BB rear end
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Joined: Aug 1999
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From: Connecticut, USA
There has been myth out there for years that a BB diff is somehow a lot stronger then a SB diff. The fact is the only difference are the axles as mentioned and the stamping on the diff. I have never seen an axle yoke break, I have seen u-joints break- usually the outer one but I have inners too. The caps on the axles are fine but I wouldn't call them a superior part. The internal parts over the years are what I look at. Also it has been said the BB posi cases were shot peened, I have never seen evidence of that and have taken apart a lot of original vette diff's.
You would be best served to know what you have now and the only way to know is to remove it and open it up for a look by someone who knows what they are looking at. You can post pictures here if you like and I would be happy to look them over for you. For performance builds I do not use 63-66 housings or 63-70 posi cases. The best parts have been supplied by Tom's Differentials in Ponderay ID for years. Tom passed away in Jan but his wife is running the business and there is still stock on parts to my knowledge. If you are thinking of a real upgrade- not a common bearing replacement called a rebuild, you should call Tom's to see what is left. Whether you build the diff or someone else does you want to use the best parts.
You would be best served to know what you have now and the only way to know is to remove it and open it up for a look by someone who knows what they are looking at. You can post pictures here if you like and I would be happy to look them over for you. For performance builds I do not use 63-66 housings or 63-70 posi cases. The best parts have been supplied by Tom's Differentials in Ponderay ID for years. Tom passed away in Jan but his wife is running the business and there is still stock on parts to my knowledge. If you are thinking of a real upgrade- not a common bearing replacement called a rebuild, you should call Tom's to see what is left. Whether you build the diff or someone else does you want to use the best parts.
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Joined: Aug 2013
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From: Alexandria Minnesota
Thanks Great info,
Tell you what I bought, 1972 BB, frame off nut and bolt restored, restored with (sorry I'm a marginal gearhead) Engine, competition hydraulic roller and lifters, speed pro f60 cam, speed pro pistons and rods, Elgin Valves, Competition springs, Balanced and Blueprinted, bored and honed with plate, polished crank, Balanced assembly, ported and polished heads. It also has Richmond 3.55 gears. Open the hood, it looks stock with exception of plain air cleaner cover. I know there probably is some redundancy in my description, Thanks
Tell you what I bought, 1972 BB, frame off nut and bolt restored, restored with (sorry I'm a marginal gearhead) Engine, competition hydraulic roller and lifters, speed pro f60 cam, speed pro pistons and rods, Elgin Valves, Competition springs, Balanced and Blueprinted, bored and honed with plate, polished crank, Balanced assembly, ported and polished heads. It also has Richmond 3.55 gears. Open the hood, it looks stock with exception of plain air cleaner cover. I know there probably is some redundancy in my description, Thanks
Thread Starter
Advanced
Joined: Aug 2013
Posts: 52
Likes: 8
From: Alexandria Minnesota
Thanks Great info,
Tell you what I bought, 1972 BB, frame off nut and bolt restored, restored with (sorry I'm a marginal gearhead) Engine, competition hydraulic roller and lifters, speed pro f60 cam, speed pro pistons and rods, Elgin Valves, Competition springs, Balanced and Blueprinted, bored and honed with plate, polished crank, Balanced assembly, ported and polished heads. It also has Richmond 3.55 gears. Open the hood, it looks stock with exception of plain air cleaner cover. I know there probably is some redundancy in my description, Thanks
Tell you what I bought, 1972 BB, frame off nut and bolt restored, restored with (sorry I'm a marginal gearhead) Engine, competition hydraulic roller and lifters, speed pro f60 cam, speed pro pistons and rods, Elgin Valves, Competition springs, Balanced and Blueprinted, bored and honed with plate, polished crank, Balanced assembly, ported and polished heads. It also has Richmond 3.55 gears. Open the hood, it looks stock with exception of plain air cleaner cover. I know there probably is some redundancy in my description, Thanks
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Tech Contributor
Joined: Aug 1999
Posts: 15,175
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From: Connecticut, USA
sounds like a nice car, enjoy it.
The Richmond gears are replacements so you know someone worked on the diff. If they're quiet leave them alone, if they are whining get a set of Tom's if you still can.
The Richmond gears are replacements so you know someone worked on the diff. If they're quiet leave them alone, if they are whining get a set of Tom's if you still can.
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St. Jude Donor '09
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From: Alexandria Minnesota
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From: Orlando, FL
Tech Contributor
Joined: Aug 1999
Posts: 15,175
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From: Connecticut, USA
I am assuming you are referring to the posi springs between a 1970 and 78- I have boxes of them sitting in my shop, I never build a 63 -79 Eaton posi with the springs or plates. To answer your question they should be the same. 78's had poor axles, posi clutches, and ring gear bolts.
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Joined: Apr 2018
Posts: 181
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From: Orlando, FL
I am assuming you are referring to the posi springs between a 1970 and 78- I have boxes of them sitting in my shop, I never build a 63 -79 Eaton posi with the springs or plates. To answer your question they should be the same. 78's had poor axles, posi clutches, and ring gear bolts.
I was planning on using my 70 axles (if still good) new clutches and APR bolts (previous recommendation you gave.)
Tech Contributor
Joined: Aug 1999
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From: Connecticut, USA
Sorry, I'm a little confused. Are you saying you never reuse the springs or plates from those years and just get new ones, or rebuild the units without them entirely because you blueprint and they don't need them after?
I was planning on using my 70 axles (if still good) new clutches and APR bolts (previous recommendation you gave.)
I was planning on using my 70 axles (if still good) new clutches and APR bolts (previous recommendation you gave.)
Instructor
Joined: Apr 2018
Posts: 181
Likes: 6
From: Orlando, FL
I never use the springs or plates. I tune all my posi's as you can see the late Tom Watt tune a vette posi on YouTube. I also polish the posi cases well beyond what I have seen posted here. If you take your time you can do it too. If your axles measure 190-200" and are hardened you can reuse them and they will be better then current market axles. Be sure to check the seating of the ARP bolts before you install them. USE #271 LOCTITE on them on final install.