Checking Diff Ratio & What Ratios Were Available

[griffithbuilt]

Hi all,

It has been a long time since I was on the First Fives boards. My first car was a Hardy & Beck prepped '77 e12 530i which was lost in a wreck. I have since ended up with a '75 3.0 CS, a '69 2500, a '73 Bavaria and an '88 535is Turbo.

Anyway, my Bav has a 528i engine/trans combo with Lambda L-Jet and I started doing work on it today - it's been on the back burner for a while.

I haven't been able to determine the gear ratio of the open differential and I'm curious of the proper way to accomplish this. Holding the passenger hub and turning the pinion once resulted in just over 2 turns of the drivers wheel. This seems insanely low. But that is totally how it behaved the one time I drove it. I think we were doing 65 in third at 4000rpm or so. It just made no sense.

The lowest gear ratio I'm familiar with in the sideloader is a 3.07 from the 6ers and M535i - basically the dogleg five speed cars. This is not one of them I'd guess as all of them appear to be limited slips with the L mark on the case, this one does not have that. This car used to be an automatic in which case it would have originally had (i believe) a 3.25:1

Also, what ARE all of the available short neck sideloader differential ratios for these cars?

Jason

[Techboy]

I know that 3.45 is a pretty common ratio

TB

[Mike W.]

I think all US spec cars were either 3.45 or 3.64. Very early Bav's were 3.45, later they went to 3.64, then I think, repeat think, later they went back to 3.45. E9's I'm less familiar with, but I think they pretty much followed Bav specs. E12's used 3.64 for 75/76, then went to 3.45. Early euro 635's used 3.07 with the dogleg tranny, but I havent heard of a 3.25 sideloader. Not that it doesn't exist, but I've heard of most of them and I'm not familiar with it. At least on cars imported into the US in quantities greater than you can count on both hands, LOL.

[alotawatts]

appear to be limited slips with the L mark

Is'nt it S ?

[pappentl]

The euro cars also came with a 3.91, I have one in the garage.

...tom

[griffithbuilt]

appear to be limited slips with the L mark

Is'nt it S ?

My 3.07 has a giant L (or 7) on the top of the cover, but I do think you're right that it's an S. The 3.07 I have is certainly a high lockup limited slip.