Gear ratios??

[Treeman612]

My 320i , with standard diff (4.1, I think!) shows 55mph @ 3000 revs in fifth. does this sound right? - I think thats a lot of revs for a 2 litre car, so I am wondering if either the dials are lying, or my g/box has different ratios from standard?

[Davenotouring]

That is probably correct.

The 2.0 does rev highly on the motorway.

About 4k at 80mph

You can change the diff for a higher ratio one if you wish.

[Treeman612]

Cheers, Dave - any ideas what ratio diffs are about/ - don't want to blow shedloads of cash on an LSD, cos I don't thrash about enough to notice the difference - any advice on what car to look for a donor diff from (non-lsd 325 for example?)

[Davenotouring]

Your 320 will have a small case 4.1 (I think it's 4.1 - might be 4.27)

You could get a diff from an e36 compact 318ti which fits straight on, and it's 3.38 Great for the motorway, not so good off the lights. Good mpg from that.

You could get a large case diff off a 325...likely to be 3.91 or 3.64.

You'll have to adjust the length of the prop to get that on though. Not too bad to do. (Unless you have to undo the nut, which means dropping the exhaust).