Looking for some other opinions here... my 88 IROC G92 always had a noise from the rear end since I bought it.... last year i took it apart and tried to better set the gears... but that was under the car, driveline still mostly in place. It got better... but not where it should be.

When i took it apart and checked the pattern, it was way out on the heel on the drive side.... So I played around with pinion spacers.... 0, 0.008, 0.016, and 0.024. I settled on 0.016 and reassembled. The drive pattern looks ok but the coast side always looks like its on the toe.... for all the pinion shim combinations and 3 different carrier shim positions...

If these are original... they have 100,000 miles+

Here is where i am now...

Drive side pattern right now

Coast side pattern right now

Another shot of the drive side.

 

Might I add that the backlash is .005 inches measures at the outside of a tooth on the heel of the gear... (the outside edge).

 

Sofa should be along shortly to chime in on this.
But for now - backlash is too tight.
And you most likely don't have enough side preload.
So if I were you, add as much shim as you can to the passenger side. Don't change anything on the driver's.
This should give you more backlash - go for .010". Recheck the pattern and report back.

 

I was able to add .008" to the passenger side... It pushed the pattern toward the heel of the tooth for the drive side... didnt change anything on the coast side. I think i am pushing out too far on the drive side. Depth still seems to be getting high... would like to see it deeper on the tooth.

The backlash was unchanged at .004-.005"... at the low end of the spec in the service manual.

Tougher to read the pattern in the really cold garage. been trying to loosen up the compound with oil....

drive side... getting high

coast side

service manual, Borg Warner section

 

Here is the setup when I first opened it up... this setting was a bit noisy once you got going. Drive and Coast... way out on the heel in Drive...and high on the tooth in Coast...



Drive side

Coast side

 

I agree. Pinion needs to go deeper.

 

As in take shims out from behind it?


Deeper into the case...

 

Pinion gear needs to move closer to the ring gear.

 

OK... added 0.008 behind the pinion.... here is the new pattern... backlash is 0.07"

Drive side looks pretty decent... depth is about 70% of tooth face.

Coast side looks much better. depth is about 80% of tooth face.


Drive side

coast side

drive side depth

coast side depth

 

That's a step in the right direction.
It is said that is very hard to see the pattern with used gears and yours have 100K+.
I would give that a try.

 

Was able to get more resistance on the carrier... much better pics... the coast looks good... the drive could be better... On the toe too much. ... Backlash is at . 007


Coast

Drive

 

If i put a shim behind the pinion, the pattern on the drive side goes to the toe....the coast side looks ok. (see above)

So I took the shim back out (0.008") and set the backlash to 0.008". The drive side looks good. The coast side is on the toe.... not great but i would prefer the drive side be the better pattern.

Here is where i have ended up.


Drive side

coast side

 

I don't like that at all.
Look here: https://www.thirdgen.org/forums/tran...ml#post6456940

You want this.


View the ring gear tooth as a rectangular box. Set your pinion depth using the long sides of that box by getting the contact centered in the middle.
Then you work on getting the pattern centered in the short sides of the box by adjusting your backlash.

 

The drive side is centered ...first pic... But if I add or subtract behind the pinion, it goes way off center....add a shim, it goes way on the toe, ....subtract a shim, its way on the heel.....on the drive side.

Backlash is 0.008.... tighten it up and it goes way tight.... 0.004... one shim over and it jumps to 0.015 and is very loose....

I can't find any resource that shows one side centered with the other side way off. The drive side still looks right ... But the coast side..... Moving it sends the drive side way off ...

 

I can't really see what the drive side pattern looks like, but does this match your coast?


Open this link for all the patterns and how to correct: https://www.thirdgen.org/forums/tran...ml#post6456940

 

Your "one side centered and the other way off" in your first post first 2 pictures is effectively drive side slightly heel and coast side too far to toe. That's addressed as "Pinion position shim correct. Decrease backlash."

I don't know if you can come up with different shims to attain smaller changes to effectuate that. But it sounds you're getting it done shimming DS.

But possibly a decrease in pinion shim will be needed too.

 

Backlash is 0.008.... I don't think I can or should tighten that up....

I have taken this apart more than a dozen times now.... And moved the pinion a lot...pulling the coast side away from the tow sends the drive side way up the heel....

I live how every video or reference shows a straightforward result.... Every adjustment I make sends the drive side way out of wack.... It would make sense that there is too much slop in the gears and that's why the drive and coast sides do not match up.... But my backlash is in spec....

I am thinking of trying to get more preload...the carrier may be moving side to side if it's not enough....that might cause the mismatch pattern....then get proper backlash... It's just tough to get thin shims in with tight preload....

Maybe this is what you get after 100k miles.... And someone previously setting it up poorly .. (it was really noisy when I got the car)...

 

Here is where i ended up... Backlash at 0.008 inches... I was able to add a couple more carrier shims... its now pretty tight without carrier movement. Doubt I could get more in....

Pattern in the center vertically... .slightly to the heel.

I think i am just going to go with this and see what i get... its a lot better than where i started.

 

Looks good.