Race Engine Forum UK

On my homebuilt Locost Car (you can find it at http://guy-croft.com/viewtopic.php?t=422 ) I used an old 124 sport Coupe rear axle. This winter I bought an LS differential and today aI was trying to mount it to the car.

My new LS differential was 193 mm long (the old one 206 mm) se pictures
The new differential had 68 mm from bolt to bolt and the old one 73 mm.

Could someone tell me which car I should take the rear axle from ???

The old differential has 10 grade bolts and the new has 8 grade bolts ???

Hi

The 193/68mm diff is Fiat 124 Spider <78.
I can not tell you where the bigger diff comes from, I thought the coupe ones was identical. Maybe the previous owner swapt it?
But I heard that the early Fiat 125 had a similar, but bigger diff as the early 124, you could ask the Fiat 125 racers in the forum for advice.

Have you considered just to exchange the LSD diff's body into yours?

Basically you need to check:
inner diameter of crownwheel
bolt pattern and bolt size of crownwheel
diff body side bearing outer diameter and distance inbetween
and of course the splines, just use your halfshafts to check, there should be a tight fit.

If all is identical, you can put the your old crownwheel onto the new LSD diff-body mount it with 10grade bolts and adjust the bearing preload and distance of crownwheel to pinion. I can supply you with the data and/or workshop manual.

Thomas