Does anyone have info on all diff ratios through the e34 ran

[beast 0]

As title suggested really.

I've changed my diff for second hand one from here and it seems a little revvy to me. Great for pulling away etc but hammers the mpg

Got a 525 M50 manual and its doing 3100rpm @ 70mph.

[e34-520i-24v 0]

what diff ratio did you put on, and what was the diff origanly off, sounds like you have a auto diff, not that it would make any diffrence other then what your experincing,

i do belive a 525 ratio should be 3.73 so you may even have the later post 1990 auto diff which is like 4.10 witch would explain the high revs and a pre 90 auto dif being a 3.91.

if and when you sell the diff after geting a replacment if its a 3.91 diff i would be intrested in buying it,

suppose at least you know your not stuck with one you dont need,

lastly how did you get it from maybe give them a inbox and ask what ratio it is

[beast 0]

I have no idea of the ratio of the diff I have, is it stamped on it somewhere, yeah if and when I sell it I'll look you up. He just grabbed it from a mate breaking an e34, said he didn't know what it was but was a 2.5. Its a rocket of the line I can't argue with that, but you do get that feeling of my engine is working hard on the revs just to cruise at 70mph.

[e34-520i-24v 0]

i think and dont quote me but its stamped on the left (looking at rear of car) flange on the part that meets the bearings

or on a tag by the speed sensor

[KK-M5 0]

I've got two BMW brochures, one from early 1990 (M20-M30 era) and one from 1993 (M50 and M60). They state every single final drive ratio, including automatics.

e34-520i-24v has given the ratios for the M20. It's 3.73 for the manual and 3.91 for the auto. There is no version of the car with a 4.10 at all.

The M50 525 has a ratio of 3.23, both for manual and auto.

Frankly, I'm a bit surprised you say your car is revvy. My manual M50 520 does 3200rpm @ 70mph. I would expect the 525 to do less, but not by far. Perhaps someone else can shed some light on this though.

If you would like to know the diff ratio of any other versions, let me know...

[e34-520i-24v 0]

518 auto got a 4.10

[KK-M5 0]

Hmmm, I see. Well, I guess it has to do with when exactly each car was built then.

It's the change-over points that can be tricky...

[doug 1]

My autobox 94 tds pulls 70mph at around 17/1800 rpm

[beast 0]

Auto's have an overdrive system so they do drop to very low cruising revs.

Wish I could remember what my speed rev ranges were before the diff change.

bloody car,

[KK-M5 0]

@ e34-520i-24v:

Mine has to be a 3.46, same as yours I presume.

I think the diff-casing of a 525 is different to a 520, so probably not a straight swap. Not 100% positive though! But I believe the 518 and the 520 are the same, although still not 100% sure...

Anyone else know???

[e34m525i 179]

what ratio is a 525td auto diff? as that sounds like a great switch for an m50 economy machine! and then for a track day bolt the l.s.d back up!

[KK-M5 0]

Oddly enough, the diesels are not included in the brochures I've got. But from the link that e34-520i-24v has provided, it looks like you're after a 2.64, which (besides economy) would make it quite interesting to see how the car would accelerate with that.

[duncan-uk 2,249]

from memory the M50's have a 1:1 top and so do rev quite high anyway but as they have a long rev range 7K ish redline for the engine its not thrashy, try a 205 GTI - the 'long' geared 1.9 did 4k @ 80, my M30 D/L box is 3k @ 70.

I find 3k @ 70 'high' but then i also run a 330d which i think is a touch over 2k @ 70!

[e34-520i-24v 0]

the car before my e30 was a corolla gti-16 5k @ 80mph !! but it sure got there quick enoth

[g164rge 4]

Frankly, I'm a bit surprised you say your car is revvy. My manual M50 520 does 3200rpm @ 70mph. I would expect the 525 to do less, but not by far. Perhaps someone else can shed some light on this though.

My 2.5 Sport sits around the 3k mark @ 70mph, so pretty bang on mate.