Pinion shim does not sit flat

[500/600]

500/600, the shims needed opening to 1.560" to get them to sit flat. I'm beginning to think I need to look for some aftermarket gears....

I’m of the train of thought that the instant that the center is just large enough to sit flat, you are at the perfect size that keeps the shim perfectly centered. What am I missing? I spent my college years setting up hundreds and hundreds of gearsets, mostly factory and mostly GM, and have never seen this occur. Use whatever sleeve that you’ll be pressing the bearing on with to press down on your ‘setup’ bearing with the 1.44” shim installed. The shim ID will bend but the bearing should completely seat as the bearing radius is almost positively larger than the pinion radius. And it will be perfectly centered. Try it. Don’t just lay it on, press it on.

 

[64nailhead]

Where did you get the kit from? And who's the manuafacturer?

I'm sure you want to get this don, but you have wrong arts. Modifying a shim that cost $.80 in an effort to get it together today is not sensible to me. Also, these shims are available locally to me - Napa, Advanced Auto, my basement lol. Where are you located? Most any speed shop or local circle track group will have a member with a couple of spare shims.

 

[Bailey28]

According to Ratech their 1104 shim kit fits all 7.xx diameter ring gear rear ends:

GM Individual parts and Kits

Now look at the shim I.D> 1.450"...... that puts the shim up onto the shoulder causing the gap... so back to square one.

1104

Today I will attempt to remove the original shim from the pinion gear.

 

[Bailey28]

500/600, the shoulder doesn't have a nice 'step' on it to center a shim, its a curved radius. The inside of the bearing has the same curvature to it. The problem is once the shim ID is large enough to sit flat there is nothing to center it. The shim is loose and free to fall off center when installing to check pinion depth..

So you're saying just press the bearing on with this gap and don't worry about distoring the shims?

 

[Bailey28]

Most of you all think I have the wrong shims. To clarify please advise what I.D. the correct shim for my application is supposed to be. GM 7.5 rear 1984 open differential. Ring gear lists p/n 26017961.

 

[Bailey28]

I just did what 500/600 advised and pressed them down gently under the slip fit bearing. The shims did flatten out. The shims also are now distorted slightly in the center. Perhaps this is by design. I will pull off the old bearing today and look at the shim.

Its intereresting that nowhere in all of the literature I have been reading about setting up gears did anyone note that this would happen.

I have experience with motorcycle suspension tuning shim stacks in forks and shocks. Those shims bend at the edges to allow oil to pass but all shims were mounted flat and square to the cartridge or shaft. I have seen shims that are cupped due to wear over time that were distorted. Upon occasion we used preloaed shims which slightly bowed upon install for different situations but not distorting them at their I.D.

I can't be the only person on the planet to have noticed this when dealing with pinion shims.....

 

[Bailey28]

Old shim is .037" the tabs hold it away from the shoulder. To the left are the new shims after I pressed them down flat.

 

[Scoot-71]

I wouldn't recommend using a shim that interferes with the center radius, just enlarge the inner diameter so it don't.

 

[pontiacgp]

I checked with my friend and it's a .035 shim he starts with and over 90% of the time that works. I would try the .037 and if that works use it. I think you are overthinking this minor issue.

 

[500/600]

If you distort the shim and the bearing won’t press on all the way = not good. If you distort the shim and the bearing does press on all the way, it’s because the bearing radius is significantly larger than the pinion radius, which it almost positively is = good. If the factory 4-tab shim is 1.44” across the tabs the you can bet the tabs distorted after installation. If it is more than 1.44” across the tabs then it is loose just like your 1.56” modified shim. You are in a lose-lose situation because of the radius on the pinion. Do you think GM designed a lose-lose situation?

Do one or the other. They’ll both work.