Re: Re: Cragar SS rims

Thanks, Dan. I certainly learned something new from reading this - I wasn't aware of this before. I'm also running a '68 GTX 8 3/4 in my '64. It was a nice easy swap for me.

Dave
'64 Belvedere 2DHT
318 Poly, Push Button Auto
Originally Florida A/C Car

From: Daniel McCormack <mcwheels@xxxxxxxxxxxxxx>
To: 1962to1965mopars@xxxxxxxxxxxxxxxx
Sent: Friday, December 2, 2011 8:39 AM
Subject: RE: Re: Cragar SS rims

Here’s a section of an article on 8 ¾ rear ends. The reason for the axle length problem is because of differences in sure grip and non sure grip thrust blocks prior to 1964.

Dan

Section 1: Thrust Block Variations

There was a difference in thrust blocks prior to 1964 that make center section

interchange, as well as axle interchange problematic. The thrust block, or "axle shaft

thrust spacer", it thr block that both left and right axles butt up against inside the center

of the differential. Prior to 1964, all open differentials used a thrust block was

approximately 1/8" to 1/4" thicker than units made after 1964. The Sure Grip thrust

block prior to 1964, however, was indentical to all 1964 and later Sure Grips and open

differentials. In 1964, the thrust block width was changed to match the Sure Grip thrust

block width.

This difference in thrust blocks between Sure Grip differentials and open differentials

required that two different axles be produced for each 8-3/4" housing manufactured. This

is true of all 1959-1963 cars with 8-3/4"s.

A 1964 and later differential, or any Sure Grip differential, cannot be used with 1959-

1963 rearends and axles originally equipped with an open differential. The original axles

must be machined or original Sure Grip length axles must be used.

From: 1962to1965mopars@xxxxxxxxxxxxxxxx [mailto:1962to1965mopars@xxxxxxxxxxxxxxxx] On Behalf Of Mike & Deb
Sent: Friday, December 02, 2011 8:05 AM
To: 1962to1965mopars@xxxxxxxxxxxxxxxx
Subject: Re: Re: Cragar SS rims

Nick,
I had the same problem with my 63 Savoy back in the 60's. Same solution. So I'd guess all the pre 65's need a shorter axle shaft to install a Sure Grip unit. The 65 and later housings must have enough adjustment range to allow for the Sure Grips' extra length. Does this sound correct?
Mike LeFevre

On Dec 1, 2011, furyus63@xxxxxxxxxxx wrote:

Damn, now I have to buy coffee. I can't make it out there so I'll have to send Rich in my place.

This has nothing to do with Crager SS wheels but those 30 1/2" axles can be a problem. My 63' Fury has the 2070539 housing using the 2070573 axle @30 1/2". This axle is made for a 741 case w/o Sure Grip. When I installed a new 742 case w/Sure Grip the axle was 1/16" to long. The 742 case requires the 2404050 axle @ 30 7/16". I shortened each axle by 1/16" and it flew...Nick

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