Hi guys
It's me again. Just received my new side yokes. When I installed them the spline is touching the center pin in the posi track, is this normal. I have .030th end play. On the ones I removed, I have .080th. is this within spec?

Thanks
Clyde

 

Measure the new yoke faces to the snap ring. Should be int he 182-187" range. If you did not tune the posi and just check it up like a typical posi then you may find the play is in the clutches and not the new yokes.
Just about every posi I tune I have to grind the new yokes or sometimes the original ones to set the endplay. I'm doing 70 diff now and it is the same.

 

Gary
First of all, thanks, I really appreciate the response. I guess I need a lesson on how all of this works. When we tore down the diff. a month or so ago we had to use a dremel to remove the side yokes they were mushroomed so bad. We did nothing with the posi unit itself. We replaced the bearings and crush sleeve. We torqued te pinion until it took approximatly 22 inch pounds inorder to rotate it, and shimed the bearings until we had .007 th back lash. When we reassembled it we had about .080 th end play on the side yokes. I posted pics of this and you responded and said they were shot and replace them. I just received the new ones, installed them and now we are down to .030 th, but the end of the yoke is touching the pin in the posi. I took a little tome to try to figure out what is suppose to take the stress of the car courning and if it isn't the end of the shaft on the pin then the neddle bearings against the yoke flange. Forgive me if this all sounds way off base to you, but this exploring a whole new area for me. Any advise you can give me would be great.
Thanks
Clyde

 

The side yoke is supposed to touch the center pin. If you pull on the side yoke hard and the snap ring bottoms out against the plate, the distance between the side yoke and center pin is the endplay. .030 is within specs. As the clutches wear this will increase.

 

63Mako Thanks
That's what I was wondering. Garry is really great, I practially rebuilt the suspension with his and jims papers, but sometimes he explains things way over my head. I've attached a couple of pics. The first one is with the yoke against the pin, the second is the snapring against the plate. The dial indicator is against the opening for the U-joint on the yoke.






This is a pic of the new yoke on the left and the old yoke on the right. You can notice the difference between the snapring and the spring plate.

The old yoke had .080th diffrence, but more important, there was very little meat left between the snapring and the shaft end.



Thanks again, C/F is better than all the manuals written.


Clyde

 

I have on occasion I have made spacer washers for my side yokes. Since the yokes are "captured" in the side gears, there is no wear factor BUT use hardened washers when you make them (sometimes valve spring shims can be used try an automotive machine shop for the shims.)

 

.030" is common in std rebuilds. Many use them like that. If this was in the car and an original untouched diff and you asked me I'd tell you to leave them in.

Mako is correct the clutches will wear but not as much as you may think. I mic'd up my 69's originals and there was .001-.002 wear on them. They were the solid clutches as well.I reused them and tuned my posi. Since this was my car I chanced reusing them, normally I'd install new solids.

Since you didn't touch the posi I'm 100% positive that is where the play is. Look at the picture of your new LH yoke installed. The chamfer is clear on the end of the yoke. That is a quick check, if you don;t see that chamfer then they are worn out.Those are Lonestars,as just about all the rebuilt ones are, and have the new green snap rings. Those are good.

I'm just finishing up an original 1970 diff tonight that I tuned the posi. I was able to reuse the original yokes. When I got it in there was .030-.040 endplay like yours. I had to put the yokes in the surface grinder and face them .005 to get to .005-.010 endplay. The tuned posi is that much tighter and better then a stock setup.

Using the indicator is good BTW. You can also use feeler gauges in between the yoke and cross shaft.

About the only thing you can do is either leave it and drive the car or drop it out and tune the posi. Then you're going to have to go over all the pattern setup again.

Good luck.

 

I have the exact same situation as cboyd. (not to hijack)- I too have read gary's paper & am in over my head w/ regard to tuning the posi. I do understand. Is there measurements for the steel plate posi plates? Mine look good, but I have .035" end play on my stubs & they measure out with in the posted tolerances... Perhaps more info on the shims between the c-clip & plate... thanx

 

I have never found any published spec for yokes. It may be available I just haven't found it. When asked about endplay while the diff is in the car, I usually use .030-.040" as a reference. This is based on wear of the yoke face. These were case hardened and that is about .030" so that is what I base it on. Kind of rule of thumb, the earlier yokes are usually in much better condition then the later C3's (76-79). Of course every job could be different so the only way to know is to take it apart and check.

Now as far as play in the posi. The play comes in from setting the backlash on the spiders. If there is a lot of BL then there will be more play. To remove backlash the spider side gears are shimmed. This shimming moves the side gears deeper into the pinion gears and closes the BL.

The posi plates are used to support the posi springs and there isn't much wear on them. Since I never use them it doesn't matter to me. They are not the cause of the ..035 endplay.

I have never used any type of shim on the yokes behind the snap rings so I can't comment on that.

 

 

Gary

Thanks for the reply, I appreciate your time. I am going to settle for what I have now, I've already pulled this thing and stripped it twice. I won't be doing a lot of hard driving and I would like to get the chassis re-assembled and move on to the body. However i am very interested in the workings of these diffs, for future reference. When time permits, I would like to pm you for a little lesson in tuning the posi, if it's O.K.

Thanks Again
Clyde