why did I pull the yoke?

[DOC]

I was having my driveshaft balanced and then rebuilt and he needed the rear yoke pulled off and brought to him.well against my better judgment I pulled it without marking it and now I'm worried about reinstalling it and blowing the whole differential. my 66 mustang has an 8.8 or 9 inch rear but I don't know which. did he have me do that so he could send me to his Buddy's shop?

[Colorado Osprey]

That's weird... why did he need the pinion yolk?

Anyway, there is no big deal with placement as the pinion is splined. There is no wrong spot unless your splines are keyed.
It is a good idea, but not required to re-check your lash between your pinion and ring gear after you re-install the yolk.
Although, this will require removal of the third member... so most don't bother.

[BPTactical]

^^^what he said.
Unless there is a master spline don't worry about it. Differential assemblies are not balanced and if somebody had one that was balanced they overdosed on anal. I can appreciate the drive shaft guy wanting the yoke to factor it in but probably unnecessary.

[trlcavscout]

Just make sure it gets torqued properly going back together and the backlash is right otherwise you will be doing a rear end soon.

[BPTactical]

Just make sure it gets torqued properly going back together and the backlash is right otherwise you will be doing a rear end soon.

Might as well toss in a new pinion seal while your at it.

[CHA-LEE]

I am not sure how the pinion depth is set on a Mustang, but on a GM it is done via a crush washer. On a GM diff, if you remove the yoke you almost always have to replace the crush washer and redo the pinion depth setting. I have seen several GM diff's get nuked after someone has remove/replaced the pinion yoke without replacing the crush washer and redoing the pinion depth. They simply crank on the pinion yoke and it pulls the pinion depth out of alignment and it screws up the ring and pinion mesh, resulting in a howling diff that eventually fails.

If you have not properly setup the backlash on a diff before, it may be worth the time and $$$ to take it to a shop to do it right. I consider myself a fairly competent weekend warrior mechanic, but screwing around with the diff backlash is something I will not touch with a 10 foot pole. I have learned that lesson the hard way already.

[DOC]

How can I do that? I don't have the tools.

[CHA-LEE]

If you don't have the tools or knowledge to properly setup the backlash / pinion depth, then simply take the diff out and bring it to a shop that has experience in doing it.

[KS63]

You probably have an 8 inch rear end. Just install a new seal while you're at it.

[DOC]

The seal is getting changed for sure.

[Great-Kazoo]

The seal is getting changed for sure.

The diff shop should include it as part of their fee.

[DOC]

What should they charge for this? I talked to the guy he recommended and he said to take out the 5 bolts holding the pinion in and bring that part in to have it torqued. I am already pissed about having to pull the yoke for no reason when he could have taken my word that it was a recent rear end that takes 1310 caps. But I didn't know that I would open a can of worms pulling the yoke off. I know its not the entire 3rd member but just the pinion part. But I want to know if there is anything that will be a problem pulling that off? And why can't I just screw it back on and torque it back down with a torque wrench? I know that I have seen advice saying I need a inch pound torque wrench to get it right. However, the pinion angle is set by the shims in a ford rear end not the crush sleeve. I could tighten it down and be good right? Or is that a gamble with rebuilding a rear end which I was lucky with this one and don't really want to do again since I had to weld mounts measure a million times. Beg for the money from an asshole that owed it to me but acted like he was doing me a favor and still needs work on the leaf springs....
what would some of you suggest? Its just a bolt right or the weakness in the death star?

[BPTactical]

What the torque wrench measures on a fresh setup is pinion preload and that is set with the crush sleeve. On your setup which is a "run" unit if it is a hair light on the preload that shouldn't be an issue. What happens most of the time when the pinion nut is removed is people over tighten the nut and put too much preload on the bearings which fries them.
You can put it back on by feel and do ok. Clean the yoke and pinion shaft and put a light smear of oil on the seal and splines. Slip the yoke on and slowly slide it in until it seats. If it is snug tap it in lightly but don't wail on it. You just want to bottom it on the crush sleeve. Now take the old nut, clean it up and red Loctite it and using just a breaker bar(no impact) tighten it to a good two handed pull, 75- 100 # or so. Now turn the yoke by hand, it should not spin loosely nor should it be unduly tight.
Pinion DEPTH is accomplished with shims and that dictates the contact pattern on the ring gear. As long as the bearing and shims are not disturbed then that should not be a problem.