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Old 08-17-2009, 11:55 AM   #1
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Default The YR F2 thread

It had to have a thread of its own.

I recently acquired a YRF brand new and set about building it. Couldn't resist and made a few mods I am going to detail if interest warrants it.

One paramount rule I follow (with all my mods) is that no original part can be modified, so if the need may be, the car can revert to complete originality.

First thing I did was to collect all the annoying hopeless philips head screws and replace them with allen head screws of equal length if possible. The long screws at the back presented me with the first problem because high tensile allen head countersunk screws don't come threaded all the way, and some lenghts are not available (40mm) or not easy to come by anyway. I decided to replace then the threaded spacers with straight drilled ones I made on my lathe and used locknuts at the top to hold everything down.

Looking at the tall screws the rear CF plates slide against at the rear, I didn't like the arrangement so I made a couple of neat little aluminium sliders to guide the plates up and down.

I replaced all the front suspension and steering straight rods with titanium turnbuckles to make adjustments easier.

I built the diff with ceramic balls, and replaced the spring washer with a diff spring I made form a spring I had lying around. the diff is smooth but I have some problems with it coming loose. The screw might need some threadlock. There is also a question about the inboard end of the driveshaft touching the screw head and casuing it to come loose. I am looking at the moment into the possibility of replacing the driveshafts with Tamiya universals with 42mm swing shafts and 53499 axles. They're on their way.

Looking into the possibility of replacing the diff joints I found the joints from an HPI RS4 Mini will fit straight in. I have one on standby for now. There may be some issues with clearance to the inboard end of the driveshafts but I'll look at it when I get there.

I have replaced the spur with a 64pitch 105 tooth form Kawada and the pinion with a 29 tooth (Kawada again, they're the smoothest on the market and good quality dural), and the car is silent at full chat as a ghost. This pair gives the closest ratio to the kit stock (7.81 vs 7.80), but I found the spur was very close to the top front suspension plate. I replaced then the spur with a 103 tooth which gives a tad more clearance. This should be used with a smaller pinion but the adjusting slot on the motor support does not allow for proper mesh, so I went instead to a larger one at 30 tooth for the moment. Enlargin the adjusting slot in the motor support is not an option either because the motor would hit the belt pulley. I ended up with a slightly higher FDR (7.7) this way, but that shouldn't be a problem for a silvercan. Perhaps the adjsuting slot should have been at the bottom instead of at the top of the motor plate but that's an issue I will look into later if I decide to up the power a bit.

I moved the spur a little bit further out by grinding the spur shaft locking key all the way to the end (the only original part that was modified) to allow the holder to come out a few mm, and used a spacer between the holder and the bearing in the bulkhead. This mod is needed to give a perfect alignment between spur and pinion (originals were offset by a good three mm, because the pinion was sticking out too far even when pushed all the way to the motor bushing, so it wasn't a problem introduced by my replacing of the box parts with the 64 pitch gears) whilst at the same time allowing a better fit ont he motor shaft because you don't have to push the pinion all the way on the shaft to the motor bushing to get as much contact as possible between spur and pinion.

Next I looked into using Lipos. I thought about modifying the chassis slots which are spaced for Nicd so are closer together than the high capacity Nimh (or dimpled bottom Lipos) would require. I decided against it for reasons I have explained above as well as an idea I will elaborate on further down. An orion 3800mAh will squeeze in but it will force its way a bit. I removed the rear post from the bottom chassis plate and made a custom plate from blank PCB that sits at the top, under the top deck, floating on the two rear top deck supports (these have a collar machined at the top) and has a stopper coming down at the back. The stopper is a screw with a long nut machined from brass hex spacer as used in electronic equipment. This was positioned to give a couple more mm of battery space, enough for the Lipo to sit comfortably in its cradle. Of course the original battery strap didn't fit anymore because this is meant to rest on the rear posts above the collars where I have now the custom made plate. I had then to make a new strap which I made again from PCB blank and I machined another four brass hex spacers to allo foe the slightly wider lipo to fit snuggly. It worked a treat.

Some pictures will happen soon, I hope.

Next on the tuning list are dampers and I am looking at some good quality dampers if the kit ones don't work satisfactorily. The rear shouldn't be a problem, but the front might require some smart work to squeeze in.

A nice low profile servo is needed too, I don't like the sight of the standard servo hanging off the plate, waiting for a t-bone whack to wreck it.

As it stands the car is 200grams below weight. I expected this and this is the other reason I decided not to bother modifying the chassis battery slots. I will make a custom lead tray for the lipo and the slots will end up full of lead anyway.

Hope to hear from anyone who has worked on these cars and am interested in your solutions to these or other problems.
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Last edited by niznai; 08-17-2009 at 12:19 PM.
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Old 08-17-2009, 07:09 PM   #2
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I have one and I love it... I'm running 30mm foams in the front and 26mm (or28mm?) foam in the rear... I'm using a Novak 4300 brushless system and an Orion 3400Mah LiPo....

the only problem I'm having is that the tall body posts in the rear allows the body to move side to side over the rear wheels... I'm using a Frewer Honda Civic

I already posted it in the other FWD thread (http://www.rctech.net/forum/electric...mantis-ff.html) but here it goes




Last edited by akura2; 08-20-2009 at 03:33 PM. Reason: Better photo server
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Old 08-17-2009, 10:52 PM   #3
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Thank you for your answer. How is your diff faring so far? Did you experience my problem with it coming loose? Did you build it using the kit supplied spring washer?

I can not see your pictures for some reason, maybe they didn't attach properly.

Anyway, back to my mods. I forgot to mentiona bove the steering which seems somewhat flimsy. Trying to see if the saver works, I noticed the idler arm posts flex probably because they are only attached to the bottom chassis plate and that is only 2.5mm CF. I knew I had to do something about it so i made a brace that attaches at the top to the posts and the bulkhead rear top screws just under the gearbox cover plate. That is a tight squeeze, so I had to sand down the screw heads there so they wouldn't foul the cover plate. Not by much, probably just .5mm is enough. The steering idler posts had to be extended, you will see in the pictures, I used another machind brass hex spacer on the left and came with a screw from the top, through the brace, whereas on the right I had to use a 2mm aluminium spacer and a long screw (again coming from the top) because the servo saver post only has thread at the bottom.

Here's some pictures to show the rear suspension arm sliders and the rear top deck support posts. To replace the 40mm long screw I had to use a 25mm long allen head through an unthreaded spacer and above the balljoint a hex spacer machined to 8.2mm to replace the original aluminium. This is because a round threaded spacer is difficult to take off the screw with nothing to grip on. The hex is much easier to manage. The screw coming from the bottom (the allen head 25mm long) doesn't go all the way, so at the top I had to extend it with a 16mm set screw and lock the top deck in place with a locknut. There is enough thread projecting above the locknut to screw on the body post.

Next two pictures show the 64 pitch gears and the spacer used to move the spur out a few mm. The motor comes very close to the belt pulley, but there is about 1mm of clearance left which I think is enough.

The last two pictures show the rear battery locating plate with the stopper and the way the plate is retained floating above the collars on the two rear lateral top deck posts.
Attached Thumbnails
The YR F2 thread-dscf1399.jpg   The YR F2 thread-dscf1402.jpg   The YR F2 thread-dscf1439.jpg   The YR F2 thread-dscf1404.jpg   The YR F2 thread-dscf1405.jpg  

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Last edited by niznai; 08-17-2009 at 11:16 PM.
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Old 08-17-2009, 11:20 PM   #4
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Just one more picture to show the spur gear clearance to the top suspension plate.

Next, the battery top plate. Pretty straightforward, the notch at the end locates in the stopper stud in the rear battery holder plate.
Attached Thumbnails
The YR F2 thread-dscf1437.jpg   The YR F2 thread-dscf1431.jpg   The YR F2 thread-dscf1432.jpg   The YR F2 thread-dscf1447.jpg   The YR F2 thread-dscf1448.jpg  

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Old 08-17-2009, 11:56 PM   #5
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Last set of pictures, the steering idler posts brace. Note (last picture) the brace goes under the gearbox cover plate and there's two screw heads in that little space. I didn't want to use countersunk screws because the fibreglass plate (PCB material) is on the thin side, so the countersunk would have to project below it a bit into the top of the upper deck plate.
Attached Thumbnails
The YR F2 thread-dscf1408.jpg   The YR F2 thread-dscf1410.jpg   The YR F2 thread-dscf1415.jpg  
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Old 08-18-2009, 03:14 AM   #6
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Quote:
Originally Posted by niznai View Post
Just one more picture to show the spur gear clearance to the top suspension plate.

Next, the battery top plate. Pretty straightforward, the notch at the end locates in the stopper stud in the rear battery holder plate.
The manual should give instructions for two different battery plate assemblies. One places the upper battery plate just like in your pictures.

As for the factory screws used on this car, they are awfully soft and will strip really easily. I replaced them by titanium hex heads all over my car.

You can get some nice alloy parts from http://www.end-of-line-rc.co.uk. The alloy steering assembly will remove the built-in servo-saver, so you'll need to use a servo-mounted servo-saver.
Furthermore, Team Suzuki YR-4 alloy parts should fit in place of the rear uprights and front C-hubs (some minor sanding of plastic parts may be required).
Apparently alloy front bulkheads exist, too...

Do you know where I could find 90mm turnbuckles for the rear camber links?
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Old 08-18-2009, 03:49 AM   #7
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I had another look in the manual but couldn't find the page where it gives instructions for the alternative battery strap placement. If you could scan yours that would be very much appreciated.

I have ordered some of the parts from endofline (front suspension arms and holders) but not the steering assembly. I am not sure those would solve the problem with the steering posts as the problem is with the chassis plate which allows flex (or better put with the screws not holding into much material) so i prefer the brace I made. I am aware that my solution only moves the weak point elsewhere, all i want is to protect the chassis because if the screws are pulled off in a crash, that is the end for the chassis plate. If the steering idler arms break (or any part of the steering assembly), that's okay, I have a new set on stand by. I am aware as well of the parts that fit from the YR4 chassis (I have an YR4 M2 J Pro car I used to race) and have a bunch of spares that will fit (C-hubs, steering knuckles and rear hub carriers).

Now alloy bulkheads would be great, if you have more info on that as well as the Team Suzuki parts, would be nice if you'd share.

I have some aftermarket alloy rear hub carriers (I bought them for my YR4) made by Trinity I guess, but they're not the best quality so they'll wait in their plastic for now.

About the screws, where did you find a 40mm countersunk Ti screw? Was it threaded all the way (not that it needs to be, really, I like my solution better, it's so much easier to disassemble those when you only have to remove one nut rather than two spacers with no hex). The kit screws are so soft they will actually bend even though they go through the spacers. Absolutely hopeless.

Thank you for your input.

As for the rear turnbuckles I am not sure I have seen something that long. I was looking the other day into Lunsford titanium turnbuckles for my crawler and the shop assured me the longest they have ever seen was about 67mm. There is a chance though some of the companies that make aftermarket parts for crawlers or some of the truggies (Traxxas maybe) may have something that will fit, but I am not sure I want something very strong there as I would rather the rods bend in a crash than break the hub carriers (or even worse, the suspension holders or the CF plates). These are all rather weak parts, so I am trying to protect them. Some ingenious way to replace the suspension holders (perhaps alloy) would be nice and would help stiffen the CF plates I guess.
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Last edited by niznai; 08-19-2009 at 09:13 AM.
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Old 08-18-2009, 04:23 AM   #8
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i have been looking online but havent come across any kits.
Would be awesome if a manufacturer came out with a new FWD chassis.
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Old 08-18-2009, 05:26 AM   #9
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I am quite sure that is very unlikely given the lack of interest/support in the market. I mean what would the appeal be? It is not legal in racing anywhere, as a basher doesn't have obvious advantages (not that the bashers care) so what segment of the market is still there? A handful of die hard fans? It's a lot of trouble for the manufacturer (read time/money) to develop a product that is not sure to sell in significant volumes.

And I think that's the reason we don't see more 1/10 TC RWD cars being developed either (leave aside platforms based on pan-cars or F1, i.e. with rigid rear axle).
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Old 08-18-2009, 06:59 AM   #10
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Its a shame we dont get to run these cars much anymore... I still throw my old Tamiya FF01 out on the track every now and again, always wanted one of these cars but can never seem to get my hands on one, nice pics on here, thanks for sharing.
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Old 08-18-2009, 07:09 AM   #11
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Here's mine. Don
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The YR F2 thread-p1010002.jpg   The YR F2 thread-p1010003.jpg   The YR F2 thread-p1010004.jpg   The YR F2 thread-p1010005.jpg  
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Old 08-18-2009, 07:10 AM   #12
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There's quite a few fellas around who have stashed them away new in boxes, and hope to make a killing when they sell. I have found three such prosepctive sellers all around the world but waiting patiently paid dividends in the end. Keep an eye on ebay especially in Germany. They have almost anything you can think of. Almost all my rare cars have come out of there.
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Old 08-19-2009, 04:13 AM   #13
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Quote:
Originally Posted by niznai View Post
I had another look in the manula but couldn't find the page where it gives instructions for the alternative battery strap placement. If you could scan yours that would be very much appreciated.

I have ordered some of the parts from endofline (front suspension arms and holders) but not the steering assembly. I am not sure those would solve the problem with the steering posts as the problem is with the chassis plate which allows flex (or better put with the screws not holding into much material) so i prefer the brace I made.
You can use longer screws with the alloy parts. However, they come with no instructions (assembly is not straightforward and may need some additional parts) and include a turnbuckle that is too short. I suspect they are for the glassfiber version of the car.

Quote:
Now alloy bulkheads would be great, if you have more info on that as well as the Team Suzuki parts, would be nice if you'd share.
I've only seen the alloy bulkheads on a car that was being sold for way too much on an auction site. The Team Suzuki parts are hard to get but cheap if you can find them and were distributed by Yokomo themselves.

Quote:
About the screws, where did you find a 40mm countersunk Ti screw?
Actually, I haven't found those yet (my YR-F2 is in pieces until I've got all the turnbuckles I need). Square makes 3x35 mm countersunk screws, which are the longest that I have found until now. Otherwise I'll use good quality steel machine screws.

Quote:
As for the rear turnbuckles I am not sure I have seen something that long. I was looking the other day into Lunsford titanium turnbuckles for my crawler and the shop assured me the longest they have ever seen was about 67mm. There is a chance though some of the companies that make aftermarket parts for crawlers or some of the truggies (Traxxas maybe) may have something that will fit, but I am not sure I want something very strong there as I would rather the rods bend in a crash than break the hub carriers (or even worse, the suspension holders or the CF plates). These are all rather weak parts, so I am trying to protect them. Some ingenious way to replace the suspension holders (perhaps alloy) would be nice and would help stiffen the CF plates I guess.
Yokomo supposedly makes 90 mm turnbuckles, except that I've not been able to find any shop that actually sells them. Crawler turnbuckles tend to have 4 mm threads or larger. The suspension holders actually exist in alloy, but endoflinerc was out of stock when I tried to order them
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Old 08-19-2009, 09:21 AM   #14
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Quote:
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Here's mine. Don
That's a really interesting one Don. Would you care to scan some pages of your manual? Your car has quite a few differences to mine. Where are th erear shocks/springs? The front suspension plate is different too and with only one spring, is that OEM or custom mod?

Today I took mine to the track for the first time. It's really weird how it handles and in just a few minutes of practice I can't say I got the hang of it but it was nowhere near as difficult as mi RWD mini. It has however way too much rear grip so it's skipping the rear around corners. What was suprising is that it doesn't understeer at all. On the contrary, it steers very accurately and tight, so much so that I could floor it very early in the corners. It actually worked better that way because it has the typical FWD car lift-off oversteer. Very nice. And a lot of fun. I wonder how much power they can handle. One thing I have discovered is that the diff has to be built with the spring washer they give int he kit, otherwise you're not going to have the diff tight enough, and this is crucial to the car. I will try other diffs but for now, I am quite happy with the kit. My worry was that with a tight diff it would understeer hopelessly but this is not at all the case. It is meant to have a really tight diff and it works very well with it.

One last thing, i had to make a weight tray to bring it up to our club legal weight. I didn't race the car, but just to keep it in line with the cars I race, I made a custom lead tray that fits the lipo very neatly and ont he bottom it has extra weigths that fit in the chassis slots. Here's some pictures:
Attached Thumbnails
The YR F2 thread-dscf1458.jpg   The YR F2 thread-dscf1456.jpg   The YR F2 thread-dscf1455.jpg  
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Old 08-19-2009, 09:34 AM   #15
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I used to roll with one of those back in the 90's and the only major issue I had was with stripping the spur gears on a dusty parking lot.

Wether it was debris of the motor mount/drivetrain not holding up properly I don't know but it is something I would keep an eye on, for sure.

It handled well all the time it would drive though!

Very light due to its construction, looked good too!
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