MN-VERT-VET

How many bolt rear end did stock 1972 Big Block Have? Positraction standard?

GTR1999

All 63-79 vette diff's were 10 bolt diffs. Posi was standard starting in 1970

MN-VERT-VET

Thanks greatly appreciated!

dmaxx3500

BBC car had caps,,sbc cars had u-bolts on the axle shafts

MN-VERT-VET

Just wondering how a stock BB rear end would hold up if engine was built with more HP and torque?

GTR1999

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.

MN-VERT-VET

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

MN-VERT-VET

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

MN-VERT-VET

GTR1999

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.

Jughead

good to see you still around.

MN-VERT-VET

Thanks appreciate the great info

Sidneyhop454

Good to know. I'm rebuilding a 78 posi but was going to use the springs out of my 70. How do they hold up?

Sidneyhop454

nice :-)

GTR1999

Hi Jug, yeah it's been awhile. Not sure how many "ole timers" are left.

GTR1999

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.

ddawson

Damn nice looking engine.

Sidneyhop454

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.)

GTR1999

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.

Sidneyhop454

thanks for this info. Great vids. Best to use an angle grinder and polishing pads to polish the case? Any ref for this? I didn't see anything on YouTube. Also, what grit stone for the ring gear? Sorry for all the noob questions.