8 1/4 swap

[65Vart]

Hey guys , money is tight and I might be able to get an 8 1/4 4:10 SGrip to replace my time bomb 7 1/4, instead of the 8 3/4 I really want..everybody has heard that one before right.
My question is
1. Will I have to cut my drive shaft to fit this? I just got a brand new one with my new rebuilt tranny.
2. Will my brakes (9") fit this set up (for now).
Any help (tips) would be appriciated......never had to do this before..just changed a lot pumpkins on 8 3/4s,,a lot easier.

 

[moparlee]

I doubt the brakes will work, cause of the wheel spacing won't be the same. Any yes, I had to shorten the driveshaft. The cool thing is the 7 1/4 rears from the 80's have the 10x 2 1/2 shoes and that brake hardware will fit the 8 1/4. Done it. Heck the 9 1/4 rear brakes will fit the housing also...........get the late 70's early 80's with the 4 1/2 pattern and the brake hard will fit off a truck. Some of those were 11 by 2 1/2 stuff. Done that also.

If you have lots of go get lots of woa...................if you are going to get different backing plates and drums and all the hard ware go bigger.

 

[66dartgt]

I agree with Lee - you'll need to shorten the driveshaft maybe 1 inch. Depending on your driveshafts length maybe not at all. Take your measurements to a driveshaft shop and tell them what you have and what you want.

By all means switch to the larger brakes, 10 x 2.5 minimum would be my recommendation. As Lee points out - these are virtually interchangeable between any and all mopar rear axles. Besides - you'll need the 4.5 bolt circle anyway on the 8 1/4 axle so why not get it set up the way you want it. If your car already has the smaller bolt circle - now is the time to change it, your old small bolt pattern brake drums wont work anyway !

I'd switch to the 70's design for the brake hardware, readily available at most parts stores. Reuse the parking brake stuff from the 8 1/4, adapt the 7 1/4 emergency brake cables, and you are good to go !

 

[rumblefish360]

I popped on 11 inch backing plates and all the hardware from a '78 Cordoba onto my 8- 1/4. It was a snap. This is surely well worth the time and money doing this.
Take the 9 inch stuff and use it as a anchor. It's worth the wait IMO.

 

[Orv Grote]

65Vart. Here are the EXACT measurements you need to shorten your
driveshaft. 7 1/4 is 10.09" centerline of axle shaft to centerline of
rear u-joint. 8 1/4 is 11.69. Shorten your d-shaft 1.6". Info. from
www.440magnum-network.com

 

[65Vart]

Thanks everyone ...........great info/bunch of stand up guys on here salute: