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JK Racing wrote:RPM re-released the RC10 front bumper...that is my plan.

Did they really? That's awesome news. Now, I just need to find one or two...

The front end steering set up is mint. The spring (with the arrow in the picture), how did you set this up? It's slick, and I would like to do the same thing. I notice on the other 2 cars I have done that the steering needs to be at less of an angle. Looks like you have solved that one.....

It's not a spring, it's a fluted spacer made by GoFast Race Parts for shimming motor plates, gearboxes, tie-rods, steering linkage, etc. I had a couple of the pink anodized spacers in my parts bins from old dirt oval cars. I hated the extreme angle too, and like my steering linkages to be as straight and right angled as possible, so I used this standoff spacer and a long button-head through a captured Dubro 4-40 link trimmed down a little. There are plenty of simple aluminum stand-offs on the market that would be easy to adapt, too.

at first glance i though it was an old trinity brush heat sink...............

scr8p wrote:at first glance i though it was an old trinity brush heat sink...............

Sorry for the crappy cell phone shot again. Close resemblance if you can tell thru all the dirt on this old forgotten motor.

Hi Doug, did you move the inner rear ballstud down to compensate for the lower position of the B4 rear hubs?

I have an old RC10 in need of some TLC and was thinking of doing this rear end conversion instead of hunting for rear wheels.

Not to Hyjack Doug's thread, but you do not have to move the inner location-it's just right and parallel to the arm

Nope, like Reg said, it's all OEM fitment. I did use a later model rear bulkhead, though, with the far interior ball link location, which is in the bottom of the wing tubes on the original bulkheads.

Outside of reaming the outer hub hinge pin holes to .125-.126" for original RC10 1/8" hinge pins, there was ZERO modification to the car to adapt the B4/B44 parts. It helps to be a little creative with shims and washers, but there is nothing out of the ordinary difficult in this conversion.

Doug,

Thanks for the stand off idea. works the nuts!

Ron

The reason I ask about the inner ball stud location is because if you don't lower it the same amount of height as you lose on the outer location going to the B4 hubs then the camber gain will change. The car should lose rear sidebite.

Great looking mod, I'm thinking of using Losi CR rear hubs because they have vertical studs and should also widen the rear a touch over the AE parts. I know it's blasphemy...

The CR hubs require substantial milling to make them work on the rc10- These are now on JK racing's RC10 Retro-Racer

And camber gain ( at least how it would be effected by a lower inner location ) with the current generation of tire design is not a favorable option- most tires and setups all work because of the weight transfer causing positive camber to the outside tire. Plus, shimming the outside vertical ball
has the same effect, which is magnified even more than a shorter link ( which you can still do )

I jacked the rear of the car up and removed a wheel so you can see that when the lower arms are parallel to the ground, the upper tie-rod is virtually parallel to the lower control arm, and slightly longer (2.25" lower and 2.40" upper). The camber change throughout the movement of the rear suspension is virtually nothing. Negligible change, if any.

While I would love to have vertical ball studs on all 4 corners inside and out, it still IS a 25 year old car with limits. For the most part, those limitations are probably not a bad thing for me to have in a weekend warrior. I should be able to dial in handling that I want within 9/10 by shocks, springs and tires. Everything else after that would be gained in a brand new B4.1 or RB5 SP2.

If I really decide that I have tuned this car to its limits and can't make any other changes that I need to do, I might look at a new design on the rear bulkhead, rear toe adjustments or some different hubs. But for now, this retro-fit is easy, cheap and so far works in theory and assembly. And I don't race enough or take this seriously enough anymore to really make it something to need to do. I'm happy that I can buy most of these parts at the local hobby shop.


Time will tell.

Somewhat on/off topic, but one major change I would like to engineer on my car is a longer front camber link/ more inboard location. I think that is way more of a weak spot in the retro-racer than the rear end.

Charlie don't surf wrote:Somewhat on/off topic, but one major change I would like to engineer on my car is a longer front camber link/ more inboard location. I think that is way more of a weak spot in the retro-racer than the rear end.

Agreed. And I also think the steering geometry could be adjusted using shorter steering bellcranks with a thicker front tower, and then some type of mount for a vertical ball stud in the inner front tie-rod link that could be adjusted up and down and in and out. Fine tuning front and rear roll centers in contemporary cars is one of the biggest improvements over old school chassis like this one. Most people don't even know how they work anyway, so it really is a 10/10ths kind of modification.

Eau Rouge wrote:Most people don't even know how they work anyway

Hey! I resemble that remark!!

Following (okay copying for the most part) this build up closely. I look forward to your track reports, today's "plug n play" set ups that can be downloaded from the 'net have dumbed me down and I became a sheep and just followed the set up of the week. I have a lot to relearn again...



As always, fantastic build.