Hey guys,

A little while ago I rebuilt my 10 bolt rear end (open diff), and I decided I wanted a new gear ratio and posi, got some 3.73s, 28 spline axles, and a zexel torsen carrier. During the install we got everything to what we believe was an accurate install regarding the shims and backlash and what-not.

After we got it all back together I did a little test drive and it felt completely the same, there was no grinding, whining, or any different feeling really so I assumed the install went well. (We recently replaced gears in a mustang and couldnt get the play right, ended up wearing bad on the gears and would howl and grind like crazy when letting off the throttle)

It wasnt until a while ago when I was working on my car that I tried to roll it backwards (pulled the engine a while ago and have been cleaning/preparing for new engine). Upon trying to roll it, it felt as if the car was in park, but theres no transmission.. it would roll a couple inches and felt like it would hit the park gear. Pushing just a little harder would pass that little "bump" and it would roll fine.

Is this normal? Anything you guys can think of that would explain to me why exactly its doing this? Error on the install? Ive never installed a new carrier before or even installed posi on my own, so im rather confused as to why it would do this.. thanks in advance

How did you set the bearing preload? Did you use new bearings and did you set the preload to around 19 inch pounds?

I did use new bearings from a rebuild kit but i dont remember if we torqued them to that or not. What would be a result of setting them too tight/loose? Also what is recommended for the pinion torque spec to the driveline? I remember us having some sort of issue with it being too tight and having to reset it to a lower torque..

If you get the bearings too tight they will over heat and burn up. If you get them too loose the pinion will move around and not stay in line with the ring gear. Pinion bearing preload is very important.

If you get the preload too tight and have to back it off you MUST remove the pinion and install a new crush spacer. You can NOT use a crush spacer that has been crushed too much. It must be replaced.

I gotcha, so I was trying to remember what I did to the rear when I did it, the bearing on the pinion was NOT new, it was in good condition, I noticed on another thread you commented on about the bolt on the pinion to the driveshaft side was to be torqued to around the 150 area, I did not torque it to 150 because it got the same amount of play as the old setup had. So is that the bearing preload you are talking about? Or would it have anything to do with the axle bearings? I might have to tear it back down and inspect everything, luckily after installation I only drove it maybe 50 miles. After the trips I would crawl under and feel the diff and it wouldnt be hot or anything, it was still cool enough to hold my hand to it.

So your belief is that the pinion bearing could be preloaded too much?

Sorry for the dumb questions, im not completely involved with these gear swaps, father in law was the main labor.

So how could I check to give you any more information so you could give me an accurate guess as to what I need to be doing exactly??
Thanks for the help I really appreciate it!

When I recommend torqueing the pinion nut to 150 foot pounds that is only for replacing a pinion seal or a yoke. That is not for gear changes. If you need to replace the pinion seal or yoke and no other parts are swapped then you can torque the nut to around 150 foot pounds and it will be fine.

When replacing the gears you must use a new crush spacer and set the bearing preload. If the bearings are new then the preload should be set to around 17-19 inch pounds. If the bearing are used then it should be around 10 inch pounds. You should not mix new and used bearing. Bearing preload is the amount of torque required to turn the pinion, not the amount of torque on the nut. As you tighten the nut the bearings will get tighter. Once you get the slack out of the bearings you can make a very small turn on the nut and make a big change in the load on the bearings.

Ok im understanding now! Thanks for clearing that up for me.
Guess ill be ordering some new parts, thanks for your help!

I used crush sleeve eliminator shims on the 9 bolt I rebuilt. Can that be done with the 10 bolt too?

Yes.

http://www.summitracing.com/parts/rat-4111

Yea, I've got a solid spacer for a 7.5 on the shelf that I ordered for someone a few years ago and they didn't take it.