Yokomo universal driveshaft's part # versus model?

[fakiee]

Since this thread is already talking about Yokomo universals maybe I could ask a question on the topic....

I have the two universals shown (ZC422 and ZC423) with the lengths listed (not full length as can be seen in pic - this is because I believe that there are also a few lengths of axle which could throw the measurements off). I'm looking for a yok universal that measures 1mm longer than the shorter one here (so I'm looking for 69.5mm to 70mm dimension). Does anyone know if this exists? I know that ZC421 is too short but does anyone have a measurement for ZC422A or is there another part number that I don't know about? The ZC423 is just too long for what I need it for and the ZC422 pops out of the diff outdrive at full suspension extension.

Thanks everyone,

Jeff

What Yokomo are you trying to fit these to, is it all stock parts including hub carriers, wishbones, etc?

[xxxmain]

Hi jeff

Ii've got something here that is that lenght but the shaft is 6mm with a 4mm screw on the end if you give me your email i'll send a pic, i just measured it up with a mx4 cvd at it uses 6mm bearings and it exacly the same lengh so i'm thinking it might be be the from the mr4bc? the other problem is i only have the one...

peter

Thanks for checking Peter but no need to send a pic - the universals I have now will be closer to the Masami ones than what you are describing. The use of a 5mm shaft and a setscrew to secure the aluminum wheel hub is a must. I just wasn't sure if there were any new part numbers for the standard 870C style of universal.

[xxxmain]

What Yokomo are you trying to fit these to, is it all stock parts including hub carriers, wishbones, etc?

It's a 1989 Masami Worlds Yokomo so it has custom rear machined arms and modded RC10 hubs.

[Charlie don't surf]

Jeff, I don't have a chance to take measurements until this evening. My money says that they are the wide front 422/422a

[xxxmain]

Jeff, I don't have a chance to take measurements until this evening. My money says that they are the wide front 422/422a

Yea, that's what I was thinking too Reggie. Let me know what you find but I'm not holding my breath.

Seeing as how this seems to be a long shot I do have one more idea.... I could machine the inner portion of the RC10 hub where the bearing sits in by 3mm and use the longer ZC423 universal (which is 5mm longer than the ZC422). I'll have to play with this stuff a bit more tonight.

[jwscab]

if all you are looking for is a 1-2mm longer bone, you might have an easier time trimming the front edge of that RC10 hub, so that the bearing sits farther inboard, allowing the bone to move inboard. Then put 1mm of shim on the inside face of the universal to take up the lost width.

if you are making a replica, and those are custom rear arms, unless you have a real set, it's hard to tell the actual width and something like 1-2mm is hard to determine from a picture in this kind of scenario.

I would guess that masami took a known good universal, the rc10 hub, and then figured out what width arm to make it all work. modding the bone or making a custom bone seems to be the 'hard' way to set it up especially for replacement parts while racing.

with the way the yokomo hub sits on the axle, you could re-shim on the outside of the hub with 1-2mm and probably still securely mount the hub to get back any lost width.

[xxxmain]

if all you are looking for is a 1-2mm longer bone, you might have an easier time trimming the front edge of that RC10 hub, so that the bearing sits farther inboard, allowing the bone to move inboard. Then put 1mm of shim on the inside face of the universal to take up the lost width.

if you are making a replica, and those are custom rear arms, unless you have a real set, it's hard to tell the actual width and something like 1-2mm is hard to determine from a picture in this kind of scenario.

I would guess that masami took a known good universal, the rc10 hub, and then figured out what width arm to make it all work. modding the bone or making a custom bone seems to be the 'hard' way to set it up especially for replacement parts while racing.

with the way the yokomo hub sits on the axle, you could re-shim on the outside of the hub with 1-2mm and probably still securely mount the hub to get back any lost width.

Everything you say is correct and a great idea... but I already tried much of it. I'll try to explain and I actually have some pics that may help. First off, you're totally right, I would assume, about Masami having the arms made to work with the universals and RC10 hubs that he already knew dimensions of. I am using the dynotech machined arms in the rear and the RC10 hubs so those dimensions are set and now I have to work with the universals only (and some rc10 hub mods) to get it right.

The problem with using the ZC422 shorter of the long universals... and then shimming them 1-2mm on the inside bearing and removing the material from the outside of the hub is that I can't remove enough material from the outside of the hub to allow the universal to protrude and be close to flush with the outside of the aluminum wheel hub (as can be seen in the Masami car pic from RCCA). I basically need an unshimmed axle to ensure the universal doesn't sit well inside the aluminum hub.

This is why I think I may be best to machine the inside of the RC10 hub and use the longer ZC423 universal. This may allow me to get the universal to the correct length while still giving me the full axle length so it sits flush with the wheel hub. I've attached a few pics of a mock up I have on the car now.... One side shows an RC10 hub that has been shortened at the outside as you can see the aluminum hub really close to the RC10 hub and the other side hasn't had any material removed from the RC10 hub. Both universals installed are the ZC422 and each has 1mm to 1.5mm of shimming on the inside... which has caused the universal to recess into the aluminum wheel mounting hub by about 1mm (not shown in pic). I have no idea if any of this makes sense but please keep the ideas flowing..... A solution to this is always easier to obtain with this many smart minds tackling it. Thanks again for all of the help.

Jeff

[jwscab]

yep, I see what you are saying.

are you planning on running this or will she be a shelfer? From that answer, I would say it appears that you have a very large amount of droop on the arms, and if this won't be run, I would just adjust the internal spacers to prevent losing the bone, and call it good. It's an excellent replica as I see it.

if you plan to run it, it's possible that you might be able to re-drill the rc10 hubs with another suspension pin hole inboard by the amount necessary to use a wider universal joint and get the u-joint farther in.

one question, how are you using a 5mm axle in the imperial hub?

counterboring the hub will give you some options.

[xxxmain]

She's going to be a shelfer so all of this is for cosmetic reasons but the suspension still has to work from full to compression. But, as you said, I probably would be ok to lose a bit of droop - but that still presents a problem. Even if I limit the shocks I won't be able to limit them enough to keep the bone in without the use of any shims on the inside of the bearing. Even the slightest shimming will cause the axle to recess in the aluminum hub. I'm thinking the counter bore may be a decent option. I'm going to get some measurements shortly.

I drilled out the hubs to fit the 10mm bearings but I screwed up my first set which is why I have these hubs to play with shimming, grinding, and spacing.

[xxxmain]

I just looked at the RCCA article again and although the angle is bad, if you compare this pic to the ones I just posted it looks like the universal on the masami car does go in further towards the back bearing within the RC10 hub so he may have had the rear of the hub bored a bit to move the inside bearing further out from center allowing him to run the longer ZC423 universals!

[jwscab]

i figured out what you need to do. Use 5x11 bearings, and counterbore the front and rear of the hub to space the axle out as far as you can. I believe the center to center spacing of the bearings in a yokomo hub is smaller, which means the length of axle supported is shorter.

If you can find an 11mm reamer, you can ream to a depth, and the difference between 3/8" and 11mm OD will give you a good lip inside to seat the bearing against(the inside of the rc10 hub is one diameter, and it relies on the flange on the bearing to locate it). a 5x10 bearing is very close to the 3/8" and the internal lip probably wouldn't be strong enough to keep the bearings located properly.

once that is done, hopefully you will be able to use the longer universals.

[Charlie don't surf]

What Joe said makes good sense! And it looks a bit like Masami used front hub adapters ( thinner ) instead of the thicker rear ones you have on there-

[scr8p]

i noticed that too, the hubs do look thinner.

[xxxmain]

What Joe said makes good sense! And it looks a bit like Masami used front hub adapters ( thinner ) instead of the thicker rear ones you have on there-

It's the same hubs, Masami has just machined the backside of them to save weight and increase clearance around the suspension arms I believe (I have a set out being machined and I'm just waiting to get them back). Here's a pic of another angle. He may have taken a hair of material off the back as well to make them slightly thinner which could explain why the universal axle protrudes so much... but the more I look at the pics I think the RC10 hub was just bored in at the back bearing to increase clearance for the longer universal. Remember that the YZ10 bearings are 5x10mm flanged so all the hub needs is a 10mm through-hole and the bearings just stuff in. I'm going to do some Dremel grinding tomorrow on my spare RC10 hubs to check some fit ideas and I'll post the results.

[Charlie don't surf]

You have you 1700 cells already, right?