[Scarebird]

Originally Posted by Pitch 400

Yea, that's a good question. I asked Moser about using their bolt-in axles with the tapered bearings with the disc brakes and they said it would'nt work.

wut?

If your backing plate is the same thickness in the bolt area it certainly will...

[Overkillphil]

Originally Posted by Pitch 400

Yea, that's a good question. I asked Moser about using their bolt-in axles with the tapered bearings with the disc brakes and they said it would'nt work.

Rear discs afford one the luxury of a c-clip "backup system".

[Skip Fix]

I have their axles w/ taper bearings- they do work with the factory discs BUT the pilot will not locate the wheel as it barely sticks out of the rotor. So it makes the lugnuts needed to locate it. Problem is snowflakes(or turbos) have a .700 lugnut and around a .740 hole so enough to move the wheel around on the lugnuts and make it not centered.

Factory disc axle pilots are darned near .750 for that reason as the rotor is thicker than a drum brake hat. Moser also tells you they should be lugcentric.

[camerjeff]

Just to clear up some confusion on what 73-75 10 bolts axles used bolt in axles.

If the axle is in a GMC Sprint, A-body Wagon, or a Chevy Elcamino it is probably not an 8.5, most versions of those bodies came with BOP 8.875" axles, a shorter version of the Big car axles. And again most of those are C-clip Axles. My 73 4-speed Lemans Wagon came with a Bolt in axle 3.42 Posi 8.875" axle. I do not know what other aplications they were used in, also my car is a fairly early 73 build of 2nd week of October 1972.
Later in 76 or 77 all those cars came with revised and lightened 8.75 axles, and all of those are C-clip axles.

I have also never seen a 8.5 axle with bolt in axle retainers, does not mean they didn't make them.

Most non-station wagon or B-body people do not seem to know about the large car axles.

[Grand73Am]

I have 2 8.5" rearends with bolt-in axles in my 73-75 a-body cars. You can see in the factory service manuals that the B(Buick) and O(Olds) a-body rearends are the bolt-in (non-c-clip) axles. And sometimes the B and O rearends were put in Pontiacs. My 73 GTO and 75 Lemans have the Buick rearends in them, with 3.23 and 2.56 gears respectively. Other Pontiac a-bodys came with Chevrolet 8.5" rearends, like my 73 Grand Am with a 3.08 posi.

['ol Pinion head]

missed this one, looks like original posi carrier topic went a couple different directions. guess I'm as much to blame as anyone.


Cliff, thanks for the you tube link. Very impressive! will send you a PM.


Skip, If Moser would just source some axle blanks that were thick enough, they could machine 'em & make everyone proper fitting disc axles. It irks me too, we can't buy a HD axle with the .740 pilots. Have a local friend, we went through this on his rearend build with 30 spline axles for his 79 T/A. The Moser pilots were right under .500 thick. He works in the oil patch & picked up some 3" diam steel washers that were 1/4" thick. He had a local job shop, center & weld the washers on the ends of the pilots of his new Mosers. His machine shop buddy, then slightly turned down the washer & put a small bevel on it in his lathe. Not exactly what I'd like to see, I've seen things rigged worse. That said, this actually worked & looked decent. his snowflakes are centered.

On the other tangent... there are 4 different bolt-in axle corporate 8.5 housings, all came out of '71-76 A-bodys. Nearly all local factory stock circle track guys used to run '73-77 A-bodys, as a result, the bolt-in axle rears out of these did not last long in the crusher yards. Occasionally have built the 73-77 version.

[Skip Fix]

I talked to one of the techs at Strange and evidently the Mustang 8.8 blonaks they use have a longer pilot and close to the GM diameter. Not sure about getting the correct spline count on them.

Wonder if you could turn down the pilot 0.500 OD then just press on a bushing(with some Loctite) that is long enough like you buddy did. What are the GM pilots like 2.775-2.800 OD?

[Larry Navarro]

FWIW........BOP rear end strength is vastly increased using the LPW rear diff cover with bearing cap pre-load hardware.
The rear-end in my '79 t/a is factory stock and outlasted the 4 speed trans that grenaded under hard acceleration.

[rohrt]

Originally Posted by 'ol Pinion head

Leaf spring rears: HD bolt-in axle 8.5 housing wise from the factory, there is nothing as drop in as there is with the 8.5 A-body rears. On '67-69 Firebirds, they are however, the same width as the '71-72 8.5 A-body rear. It is some work, but stripping off the A-body lower perchs & TIG welding on reinforced multileaf brackets in a jig yields a stock width 8.5 early Firebird housing or 2nd Gen F-body rear.. One can also cut the c-clip housing ends off the 1" narrower Nova 8.5 housing & jig weld on bolt-in axle ends (either new or used A-10 GM ends) then order bolt-in tapered bearing axles. I really like the A-10 bearing end 8.5 A-body housing, but they are tough to find & as housings and have always been used up quickly. About 15 years ago, I ran across a B series GM housing with A-10 housing ends. Out of local crusher yards & Pick-N-Pulls managed to cut off several dozen pairs of A-10 housing ends. After trimming them, putting a bevel on them in the lathe & properly welding them on, the A-10 ends look like they came on the leafspring 8.5 housings I've welded them on. Of course one can buy the CNC' ed aftermarket ends... I just like the stealth look of the A-10 ends a little better & a 2.9" OD A10 tapered bearing & seal is a whole lot less expensive than Mosers 3.150" road race tapered bearing. Both can support a very beefy axle & aggressive cornering. Last, if a car is built for great handling, it does not need sealed ball bearing axle bearings, something one needs to consider when custom ordering any performance rearend.

Can you explain what the A-10 bearing end is. Is this the press in bearing with the backing plate your talking about?

I have a 77GP with a Buick rear that is a 8.5 with the press on axle bearings and backing plate. Would this be the same axle bearing that the 8.2 rears have?

I always thought the ford ends were the way to go to eliminate the C-clips?

[PONTIAC LARRY]

Originally Posted by Grand73Am

I have 2 8.5" rearends with bolt-in axles in my 73-75 a-body cars. You can see in the factory service manuals that the B(Buick) and O(Olds) a-body rearends are the bolt-in (non-c-clip) axles. And sometimes the B and O rearends were put in Pontiacs. My 73 GTO and 75 Lemans have the Buick rearends in them, with 3.23 and 2.56 gears respectively. Other Pontiac a-bodys came with Chevrolet 8.5" rearends, like my 73 Grand Am with a 3.08 posi.

Exactly..to match my post early on. I got a rearend out of early 73-74 ish GMC Sprint, 8.5 28 spline 10 bolt not a 8.875, this is the housing I had cut down to fit my old 84 S10 drag truck, I also had a little problem with a different in posi units with the bolt in axle units not having a recess for a c-clip in the side gears if I used the posi in a c clip axle housing later. If you use a posi from a C clip model it will work with the bolt in axles fine but the reverse is a problem. All 8.5 with leaf springs are C Clip. ALL 71-72 A body OLDS and BUICK are 8.5 and bolt in ... need a pic? got one in the garage. Also pulled a 3.23 posi from a rare 73 Grand am 4 speed car many years ago in the bone yard, bolt in axles... installed 73 GA housing into buddys 76 Buick Century coupe and the 2.56 pulled out was also bolt in axle!
I like the idea of buying 30 spline Mosier axles with the 71-72 olds stock size bearing and seals and installing the later model 30 spline posi, get a cheap junkyard 30 spline posi from a 89-95 ish Impala or Caprice or Roadmaster LT1 car. many are ex cop with posi, mate up to a cheap 3.42 or 3.73 gear set from a any 83 up to 2000+ model 1/2 gm pick up or suv.
I built another narrowed 8.5 bolt in posi for a buddy's S10 that came from a 74 Cutlass, Mosier 30 spline axle was ordered and factory olds seal and bearing was used (installed by paul Peyton who narrowed housing, it worked. but I did a full spool instead on a set of GM 3.73's from a SUBURBAN, worked great.

[smittyseng]

I build alot of rear ends in the course of my business, I also have customers running into the 10's with 8.5 eaton clutch type posi's w/30 spline axles, studded caps and the heavy duty rear cover. Someone mentioned tru-tracks early in this thread, I have had customers break them with vortec 350's in bone stock z-71's so I refuse to install them anymore. As far as newer factory posi's, they are total junk, the gov lock governor usually loses the teeth and is laying in the bottom the first time someone spins there tires hard, more junk that should be avoided. I have probably rebuilt 200 chevy truck 8.5's in past 15 years after GM decided to bore out the factory carrier and install 30 spline axles to fix a non-existent problem. The factory carrier shears off the side shoulder where the side bearing is pressed on, then the ring and pinion usually self destructs while the owner keeps driving it with the axle centering the differential, these parts shopuld be avoided also, Smitty

[Cliff R]

"Cliff, thanks for the you tube link. Very impressive! will send you a PM."

Thanks. I would also mention, that we're running pretty "soft" to stay roll bar legal. Timing is retarded a few degrees, added some weight, and shifting at 5000rpm's. The car is a blast to drive on the street, quiet, smooth idle, drives like grand-ma's station wagon from stop light to stop light.....Cliff

[PONTIAC LARRY]

Ditto to Smitty's mention above on gov-bombs... , i only mentioned the auburn cone style posis in the lt1 fullsize cars as a cheap source for junkyard build 30 spline 8.5 a body rear, a new eaton is my first choice too or a full spool

[Don57]

I've recently acquired a 1979 Cadillac Seville and was told it was a posi. I pulled off the rear cover and it has the S-spring carrier. Is this an Eaton or an Auburn? I counted the teeth at ended up with 47-21 which I think is 2:24. Wow! Talk about highway gears. I got the car cheap and mostly interested in the BOP TH400.

['ol Pinion head]

S spring carrier is known as the Corporate S spring posi. While its a clutch type posi, like an Eaton, no internals interchange. In Pick-N-Pulls I used to pull all the mid 78-79 Seville rears I could for housings, posis, disc brackets & disc calpers. Pitch the 5 on 5 stuff & grab some Nova axles. Have never ran across an 8.5 gear higher ratio than a 2.41. Most Sevilles had a 2.56's