Help me pick a rear axle for Dad's car...

Posted By: MarkZ

Help me pick a rear axle for Dad's car... - 03/09/15 03:19 AM

Dad is building a 10.5:1 408ci roller motor for his Coupe and we're having some serious reservations about the 8.25 that is in the car now. The trans is a 727 and the car will be street driven mostly with 295 radials in the back; it will occasionally see slicks for track use. The motor will be pushing 500HP and the budget for the axle is $1,000 give or take. So far our options seem to be:

8.75: The original idea was to grab one out of a 66-70 B body as the flange to flange width is 55" vs the 54.34" of the original axle. Problem is finding one of these isn't very easy to do anymore.

9.25: I did manage to find one out of an early 80's Ram with a 5x4.5 bolt pattern, SG and 3.23 gear. All it would need is new brakes, perches, and to be cut down. Junkyard wants $150 for it.

D60: We're not opposed to it, but don't know what to look at for one that will require the least amount work to get it to fit. I assume it would need everything the above 9.25 would need with the addition of axles to change to the bolt pattern.

Thoughts? Thanks guys..

Posted By: RUNCHARGER

Re: Help me pick a rear axle for Dad's car... - 03/09/15 04:06 AM

If there is a place near you that can narrow a D60 that's by far the cheapest and best way to go. Get a truck one with either a 3.54 or 4.10, get a set of the correct length axles and the differential unit of your choice from Dr. Diff and have at it. The end cost will be the same as the 8 3/4 or the 9.25 by the time you fix them and you'll never do anything to the D60 after you bolt it in.

Sheldon

Posted By: RapidRobert

Re: Help me pick a rear axle for Dad's car... - 03/09/15 06:07 AM

Quote:

The trans is a 727 and the car will be street driven mostly with 295 radials in the back; The motor will be pushing 500HP and the budget for the axle is $1,000 give or take. So far our options seem to be:

8.75: The original idea was to grab one out of a 66-70 B body as the flange to flange width is 55" vs the 54.34" of the original axle. Problem is finding one of these isn't very easy to do anymore.

Thoughts?

There's gotta be the right width 8&3/4 somewhere (try local Cl in your/nearby cities). This'd let you change ratios later on if desired. 727 Auto/street tires I wouldn't be afraid of an 8&3/4

Posted By: draginmopars

Re: Help me pick a rear axle for Dad's car... - 03/09/15 06:14 AM

Since you are changing the rear
and may run slicks

You might want to look at "Wheel spacing"
left to right
So either set of wheels will fit with out rubbing.

I like the 80"s ford 3/4 ton rears

The tubes are thick almost a 1/2"
and 3" dia

watch out for the D-61,
pinion has alot of off-set.
Not a good gear selection

We just finished a Dana with Set up kit from Dr. Diff.
has 3.55 ratio, Tru trac unit
all new brake hardware, lines

ONLY, due to logistics
Moser narrowed the rear, welded on housing ends and spring pads

Posted By: Cab_Burge

Re: Help me pick a rear axle for Dad's car... - 03/09/15 08:51 PM

If you want to reuse the brakes off of the 8 1/4 on the Dana 60 that works very well

(these are off of a 8 1/4 I had) As long as you have the proper axle ends put on it

I use the Moser brand 8 3/4, Dana 60 ends

this dana 60 was out of a Van with 3.54 gears and a open carrier, I found a 3 sereis clutch type posi and converted it to 35 spline Dana axles

Oops, forgot to atttach the picture

Posted By: Steve Bryant

Re: Help me pick a rear axle for Dad's car... - 03/10/15 12:25 AM

8 3/4's are not hard to find. Last year I picked one up for my E-Body and cost me $200 plus the drive to pick it up.

Posted By: finadk

Re: Help me pick a rear axle for Dad's car... - 03/10/15 06:10 AM

I heard that Ford Explorer 8.8's are the right width and can be found with disc brakes. Cheap in the yards and a few gear ratio options.