by adding a rear X-brace. The overall result is a slightly lower center of gravity. The pod is offset left for oval with a 1.25 inch right hand hub. The side plates shows some really nice bevels on the edges that lighten the parts and improve the appearance. Good engineering again as the majority of the large forces from the heavy motor on the pod exist at the right pod plate. More to come.

Hit your full screen box for the best view of these pictures after opening them.

John

John Stranahan 05-22-2008 11:55 AM

3 Attachment(s)
Adjustable Servo Plate
Here is a pic of the servo plate that allows for servo adjustment fore and aft (this should be helpfull in fine tuning Ackerman) and side to side to get that servo horn exactly centered in the car.

Pro Strut Front End
The second pic is a side view of the Pro Strut front end. This front end come on all the newer CRC cars including the 1/10 Road Car. Things that are changed over the older Associated style are: The upper pivot is now a large pivot ball. You can see the hex socket in the pivot ball to adjust camber and the slot on the pivot ball retainer to adjust play. This will allow you to have a very free suspension which is critical on the oval and on road. There is a titanium pivot ball available. I have one coming. There is also a long kingpin available that increases travel and allows the use of tall springs. These may or may not be already installed. The axle is aluminum but is 3/16 in diameter or 1/16 in bigger than the stock associated. It should hold up well. The steering arm bolts on separate to the steering block. There is an optional graphite bit that I have coming that may allow adjustments to ackerman. Titanium turnbuckles are also available. I have a set coming.
The third photo shows the screw that will adjust tension of the lower pivot ball. I have a set of teflon coated pivot balls on the way. You can also see the very beefy lower arm. It is going to hold up well. A set of these molded ride height spacers on the very bottom are available from CRC at a good price. I have a set coming.

John

John Stranahan 05-22-2008 01:33 PM

1 Attachment(s)
Durability improvements
I weighed the car with and LRP sphere speed control, Novak 13.5 brushless, Spectrum pro receiver, a clear body, no wing, and a small servo. It weighed about 39.7 ounces. The wing I use will bring that up to about 40.1 ounces. I have a little weight to spare so I can increase the durability of a few parts.

I had a long experience with the CRC Pantoura which has a similar pod to main chassis assembly as the Battle Axe. It is a center pivot side link car. I found that outdoors, on my track, that the center aluminum pivot ball wears quickly and then the center pivot starts to fill with grit and bind up. I like a steel ball here. It is available from an older Associated Car, ASC 4336 at TowerHobbies.com or StormerHobbies.com
I had a crash in the Pantoura that pulled one of the side pivot screws up through the lower pod plate. You need a steel screw here with a good wide head. These are installed already in stainless steel on Rick's Battle Axe. In addition I like steel pivot balls here on the side links on my outdoor track. The balls from the Losi JRXS are similar to the Aluminum ones in hardened steel. LOSA6009. I put one thin Losi Belleville washer (spring washer) LOSA3078 under the ball to spread the load of the somewhat smallish hex on these balls. The washer is thin so it does not change the pivot height much. One goes under the center pivot ball as well to keep all balls the same height. Here is a pic of the strength and wear upgrade parts.

John

lidebt2 05-22-2008 05:57 PM

PM's
 
Jack ... you have 2 PM's.

What did you do to my car?????LOL

Hope it didn't arrive like that!!!!!!!!

John Stranahan 05-22-2008 06:46 PM

1 Attachment(s)
Here is a right view of the chassis with the heavy duty balls and washer. I raised the football up by the height of the Bellville washers (.020 inch) to keep the parts in the same plane. A tip from the Pantoura manual, I believe, is to preassemble the pivot parts and side links and then tighten the football last. This way the pivot parts are not in a bind. I put my current 3-link oval cars on the scales one last time. The left preload was 10.7 ounces. I had tried less. The rear preload was 8.3 ounces. This means the rear weighs 8.3 ounces more than the front. I had tried moving the battery forward to reduce this, but did not like the way the car drove that way. I'll put up pictures on the scales when I get that far. I should be ready for a practice on Saturday against some competition. Our race was postponed a week.

John

John Stranahan 05-22-2008 07:00 PM

1 Attachment(s)
Non Factory Options
Some of you guys that own this car may have noticed some of the other non factory options that are already on the car when I took pics.

Red Aluminum Screws
Firstly the car came with the full compliment of red aluminum screws. Steel screws are used at the side link pivots and center pivot.

Bumper
The rubber bumper was slit and glued on by Rick. I may have to sand just a little off the bottom on the belt sander to clear the track at a low ride height.

Diff Thrust Bearing
The diff has a very nice looking thrust bearing added to it. I plan to add carbide balls and lightlweight diff rings. It will be ultra smooth then. It is a little rough now even though it is unused. I'll see whats up.

Body Posts
The aluminum Body posts are from lefthander-rc.com. They are favored by the experienced racers at my track. I will probably run the front two in plastic to preserve the graphite bumper.

John Stranahan 05-22-2008 09:07 PM

2 Attachment(s)
Electronics Install

The install went well. I am running 4 cell superstock so I wanted to use 12 gauge wires and either a 4 cell GTB or Sphere Comp TC edition. I chose the former. It has good punch in the car, equal to the TC edition.

I rebuilt the diff just like my procedure posted above. I used 8 carbide balls in an 85 tooth spur. I used the Associated shim. The diff was super smooth after only a short breakin. I think the Belleville (spring washers) are an important part of this. I used 3 with the standard thrust cone. I also locked it in with a TC3 wheel nut for a more permanent setting. The gear has very little wobble, but enough play for good diff action with the shim.

I was using an 85 spur on the 3-link car. I noticed when guys got back from the carpet nats that they were all using the small spur as well. It gives you less rotating mass. It does position the motor closer to the rear axle and makes it more unsprung mass but my 3-link proves that this is not a drawback as the entire pod is unsprung on the 3-link and the car works very well.

The car is ready for final ride height adjustment and maybe a road test tomorrow. I'll see. I'll be able to run against some other cars on Saturday.

I am very pleased. Everything fits really well. The car is super nice looking with all the red anodized parts.

Pivot Height adjustment, Steel Screw Locations
The second pic shows a series of holes lined up under the center shock forward mount. This made it easy to get the pod droop and pivot height that I wanted. I also had to extend the shock end on the shaft about 4 turns. This will replicate an ajustment the guys at the carpet nats were running. Rear pod droop, combined with forward chassis rake to give a high pivot. This gives the car more antisquat and better forward traction.
The pic also shows the screws that are stainless for strength and the one center pivot screw in carbon steel for the highest strength available.
John

Der Dicke 05-23-2008 09:19 AM


Originally Posted by John Stranahan (Post 4470935)
Electronics Install
I rebuilt the diff just like my procedure posted above. I used 8 carbide balls in an 85 tooth spur. I used the Associated shim. The diff was super smooth after only a short breakin. I think the Belleville (spring washers) are an important part of this. I used 3 with the standard thrust cone. I also locked it in with a TC3 wheel nut for a more permanent setting. The gear has very little wobble, but enough play for good diff action with the shim.

Why don't you use 12 balls instead of 8? Aren't more diffballs an advantage?

John Stranahan 05-23-2008 10:24 AM

That small gear only has 8 holes. In pro stock it is actually an advantage to have less weight here. In onroad mod I use a larger gear with the full compliment of 12 balls.
John

GreaseMonkey 05-23-2008 01:44 PM

I'm not sure how it is in oval so this might be a dumb question but do the short 12 guage wires restrict/affect the pod to chassis movement?

John Stranahan 05-23-2008 02:23 PM

1 Attachment(s)
I asked about 12 gauge use at the nats. It was very common in 13.5 class. My wires are short but they have a nice curl to them which makes them quite flexible. It also helps if they don't touch each other and create friction. The deans wire being a high number of strands also helps here. They don't feel like they are inhibiting the pod rotation much. If they did add some spring or resistance it is of a spring like nature and I can reduce the side spring tension to compensate. I don't think I will have to. I do have a full set of side springs and center shock springs coming for the car.

Left Hub Clamping Screws
Note also in this pic the left hand hub clamping screw. It must be steel. Use blue locktite on it or you will lose the left wheel on the track on occasion. Tighten the crap out of these.

Wheel Lugs
I use four short 5/16 inch aluminum screws that just reach the back of the threads for low rotating mass. Some use two, but I found my wheels more warped after a couple of runs this way. I am back to four Aluminum screws. Tighten only very snug.

John

John Stranahan 05-23-2008 03:09 PM

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I added text above.

Strut Front End
If you have an associated style strut front end, there is no doubt that it will profit from some handwork to make it smooth along its entire travel. The procedure is well described here with plenty of good diagrams.

http://www.swiftracingproducts.com/Page.cfm?InfoID=5192

Now the goal is to remove the spring, push the suspension up by the kingpin snap ring all the way, and then have it drop by gravity alone. Now put the spring on and push it up again and feel how smooth it is after you have completed the procedure. I can do this last push test now, and by feel tell if somebodies car has too much front end friction (stiction). When you get it smooth you will be rewarded by usable front end traction like never before.

CRC Pro Strut front end
This front end is a little different. The steering block now extends up to a pivot ball similar to what is used for Nitro 1/10 and 1/8 scale car. There is an adjustment retainer or ring that can be used to give the ball just the slightest amount of play.
Remove the spring. Push on the kingpin and feel for gummy friction or drag. There should be little. The suspension should drop back down by gravity alone. This one did not. There was extra friction at the kingpin to the lower pivot ball which is the standard Associated type of pivot ball. The pin was well polished as advertized but the hole in the ball was slightly undersize causing the drag. I polished the pin some more until it would drop free (I removed maybe 1 or 2 tenthousandths inch off the diameter of the pin.). Chuck about 1/8 inch of the snap ring end of the kingpin in the drill chuck of the dremmel and polish the remaing part of the kingpin with fine sandpaper. (I also have a new kingpin and teflon coated pivot ball that may also solve this problem.)

Note in the photo that the upper arm is supporting itself up high wihout the kingpin. This is not good. I will remove the upper A-arm hinge pin and remove just enogh material from the arm pivot end to make it drop free. The pin was tight in the A-arm pivot although the pin was nice and smooth. I spun an undersize drill bit at medium speed in the dremmel and opened up the A-arm pivot until the pin would rotate easy by hand. Now that upper arms drops free with gravity.

Also note in the photo that tiny brass 4-40 set screw. It let's you screw in your kingpin assembly by hand and then tighten the screw when you have removed vertical play. I ordered a couple of spare set screws. As delivered the car had a lot of preload. This makes it act more stiffly sprung than without preload which is my standard.

am going to try fairly soft blue front cylindrical springs from windtunnel racing first. I am using thin blue spring buckets which will give you more clearance at the wheel when you remove all the play.

I sanded the bottom of the kingpins which are the large 1/10 scale size on the bottom to have a little more clearance with the wheel rim with the pin set for 0 preload on the windtunnel springs. There is still enough allen socket left to adjust the pin and enough lip left to support the E-clip adequately.


On the lower arm you will see an additional screw that lets you tighten or loosen the play of the pivot ball in the arm.

when I push the front end down, it feels smooth and soft like the back now. The aluminum teflon coated lower balls are in.

Note the assembly should have no upper spring bucket. Progressive spring pointy side up or cylindrical spring.

John

John Stranahan 05-23-2008 08:06 PM

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Side to Side Balance

On a road car we want the side to side balance to be equal. You use a setup similar to that in the photo with two scales and two beams and try to make them both read the same. More detail on road cars here on the TC5 tips and tricks thread.

On the oval we take advange of a unique property of rubber and the mechanics of weight transfer to get a little more cornering capability turning left at the expense of cornering right.

The property of rubber is this. Rubber is more efficient at developing cornering g's the more lightly it is loaded. Thus the way to have two tires on one axle (one left and one right tire) have the highest cornering capability as a pair is to have them carry equal weight.

The dynamics of weight transfer is this. The higher the cornering power, the heavier the car, the higher the car, the more narrow the car, the more weight is transfered to the right on the oval. When this weight transfers right it kills the efficiency of the right hand tires to some extent. The axle has poorer cornering power every time there is lateral weight transfer on an axle.

So what we do, to take advantage of these two situations, is preload the left side of the oval car. When weight transfers right the tires approach that happy 50-50 weight distrubution on the pair. Efficiency remains high. Cornering is good but only to the left.

I have seen setup guides that suggest a 12 ounce left preload on the oval 1/10 scale pan car. I made some small movements of the only things in the car that can be moved to bump my left total to 12.1 ounces left. I moved the receiver back and left. I moved the transponder left. I also can move that big Novak capacitor back and left on top of the speed control if I want more weight back.

Front to back weight balance
Front to back weight balance is measured with the same setup. Just put the front tires on one beam and the rear tires on the other. This car has a 5.6 ounce excess in the rear. This is less than my other car had. We'll see. The optimum position of front to rear weight is a complex function of front and rear tire width (contact patch size), Front and rear compounds, and motor power. So one thing you can do is try and match the front to rear balance to the tires and motor on the car or you can do the opposite and set the car up to drive well on the front and rear balance that you have. I can move my weight only a little due to the fixed nature of the battery tray. I can move it one cell forward, but previous experience tells me I am going the wrong way.

If you are driving mod pan forward traction is at a premium. I put lots of weight back. As one author said, "you can't put too much weight on the back of a two wheel drive". Of course he is talking about a powerful full size car. If the motor is detuned like in stock or superstock then we can concentrate on improving cornering speed at the expense of some forward traction. Maybe move the weight a little more forward for road superstock.

Plastic Body Posts
I replaced 5 aluminum body posts with 6 plastic ones. An extra supports the center of the bumper. I lost 2 ounces. I am happy this BSR blue foam bumper will survive and protect the graphite of the car because of the way that it is supported by the 3 body posts. I will test the CRC Battle Axe posts eventually. They are plastic but use a screw to put on the body. That really looks neat.

Black strapping tape from lefthander RC $6.00 instead of $20.

jla8874 05-23-2008 08:41 PM

.

John Stranahan 05-23-2008 09:41 PM

2 Attachment(s)
Well thanks. Just passing time till I die and if some race car science passes through to you that would be nice.

Here is the car ready to race
The Aluminum pivot balls did not fit the kingpins. Both are a little undersized, but the pivot balls are smaller on the ID than the kingpin OD.

I have a full set of Windtunnel center and side springs for testing.

I can move the motor over left by two full spacers if I need to tighten the rear.

It should be ballistic. Mike D is going to cry!:D

Second pic is the fit of that BSR blue bumper. It touches the body on the top front corner. My undercar aerodynamics should be improved.

John

lidebt2 05-23-2008 11:15 PM


Originally Posted by John Stranahan (Post 4473732)
Well thanks. Just passing time till I die and if some race car science passes through that would be nice.

Here is the car ready to race.
The Aluminum pivot balls did not fit the kingpins. Both are a little undersized, but the pivot balls are smaller on the ID than the kingpin OD.

I have a full set of Windtunnel center and side springs for testing.

I can move the motor over left by two full spacers if I need to tighten the rear.

It should be ballistic. Mike D is going to cry!:D

Second pic is the fit of that BSR blue bumper. It touches the body on the top front corner. My undercar aerodynamics should be improved.

John


Hi John,

What body is that?

Have fun tommrow!!!!!!!!!!!!

Rick

John Stranahan 05-23-2008 11:25 PM

Thats is a Monte Carlo HD lightweight from Protoform. The guys at my track prefer the HD charger that you included. I have a charger ready with similar paint. I like them both. This one seems like it has less front and rear overhang and is maybe a little more maneuverable in traffic at the expense of some all out downforce. Not really any lighter except maybe .1-.2 ounces. I purchased it to be lighter.
Will do.
John

John Stranahan 05-24-2008 09:55 AM

1 Attachment(s)
Bump Steer
Bump Steer is when the wheel goes up in bump from either a bump or chassis roll, the wheel changes steering direction by itself. Bump steer is easy to check. Hold the car in your hands with the wheels straight forward. On this associated style pro strut front end push up on the front of the upper A-arm with your finger all the way to the stop. View the wheel carefully. If it is changing directions then you have bump steer. If it steers out as the tire goes up in bump you have bump toe out. If it steers in you have bump toe in. Bump toe in can cause the car to oversteer as it rolls in the corner. I avoid it. A little bump toe out is OK.
The car had some bump toe in. The inner steering link pivots were mounted in the middle outer holes of the servo saver. I moved them down one hole and at the same time replaced the aluminum ball studs with hardened steel. You can also make small changes to bump steer with washers under the outer pivot balls on the steering link.
John


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