57 rearend in my 56?Is it better than the 56??

oldfart · Nov 23, 2010

If I understand correctly the 55,6 rearend has no drain plug on the bottom of the rear end housing.
The rear end on the 56 has a drain plug.I ran the #s (GM 14,3725899)on it and it comes up as a 1957 non-posi stock rearend.
The rear springs appear new also although the rubber bushings for the springs are pretty rough.
Keeping in mind that the 56 has been passed around and around for probably the last 20 years,maybe one of the POs had a 57 rearend layin around & used it because the original was junk. OR is the 57 rearend superior to the 56?

acardon · Nov 23, 2010

It's easier to change the oil in the 57. That's about it.

The axle bearings are different so if you need a bearing, you have to order a 57 bearing.

angs1957 · Nov 23, 2010

I did not realise the 56 rear end did not have a drain plug tried looking in the w/shop manual could not find a clear enough pic, the closest i found was this one

http://www.trifive.com/garage/56 Chevy Assembly Manual/5-5.gif

Pops @ Tri-5.com · Nov 23, 2010

OF....I don't see a drain plug....Is it my eyes or a bad angle for me?

The ring gear in the 55/56 is thinner....So, I would say maybe the 57 is more beefier....(57 on left ande 55/56 on right; both 3.70 GR)

Earlc · Nov 23, 2010

case is stronger

if you pull the dropout ( center section ) out and compare with a 55/56 you will see that the 57 has beefier or thicker supports in the housing ( for lack of better words )

oldfart · Nov 23, 2010

557B210 said:
OF....I don't see a drain plug....Is it my eyes or a bad angle for me?

Dave,have Sherri check it for you.Its there.:anim_25:

flamed55 · Nov 23, 2010

drain plug

There's a drain plug there, making that a 57 rear end. As was already mentioned bearring size is different. I once had a 55 that had a 57 rear end and I didn't know that till I ordered bearrings for a 55 and they were to small.
Jim

56owner · Nov 24, 2010

Thicker Gears ?

Hey guys isn't ring gear thickness actually based on what the gear ratio is? deeper. Thats why ring gear spacers are used for 4:56 & deepper gears.

Pops @ Tri-5.com · Nov 24, 2010

56owner said:
Hey guys isn't ring gear thickness actually based on what the gear ratio is? deeper. Thats why ring gear spacers are used for 4:56 & deepper gears.

See this post at CT for clarification:http://www.chevytalk.org/fusionbb/showtopic.php?tid/252789/

57 rearend in my 56?Is it better than the 56??

oldfart

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