MIKER

Does anyone know what the end play specs are for the 80-82 differential side yokes?
I have not been able to find this information in my GM service manual.

MIKER

I'm sorry for running this back up to the top but.... I'M IN NEED!

Anyone? . . Anyone? . . Anyone? . . .

45ACP

Between .0005"and .0085"

I set mine up at .0005 on both sides.

MikeC

Wow! Ithink I need new side yokes. If memory serves me, I had a lot more than that!

MIKER

Thanks for the numbers! In what manual can these specs be found?

How did you "set" yours up to those close tolerances? I can see no way to adjust this clearance other than to replace the yoke OR weld extra material onto the end of the shaft and machine it back down to the desired spec.
I'm guessing that this is what they do to "REFURBISH" these yoke shafts.


[Modified by MIKER, 9:03 PM 11/27/2001]

MIKER

Mine were .014 on one side and .015 on the other. :confused:




[Modified by MIKER, 9:15 PM 11/27/2001]

45ACP

I have never been able to find specs for the '63-'79 rearend. The numbers above are for the C4 rearend. I cannot think of any reason not to apply them to the C3 also.
You may find it impossible to achieve a fit that close, even with brand new yokes. IMHO, the closer you get to these figures the better off you will be. That yoke/halfshaft arrangement, besides transmitting power to the wheel, plays a part in controlling the wheel camber. So . . . the question is, how much do you want your camber setting to flop around? My answer --> as little as possible, while allowing for some clearance for lube. I got around the "problem" of excessive endplay with lightly worn yokes in a (relatively) unconventional method. Being a machinist, I have the option of re-working most anything to the specs of my choosing. The yokes were no exception. I used hard facing rod to build up the ends, then mounted them in a milling machine and ground them back to the appropriate length.


[Modified by 45ACP, 10:22 PM 11/27/2001]

MIKER

[QUOTE]I have never been able to find specs for the '63-'79 rearend. The numbers above are for the C4 rearend. I cannot think of any reason not to apply them to the C3 also.
You may find it impossible to achieve a fit that close, even with brand new yokes. IMHO, the closer you get to these figures the better off you will be. That yoke/halfshaft arrangement, besides transmitting power to the wheel, plays a part in controlling the wheel camber. So . . . the question is, how much do you want your camber setting to flop around? My answer --> as little as possible, while allowing for some clearance for lube. I got around the "problem" of excessive endplay with lightly worn yokes in a (relatively) unconventional method. Being a machinist, I have the option of re-working most anything to the specs of my choosing. The yokes were no exception. I used hard facing rod to build up the ends, then mounted them in a milling machine and ground them back to the appropriate length.[QUOTE]

Sounds good to me! I plan on doing the same. I cannot see paying $100 to $200 each for yokes.
Thank you for the information.

45ACP

AH-HA! A fellow machinist!

Yeah, there is certainly no need to buy new ones. It's just too easy to re-work the old ones, with the added bonus of getting a GOOD fit. Heh. I don't think I used half of a 1/8" dia. piece of hardfacing rod to do the ends. It took -maybe- 3 mins, haha. After they cooled down, I just set each one in a v-block that I'd clamped onto the table of a Bridgeport. I mounted and then trued up a stone on a simple little arbor that I made up with an R8 end to fit the spindle. The ends came out so perpendicular to the axis it nearly brought tears to my eyes. Heh. It took about 30 minutes each - had to go slowly, no coolant (and don't like the color blue) - to get them to proper length.

Geez, don't ask me what rod I used, it has been too long, although I do recall that it was spec'd to be 60+ on the C scale. Hehe. I'll tell you what, I think they'll probably last a 1000 years as long as they get enough lube.

GTR1999

Instead of the Bpt, how about using a surface grinder? Did you have to recut the snap ring groove too?
Thanks,
Gary

45ACP

"Instead of the Bpt, how about using a surface grinder?"

Yes, absolutely.


"Did you have to recut the snap ring groove too?"

No. I only needed to build up the ends .020 or maybe .030, so I didn't even need to fool with splines much, never mind the snap ring grooves.

WATTAC

I believe everyone in this post is confusing differential side yoke end play with rear wheel spindle end play. The 0.0005 to 0.008 is wheel spindle end play. Differential yoke end play, as far as I've been able to find out was not spec'ed by Chevy. New ones generally allowed the yokes to move in the 0.010 to 0.020 range. Wear will move this up to about 0.125 max before the yoke retaining C ring drops off into the differential case and the yoke is loose and can be pulled out of the diff.

One note is that I'm sure of this for the '63 to late '70s, not absolutely certain of '80's, but there wasn't much change in all these years.

Comments?

Andy

45ACP

No confusion here.

Ingar, Norway

I don't know either, but from my experience you should have no end play.
I had some barely detectable end play and opening the differential revealed a worn center pin. Maybe this is special to the new differential, I've never seen any other post on center pin wear, only yoke.
After replacing the pin there was ~zero end play.

mrvette

Well, that all depends, but anything over 1/16th of an inch is in troubles, I"d certainly inspect it closely, pull the cover off and inspect....the cross shaft and the yokes may be worn excessively....play on the inward side caused by yoke/cross shaft wear....and can let the yokes slip out eventually, and of course affect alignment....
thing is, there can still be significant slop to the outward side even with new yokes/shafts.....as the side gears are spaced only by the posi clutches pack...and shims....as wear takes place in the clutches...they get thinner...and so the yokes would be permitted to move out, that will happen only on a hard corner, enough to pull them outward, as the normal stance forces them inward onto the cross shaft...that's why it wears out there so much....
in the hard corner, obviously the outer wheel is forced inward at the strut and outward at the yoke, pulling on the C clip, IF you corner hard enough and that clip is worn off, the yoke could theoretically slip out of the diff housing....but that would take several inches of travel, and I"m not sure that is possible before tire adhesion breaks loose....certainly the camber would be SO far out that NO amount of body roll could 'compensate' to keep the yoke inthe housing.....in a C3-4 it would certain twist hell out of the trailing arms/controll arms....well as the tire leans out, the patch looses contact and the car would slide out in the rear, thereby letting yoke back in toward center....I would not want to try this, but it seems things would react that way from thoughts on the topic....

GENE

MARKUS_P

This is the second time that this discussion comes up.
IMO there´s no minimum setting for play....
If the car rests on it´s wheels the carweight forces the sideyokes in against the diff.center pin.. that means there´s always contact between the yoke and the center pin. Clearance will be now only behind the c-clips and the surface it secures to....
Everybody talkes about complicated refurbish methods.
If you have some material left between the c clips groove and the inner end of the yoke, you can simply use spacers between the clips backside and the surface where normaly the c clips is pressed on if the wheel is without any weight (otherwise it will cause the yoke to slip in as described before).
Just my 2 cents....





[Modified by MARKUS_P, 8:00 AM 11/28/2001]

norvalwilhelm

I would want as little play as possible. When I removed my yoke with excess play I first tested there hardness. One was soft and one was still hard, above 60 RC. For the hard one I machined the groove to accept 2 clips. With carefull machining of the groove I could move it to accept the 2 clips and at the same time remove all clearance. For the soft one I made a 01 tool steel button and pressed it into the end of the yoke. By carefully machining the depth of the indentation for the button and the thickness of the butto all clearance was taken out.
I am installing the 6 link right now so I will remove my yokes and clearnance them so they no longer touch the center pin.

GTR1999

45- another question. I have a Bpt and KO Lee surface grinder in my shop so I can go either way. I'm thinking that I don't have to build up the full diameter of the yoke,just enough to bottom of the splines. I think that will give it enough support. What do you think?
The only thing I don't have access to is a welder, so I'll have to bring it to a local guy to weld.
Thanks,
Gary
(former Bpt service tech)

MIKER

45ACPSorry if I mis-lead you, I’m not a machinist but I do have connections at work to good machinist with good equipment. However, I do plan on trying to talk my brother in-law into selling me his “Drilling and Milling machine. I believe it would be a handy piece of equipment to have in my shop. I sure hope that there is not a law against impersonating a Machinist? :D :lol:

WATTACAndy, you stated that “NEW” ones generally had “0.010 to 0.020” clearance / movement. Knowing what tolerance that GM allowed would be great for reference if nothing else. Where did you get this information? Books? Did you perform actual measurements new differentials? I wonder why GM didn’t publish these values?
Either way, setting these clearances as tight as can be practically achieved appears to have it’s advantages for maintaining alignment specs and minimizing camber changes due to sloppy clearances.
Will I be able to feel any handling improvements from decreasing this clearance? I have no idea but I guess the total of all the little changes we make to these cars can yield noticeable improvements in handling.

I also have wear on my center pin similar to what Ingar’s picture shows. I plan on simply rotating the pin to expose the un-worn surfaces to the ends of the shafts.
Based on the replies to this thread, So far I see five options and may use a combination of them:
>Use hard facing rod to build up the ends, then mounted them in a milling machine and ground them back to the appropriate length.
>Rotate or replace worn center pin.
>Replace worn posi-clutch pack.
>Machine the groove to accept 2 clips.
>Don’t worry about it because my values fall right in line with those provided by WATTAC.

If I were to machine the shafts for minimal clearance while using my existing posi-clutches, I would have to again re-machine the shafts if I install new posi-clutches in the future because of their added thickness.
I am not planning on replacing the posi-clutches at this time because they seem to work fine now and may last for several years yet!

Thanks SO much for all of the responses. I’m not in a big rush to complete this project but I will post the results.

Ingar, Norway

I'm not sure if rotating the pin is a solution. This because the pin rotates freely and most probably will find a resting position at the point of wear.
That was at least my conclusion since my pin only had wear at on point, as the image shows. (I have rotated the pin to show the damage)

As also can bee seen from the image, the hardened end of the yoke has eaten into the pin, but the spines has not, at least to a much lesser degree. They must be softer than the hardened area.
That caused the splines mushrooming.
I grind them down with a Dremel to get the yokes out, that was time consuming work.... The image was taken after this treatment.
I later decided to take it all apart again and replace the pin. It's not difficult.
When you have it all apart it's also easy to replace the yoke bearings and seals.



[Modified by Ingar, Norway, 1:45 PM 11/28/2001]