V8 Cabrio differential

[norman ball192]

My supercharged 3.9 V8 Cabrio is going through drive shafts at a rate of knots. The Sierra 3.9/1 diff uses I believe the tryptich drive shafts, and the power output is just too much, bending the drive shaft spiggots which causes vibration prior to failure. I want to fit a stronger type of drive shafts, does anyone have any suggestions for this without having to change the back end to the larger Granada diff with disc brakes???

[jon_cox]

Re: V8 Cabrio differential

Hi Norman,
Sounds like a great engine. Must be a blast to drive.
Speak to Mark at GKN Driveline - motorsport division. He will be able to advise you.
http://www.gknservice.com/global/motorsport/contact.html
Or these guys are a customer of mine, but I do not know much about there motorsport side....
http://www.ctgltd.co.uk/page/motorsport/42

[djj_engineer]

Re: V8 Cabrio differential

Hi Norman
What about Cosworth 2wd shafts will they fit?
Have you thought of checking the rear tracking while you are looking at the front. We havn't found one that is correct yet and our record is 17mm toe in. Plays havoc with the tyre wear!!!!

[Mike]

Re: V8 Cabrio differential

Norman
Aere your drive shafts the Non Lobro type?
I beleive it is possible to change the drive shafts from the non Lobro to Lobro, which are thicker in diameter. Simon gregory has done the reverse, fitting lobro joints/shafts to a Disc brake set up, so presumably you should be able to do the reverse?
What is the diameter of your drive shafts?
have a look on Simon's site:
http://www.flickr.com/photos/marlin_bmw_cabrio/264157847/in/set-72157594349599658/
These are non lobro thinner shafts. I believe you would be able to remove your shafts and joints, slde the diff drives out of the diff, insert the ones for the lobros and swao your drive shafts relatively easily with changing your diff or brakes.
The guy who will know for sure is John at Kit-fit. He is very knowledgable on his Fords. His number is 01636 893453.

[Cabrio_Simon]

Re: V8 Cabrio differential

Hi Norman,

When installing the BMW M20 engine I did a complete axle swap (i.e. diff, driveshafts, brakes, suspension arms etc.)as it was easier than trying to upgrade the various components and avoided the problem of parts not fitting properly.

My car originally had a 7" diff and drum brakes which I replaced with the 7.5 inch (stronger) diff and disc brakes. I seem to remember the driveshafts were also thicker too.

Complete Sierra disc brake rear axles come up for sale on Ebay (where I got mine from) quite often and are reasonably cheap to buy, overhaul and install.

For info, my Cabrio chassis was pre-drilled to accept either 7" or 7.5" diffs so the swap was quite straight forward.

Hope this helps & good luck

Simon