8.8 gear setup question

[BBR]

I have done several Mopar 8.75's in the past, but this is my first 8.8.

I would like to get close on the pinion bearing depth the first time with out having to pull the bearing a gazillion times.

I keep running across the number 4.420 (+/-.002") as a total pinion depth spec for 8.8's.

Is that only for factory Ford gears or is it a universal number?

Reason I ask is this:

1.868" = Pinion head (NO shim)
2.554" = Checking dist marked on pinion head

4.422" = would equal no shim needed at all

How often do they require no shim at all?

Strange.

[min301]

Re: 8.8 gear setup question

Many 8.8's I've worked on required the factory shims,
and as I've found, the cases are much closer to spec
than many others I've worked with.

But, that is my expirience, yours may be different.

[milner351]

Re: 8.8 gear setup question

Dave and I pulled .026" shim off the factory installed pinion, and ended up installing a .012" shim to get the pattern close, this is with a set of ford racing gears, using an eaton posi unit.

in the past - I've been able to re-use the factory installed shim and been really close...

[A/Fuel]

Re: 8.8 gear setup question

I think the shim depends more the housing than the gear. If you bought a new pinion bearing, you can take your old one and grind out the center so it slides on and off. that way you can check the distance in a minute or so, then keep it as a tool for the next one you do.

[BBR]

Re: 8.8 gear setup question

That's probably what I am going to do. The pinion bearing is cheap enough. ~$17 at Oreilly.

[DanStokes]

Re: 8.8 gear setup question

I have a ground down one in the box. Will loan to interested parties.

Dan

[A/Fuel]

Re: 8.8 gear setup question

I just re-read this again....All though I've never done a 8.8, I've done a few 8.5 gm's and I think they're close enough for me to comment.
I've always used some kind of shim, even if it's real thin, just to keep the bearing from touching the housing. Kinda the same theory as instaling valve springs, if you know what I mean. I'd be intrested in hearing what others have to say about this.

[BBR]

Re: 8.8 gear setup question

I have a ground down one in the box. Will loan to interested parties.

Dan

Thanks Dan but I think I'll just pick up a new one. Oreilly's is on my way home from work.

;D

[nosnerd]

Re: 8.8 gear setup question

could that be the MHD?? (master housing dimension??)


probably a buck short and a day late here though.... :

[BBR]

Re: 8.8 gear setup question

Yes that is the MHD. I have not worked on it again because of the snow we have.

I found out later the 8.8 has a master housing dimension of 4.415-4.420"

[milner351]

Re: 8.8 gear setup question

not sure where the reference points are for the MHD, but if you run into an issue - let me know - I have a friend that has been working in the sterling axle plant as a problem solver for a few years and likely knows these things better than most.... he's the one that got me the c-clips. ;D

[revolutionary]

Re: 8.8 gear setup question

I've doen a bunch of 8.8's and what I've seen is that when using the Ford Racing gears you can pretty much use the factory shim that cam with the original chunk but any aftermarket stuff is a crapshoot.

I took a new pinion bearing and honed out the ID on my rod hone so it just slipped over the pinion and used that to setup depth/shim then just pressed on the permanant bearing when I got the pattern right. Works like a charm.

[BBR]

Re: 8.8 gear setup question

The stock 0.030" shim ended up being the right one after all. lmao

;D