8 3/4 Rear axle modification

[65 Valiant]

Ho folks,

this is my problem:

Car: 65 Plymouth Valiant-had a 7 1/4 rear end but will be changd into a 8 3/4 one.
I got a good 8 3/4 housing from an B-body. Now i had to narrow the housing that it will fit my axles and diff.

I bought my center section from Doctor Diff: "Nodular 489 case with US 3.55 gears, Eaton True-Trac, crush sleeve eliminator and 1350 yoke" and "Strange S/S 28" 30 spline".
He gave me the info that i have to cut the housing on 52 5/8". I did. We cut it near the middle because we want to use the old flanges.
We made our own sleeves to fix the parts correct together but the sleeves will not fix them in the correct position.

some pictures:







There is a nice article on: carcraft.com
They use a fixing tool or whatever.



Now my question: Who had done this,perhaps with the same probs and has an idea to fix the parts 100% correct?

We plan to build a backing frame from wooden plates or something else.
the vertical and horizontal measures must be correct!!!

BTW: rear wheels are: 8x15 steel wheels wit 255/60/15 tires
Rims have a 4,25" BS
I think i can use my old front and rear hangers without using a relocation kit and offset shakles, isn't it? Springs are XHD ones

 

['64 Cuda]

Don't know how many things are "set in stone" so to speak. You haven't said what brakes you plan to use. If you cut your housing to a stock A body width, use the B body brakes, and use the wheels you mentioned with a 4.25" backspace I don't think your tires will fit in the wheel wells. Even with a set of stock A body brakes, which are narrower, I'm not sure it would work.

I've crawled around under the back of my '64 Barracuda (same fender wells as your car) off & on for years trying to figure out how to stuff the biggest possible tire in the stock wheel wells. There's some pics of things (as well as some of my ramblings, LOL) here.

http://www.forabodiesonly.com/mopar/showthread.php?t=14745

Read it all because I went back & re-measured things a couple of times. You might also want to use this calculator.

http://www.rimsntires.com/specs.jsp

It's a really handy tool.

Currently my car has a completely stock A body 8 3/4" housing from a Demon. Stock brakes & all. As I have things figured, if I use the Mopar offset spring kit to move the springs inboard, I can fit a 255/60 15 tire with a 7" wheel with about 4 1/4" to 4 3/8" backspace or an 8.5" wheel with a 5" backspace. I believe this figures out to be a 6mm positive offset.

With your housing cut as you show it in your pictures you're in kind of a unique position. You can mount your housing in the car with the brakes in place, install the wheels & tires, and then adjust the width for a perfect fit. Once you determine exactly what you need you can then remove it from the car & weld it all up.

As far as making things perfect when you weld it, you look like you are on the right track. You need to make bushings to fit the axle ends to hold them in alignment with the bearings in the differential. They just need to slide onto the round bar you are already using.

The biggest problem I see is that in your pictures it looks like you might already have a set of aftermarket axles. If you do then you're sorta' stuck with things as they are unless you send them back or cut them down & respline them. If you have to use things as they are you'll probably have to use a set of wheels with a different offset to fit the tires in the fenders.

Or there's always air shocks!:toothy10: