If you’re using a Sierra transmission is it strictly necessary to widen the tunnel to the rear of the cockpit on the drivers’ side, or is it only required when using an Escort axel?

The sierra builders will probably go into more detail in a minute, but I think the sierra diff is offset a little, they have different length driveshafts apparently.

It is not good for a propshaft to run dead true, the needle rollers do not revolve in the case as the are designed to, and wear out the case rapidly

Now you come to mention it I had noticed that the transmission wasn’t symmetrical, but didn’t know why. I was hoping to use the space to fit me in, but it’s prolly best to leave it as is.

Cheers.

I'm sure the sierra builders will say exactly how far it should be offset

I was under the understanding that diffs are not central cos the crown wheel assembly throws part of the diff to the side, and you get unequal drive shaft lengths.

I mounted my diff centrally. (sierra type). The big advantage was that it was possible to taper the tanny tunnel to the rear and get more ass / hip room towards the back of the seat.

The disadvantage was that I have to get one of the drive shafts modded.

The prop wont run 'true' as its slightly sloping downhill from box to diff.

It was once stated on here that diffs were offset as a vital aid to preserving the prop shaft - no one did put a reason forward for this possible myth?


atb

steve

The diff prop shaft flange can be mounted centrally because as Steve says it is the crownwheel offset that accounts for the different length prop shafts. The actual mounting points are all equally spaced either side of the prop flange axis.

I've reduced the width of my tunnel to 90mm between a & b but I'm using 25mm RHS for a & b which gives an outside width of 140mm which will:
allow the prop shaft to be fitted, (the UJs are a close fit past the k tubes but OK when installed)
allow the front mount on the diff, (120mm wide) to be attached to a & b

Using these measurements I do not have to widen the tunnel at the rear.

Cheers Mick

[Edited on 8/5/04 by Mix]

Mick, cheers. That's exactly what I was hoping for. Think I'll give it a go.