A-body 8 3/4 rear, redrill small bolt to big bolt?

-
migsBIG

migsBIG

Well-Known Member
Joined
Aug 15, 2007
Messages
1,301
Reaction score
231
Location
San Jose,CA
This is my first time posting a question here in the tech section, so hi to all and hope to learn something.


Just picked up a 1970 dart 8 3/4 rearend that was pretty much fresh and ready to go, only problem was that the big bolt adaptor I was going to use won't work with the wheels I have. I remember a few guys who took their stock small bolt axles an drums down to a shop and had them redrilled for big bolt pattern. They drove well and never had any problems. Would be alot easier than buying all new axles, bearings, studs and brake drum assemblies. Since the car is only getting a 300hp 340, I won't have to worry about parts brakage.

Has anybody done this or offer some helpful advice?
 
I have a drill jig, I use to drill axles/hubs and drums to the 4 1/2 incxh bolt pattern. I have had zero problems. I do recommend using 1/2 inch studs that screw into the axle flange. That way you drill a smaller hole, then would be required for press in studs, and allow more "meat" to the other holes. It is critical to have the holes drilled and tapped on the "exact" correct bolt circle, and square to the flange.
 
I have the same problem im intersted in drilling my axels also . i live in swst fl.if charrlie s is interested i would like mine done will pay.you can contact me at 941-255-0970.
 
If you have small to big bolt pattern adapters in hand you could knock the studs out of one and use it as a pattern / locater.
 
There is a reputable source here in my erea that builds rearends, so I would probably use them. They have build a bunch of rearends for locals and had no problems with them.
 
When i blew up my 7 1/4 (which had bbp) and i got my 8 3/4 it had sbp. I took the backing plates off of my 7 1/4 and they've been working great!
 
73golddusterkid said:
When i blew up my 7 1/4 (which had bbp) and i got my 8 3/4 it had sbp. I took the backing plates off of my 7 1/4 and they've been working great!
Click to expand...

I wondered about that. I have my brakes totally rebuilt on the 7 1/4 so if this works I can simply switch over to the 8 3/4.
I didn't know if they would match and bolt up or not.
 
Oklacarcollecto said:
I wondered about that. I have my brakes totally rebuilt on the 7 1/4 so if this works I can simply switch over to the 8 3/4.
I didn't know if they would match and bolt up or not.
Click to expand...

i had both axles in my garage and was looking and decided to try, and it just so happened to work. I've had the swap done for a few months now and haven't had a problem.
 
I am thinking of buying a LBP 8 1/4 SL and wondering if anyone has ever redrilled LBP to SBP. Wouldn't be an issue except I just bought the SBP ralley wheels and SBP disc brake conversion, and have it all in my hands.
What to do, what to do???????
DR
 
i've heard of guys doing this before and having some luck with it. I also have heard that it weakens you axles quite a bit, but i'm not positive on that. But you say you're putting in no more than 300 hp. so i wouldn't worry about it. I'd just give it a try and if they break, owell then you can buy new ones. no hurt in trying.
 
I have heard that all adapters are bad news..are there any good ones out there ? It would shurly make new rims a heck of a lot cheaper.

ian.
 
You must log in or register to reply here.
-

Back
Top