Thread: Differential conversion

I know this topic has been discussed in the past but can't find all the info I think I need and the availability of certain driveline parts seems to have diminished a lot recently.

The front diff on my late 89 RRC 3.9 auto is very worn and I want to rebuild it and also convert it from 10 spline to 24 spline. I did this with the rear diff and ran into complications using a 2nd hand Discovery 1 diff which had a different stud profile securing the diff to the axle case. Found the best way was to use the original casing and transfer all the D1 gears into it. Plus 24 spline axles.

I want to do something similar on the front diff but need advice about which 24 spline axles will fit and what CV joints will fit and go straight in.
Also how to identify which Discovery models can serve as donor parts.

As it's difficult to source a 2nd hand diff locally and anyone willing to freight it to the Gold Coast, then the reconditioning of same, I've considered getting a reconditioned diff from Ashcroft which works out at around $1620 with shipping and GST.

Any advice appreciated.

Hi mate, I'm going to jump on the bandwagon looking for the latest advice on the best conversion as I've just blown my own front diff. Broke the pin, lost one of the spindles sitting in the bottom of the housing and chewed the crown wheel to pieces.

So with that much broken it's time for me to do an upgrade. Looks like Ashcroft gear is the way to go on reasonable availability these days? Not sure I want to go the complication of air locker on the front and the ATB looks a good bit of kit.

Of course that means upgrading to 24 spline half shafts. And I might as well change the ratios on the diffs seeing as I need the crown/pinion set for at least one of them... the dollars are adding up quickly...

I think I can keep the 23 spline 606665 CVs I already have with the 23/24 aftermarket half shafts? Honestly I would be much happier blowing the CVs over the diff centre or the LT230, so if I can keep those stock that would work well. Unless someone with experience tells me otherwise on the fit-up?

Originally Posted by aRRon

Thanks Red90.
Not looking to make anything stronger just to get a front diff back to good condition and knowing that the 10 spline axles are no longer available, not even overseas as searched when I did the rear diff.
24 splines take you into the later Discovery models and new parts still available

As it turns out I have a perfectly serviceable pair of 10 spline front half shafts I'm not going to need for much longer...