What to do with 2.56:1 posi

[Gary S]

I have been hearing this for years, but haven't actually heard or seen a failure. I think its an urban legend...

Ask a professional like big gear head.

 

[BondoSpecial]

I don't believe in spacers but Robert Herndon had a thread on here where he proved that the shim did not put the ring gear out past the machined register on the 2 series carrier, so the ring gear did not lose its center. So at least that part is good. You are still using much longer bolts to hold the ring gear to the carrier though, and IIRC he found the mr gasket shim was not of consistent thickness so it was causing ring gear runout relative to the carrier, and the shim had to be hand-planed to get it flat. I think that was a case of, a talented installer can make anything work, but it was not plug and play.

3 series carriers are a better option unless you can't get one

 

[big gear head]

I have been hearing this for years, but haven't actually heard or seen a failure. I think its an urban legend...

I have seen several failures due to ring gear spacers. I have pictures to prove it. I've seen all of the ring gear bolts sheared off, I've seen uneven wear on the gears and I've seen gears run off center. These are not stories that someone told me, these were actually in my shop to get fixed. A ring gear spacer should only be used if there is just no other way to go.

 

[Protour-Camaro]

I have seen several failures due to ring gear spacers. I have pictures to prove it. I've seen all of the ring gear bolts sheared off, I've seen uneven wear on the gears and I've seen gears run off center. These are not stories that someone told me, these were actually in my shop to get fixed. A ring gear spacer should only be used if there is just no other way to go.

Could you share? Like I said I have never seen actual instances. Were the failure solely because of the spacer or other influences? I would think to shear 10 bolts, there had to be incredible forces.

 

[teslasbrain]

Not to hijack the thread... famous last words, but I have 2.73 posi 10 bolt in my 70. Am I in the same boat? I heard later 70's 10 bolt carriers are stronger, is that true? Will they fit in my housing?

Thanks

 

[Gary S]

The 70 8.2" 10 bolt is smaller and weaker than the 71 and later 8.5" 10 bolt. You would be best off replacing the entire rear end with a used one from a 71-81 Camaro or Firebird. If you shop around, you might find the ratio you want and a posi so all you have to do is freshen it up and install it on the car.

 

[big gear head]

Could you share? Like I said I have never seen actual instances. Were the failure solely because of the spacer or other influences? I would think to shear 10 bolts, there had to be incredible forces.

I've posted the pictures on here several times, but when Webshots sold out all of my pictures got deleted. I don't have an account anywhere else yet, so I can't post pictures at this time.

 

[teslasbrain]

The 70 8.2" 10 bolt is smaller and weaker than the 71 and later 8.5" 10 bolt. You would be best off replacing the entire rear end with a used one from a 71-81 Camaro or Firebird. If you shop around, you might find the ratio you want and a posi so all you have to do is freshen it up and install it on the car.

Thanks, Gary. I will take your advice.

 

[Rich Schmidt]

Not to hijack the thread... famous last words, but I have 2.73 posi 10 bolt in my 70. Am I in the same boat? I heard later 70's 10 bolt carriers are stronger, is that true? Will they fit in my housing?

Thanks

Nope,2.73 and up is the good carrier. They never made a "3's" or "4's" carrier for the 8.5. The only concern I have is that if it is a 1970 rear,it is probably an 8.2" rear not the 71-81 8.5" rear.

As for ring gear spacers,I have ran plenty,even in 600 hp cars with 12 bolts,and the spider gears broke long before the ring gear failed. One of the important things is to use ONLY the bolts from the spacer kit,not the stock bolts or any other kind of replacement bolts. The bolts with the kit have a shank that registers in the spacer to keep it running true.

 

[roeville]

I believe you can still buy R&P sets with the thicker ring gear to compensate for the spacer?