Who has setup their own gears? Question about pinion shims...

[CMars45000]

Well I was setting up my gers in my 12-bolt for my 71 last night. The axle originally had a factory eaton posi and 3.07 gears. I have a new 4-series Eaton posi and 3.73 gears that are going in.

When you guys have set up these gears how many shims did you need to get the pinion depth right? I measured the pinion depth and came up with a really screwy number so I am just gonna go by trial and error at this point. I started with .025" and it was to far out then I went to .095" and it was binding so now I have .045" but was too tired to put the rest back together and finish running a pattern last night...


does .030-.035" sound about right?

[crazy longhorn]

I havent done too much on gears, but mine had a .033 shim factory, & setup with an .035 ,going to 4.10 gears. after the backlash was set in the .008-.010 range the pattern looked good. they all will vary, due to orig specs on the housing, but you probably wont be too far from the orig factory shim. What shim did the orig pinion have? L

[RACINJASON22]

crazy longhrn is right

they all will vary, due to orig specs on the housing

Sounds like you are doing things right though. You would never believe the guys that I have seen set up there rear gears for the roundy round stuff wrong. (Seems they think this shim came out here we will put it back in here and think it will be fine) check, double check back lash and wear patern and you will have a happy rear end. GOOD LUCK and keep us posted.

[69TowRig]

Always start with the original shim stack height and add or subtract based on the checking distance difference between the old and new gearsets. That gets you to a really good starting point for the finer adjustments, sometimes ends up damn near perfect. I'm thinking it may be too late (did you keep the original shim stack intact to measure off of?). If so, just keep pecking at it and you will come up okay eventually.

[mnunn454]

Almost 2 years ago I installed an Eaton 4 series posi carrier and a new set of 3.73's in my 69. My shim ended up at .030", so you should be a little deep with a .045" pinion shim, but all housings differ. I think I had mine in and out 4times. Man that gets old in a hurry.

Even though the pinion depth is as close to ideal as I could get it, and the test pattern looked perfect, I can still hear a slight whine at about 25-30 mph if I'm not dogging it. It has about 1000 miles on it now and I seldom ever hear it at all recently, so I guess it's worn in a little.

If you are going to ever do this again, it'd be worth picking up a pinion depth tool specifically for that axle housing. A variety of places sell them. After mine was in (of course) I found some nice ones for less than $100.

[gotchevys?]

This past summer I removed the factory 10 bolt from my 89 Suburban and replaced it with a 12 bolt. Then I changed the gearing from 3.08 to 4.10. I just used the instructions with my Richmond ring and pinion set and things went great and still no problems even after 6000+ miles and some occasional towing.

As far as pinion depth tools are concerned there are several different types
I tried this on first http://store.summitracing.com/partde...5&autoview=sku But it was a joke. The threads on the dial indicator stripped out the first time I threaded the extention into them and I had to usse teflon tape to make them snug enough to take readings and every reading was different because of the cheesey design of the tool. The tool I wanted was like $400 bucks!!! But I decided to try this one for $30 http://store.summitracing.com/partde...5&autoview=sku It worked great!!! This was my first ring and pinion setup and it was cake when I got that tool.