Eric-86sc

iTrader: (18)

I tried a search and couldn't really find what I need. I have a 1989 pbr 9 bolt, a drum 9 bolt, and a drum 10 bolt.

Heres my dilemma
1. Are 9 bolt and 10 bolt axle shafts the same length and spline cut. Basically will a carrier that accepts a 28 spline 10 bolt axle shaft accept a 9 bolt one.

2. Are there any conversion brackets out there to convert a drum 9 bolt to rear disks.

Basically I want to have an 8.8 built after finding a killer deal on getting a housing made. What i was thinking was using the drum 9 bolt for the f body donor since i wouldn't have to track down 28 spline shafts and they are bolt in axles instead of c clip. I then would want to swap the pbrs on the new 8.8. Does this seem like feasible plan or should I just track down the correct 10 bolt 28 spline axle shafts and disk conversion brackets?

Base91

iTrader: (1)

9 and 10 bolt parts are not interchangeable. Yes there are brackets for conversions. What's wrong with the 9 bolt with PBR brakes for what you want until you get your killer deal? 10 bolt stuff is cheaper and easier to get than 9 bolt.

Eric-86sc

iTrader: (18)

There is nothing wrong with the nine bolt I'm using now. It's low mileage 3:70 gears w/ pbr brakes. I just want something stronger so it won't break at the track with slicks.

What I'm trying to do is utilize parts I have to avoid tracking stuff down. The 8.8 I'll be using is 28 spline. I think I could use the drum 9 bolt I have for an axle tube donor because it already has 28 spline axle shafts. I know 28 spline 10 bolt shafts will work but I don't have a set right now. If 9 and 10 bolt axle shaft splines are cut the same then they should work for what I need. I also want to keep rear disk brakes but if disk brake conversion brackets are unavailable or ridiculously expensive, I'll just scrap the idea of using the 9 bolt for a donor and track down 10 bolt stuff I know for sure will work.

Base91

iTrader: (1)

I get it now. You want to use the 9 bolt, 10 bolt and 8.8 parts to build a rear. Let us know how it goes.

big gear head

I'm pretty sure that the splines on the 9 bolt axles are not the same. I think I have tried to put a 10 bolt axle in a 9 bolt differential before and it wouldn't fit. I can check when I get home if I can remember. I have a 9 bolt differential on the bench and a 10 bolt axle.

Eric-86sc

iTrader: (18)

I'll make a thread when progress really gets going.


If you could check on the spline differences that would be great. That would tell me right away whether to abandon the idea of a 9 bolt donor for this project.

big gear head

I stuck the 10 bolt axle in the 9 bolt differential and it fit. I don't have a 9 bolt axle to put in a 10 bolt differential to see if it will fit. Sometimes it will go one way but not the other.

sofakingdom

iTrader: (1)

Not one single internal 9-bolt part is interchangeable with its 10-bolt equivalent that I know of, with the possible exception of the little 5/16" head screw through the cross shaft.

That means, not gears, not carriers, not bearings, not seals, not axles, not backing plates, not ANY part.

Externally however, once you get outside the housing, they are the same as far as bolting into the car, brake system against brake system.

AFAIK nothing about the Frod rear end is interchangeable with either of the GM rears with the possible exception of that same screw.

There's more to the "axle spline" deal than the # of splines. Length, diameter, bearing configuration, seal details, C-clips, ... the list just GOES ON AND ON as to what potential there is for variation. Don't hallucinate that just because the spline count is the same, that ANYTHING else is.

What people usually do for disc brakes on that rear in other cars is, get the brakes off of a 90-something Frod Exploder. Something around 96 - 97 is the ticket IIRC but I could easily be mistaken about the years.

Eric-86sc

iTrader: (18)

The build is being done by cutting the axle tubes off an f body rear and having them welded on the 8.8 center section. I know a 28 spline 10 bolt axle shaft will slide into a ford 28 spline carrier which is what I need for this project. I just needed to know whether the splines on a 10 bolt and 9 bolt are cut the same. If they are then I know the 9 bolt axle shaft will slide into the ford carrier making a 9 bolt a possible donor for axle shafts. 10 and 9 bolt part comparability doesn't really matter for this build.

Eric-86sc

iTrader: (18)

https://www.thirdgen.org/forums/tran...xle-build.html

This is basically the build I will be doing but with a different torque arm setup