Axle Options? Early Trans into Late Chassis

[Jim2]

I need some input from anyone who is literate with axle fitment.

I'm installing an early 915 box with a corse spline lsd into a 1986 chassis. The trans axle flanges are not compatible with the CVs on the 86 chassis, and the original 86 trans axle flanges are fine spline. The early 915 box I'm using has 108mm 4 bolt flanges.

After searching and reading numerous threads regarding fitment issues which other people have encountered it appears there are no corse spline flanges which will fit the 86 style CV so I'm assuming my only way around this is to swap out the axle from the trailing arm. If this is the correct path, can you advise what year range axle assemblies I need?

Will there be any compatibility issues at the wheel hub?


Stumped,
Jim

[Grady Clay]

Jim,

What size (OD) are your CV joints on your ’86 chassis – 100 mm with six M8 bolts or 108 mm with six M10 bolts?

If 108 mm with six M10 bolts, you can modify the 4-bolt (M10) flanges by drilling through the provision for the 10 mm roll pin and installing two M10 threaded inserts in each flange.
There is an issue of the end-cap interfering with the flange.
I recently posted this technique.

If 100 mm with four M8 bolts, there are 100 mm, 6-bolt, course-spline flanges from 915s starting in 1976 through 198?.

If you have 100 mm CV joint axles (sized for the type 923 912E) and want to change to 108 mm CV joint axles, you will need the axle assemblies and the 108 mm outboard stub axles.
You can modify your 108 mm, 4-bolt flanges as above.

Best,
Grady

[Jim2]

Thanks for your feedback Grady.

I'm on my I phone and don't know how to post pictures from it, however I can confirm that both the early flanges as well as the 86 CVs are 108mm with m10 hardware. I had thought about drilling the two stud holes and using nuts on the back side until I realized that the tin cap on the 86 CVs collides with the early flanges.

You mention a method to deal with this. I likely missed that info among the abiss of posts I read.