Diff' ratio's

[535ise]

Hi all

I'm going to change the diff ratio on my e34 535 manual and was wondering weather any ones got any part numbers so that i can check the diff that i'm buying second hand is the correct ratio.

I'm thinking of changing from the standard 3.46 to a 3.73 or 3.91.I don't do a lot of motorway miles so the higher revs in 5th don't bother me that much,but i want it to accellerate better.It's to long geared at the moment.I can get 120 mph in 4th and 110 mph in 5th @ 4000rpm.

3.73 is APX 8 % change in ratio from standard
3.91 is APX 13% change in ratio from standard

Has any one tried either ratio on there 535im ?

I'm leaning towards the 3.91 as a local scrap yard has an open(non-LSD) diff from a e34 535 auto for £ 95.

Thank's

Andrew

[mjradin]

1990 535im - Jim C Chip

I lost the pinion bearing on the original 3.46.

I love the 3.64 - about 400 more rpms. The increased performance is very nice. A 3.71 would be even faster - at the cost of top end speed. I am very pleased.

Feel free to call if you want more info 617-832-2515

Michael Radin

[Unregistered]

I put a 3.91 on my US 535i last fall and broke out in a grin as my car finally showed life in the lower speed range. Acceleration was greatly improved. I never did learn what the exact impact is on my spedometer though...
Alan

[jplacson]

Are the diffs a separate part from the transmission? I'm running an M20 520im and most of the 'surplus' diff available here are from 525ia and I was wondering if they'd just be a direct bolt on.

[Paul in NZ]

use the 3.91 on the e34 b10 non turbo

[jplacson]

I currently find my 1st & 2nd gears a bit too tall..seems to take forever to reach 40kph. I'm pretty happy with the reast of my gearing, cuz I usually use them for crusing already, and they keep fuel consumption down at highway speeds... will a differential from a 525ia solve this? Or will it decrease fuel economy on the higher gears?

[Martin in Bellevue]

The 3.64 is much livelier about town. Dunno if it is coincidental with changeover from winter fuel, but I saw an immediate increase in mileage. It isn't a huge increase, but it is noticeable.

I was afraid of going to a 3.91 as 1st gear might become useless with my driving style. I'm not big on hanging near redline, though my car does run a bit better after Jeff's drives it.



1990 535im - Jim C Chip

I lost the pinion bearing on the original 3.46.

I love the 3.64 - about 400 more rpms. The increased performance is very nice. A 3.71 would be even faster - at the cost of top end speed. I am very pleased.

Feel free to call if you want more info 617-832-2515

Michael Radin

[MikeV]

Go all the way...get the 3.91. I went to a 4.10s from my stock 3.15 (30% !!!) ... and couldn't be happier. Yeah, yeah, highway mileage will suffer a bit, but the difference in driveability is amazing.

[Martin in Bellevue]

My 635csi had a 3.91. It was too damn short for me. 1st gear was useless. It took 3rd gear to get out the driveway.

Mike, the gearbox ratio's you have with that 530iA are alot more suited to 4.10's & 3.91's than are the manual gearboxes. I am noticing slightly improved around town mileage with the move to the 3.64lsd.

I prefer some legs with my relaxed driving manners.

How about some pictures of the MR2? Those things are great. In college, I had Fiero v6 with the manual 4 speed. A buddy went through a couple MR2's. I enjoyed the cornering. Seemed any corner could be taken at whatever speed you were willing to try.

[Warren N.CA]

After, you've got a chip, then go for 3.91, but get an LSD for best drivability. But really, the chip is so much cheaper and easier, and should give a bigger improvement. I love my EAT.


Hi all

I'm going to change the diff ratio on my e34 535 manual and was wondering weather any ones got any part numbers so that i can check the diff that i'm buying second hand is the correct ratio.

I'm thinking of changing from the standard 3.46 to a 3.73 or 3.91.I don't do a lot of motorway miles so the higher revs in 5th don't bother me that much,but i want it to accellerate better.It's to long geared at the moment.I can get 120 mph in 4th and 110 mph in 5th @ 4000rpm.

3.73 is APX 8 % change in ratio from standard
3.91 is APX 13% change in ratio from standard

Has any one tried either ratio on there 535im ?

I'm leaning towards the 3.91 as a local scrap yard has an open(non-LSD) diff from a e34 535 auto for £ 95.

Thank's

Andrew

[535ise]

Thanks for your reply's :)

Since i first posted i found an 3.91 open diff for £ 110 but it came with out one of the part's of the diff that the drive shafts bolts up to but i nievely(sp?) thought that i could use one off my old diff.The splinded shaft that goes in to the diff was the wronge size,took it back to the scrappy and they tried to get one for me but after a couple of weeks of getting pissed around i got a refund.

I've now found a 3.91 from an auto 535 sport(LSD ?) for £ 180 inc P+P and i'm ordering it on monday so i'll let you know how i get on with it once it's fitted.

See ya later,

Andrew

[535ise]

After, you've got a chip, then go for 3.91, but get an LSD for best drivability. But really, the chip is so much cheaper and easier, and should give a bigger improvement. I love my EAT.

Hi Warren

I should have listed my mods in my first post.

After being messed around with the first open diff i've now found a 3.91 lsd and i'm ordering it on Monday.

Ported/flowed head and intake manifold
Schrick cam
sports exhaust
Stand alone fully mapperble ECU that does away with the afm

It's was mapped not long after the head/cam work and i got 240 bhp @ 6000 rpm and 230 lbs.Now that i've done a few thousand miles it's going even better,it's got to be about 250 bhp now.

Here's a picture just after i wired up the ECU,i've since tidied up the wireing.

http://www.hpphoto.com/servlet/LinkPhoto?GUID=5f0345b7-585f-7271-1e48-75c077745bfa&size=

[MikeV]

Stand alone fully mapperble ECU that does away with the afm



What ecu are you using, and how hard was it to tune?

[535ise]

What ecu are you using, and how hard was it to tune?

I'm useing an Emerald ECU that i bought over here in the UK.

http://emeraldm3d.com/

It comes with some easy to use soft ware if you want to try to set it up your self but to do it right you need to get it on the rollers to get it set up.

The wireing's easy enough to do it your self.