I'm just wondering if there's an optimum angle for my Sierra LSD diff to be mounted.

At the moment my plan is to mount it such that the plate that the prop mounts to is vertical- is this ok?

Cheers,

James

Hi James
Thats the usual way to mount them, but i don't think its critical.

Wadders

I suppose in an ideal world the front flange nut on the diff would be inline with the gearbox output shaft.

Just nipped to the garage and tried mine, oh ffs, you would think the diff flange would be slightly tipped up to match with the g/box which is higher (with me?) but no, pointing down about 10 degrees off vertical. do you think I could slot the two top(or bottom) mounting holes to make it adjustable??

The diff and gearbox should be parallel to each other but not in line. There should be an angle between them or the u.js will knacker up in no time.

yours, Pete.

don't know the precise angle, but the crankshaft is supposed to be angled downward towards the rear. The input to the diff is supposed to be agled upwards towards the front, at the same angel to put them parallel.

On some carbed engines this angle can be seen if the engine is mounted such that the float bowl of the carb(s) is level. If the carb is level when properly mounted on the engine, then the crankshaft will slope downwards toward the rear. EFI doesn't have a floatbowl, so seeing the slant is not so easy.

dave

The propshaft should be angled +/- 3º (degrees)

João

The diff should be level so the flange is straight up. Check your driveshafts on the sierra, is one longer than the other?. Is the diff off centre and the engine on centre to give the angle on the propshaft?.

yours, Pete.

lots of confusion here. The propshaft will tolerate 4 degrees of movement of the centre line. Universal joints are not constant-velocity type joints (which is why they are not used on front wheel drive cars) The flanges of the gearbox must be on the same vertical plane. I.e. if one is straight up, the other must be. (or both at 2 degrees etc). The unequal length drive shafts are to compensate for the internals of the differential, not to allow angle. Ideally you want the drive shafts to be horizontal at normal ride height, therefore allowing placement of the diff. Any angle in drive shafts or propshaft will absord engine power, and we don't want that now do we!!!

Hi James,

Couldn't figure out how to post it here so have e-mailed you an attachment. Hope it helps some,

Cheers,

Martin

Hi Martin,
Thanks for that- seems quite interesting at a brief glance- will study later when I'm not at work!

Cheers,

James