Impalas.net banner

1 - 5 of 5 Posts

·
Registered
Joined
·
45 Posts
Discussion Starter · #1 ·
Hey Guys,

I need help in finding a 21 spline rear axle. I need to replace my rear axle on my 1963 Impala and thought it was going to be a 17 spline, but turns out it's 21 splines. Having a very hard time finding a 21 spline rear axle. Any recommendations of where to find one would be much appreciated as I don't want to have to replace the whole rear end because of the # splines. Thanks in advance for you help, I really appreciate it.

Best,
Jrock63Impala
 

·
Registered
Joined
·
1 Posts
Hey Guys,

I need help in finding a 21 spline rear axle. I need to replace my rear axle on my 1963 Impala and thought it was going to be a 17 spline, but turns out it's 21 splines. Having a very hard time finding a 21 spline rear axle. Any recommendations of where to find one would be much appreciated as I don't want to have to replace the whole rear end because of the # splines. Thanks in advance for you help, I really appreciate it.

Best,
Jrock63Impala
I might have one. I'll have to check the spline count. These should be the same for 62-64 I believe.
 

·
Registered
Joined
·
404 Posts
I believe the only GM axle to use 21 splines was the 7.5". That would not be a stock rear axle for your car. Do you have a drop out center section to your rear axle? If your axle has been changed it may require a different size axle length wise than what would be required for a stock 1963 rear axle.
 

·
Registered
Joined
·
1 Posts
I agree. I've swapped 17sp axles out of any year into my 62. Had to: my 1970 406sbc 12.5;1 with NO2 use to eat these like Cotton Candy!

But like most of us running these cars in the 70's" and 80's, I never had the money and sourcing 9" Fords on the internet simply wasn't in the cards, so out to the pull and pay I went!
The tube in my car is out of a 64 (again a direct swap). My P-case is a 59 with 5:57 zoom gears.
Move up to 2020: I'd love to order a set of 28 Spline axles in our 58-64 dimensions and buy / swap out either the side gears or better still a locker set. What I don't know is the possibility of swapping in the 8.2 locker designed for the 64-72 midsize cars into a 55-64 "Arm a Steel" P-case?
This kind of upgrade is common for HO72 / 3/4T Chevy C20's where guys install the really strong 14 bolt pieces...

Back to the post: if you can count to 21 (LOL), Are your splines overly thick (like 1/4" wide) or are they razor thin?
21 thin splines in diameter would put the the input diameter around 13/16" of an inch! If they are 21 thick splines I'd guess your axle assembly is out of something A LOT HEAVIER and fitted to your 58-64 car Like a Cadillac or Buick?

REGIS: the 55-64 Chevy Full Size Cars, Corvettes and 62-63 Chevy II used different wheel bearing diameters and might vary in lengths, but all came from the factory with 17 splines. Final Answer!
 

·
Premium Member
Joined
·
13,148 Posts
1957-'64 BOP rear end would be the answer if you can find one on the internet. They are rare today and as such expensive. An Olds rear went under my old '53 powered by a 409 because i kept breaking the Chevy rear end so frequently I got tired of replacing them (after replacing the rear end I then I started shedding teeth on my Borg-Warner T-10 four speeds).

I personally chose to run a Dana 60 over the Ford style aftermarket nine inch rear (no one, not even Ford, runs a stock 28 spline Ford nine inch). In fact I get my Dana sixty cores out of one ton Ford pick-ups and cut them down to run under a car because Ford dropped the nine inch decades ago as being too weak.

As to side gears the Chrysler 8¾ inch rear side gears can be shaved to fit in the Chevy case to get a stronger gear to fit your 21 spline axle. I have an old Hot Rod or Popular Hotrodding article I scanned I could send you via e-mail detailing the procedure since I no longer have the ability to share photos since Photobucket went commercial.

Big Dave
 
1 - 5 of 5 Posts
Top