Ashley P

Setting up ring and pinion..

17 posts in this topic

Disney, Mike, any experienced person...

What's your technique for getting it right?  I'm working on a 98 WS6 axle that's had a gear change and posi unit swap.  Customer blew up the original unit some time ago, swapped to this carrier and claims it was quiet for 150 miles until racing someone, then it developed a noise.  Sounded like pinion speed noise (and loud on accel), so I pulled it all down, bearings had small pits from debris and some funny wear patterns in a couple spots, replaced them, checked pattern...thought it was OK....it wasn't.  Still load on accel, this time plainly a "whine" like wear pattern.  Sure enough, rechecked pattern and it's running off the inside top of the drive tooth.

Have added .016" pinion shim, pattern is slightly better.  Probably gonna add another shim and see what that looks like.

I'm using Yukon info on patterns and adjustments.  (BTW, I lack pinion dept measuring capability.)

What do you guys like to do?

Share this post


Link to post
Share on other sites

Well a few weeks ago I helped Joey go through an 8.8 and we tried to use a chart from online that showed which way to move what to change the pattern.  The chart was wrong.  It was saying decrease backlash, but I already had it right (.008").  We tightened it up and it got worse.  I changed a pinion shim and got the backlash back to .008" and the pattern looked good.  Do whatever it takes to get .005"-.010" backlash and the pattern centered and as wide as possible.

How long did they drive it with the noise and bad bearings?  They could have just set a bad pattern in the gears and no amount of re-setting will fix it at this point.  Is it the stock 7.5, those are disposable anyway.

Share this post


Link to post
Share on other sites

In my experience, once the gears are out enough to whine, they can't be brought back to silent. Ever.

 

If I lack the ability to set pinion depth, I will always stick a .035 shim in and then set backlash to .010. That is a 99%'er. Every now and then you'll have to add more shim, but I don't think i've ever used less on a GM or Ford Salisbury style.

Share this post


Link to post
Share on other sites

No idea what chart it was, just one Joey found on a google image search.

 

For pinion depth.  I usually do this:

Pull the old pinion bearing off and measure the head of the pinion and measure the shim and add them together.  Then measure just the new pinion head.  The difference between the two is what shim I put on the new pinion.  This is basically what you are doing with a pinion depth tool.  The bearing is the only variable, but it's the most precise of them all.  This didn't work with the recent gear swap either.  Ford has changed gear suppliers in the last 10 years since I did a lot of them and the new ones are cast on the head, so the measurement of the head of the pinion must be junk.  This is why I had to pull pinion shim back out above.

So instead we just ended up with the old pinion shim on the new gear and it was fine (after removing).  I talked with a Design Engineer with AAM on one of my Detroit trips to go through a rebuild on a Nissan Titan axle.  He said they just recommend to use the same shim it had before and go from there.  Nissan does the same with their service routine for rebuilding the cargo van and Titan axles.

The AAM engineer said the process they go through in assembly at the plant to determine shims is way more complicated than any regular shop could duplicate.  They measure a lot of points on the housings and gears on fixtures and make matched sets.

Share this post


Link to post
Share on other sites

Disney, you might be right.  Considering I added a .016" shim to what he had (about .035") to make the pattern better, I'd say it's been run way wrong and "set a bad pattern" as Mike said.  Because:

Despite a slightly better pattern (marginally acceptable according to patterns at Yukon), it makes MORE noise now.   I need the smile vs brick wall on a tee shirt...

 

Share this post


Link to post
Share on other sites

I  guess some noise from bearings and a loud exhaust system hid the "contact pattern whine" from me initially.  Once bitten, twice shy.

Share this post


Link to post
Share on other sites

Oh, Mike, it's the stock 7.5 with Auburn unit and gear change.  Customer understood what I explained (rarity) and is ordering a gear set for a later appointment.   I asked if he'd considered an "axle upgrade" and he said he "wants a 9", but that's $3k...not now".

Car has nice looking headers, sounds cammed. has 6 speed.  I asked about 85% from it in 2nd gear...seemed...flat.  I'll have to ask about tune later.

Share this post


Link to post
Share on other sites

Customer just supplied me with a Jegs made in India 4.10 gearset.   Pinion was marked 0, and the original shim was .035", so that's what it got.  Put it in with factory side shims and got 0.0085" ish backlash.  The pattern looked as near perfect as possible. :yes:   Road test showed a little "sing" at 55-60 mph, in 6th gear, not as noticeable in 4th.  Maybe a little noise from gearset, maybe some from overdrive in the trans, who knows.  Either way, I'm declaring victory.

Edited by Ashley P
JohnC likes this

Share this post


Link to post
Share on other sites

Sounds great. New gears will sometimes sing until broke in (50 miles or so). Make sure the customer goes easy on them for a few days.

 

Nice work. 

JohnC likes this

Share this post


Link to post
Share on other sites

^ I leave work at work.  Or at least I try. (No place, no time, no desire at home.)

When single that's all I did, 8 hours at work, probably 3 or 4 each night, probably 10 on Saturdays.

 

Have I mentioned I'm about burned out??  lol

Edited by Ashley P
mstrpth and JohnC like this

Share this post


Link to post
Share on other sites

Notes on 1998 1500 GMC 8.5"  

Replace ring and pinion, kept .035" pinion shim, backlash = .012".  Both side carrier shims are .243ish".  Pattern is running off the top of the tooth at opposing ends (drive vs coast).

Picked up a .013"  shim and .230"    Moved carrier to the pinion .013".   Only .002" backlash.   Pattern is too deep, but now centered end-to-end.  Probably needed to move it about .005".  Monday awaits....

 

Share this post


Link to post
Share on other sites

Moved ring  .007" to right.   Backlash .007"  Pattern slightly higher than perfect.

Ended up .009" to right.  Backlash .0045".  (Spec .003-.010, preferred .005-.007.)  Pattern good, but not perfect. 

Very quiet on test drive, now can hear faint steering whine.   Diff generated some heat (hard to hold hand on it) on a 6-8 mile test drive.  Cloudy 75* day.  Makes me doubt things...
 

Edited by Ashley P
Add results.

Share this post


Link to post
Share on other sites

Pics would be nice.  Maybe I should take the tape off of the camera on this laptop...

Today's backlash was .006".  (This on a 2000 Dodge w/adjustable carrier bearings)

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now

  • Recently Browsing   0 members

    No registered users viewing this page.