Very impressive and detailed discussion ON bmw differential upgrade
after watching the video, I was in a hunt for a 3.15 LSD differential
I have a 97 840ci 4.4L automatic.
a flew questions,
is this a slap on part? I just Take out my old one and replace another part. Or do I just use the internals
ive seem some that states a large or medium case
what is a donor car that I have To look for
thanks Timm, keep The videos coming, looking forward for part 3
For my car ('93 850Ci manual) the donor came from an E32 750 with limited slip 3.15 gears. On my car the swap required transplanting the rear cover of the differential (it is specific to the eight series). The E31 rear cover will bolt onto the E32 case. The swap also requires someone to properly set the "rolling pre-load" on the pinion gear. If not properly set it will fail quickly.
I have no experience with 840s.
Last edited by ByMW; 11-30-2020 at 10:50 AM.
Mark in mid-MO
1993 BMW 850Ci 6-speed
2011 Cadi CTS coupe 6-speed
Thanks, finding out if im capable of doing it. How was The difference aftershocks Your diff change? Noticable?
Going from 2.65 open to 3.15 LSD was a huge improvement. This is a manual transmission. It made 6th gear usable on USA highways. 1st gear is still okay. The limited slip activates before the electronic anti-wheelspin, so low traction cornering is improved. I don't know how much improvement would be noticeable in an auto transmission, but it is wonderful in the 6 speed car.
(I had the original swap performed at a Porche specialist shop - the only place I could find. The pinion gear failed in 5 months because preload was not set correctly. I had it rebuilt at Metric Mechanic. Working great for the past 8 years.)
Mark in mid-MO
1993 BMW 850Ci 6-speed
2011 Cadi CTS coupe 6-speed
Thanks for The info, Will try To Find out if it would maki a difference on a matic
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