Gear Install on 8.5 10 bolt

[lhorne81]

I am attempting to install a set of 3.73s in my rear end, but have hit a couple of hurdles. A summary of where I am right now: Both races installed in the housing, new carrier bearings installed, used 2 new shims on the pinion to equal .0385 (.038 came off the old pinion), new pinion bearing installed (froze the new pinion and baked the new bearing, then the bearing slid right on), had to install new crush sleeve during installation (old crush sleeve was too crushed and could not get preload dialed in), preload set at a little over 20” lbs during rotation.

After shimming the carrier, I have what feels like a good starting point for checking backlash, but after I torque the caps to 60’ lbs I am getting a problem area during rotation of the ring gear. I have noticed that in one particular section binds up and gets hard to turn. It must only be for a 3-4 ring teeth, then it goes back to an easier turning. It happens in the same section of the ring gear every time I turn it. I have not started using marking compound because it just doesn’t feel right. It is strange because in that area, I have zero backlash, then in other areas I’ll have .030 - .040 of backlash. Any advice on how to troubleshoot this?
Thank you for your time.

 

[GoldenOne7710]

Did you spin the pinion after you set it and look for any unusual rotation? Sounds like it's not seated and "wobbling" possibly.

 

[big gear head]

Do not use a crush spacer during trial assemblies. Just set the bearing preload with the nut.

Remove the ring gear and use a stone on the back of the ring gear to remove any burrs. Also use a stone or flat file to remove burrs from the ring gear flange on the differential. Be sure that you pull the ring gear onto the differential evenly and don't raise a burr while doing that. Be sure that it seats completely all the way around.

Be sure that the pinion bearing completely seated against the shims and pinion head. I'm not a fan of doing it the way you did because you can not put any pressure against the shims and pinion head that way. I use a press to seat them tight.

If you still have a wide range of backlash after reassembling everything then put a dial indicator against the back side of the ring gear and measure run out.

Check the pinion bearing races to be sure that they are completely seated in the housing. It's very easy to raise burrs in the housing when driving out the old races. Use a .001 feeler gauge to check behind the races and be sure that they seated completely.

 

[badazz81z28]

I used a checker bearing to get my pinion depth as close as possible before I started pressing on the real pinion bearing. I agree, don’t use a crush sleeve. I used a nylon nut to keep it tight to hold the pre-load. It’s hard to say what your problem is, but it could be a ring gear not seated, a pinion bearing that is crooked...btw .030-.040 is a ton of BL!
Do you have a bearing puller?

 

[badazz81z28]

https://www.richmondgear.com/wp-content/uploads/pdfs/richmond/cat-32.pdf

 

[lhorne81]

Did you spin the pinion after you set it and look for any unusual rotation? Sounds like it's not seated and "wobbling" possibly.

I did. It spun ok from what I could tell. I appreciate your response.

 

[lhorne81]

Do not use a crush spacer during trial assemblies. Just set the bearing preload with the nut.

Remove the ring gear and use a stone on the back of the ring gear to remove any burrs. Also use a stone or flat file to remove burrs from the ring gear flange on the differential. Be sure that you pull the ring gear onto the differential evenly and don't raise a burr while doing that. Be sure that it seats completely all the way around.

Be sure that the pinion bearing completely seated against the shims and pinion head. I'm not a fan of doing it the way you did because you can not put any pressure against the shims and pinion head that way. I use a press to seat them tight.

If you still have a wide range of backlash after reassembling everything then put a dial indicator against the back side of the ring gear and measure run out.

Check the pinion bearing races to be sure that they are completely seated in the housing. It's very easy to raise burrs in the housing when driving out the old races. Use a .001 feeler gauge to check behind the races and be sure that they seated completely.

Great info big gear head! Thank you for you response.

I did not inspect the back of the ring gear for any burrs before I installed it. Maybe there is a burr in the one section where I am having the binding. Do you have any recommendations on what type of stone to use, or should a file work?

I do not have a press available, that is why I froze the pinion and baked the bearing. I did notice yesterday (after I posted my initial question), that the pinion bearing was not 100% seated on the pinion. I was able to get it seated yesterday afternoon, so hopefully it ready for future testing.

I did put a dial indicator on the both the carrier and the ring gear to check for run out. While turning both, I found 0.0001 movement in either direction of the needle (the needle maybe moved a hair during the rotation). I assumed that this was within acceptable tolerance.

I will recheck the races this afternoon to confirm that they are seated, and check for any burrs.

Now on to my other problem...After doing some research last night, I am pretty certain that I have a 2 series carrier, and trying to install 3.73 gears. I assumed that the gears that were in the car were 2.73 gears, however they are 2.41 gears. 2.41 gears in a posi unit? Who would have thought? If I am dating the old gears correctly, they are from 1976 (so maybe a Trans Am or Z28?). Either way, my new gears are not going to fit unless I put a spacer in, or buy an aftermarket carrier. Do you have any opinions on which way to go? I started thinking to myself that the spacer is $50-$75 shipped, and if I were to replace the clutches in the factory carrier, they are around $200 from what I have found; at that price I am already in the neighborhood of buying a new carrier.

Any thoughts or opinions is greatly appreciated.

Thanks again for your response.

 

[big gear head]

Any flat stone that you would use to sharpen a knife will work.

I never recommend using a spacer. I've had to fix several rear ends because of problems that came from using a spacer. If you replace the differential then I recommend the Eaton Posi or Eaton Truetrac.

If you bought a installation kit and the ring gear bolts have 5/8 heads then I recommend tossing them in the trash and use the bolts with a 3/4 head. The bolts with 5/8 head will cause problems later when they come loose.

 

[lhorne81]

I used a checker bearing to get my pinion depth as close as possible before I started pressing on the real pinion bearing. I agree, don’t use a crush sleeve. I used a nylon nut to keep it tight to hold the pre-load. It’s hard to say what your problem is, but it could be a ring gear not seated, a pinion bearing that is crooked...btw .030-.040 is a ton of BL!
Do you have a bearing puller?

Thank you badazz81z28! I appreciate your response. I am thinking that my first area to examine is if the ring gear has any burrs. Check my above response to big gear head; I have a whole new issue with my current carrier (install a spacer vs. buying an aftermarket carrier to accommodate 3.73 gears). I am eager to get the ring gear figured out and will keep the forum updated on my progress.

I do have a bearing puller. I rented one from Auto Zone down the street. I used it to remove the old carrier bearings and old pinion bearing (from original gear set).

Thanks again for your response.

 

[lhorne81]

I never recommend using a spacer. I've had to fix several rear ends because of problems that came from using a spacer. If you replace the differential then I recommend the Eaton Posi or Eaton Truetrac.

If you bought a installation kit and the ring gear bolts have 5/8 heads then I recommend tossing them in the trash and use the bolts with a 3/4 head. The bolts with 5/8 head will cause problems later when they come loose.

Good to know for sure. I appreciate the advice of an expert.

Any recommendations on a stone or file for checking the back of the ring gear for burrs?