55-57 chevy posi question

I know the carrier is different from open to posi; what about the pig? I have seen some with the "P" cast on the right side, do you have to have that or will a plain pig work? Also, I found on an old HAMB thread that the posi axles are shorter by 1/8 in.; is this true? Thanks for your help, Joel

 

If you are talking about the housing...Yes you can install a posi in one. Some need a tiny amount of grinding. Yes the axles are shorter for a posi.

DZAUTO on the chevy talk forum is a master at these old posis check them and do a search

 

I believe 57 thru 62 are the same. Someone correct me if I am wrong.

 

read this. DZAUTO is a wealth of knowledge
http://forums.corvetteforum.com/c1-...eat-of-converting-56-62-non-posi-to-posi.html

 

The 55 & 56 axels need to be shortened. Check out www.oldcarmanualproject.com . If you search under Chevrolet Positraction, a list of factory service bullitins will show up. Servicing the 1957 Positraction shows the entire procedure of installing a Posi in a 55 - 56 center section, including shorting the axel shafts. Also, 1957 (and 1958 I think), Posi cases DID NOT have a P on them. My 57 is an original Posi car, and it does not have a P on the case. However the gear ratio code that is stamped on the case shows that it is an original 57 Posi, with a 3:36 gear set. It originally had a TurboGlide, too.....Fortunately it has a Muncie 4 speed now.

 

what torkwrench said--my 57 Fuely has a 3:70 posi with no P on the case--yes axles for a posi are about 1/8 shorter

 

Thanks, guys, this info is a big help

 

????? I just pulled the posi outa my 56 and put some taller NON POSI gears in (in a different carrier) and the axles fit just fine,what gives??

 

Its going from a non posi to a posi that the axles are to long.. And the long axles will fit but will **** it up.

 

If a modern Eaton posi is used, the axles will not need to be shortened.

 

posi was new for 57'