Camaro 7.5" vs 7.625" (26-spline vs. 28-spline)

I thought most people refer to a 7.5 and 7.625 rear as the same beast.

I remember going into Autozone the other day looking for the pinion seal and asked for "7 5/8's" and the guy said, "We only have 7.5." I told him that that was the one and he wanted to argue with me. Then he checked something else and he said, "oh, it says it's also for 7.625." I said, "then that's it!" and he said, "but you wanted 7 5/8's" and you all should know the look I gave him. Practically wanted to walk out but I knew he wouldn't be around for long.

-Bruce

Bruce, So whats you thoughts here - that maybe the carrier is the same ? I'm really in a pickel here with all the differential places that I'm looking to get spider gears from - they ALL show 28-spline axle shaft/side gears for the 7.625, and ONLY 26-spline for the 7.5 inch. (where I definetly have the 7.625). So should I just order the internal (spider) gears for the 7.5 inch unit ? My fear is that they will be a tad bit smaller, and thus maybe the cause of the excessive spider gear slop ? I'm simpy at a total loss with this inconsistancy, and need any help I can get. Thanks in advance, and I'd gladly return the favor. (shall I share with you the not so well known problem with the slip yoke on a

96 F-150 automatic thansmission ?)

If I remember correctly, 28 spline axles weren't installed in the F-body until late in 1989. It looks like someone swapped your rearedn. The 26 and

28 spline axles and associated parts should be interchangable within the carriers and within the years the 10 bolt rearend was made. I'd say 82-92 rearends should all have the same basic carrier design so everything should be interchangable (as long as the spline count matches).

-Bruce

There's not really any difference between the 7 1/2 and the 7 5/8. My memory says the 28 spline axles didn't show up until the '90 model.

Cool. Yeah, I did further research, and found that starting in 1985, the 7.5" was dropped, and all diff's were 7.625" with 26-spline. And starting in 1989, the 26-spline was dropped, and all 7.625" were

28-spline. So between 1985 and 1988, the 7.625" was indeed a 26-spline. To further complicate this, and to keep em straight, the dealers (and gear joints) just started calling "all" 26-spline jobs the 7.5", and all 28-spline units the 7.625", even though between 85-88 the 7.625" was indeed a 26-spline. So yeah, it would make sence that the carrier was the same except for the spline count in the internal side gears.

Now for the age-old question/debate.... Just what

*is* the acceptable play/slop in the sipder gears ?? The service manual goes into very great detail about all sorts of shit on every aspect of this rear, and how to set ut up, and yada, yada, yada, but doesn't say BOO about the internal gears - its amazing. Its like they totally forgot to mention anything about them. You would have thought they would have "some" blurb on what to check, how to check, and what is acceptable and what is not. So in my mind, its like: what good is busting your ass with all this shim charade, and pounding in an extra .004 shims for carrier pre-load, and making sure you have .005-.009 ring/pinion backlash if you got 1/2 inch (5 *hundred* thou's) slop/backlash in the internal spider gears?? Unreal... Seems to me that the center spider gear shaft should be a zero-clearance fit in the carrier, and need to be tapped/lightly pressed into place, and the spider gears themselves should be a much tigher fit on the shaft. I realize that there is no bearings, and you need room for oil an all, but geeze! - thats what the flat is for on that center shaft - to pick up and distrubte oil. They should make these gears tight, and let them "wear" into place for clearance. So whats peoples experience on this? - I just couldn't stand the slop and clunking anymore. No matter how good you are with the clutch, in heavy rolling traffic, you're gonna have that thing clacking back and forth in 1st gear. Maybe a posi unit is in order to eliminate the carrier/spider gears all together? And recommendations?

Thanks all for everything !

Yeah, GM says that between 1985-1988, the 7.625" was a 26-spline, and starting in 1989, the 7.625" was

28-spline. You would think that their documentation (or *someones* documentation) would be a little clearer in indicating that the internal gears are teh same/interchangable.

A GM parts catalog would answer those questions (at least partially). Joe--ASE Certified Parts Specialist & 10th Ann.Club Tech Director '80 Carousel Red Turbo T/A, 26k orig. '79 "Y89" 400/4 speed 10th Ann. T/A, 57k orig '84 Olds 88 Royale Bgm 2 dr, 307 "Rocket" (lol), 141k and still going.... '80 T/A project car...

There were selective fit shims:

That went between the spiders and the differential housing at one time. Sometimes I disassembled rears with two shims stacked at each spider when I pulled the pinion shaft.

I'm sure they're still available, as I'm sure the shims for pre-loading the posi-traction clutches are.

The Chrysler, Ford and Chevrolet all use the came differential housing, with the exception of the bearing ends and splines in the side spiders, so the drive spider shims are interchangeable.

Refinish King

Joe would be the man with the proper answer!

Refinish King

:)

Well, a GM catalog would tell you:

1) What years used what differentials and their respective codes (how you identify what you have) 2) What parts are the same (by virtue of part #s) between the units.

A Hollander book (what the junkyards used) would say what "fits", but if you're swapping the whole axle, they will all likely "work" and "fit" if it's a third generation car. Joe--ASE Certified Parts Specialist & 10th Ann.Club Tech Director '80 Carousel Red Turbo T/A, 26k orig. '79 "Y89" 400/4 speed 10th Ann. T/A, 57k orig '84 Olds 88 Royale Bgm 2 dr, 307 "Rocket" (lol), 141k and still going.... '80 T/A project car...

Well, on this rear, the spider gear shims have "lips" on them that fit up into the spider gear bore a bit, so can't stack em (at least these). But yer right, I seem to recall seeing stackable shims on a 2 Crysler rears I did - something like a 77 Valarie, and a 74 Dodge Cornet. And I remember that 74 Dodge Cornet well too - with the stock 318 would smolder the tires for as long as you stood on the hammer. To this DAY, could never understand that, and I've owned a few Crysler products too, just something different about that damn ugly-ass, metalic forest green 74 Cornet full of rust. eough, wow, off on a tanget here. Dodge cornets in a Camaro NG? Silly me...

Yeah, shit, that would have been the EASY answer to my original issue, huh? So now I'm in for about $400 with an Auburn on its way, and a garage full of gear-lube smell. (God! why does that gear lube have to smell like that anyways? - anyone know ??) But ists all good I suspose (if it all goes ok), because even with fairly new Radial T/A's, I *still* can't pull out of the office parking lot in the rain without MASSIVE one-wheel spin, so some sort of posi will be welcome.

They DO ? Are these all Dana units, or Borg Warner I wonder? And BTW, did GM ever make their own rears, or are all of these Dana/Spicer units I wonder?

Where does one get one of them? Years ago, when doing a full ground-up resto on a 1971 455 H.O. T/A, I used to just go into all the dealerships in my area and ask for all of their old, outdated manuals, and they used to say "sure", and loaded up me with tons of stuff. Worked every time too !

A Hollander would tell you:

Axle interchange, complete unit interchange. But, never spider or carrier interchange. That stopped in the 60's. But I can remember back that far when I was a little tyke, learning how to get good and dirty.

LOL

Refinish King

You can stack under the primary shim:

The primary shim was an update to help the problem with the drive pinion bore elongating.

I hope this helps?

Refinish King

Now the parts managers know what that stuff is worth:

They ask: "What's it worth to you?"

LOL

If you're doing a resto, just the diagrams are a blessing, not withstanding the part numbers to reference from!

Thanks Joe!

Refinish King

Any GM parts department can look up those parts in 2 seconds and answer your questions. A couple of computer keystrokes.

Joe--ASE Certified Parts Specialist & 10th Ann.Club Tech Director '80 Carousel Red Turbo T/A, 26k orig. '79 "Y89" 400/4 speed 10th Ann. T/A, 57k orig '84 Olds 88 Royale Bgm 2 dr, 307 "Rocket" (lol), 141k and still going.... '80 T/A project car...

You can buy OEM parts microfiche from Bell and Howell who puts it together for GM. Any public or university library will have a microfiche reader/printer you can use.

Joe--ASE Certified Parts Specialist & 10th Ann.Club Tech Director '80 Carousel Red Turbo T/A, 26k orig. '79 "Y89" 400/4 speed 10th Ann. T/A, 57k orig '84 Olds 88 Royale Bgm 2 dr, 307 "Rocket" (lol), 141k and still going.... '80 T/A project car...

Thanks for the info!

I have the microfiche reader from my paint mixing system.

How can I contact Belle and Howell?

Thanks again!

Refinish King

withstanding

Simple: its called "E-bay". Man!, you dig around on Ebay long enough, and you'll find parts/bulbs for like a 1954 model or some shit.

reader/printer