would it be easier and cheaper to have new locking gears put in my existing diff, of purchase a whole new diff? the reason i ask is for my eta m2o swap, and what gears should i run? 3.60's-3.70's...
thanks
Jesse

I am personally running 3.91 LSD diff in mine and love it. I think that combined with the m20 would make a quite fun car to drive. Also the price thing depends on what you plan on doing with the car. If its a track car only then I would say just weld the diff you have depending on what kind of gearing you have. If its a dd then you should just look for a new diff it'll be cheaper than putting an LSD in your existing diff.

I currently have a 3.91 LSD in my '82 with a modified m10. I find the 3.91 too low, I run out of rpm way too quickly in first gear. A 3.64 gear would be better for me and I'm sure with a m20 you will find the same thing. The 3.91 was used to get the car moving when the 1.8L engine was used. The 2.0L cars came with the 3.64. I think the automatic cars ran a 4.10 rear gear.

There are no commonly available "locking" gears. The OEM was limited slip using clutch disks. There is at least one aftermarket differential available but it's big $$.

If it's a pure track or autoX car you need to gear it for the best performance on the track you run and that's NOT the same gears you would run on the street.

ken

1.8's with the auto had 3.64, Ken (and probably 2.0's as well, I'm just not too sure). Thats to make up for the lack of an overdrive. Any 4.10's you see are coming from the old 1600, or some of the later model small cars had some low gears that can be swaped in (down to 4.44 I think). I would be looking for at least a 3.07 (thats what the 323i had right?) or higher for an eta swap, you'll be running up the revs fast.

hijack.... I have a diffy out of an auto tragic. Is there anything that can be done with it?

There are lots of things you COULD do with it... what do you have in mind??

ken

I've always read that the 323i had a 3.45:1, as mine did. But the LSD I found came out of an automatic 323i and it's a 3.64. I'm fairly certain that it was OE in the donor.

mine will be a dd. no track, no auto-x