Rear diff advice and needed

[JDW3696]

Hello all. Need to replace my rear diff but know nothing about them. Are they interchangeable with 740 and 940 and are there any upgrades worth doing while I replace it ie lsd.
Lastly, anyone selling one?
Thankyou
All the best
Joe

[heckflosse]

swapping a crownwheel and pinion is not too difficult but they need setting up properly.Might be easier to swap a whole axle. As far as i know, 940/240 diffs are the same.Things like speedo sensor ring might differ though.
dont know about lsds, there are threads about g80 lockers on here.

[JDW3696]

Thanks very much for the reply. I'll get looking

[230ina245]

Hi
If you're just swapping the differential, it's not too difficult. You need to take the old diff out, remove the bearings on each end and take off the old shims. You replace the shims on the new diff with the old ones (in the order they were on the old diff), swap the crown wheel, new bearings & that's it. You would be unlucky for this to give you any axle noise. Whatever you do, do not just replace the diff without changing the shims over. You also need to swap the crown wheel even if the "new" one is the same ratio, as they are made in pairs with the pinion.
It's one of those jobs where you need to replace everything you take off in the same way & orientation that they were. Also if you do it with the axle in car, I would recommend cleaning the diff housing before you start. It's a very oily, dirty job & you need everything as clean as possible. Do it properly & you shouldn't have any problems. Try & take short cuts & you'll probably be doing it twice.(yeah - don't ask)
Check the tone ring on your diff before changing the new one - I found the rings were the same & didn't need to change them. Also get the diff cover with the new diff - the position of the speed sensor may vary slightly.
I would also recommend a G80 locker from a 940 turbo from 1991 on, a 960 from 1992 on, or any 940 after 94/95. You can tell a G80 locking on a car if both rear wheels are in the air. If you just turn the wheel it will behave like an ordinary diff - the opposing wheel will go in the opposite direction. You need to jerk the wheel around quickly for the mechanism to kick in, then both wheels turn in same direction.
These are great in slippery conditions - snow or mud etc. Unless you have a powerful engine or are regularly doing some form of motorsport where traction over 25 MPH is important (eg lifting or spinning a wheel in corners) a proper LSD isn't worth the cost.
Tim

[BrianH]

I changed mine at 550k miles

Then I found there are 3 different pulse rings depending on age starting at 24 No., then 48, and 96. These need to match the speedo.

Mine went from 24 to 48 and the speedo had to be modified. This was done by a company in Wales specialising in this sort of thing

BrianH 245 GL 1989 LPG 740k

[classicswede]

If you have the electronic speedo you do need to make sure the tone ring matches.

The G80 is a low speedo locker and works well at slow speed in a field or when you go off the edge of a lane passing another car.

There are two types of LSD available

Torsen geared LSD

https://www.classicswede.co.uk/Quaif..._20193202.aspx

and the clutch type LSD

https://www.classicswede.co.uk/Gripp..._18214340.aspx

[JDW3696]

Originally Posted by 230ina245

Hi
If you're just swapping the differential, it's not too difficult. You need to take the old diff out, remove the bearings on each end and take off the old shims. You replace the shims on the new diff with the old ones (in the order they were on the old diff), swap the crown wheel, new bearings & that's it. You would be unlucky for this to give you any axle noise. Whatever you do, do not just replace the diff without changing the shims over. You also need to swap the crown wheel even if the "new" one is the same ratio, as they are made in pairs with the pinion.
It's one of those jobs where you need to replace everything you take off in the same way & orientation that they were. Also if you do it with the axle in car, I would recommend cleaning the diff housing before you start. It's a very oily, dirty job & you need everything as clean as possible. Do it properly & you shouldn't have any problems. Try & take short cuts & you'll probably be doing it twice.(yeah - don't ask)
Check the tone ring on your diff before changing the new one - I found the rings were the same & didn't need to change them. Also get the diff cover with the new diff - the position of the speed sensor may vary slightly.
I would also recommend a G80 locker from a 940 turbo from 1991 on, a 960 from 1992 on, or any 940 after 94/95. You can tell a G80 locking on a car if both rear wheels are in the air. If you just turn the wheel it will behave like an ordinary diff - the opposing wheel will go in the opposite direction. You need to jerk the wheel around quickly for the mechanism to kick in, then both wheels turn in same direction.
These are great in slippery conditions - snow or mud etc. Unless you have a powerful engine or are regularly doing some form of motorsport where traction over 25 MPH is important (eg lifting or spinning a wheel in corners) a proper LSD isn't worth the cost.
Tim

Thanks very much