HWYSTR455

This may have been covered many times, but can't seem to find the info on a search.

I just had a shop rebuild my O rear 8.5, and they installed what I believe is SET 9 or A9 bearings, not sure which seal, but believe it's the wider one. The bearings are a cone and race style set, and the ones that came on the original axles are one piece. As far as I can tell (without pressng the old ones off) is that the inner diameter is 1.38, outer diameter is 2.560, bearing width is @ .677 - .680, and the seal width is @ .446/.458 (.490?). I'm doing a SSBC A125-3 disc conversion, and am worried about a couple things, mostly, bearing preload, since the seal sticks out considerably past the housing flange.

Questions:

Does anyone have a part number for the one piece axle bearings? Or does it matter? I would really prefer to use the original style bearings.

Seal part number?

Retaining plates - Should I use the flat moser retaining plate, or clean up the originals? Will it make a difference in preeload?

What's the correct combo of parts?

I'm stuck, no one know what I'm talking about, and some are trying to tell me to just go with what I've got, which I seriously doubt is right. Pulling hair here!

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monzaz

A9 is correct for the rear and the seal can be either 2146 (.460-.465) or 712146 (.490 ish) We always use the 712146 with a tapered bearing to keep the bearing into the cone/race.

When using disc brakes on a BOP axle (bolt in axle rear) you will need a spacer plate at the housing end that is the thickness of the backing plate. Some companies include this spacer plate when you order.

The stock plate are the ones to use Moser does not have a 10 bolt 8.2 plate the plate they have I believe is to larger on the inner diameter for a FORD bearing and will not provide the press you need against thew seal.

Good luck if you still need more info keep asking or PM me I wil lget you a number to call. Jim

HWYSTR455

Thanks Jim, appreciate it! Couple things:

Ok, if the A9 is correct, then why when I pulled it apart it had a one piece bearing, and not a tapered / race type like the A9?

The Moser plate looks like it will contact the seal correctly, same as the factory one, since the factory one has a lip. That lip/step makes no contact on the edge of the seal, which would seem be the only place that would offer preload.

My rear is certainly an 8.5, it has the ears at the bottom of the center section, and the guts that went into it were 8.5 stuff. (TrueTrac and ring & pinion). The builder did mention something about how the carrier bearings were different, where it fits into the housing, but didn't get the full scoop there. I would have to check the spline count on the original axles, but since I went to a TrueTrac, I knew I was going to have to get new axles, and got Moser axles (30 spline, to match the carrier). And I'm fairly certain the ring gear had only 10 bolts, as does the cover.

The backing plate I have, that came with the SSBC A125-3 kit, also came with these half-moon spacers, which slip into the center area before the retaining plate, to take up the difference and offer preload. It takes the backing plate into account, BUT, it still seems that the seal sticks out too far, and it may even distort the plate if one were to tighten it down. If it were a one piece bearing, like the original that came out, it wouldn't matter about the preload, because all it would do is control retention. And THAT'S why I'm confused about the whole tapered two-piece bearing thing, just gut feeling tells me to use the one piece.

Ames Performance lists a bearing that is a one piece, and is 2.558 OD, 1.375 ID, and .681 width. THAT sounds like the right bearing to me, but still need to call them. That application is a 1970 GTO, and supposedly, the whole BOP thing is a specialty of their's. They also insist on measuring the thickness of the seal, noting that it makes a big difference. Do you know anything about this bearing?

Is any of this making sense? I'm still confused as to what to use, parts-wise. It's holding up my whole build, like, I can't drop the engine & trans in because I can't jockey the car around without wheels on it! ARG!

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monzaz

The best thing to do is to mock up the axle fitment (install the parts WITH OUT THE CRUSH collar this way you can remove the seal and bearing with out ruining it. Measure the houisng machined depth to the axle flange outer machined end and add the backing plate thickness on top of that number. NOw measure your bearing you will use subtract it from the housing total and use the approreate thickness seal... Always use the seal that is slightly larger than the total distance to keep from having end play.) also there are shims that can be used behind the backing plate. Pontiacs use them. That can help fine tune the distance also for removing some preload.

Bower made straight roller bearing non tapered I am sure there is a factory number for the bearing BUT from 1969-1975 is the A9 bearing set9 etc.

early GTO had the sealed bearing still and the later housing used the oiled bearing.

I have MANY different forms of the A9 Set9 axle bearing ON AXLES SHAFTS. some factory some replacements some barrel type some tapered.

oldzy

Interesting. Sounds like the issue I had. The tech shop that did my rear end was adamant that the 712146 seals stuck out too far... and added TWO backing plate gaskets on each side to compensate, yet have the right 'preload'.

HWYSTR455

Did mock it up, it sticks out like 1/4", and the retaining plate wouldn't ever seat because it just can't crush the seal that much. If one did try to crush it that much, it would be too much preload, and the bearing would bind, failing early.

I called Ames, and the guy knew what I was talking about, got the bearing from the back, and measured everything for me. The bearing thickness is .665, though the inner collar was slightly thicker. That doesn't matter, because it's inside the retaining plate, and would never touch. It sounds like the bearing that's on the original axles, so I ordered a pair. The guy said it was a National / BCA bearing, so hoping I can pull a number off it when it comes in. If so, I'll post it. If you're curious, you can look at the Ames GTO catalog, think it's page 263, and they call it the 'second design'. The second design was to correct the issues found by using the tapered and cup type bearing.

With this type of bearing, there is no crush or preload issue, you just assemble it. All you have then is retension.

Ernie at Moser is interested too, and asked me to call him with the info when I get the bearing.

monzaz

I can also add that if you are expecting PERFECTION from GM or any other car company...GOOD LUCK.
Things happen in the machining process. I am sure alot came out pretty good BUT others may have had depth issues on the housing ends or different housing end specs ended up on the wrong housing. AS with most things you will need to measure once twice three times if it takes mock up the bearings and seals before a final press of the retaining collar.

Another reason for HIGH prices on any kind of car repair... Usually car repair shops factor in this headache on every JOB. I try not to do this as I charge by the problem if it does occur.

We all are here to try to help get the hobbyist through these BUMPS in the restoration road to perfection...lol. PERFECTION, use that term lightly cause these cars were FAR from that. Jim

Maybe that is why we are so in to them as EACH one is surely unique !!!

Take care, Jim

HWYSTR455

Sorry haven't updated here, don't want to leave the thread open, so will post my findings.

The bearing originally on the axle was correct, though the fact that the outter shell/race was not engaged with the race backing, it seemed it was too wide. In the one photo, you can see me holding a bearing that is seated in the race backing next to the bearing that's on the axle, and the one that's on the axle has separated from the race backing. That gives a false reading when you mock it up. Once you sandwich it all in there, it seats, and it's right.

The next pic is of the seal, which has a metal shoulder as apposed to the other which was I guess coated. I used the new/metal one when I had them swapped out, just to be **** I guess.

Pic of the bearings and seals used with part numbers.

And the retaining plate/caliper mount for the SSBC rear disc kit, showing the required spacers. Those half-moon spacers account for the thickness of the original drum backing plate, applying the right amount of preload on the bearings/seal assembly.

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monzaz

oops now I re read that...sorry dude...lol

you did not say you were using DISC BRAKES... You need a spacer for the drum plate which is 1/8" thick...then the caliper brakets...THIS is why your seal sticks out.... PICTURES... They say 1000 words and then some.

All the info would have been better to help solve your problem JIm

HWYSTR455

There's pics, and the above shows the disc mount bracket, and the required spacers. I even mentioned the spacers, and how they take up the backing plate thickness.

Anyway, the parts I originally had were correct, and they 'looked' like they stuck out too far when I mocked it up. The outter race just hadn't seated fully with the race backing plate, but once it was all assembled, and put together, tightened, it was all good. It just didn't LOOK right, and made me scratch my head and chase my tail. Because of the way the outter race and the race backing plate go together, there's no way to over-preload the bearing. If it's too much though, you would crush the seal, but that wasn't the case in my situation. It was right.

So, live and learn is my motto, especially on this one! I still need to call a few people and let them know I was wrong, just to close the loop there. Not an easy thing to do though....

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boaterbil

Hello, I have a 1972 Cutlass in my shop right now. I have been a tech for 25 years and have never come across tapered roller bearings on the rear axle except for Chrysler.
The l/r axle has about 1/4 inch of end play and yes, The seal is leaking. How do you set the end play on the axle? Any help will be apprweciated. Thanks, Bill

HWYSTR455

Most likely the seal was damaged due to an impact or something, or that would be my guess why there's that much play. Or the bearing is bad.

The end play is preset by the distance of the retaining plate and the seat the race contact in the axle tube. The seal preloads the bearing by being squeezed between the race contact and the retainer plate. If you can piture that.

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J-(Chicago)

I attempted to use those tapered bearings and race directly into an axle housing once, since they were more easily available.
I pressed the races into the housing end, and pressed the tapered bearing onto the axle. It worked great.....for about a month, and then once the bearings got comfortable in their place, I rechecked to find 1/4" of end play on the axles.

So.... for future readers, don't do that.
Use the flat disc bearings with the drum brakes.

HWYSTR455

Flat disc bearings? Do you have pics and part numbers?

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HWYSTR455

That number crosses to a Set9 or A9, which is what I used. And is a 'cone' or 'tapered' set.

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507OLDS

The original bearings that came on those axles from the factory,were a regular barrel shape,not a tapered roller,and the rode in a trough or groove,so these had no where to go.The replacement bearings are tapered roller.One thing you need to make sure of is that you have the 712146 seal.The 2146 seal is narrower,and will not allow you to put a preload or seat those tapered roller bearings.Another problem,althjough fairly rare,is that the end of the axle tube was bored too deep,giving more room for the bearing race to go into before seating.That can be solved by putting a shim behind there first.Regardless,you can NOT have any end play with the tapered roller bearings.If there is,the bearing is coming off of the seat of the race,and the weight of the car is pushing the axle housing tube down,the bearing is riding on the top of the race,and the axle shaft is pushing up on the seal,making a gap at the bottom for the oil to leak out of.

HWYSTR455

Exactly. The seal. That's the point I was trying to make too. Uh, wait a min, you say the 712146 seal? The national seal I believe I'm using is the 712145 seal, or that's what it looks like in the pic of the seals & bearings I posted.

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507OLDS

Yes,it looks like you have the correct seal,and I see that you are also using one of those disc brake kits with the split shims to put the preload on the bearings.Do you have more shims?There's a chance that if you eliminate all of the endplay,the seal might still be good,and the leak will stop.

HWYSTR455

Yeah, it's a SSBC kit, and old one, and I originally had the wrong shims/spacers. It took some detective work, and talking to the right person at SSBC to get the correct ones, they're not in the catalog, someone actually remembered straight from memory. And no, sorry, only have the one set. You might be able to get the part number off the one pic though and call them.

Mine doesn't leak, and the preload appears to be correct, but will give a final thumbs up once I put some miles on it. It's in the body shop, almost done getting painted. Soon.... (there's recent pics of the body in the project thread)

https://classicoldsmobile.com/forums...e-project.html

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507OLDS

That's one of the same rear disc kits that Summit sells under their brand.I did a gear/posi install last year,on a customer's car that had that same kit,and his had multiple shims on each side.He already had the rear discs on when I recieved the car,so I just made sure I put all the shims back where they came from.

HWYSTR455

Those spacers are a particular thickness, and with this setup, you only use one set. It uses 87-88 turbo t-bird calipers, which I don't care for, they have that stupid ratcheting piston thing, pain to crank them back in when you change pads, have to use that stupid tool. I may just gut it and use an S-10 or 98-02 f-body setup instead.

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507OLDS

Yes,his had the thick ones,but also had a few different thicknesses of thinner ones.It's just not the way I would do it,but I guess it works.

boaterbil

Thanks, I replaced the bearing with a second design set 9 all's well now. Thanks again

507OLDS

When I aquired that NOS posi unit,I acquired a few crates of various Delco bearings,that I have used in some of my "important" rears.I have everything labeled & set aside as to where it will be used or installed.
With the barrel-shaped bearings,the axle tube could have an infinite bore depth because it does not need a shoulder to press up against,like the tapered rollers.
I think the old Bowers had a similar design,but everything that I have seen made lately,is the tapered roller.I did find an old Lisle(spelling) attached to an O-axle shaft.That looked like a nice design,but I have never seen another one.

joesw31

The NOS axle bearings come up for sale every so often. Another issue that I had with the set9 was the race spun in the housing bore giving it a small notch that I had to hone out. Also a side note for those who decide to rebuild your differential is to have it checked for straightness as that will also affect axle bearings. These rears are 40 years old and who knows how many pot holes or curbs have been hit.

507OLDS

Yes,I rebuilt a nice TO 3:91 O-axle for a friend of mine about 6yrs ago.Everything was going great.I had just finished it,and set it on the floor.As I looked at it from the top,I noticed the tubes,or the rear,was bent or bowed.After putting it in a jig,it was obvious that it was bent.The carrier showed history of a broken axle,and now it was making a lot more sense.It was in a bind.Needless to say,I had to get another housing,and scrapped that one.After some more research,we found that the car had been run in a ditch at some point,and that was before it broke the axle shaft.That rear set up fine,but it never would have run right.I don't even think the car would have tracked right with the rear like that.
I remember Andy's W31 at the pure stocks,and as a watched it,I noticed it was running dog-legged.A quick peak under there revealed that the passenger side tube was coming loose from the pumpkin,and while under load,it was pulling forward,or so it looked.Another rear that needed another housing.

joesw31

I watched a guy earlier this year straighten a housing on a crank jig. It was awesome. The guy who did the work told me that the problem is more popular than people think, and was common in 4x4 trucks. He toke the sadle caps off and put these round spacer looking donuts that looked like solid bearings, then, he ran a solid round bar through the housing and determined where it was bent. Once he got it straighten, he had two more adapters that slide through the tube into the axle bearing sadles for fit.

I thought it was awesome because now some rears may be saved.

monzaz

Just about every 12 bolt Chevy rear we get in is tweaked a bit. We are always having to re-straighten the housings. What a PAIN.

Had a guy come in with a 800.00 camaro rear he had bought at a swap meet...JUST a HOUSING... It was so bowed you could run a string from one housing end tube to the other and make a bow and shoot an arrow with it...LOL.

Take care and have a Great Christmas!!!

507OLDS

Another common misconception is that people think welding the tubes tp the pumpkin will prevent any bending or failure. Wrong. It will just find another place to bend. It usually just ends up bending the tube. I did a lot of R&D with stuff like that with the 8.8 Mustang rears. I ended up fabbing some braces that welded onto the pumpkin ribs & the lower control arm bracket.
Greg Alexander broke the tube from the pumpkin,on his Moser 12-bolt housing,under his 70 W30.Not sure if Moser ever covered it or not.