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Hi guys,

A friend just gave me his super beat-up RC12L and I am considering running it just for the hell of it. I'll take it apart and clean it but it has obviously no resale value so if I don't run it I might as well throw it away. So what's my cheapest, reasonably clean and sturdy option to run modern 3-hole wheels on this thing ?

BTW I am really... puzzled by how the diff is designed. I won't even mention the fact that removing the wheel means taking the diff apart, but it seems the wheel is not actually driven by anything else than the pressure against the hub ... make no sense to me.

I have considered the following options:

-Drill and tap the original hubs at 4-40 -maybe okay for the left (not sure about the centering though), but there's nowhere near enough material to afford that on the right hub.

- Buy John's BSR tires with the 2-hole pattern- availability issues, ugly wheel, and does not solve the aforementioned problem of the right wheel NOT being driven. (How retarded is that, seriously ? Ok don't even get me started on how the old Corally black wheels system was literally perfect and SHOULD have become the standard instead of the current US-sized, 3-hole, out-of-round, no-proper-thrust-bearing nonsense. Another example of US cultural imperialism ! JK. )


Thanks !

The only way to achieve the 3 bolt wheel pattern is to buy the entire axle assy including left and right hub, thrust washers, etc.

I did the same conversion on my RC12LS and you are looking at about $50 for the axle parts nip. If you are patient enough, you might find someone selling an entire axle used.

If you want to run the car cheap, I would suggest buying some wheels/tires that will bolt up to the axle you currently have. They will work perfectly fine with the current diff you have.

Check the link, you should be able to make out the part numbers to the axle parts in the picture.

http://www.rc10talk.com/viewtopic.php?f=37&t=30324

Jake

Yeah, I'm afraid that's the only valid option... Thanks for your advice. Now about the offset of the hubs, is it the same over the whole rc12 line until the L4 ? I know BL motors changed that, but I assume a L4 would be a direct fit on my 12L ?

I have a complete 3 bolt axle I'll possibly trade for a complete older axle. Also possibly trade good low use black 3 bolt front arms and left bulkhead for used white units...

A picture of the car.

Rc10th - interested, sending you a PM.

I have not had the time to mess with mine but looking at the rear of my car, you should be ok with using the aluminum spacers which are standard with the OEM rear axle. I do not have the proper spacers so my axle is just there for looks right now. Once I get home I will end up machining spacers to place on the axle.

Hope that helps.

Jake

The 3 bolt hubs were introduced with the L3 in the late 90s, so it's virtually impossible to find old style wheels these days. Modern wheels aren't designed to fit on the old diffs so the only way to fit them is to use a modern diff. The newer wheels have a different offset, if you could fit new wheels in there it would narrow the rear as well.

heretic wrote:BTW I am really... puzzled by how the diff is designed. I won't even mention the fact that removing the wheel means taking the diff apart, but it seems the wheel is not actually driven by anything else than the pressure against the hub ... make no sense to me.

It's a design that originated with the first Schumacher ball diff, which used no right side hub and the wheel sandwiched between two thrust bearings. It's a design that works The plastic wheel gripping on the alloy hub has more friction than the steel washer on the alloy hub, but most ball diffs still manage without keyed diff rings. The reason for the change to the three bolt fixing is down to a way of changing wheels without dismantling the diff, rather than anything to do with not having enough drive.

I must admit I'm not a fan of using the flanged bearing as a thrust race in the modern diffs, but by using the radial bearing the smaller balls in them means the end load required to ensure the diff doesn't slip is lower so the diff can be run a little looser without slipping. For a 12th car there is a noticeable difference in diff action between using a thrust race or not and the radial bearing handles better.