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I was running my '94 YZ10 yesterday, which has a TCS units with a one way center pulley. I suppose on high traction surfaces, this can be very useful, but on anything other than that, this is nothing but trouble, as the car tends to over-rotate. It is manageable, but you have to be super-aggressive to keep it in a straight line and so it is not easy to drive smooth with this on a lower traction surface. I was able to address this on my 870c (which also has a one way, but no slipper) by binding up the one way a little bit, so that it is like halfway between fully locked and fully one way.

It is fairly straightforward on the 870, though, since the one way bearing and housing sits by the spur gear, and so you can just press a bushing against it with a spring and a clamp to to slow it down. On the '94 (or rather, any of them with a TCS unit), the one way is on the center pulley that drives the front belt. I haven't yet figured out a good way to bind this up in a similar fashion to my 870. Fully locked would be too tight (and I am not aware of any locked center pulleys for this that aren't plastic?) and fully one way would be too loose. My only guess is to find a bushing of the right size that can bind against the one-way pulley housing (but that would wear out eventually), and then "adjust" this with a spring between the bushing and the clamp that sits on the layshaft. Has anybody played around with this?

There is a way to have the center fully locked, as that's what I ran this year. It's from the YR series touring car. So that gives you full time 4wd OR full one way action. The in between or adjustable is what you're looking for. Hopefully one of the more experienced Yoke guys can make a suggestion or two.

i didn't have a chance to run on a high bite track at 90's here. 870C came with 2 different spur hubs in the kit and one of them was oneway clutch. then torque limiter center pulley was a usually setup than fixe pulley.
but running works '93 with tcs was so different to me. maybe someone or a magazine told us to use losi and yokomo x pattern rear tires with kyosho H or I maybe pattern on the front.
thanks for reminding my memory

Brian, does that require a new layshaft, or is it just a partcular YR4 pulley that has that option?

both. Let me search my piles and see if I can come up with a part number for the assembly.

stickboy007 wrote:Brian, does that require a new layshaft, or is it just a partcular YR4 pulley that has that option?

The pulley can be locked out by means of a pin that is placed through the layshaft. The layshaft is particular to the YR4 (not sure of the exact model) it will fit on a YZ10 but you would lose the slipper as the layshaft uses a sold hub and rear pulley. To retain the slipper you would need to drill out the layshaft to accommodate the pin, that is if the layshaft profile is the same.

I think this is the layshaft used http://www.end-of-line-rc.com/cars/option-parts/yokomo/yr4-all/yr42sp-m2-alu-spur-gear-adapto.html

Alternatively you could probably use this pulley http://www.end-of-line-rc.com/cars/option-parts/yokomo/yr4-all/front-drive-pulley-for-yr4m2j.html and file a flat section on the slipper layshaft for the grub screw to tighten down on.

One of these may work too http://www.beltingonline.com/15-tooth-htd3-pulley-15-3m-09f-7717

Edit

It's the yr4 m2 that has this option

Manual can be found here http://www.competitionx.com/rc-manuals/cars-and-trucks-t-z/yokomo-manuals/

Interesting. Definitely the one Alex.

Just to be clear, I am not looking to lock the center one way. I am looking to make it adjustable.

I think I may have found a way to accomplish this. I don't want to say yet how I'll do it, but if it works, it'll be awesome! I ordered all of the parts I think I'll need for this, so stay tuned...

Sounds interesting, my Schumacher Axis touring car (& I think the CAT 2000 also) had something like what you describe as an option part, called ABS, it was basically an adjustable one way pulley using slipper style pads & spring etc. I'm looking forward to seeing what you have planned/designed

Well, all of the parts came in and I put it all together. It sort of works, because one of the parts I ordered was a bit junk with too much slop. I am ordering what is hopefully a higher quality version of that part, which will hopefully be in this weekend. I don't want to post pictures until it's done and verified, but what I can say for now is that my "theory" does seem to work.

Almost there...

Bingo!

[youtube]tmkVS0L_C2I[/youtube]

The center one way is a ZR-674H for the hardened pulley or the ZR-674C for the standard aluminum pulley.

I found a fix that doesn't require glue. I can't believe I didn't think of this earlier...

The center pulley has 4x8 bearings at each end. You should be able to pop one of them out and replace with a 4x8 one-way, mounted opposite to the one-way that is already in there. This will make the center pulley fully locked in both rotational directions. I successfully modified one of my center pulleys this way and will track test it soon (maybe not this weekend, but next next weekend after there is a layout change at my track). I can't wait to try it out, since this should allow me to brake much harder on corner entry.