Came across this older (2013) article from Hemmings that I found extremely informative about our lesser- appreciated differentials. Plus, I had no idea BOP stood for Buick, Olds, Pontiac. Yea, I know, I'm late to the party. https://www.hemmings.com/magazine/mus/2013/01/B-O-P-Rear-Axles/3720371.html Jeff
I read through that article, and it's a good one, but I didn't see them explain that the 68-70 Buick 8.2 is a Buick only rear. The BOP gears and parts from the earlier 8.2's will not fit the 68-70 Buick only rear. The only gears I know of that are available for the 68-70 Buick 8.2 are those made by Fabcraft, 3.42 and 3.64. Up until recently, no new Posi carriers were available. I believe Monzaz has a way around that now, I can't keep track.
I have seen Eaton and Auburn posi units for 8.2 rear ends sold on Summit. Will they fit a '68 Buick 8.2? Or are they strictly Chevy 8.2s? I see that TA Performance is selling 8.2 posi units and gears. Would I assume they are correct for my '68?
There is a BOP rear, basically, 64-67. There is a Chevy 8.2, and there is the 68-70 Buick only 8.2. THEY ARE ALL DIFFERENT REARS. What you see on Sumitt is the 64-67 BOP rear parts. TA Performance sells the right parts for your 68 rear. Read page 150 of their current catalog. You can download the pdf on the TA site.
Randy's ring and pinion has been making a bearing sleeve to allow the use of the early bop 8.2 carrier to be used in 68-70 buick 8.2 for many years now.
I understand they are trying to help ...but really most of the time those articles will send false info out there... Take the 12 bolt olds carrier breaks they did not get that correct as there is a 2.56-2.78 carrier also. Missing the 68-70 Buick info is a big boo boo also. Then the early 8.2 rears there was not even a Pontiac 8.2 it did not come out till 1966 (the converging ribs. ) It is like they went on the internet and shuffled through what was out there and here is what you get. Might as well Wikipedia it. Be careful with the sleeves for the Buick carrier bearing as it really needs to be WELDED in place as there is A LOT of spinning torsion on those bearings and you do not want it to slip and the press fit must not increase the OD on the hub either or you will compromise bearing integrity. Best way is to press on your bushing oversized... tack weld it in place , then turn down to size and clean up the welded areas. The best and strongest rears are the ones that are maintained and or re-bearinged after they are out of usable spec. (which really if you keep up with maintenance will be 20-40 years usually or 100 -300 thousand miles...All again depends on the use of the car... but the ring and pinion will really out last the car most of the time as long as you maintain good oil and service. If you have limited slip oil changes are required more often as the clutch and cone debris will contaminate the oil quicker. Jim J D Race
As far as Randy's sleeve...I buy from them and looked through the complete catalog...I did not see anything for that Hub. They do have a sleeve for the Chevy gear into the BOP rear for the pinion yoke seal. But that is it that I saw. Jim
Jim, maybe, if you have the time, you could write something up on the different 8.2 GM rears and post it in the FAQ Forum. We could then make it a sticky, because it is certainly a Frequently Asked Question, and a source of confusion for a lot of Buick enthusiasts.
I don't have any more info than what they told me on the phone a few years ago. Tech support guy said it had something to do with the two different sized carrier bearings.
The 68-70 8.2" Buick shares the same ring gear bolt pattern,and inside diameter as the 71-up 8.5" 10-bolt. You just need the correct offset on the flange,to position the ring gear where it is needed,and still keep the carrier centered in the housing. The newer 8.5 units have a larger bearing hub,so you use the same SET36 bearing on the left side,as the factory did.On the right side,you use the LM102949 bearing and LM102911 race.
So Brian/Jim, Which way does the offset have to go? Toward the pinion is a spacer, away is an issue.. And, with an 8.5 case, does this allow an 8.5" gearset to work, with/without pinion mods? I have several 8.2 Buick bare housings around, just looking for options for them, beyond expensive gear sets. JW
The flange needs to move towards the center,or towards the pinion. A few different ways to do that. You still have to use the Buick gears. The Buick rear has an offset similar to a 9",do even if you machined the 8.5" gears to fit,the offset Is wrong.
Ring Pinion mesh engagement is like the FORD 9". The Pinion engages much lower than any GM integral housing. The offset of the carrier just has to do with the ring & pinion ratio correct backlash engagement. I remember when I was frost trying to make a PONTIAC 10 bolt 8.2 gear to fit. JUST WAS NEVER GOING TO HAPPEN...Blew 400.00 in bearings and races etc. SO - please lets stop worrying about what you can do with this rear as we have tried it all We all have the Fabcraft gears that Brad and I worked hard to get together for everyone. The 3.64 gears I convinced Brad to make thick so it fits the LIVE 3 series Auburn carrier not a DEAD GM 4 series carrier. It is a dead end street.... and I think there is plenty of parts to get that rear going if you really have to for Original look in your car. Again we can create a 4 series carrier Bit will require more labor for the driver side hub bearing and hole for the ring etc. Jim J D Race
Here is a Buick 3:23 with an Eaton. I'm building a 3:64 for myself,with a 30-spline TruTrac and Moser axles. No real reason. Just for kicks.
Its just money so they say. 2000.00 is nothing for a rear these days. Try building Import car rears...You think 500.00 for gear sets and 400.00 for a posi is high... try 4000.00- 5000.00 for parts for your differential. 2000.00 for just the Limited slip posi for a Z car rear 2008 I did about 5 years ago. 4.09 ratio was 850.00, rebuild kit was 375.00 for basically 4 bearings crush sleeve and pinion seal. WE DID NOT EVEN GET carrier shims in that deal...I had to machine them. Dealer did not even have the Shim parts or know what I was talking about... All parts had to be bought from Nippon direct JAPAN. Nothing is going to get cheaper. labor is expensive and parts will always go up and price and older car parts will become more and more obsolete. Sometimes it is just cheaper to buy a NEW car as they are faster and efficient etc. Took my wife's 2017 Impala 3.6 liter V6 to the track with my 16 year old daughter driving in the teen class 14.89 96MPH in the 1/4 automatic.... lol like a Sunday drive down the track... Jim
