LSD in a 540

[Jehu]

http://urlcut.com/1bysf

Have any of you with a 540 6 sp, popped anything like this 3.23 LSD in?It would be nice not to have to downshift to accelerate in high gears to pass but is there a risk of ultimately losing top speed capacity or can this be completely compensated for in some way?

[BillionPa]

compensate with rev limit remover heh, you are only loosing like, 3% top speed vs 3.15 stock. I believe the optimal ratio is 3.64

[Jehu]

compensate with rev limit remover heh, you are only loosing like, 3% top speed vs 3.15 stock. I believe the optimal ratio is 3.64

Thanks,i'd been surfing ebay to see what kind of stuff is available and saw that.I read about the diffswap on the Korman site but didn't put my mind in gear to figure out what would actually work and didn't know what the stock was.

[BillionPa]

look into Quaife ATB diffs.

[632 Regal]

get a used 3:64, you wont lose top end like you think unless you cruise around at 150 daily. 150 is still do-able but at a higher rpm.

[inkfish]

540i/6 comes stock with a 2.93 open diff, this ratio was used to get the mileage rating up for CAFE purposes. 3.23 is really the perfect ratio-it was used only on the late euro E34 M5 6 speed. As they are are almost none of these available stateside, the best bet is to find a 3.15 lsd (big dif) from an E32 740/750il as they can be had for under $400 and the install is fairly straightforeward. Input flanges must be swapped. AFAIK this is the only diff that fits in a M60 equipped E34.

Ben

[Jehu]

540i/6 comes stock with a 2.93 open diff, this ratio was used to get the mileage rating up for CAFE purposes. 3.23 is really the perfect ratio-it was used only on the late euro E34 M5 6 speed. As they are are almost none of these available stateside, the best bet is to find a 3.15 LSD (big diff) from an E32 740/750il as they can be had for under $400 and the install is fairly straightforward. Input flanges must be swapped. AFAIK this is the only diff that fits in a M60 equipped E34.

Ben

Very interesting.Do you know anyone or have you experienced the difference in performance with the big diff swap?I read that there could be an issue with losing the cruise control.What I'd really like to know is how much of an increase in acceleration in high gears will be had. In other words what i have in mind is being able to pass with a brief window while in 5th or 6th without having to downshift.If this ability is gained then it would be worth it to me.

[bbig119]

I've got the 3.15 LSD from an E32, but I bought it like that so I can't speak to any performance increase as I've never driven or been in a stock e34 540. I can tell you the car pulls better than I thought it would in 6th gear. I beleive the PO said it was a direct swap except for the flanges like somone else mentioned.

[brosher]

Are all diffs from the E32 LSD? Or were some of them open? Can someone comment on loss of cruise control?

Thanks!

[632 Regal]

you want the big unit as mentioned from a 740 or an M5, the small units from say a 530 WONT FIT. Try to go for a 3:46 or 3:64. its plug and play, no issues with speedo or cruise or anything like that. If you need to swap the side flanges its no big deal but if the front input flange needs to be swapped you better read this:

http://www.bimmer.info/~regal632/rearend.html

I did the 3:15 to 3:64 swap and its soo much nicer in the city. Im only turning around 3400 rpms @ 100 mph so theres a lot of legroom left.