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advice on sierra differential..please
novicebuilder - 20/4/13 at 10:11 PM

I am building a Haynes roadster. I have just removed the differential from my 1992 Sierra donor car (2.0 ltr DOHC with MT 75 gearbox with all its challenges) and the differential is wider than the one shown in the book (donor car had rear disc brakes). I have adjusted the support brackets and got it fitted. However whilst the differential is centrally fitted, the centre line for the propshaft is 7mm off the centre line. Does this matter? I know the prop shaft will have joints to allow for change in angle of the drive shaft. should I make sure the prop shaft end of the differential is exactly central or is 7mm off centre line acceptable. Grateful for expert guidance, please.

loggyboy - 20/4/13 at 10:17 PM

I believe its better if there is a slight angle as it allows the joints to move.

Either way 7mm is absolutely fine.

snapper - 21/4/13 at 07:00 AM

Drive shafts are of different lengths so whilst the input may not be central the out puts should also be offset
Do a dummy fit of the shafts, uprights and wishbones
Sounds like you have a 7 1/2" diff which I thought only the Cosworth and Granada used, that said Fords were not averse to using what ever they had left in the parts bins when they came to the end of a model run

neilp1 - 21/4/13 at 10:25 AM

quote:
Originally posted by snapper
Drive shafts are of different lengths so whilst the input may not be central the out puts should also be offset
Do a dummy fit of the shafts, uprights and wishbones
Sounds like you have a 7 1/2" diff which I thought only the Cosworth and Granada used, that said Fords were not averse to using what ever they had left in the parts bins when they came to the end of a model run


On my 1990 sierra it was a 7 1/2" diff.

plentywahalla - 21/4/13 at 01:11 PM

quote:
Originally posted by snapper
Drive shafts are of different lengths so whilst the input may not be central the out puts should also be offset


Not necessarily.

I have mounted my diff centrally and used two left hand (shorter) Sierra half shafts. This is partly to reduce the track from the Sierra original, and also to facilitate my inboard disc DeDion design.



I got exchange shafts with cv's. I ordered them separately and they never noticed that the second time the returned shaft was a different length!

I should add that the diff is central about the output flanges, which is not the same as being central about the mountings. As said, it is beneficial to have a slight offset in the propshaft flanges as it makes the needle bearings work and reduces wear. The flanges must still be parallel or you will get vibration.

[Edited on 21/4/13 by plentywahalla]