I know this topic has been discussed before but mostly for 850's
I want a little more umph out of my '97 840CI and I think the best bang for the buck is to upgrade my LSD.
What ratio should I be looking for and where would I find one rather quickly?
Thanks!
2016 Macan Turbo
2009 Porsche 911 Carerra S (997.2)
2013 BMW 135i Convertible
I have a 3.64 LSD on my 97 840Ci. It is out of a 1992 750iL (E32). I bought it from Bavarian Auto Recycling. I'm happy with it. I'm sure gas mileage has suffered a bit, but RPM range is better for around town driving. Before it felt like 65-70 MPH was where the engine power started to be felt. I couldn't recommend going any higher.
I would say that the best LSD is original BMW LSD unit as low mileage as possible and prepped up with one or two extra friction discks. Or if you want a brand new unit then Quiaife's torsen type would be one. Frind of mine put one in his E50 AMG and its works fine in street cars. You can do burnouts without worring about burning disck because in Torsen type there is no discks, only gears that will lock. No parts that can be wore out.
If you are talking about gear ratios, I dunno. I personaly prefer more tall ratios.
Best LSD irrespective of cost? OS Giken, or Quaife if you don't want to spend 1k vs 2k
Best LSD for cost? OEM Salisbury
Best V8 Gear ratio for performance (overall) irrespective of cost? 3.46
Best V8 ratio for off the line for cost? 3.64
Best cheap compromise performance+cost+gas milage? 3.15
To help you make your decision - download the gear calculator and see what effect each diff has on revs/road speed:
http://www.meeknet.co.uk/e31/Timms_E31_Gear_Monitor.zip
I've gone for a 3.15 LSD from an E32 750i
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I have a 3.64 and while it makes the car feel a thousand pounds lighter from a stop, it doesn't suit the character of the car. Swapping to a 3.15 in the garage soon.
Anyone know of a 3.23 compatible with our cars?
The E32 3.15 is what I'm truly leaning towards.
Anyone have any leads on where I might find a good one?
If i'm gonna be going 6spd sometime next yr, would there be a difference as to what gear ratio I should go with? 3.64 imo is still a bit harsh. Anything in between a 3.15 and a 3.64 that would work on our vehicles? Olin, was your 3.15 a noticible difference to you? I just want a bit more of a pickup from a stand still.
I'm considering a 3.64 :/ What are the drawbacks? And advantages i just want it to be more responsive from a stand-still, and at higher speeds (mainly for overtaking)
1994 E31 840CI "Sport" 4.4 - Hellrot Red - Black Nappa Leather - Every Option available - OEM 65M Wheels, EDC delete/Bilstein, M60-M62 engine transplant, updated software, CSI Steering box & AHK, Full AC Schnitzer kit, Wood Trim, Front Plate Delete, Xenons + LEDs, Tints, Black Ind. headliner, BREMBO BBK, Hamann Exhaust, Custom aluminium throttle bushings, KAW springs, Strong Strut, Greg K GenII sway bars, Camber Plates, Stut tower reinforcements, X-Brace, Wokke chips, Wokke Sphericals, PM Steer Plates, H&R Spacers, Pioneer AVIC-F60DAB + more.
1994 E34 530i - Calypsorot + Many mods
2008 E66 760LI V12 - Every Option Available + Full Individual Composition
2015 F02 750LI Xdrive - Every Option Available + Full Individual Composition
2013 E70 40d TT - Full BMW Performance Kit
2016 F06 M6 Gran Coupe Individual
3.15 is ideal for the 6-speed manual. You can get 3.23s etc, but they are expensive since they aren't just off another car. A 3.64 would be WAY too short IMO.
With the automatic, the 3.15 is wonderful, but it's not a huge difference from a stop. I think on the freeway is where it is really noticeable. You can pass people without downshifting. Anything higher than 3.23 would rev too high for my liking and uses too much gas.
- - - Updated - - -
Advantages: Fast acceleration, cheap to buy off an 850iA
Drawbacks: High revving on the highway, wastes fuel
Last edited by olinjohnston; 08-21-2013 at 02:16 PM.
Onlin you are reasonably conservative for an 8 driver. I am just like you. I've made up my mind on a 3.15. Also, maybe at the same time, we can start the 6spd together sometime next yr.
You can come try it out if you wanna see for yourself.
which LSDs fit on the 8?
1994 E31 840CI "Sport" 4.4 - Hellrot Red - Black Nappa Leather - Every Option available - OEM 65M Wheels, EDC delete/Bilstein, M60-M62 engine transplant, updated software, CSI Steering box & AHK, Full AC Schnitzer kit, Wood Trim, Front Plate Delete, Xenons + LEDs, Tints, Black Ind. headliner, BREMBO BBK, Hamann Exhaust, Custom aluminium throttle bushings, KAW springs, Strong Strut, Greg K GenII sway bars, Camber Plates, Stut tower reinforcements, X-Brace, Wokke chips, Wokke Sphericals, PM Steer Plates, H&R Spacers, Pioneer AVIC-F60DAB + more.
1994 E34 530i - Calypsorot + Many mods
2008 E66 760LI V12 - Every Option Available + Full Individual Composition
2015 F02 750LI Xdrive - Every Option Available + Full Individual Composition
2013 E70 40d TT - Full BMW Performance Kit
2016 F06 M6 Gran Coupe Individual
I have a 3.25 LSD fitted to my 840ci 6 speeder which i sourced from a E23 7 series i had the bearings and seals replaced along with it modified to make it somewhere near a 50%lLSD rather than the 25% from factory
if i did it all again yes i'd probably have waited or at least investigated the E38 3.15 diff to see if i could have fitted those gears or waited until a E32 750 appeared with that ratio although if you look at it 3.15 and 3.25 there really is only a knat's dick of difference but i find 1st gear just to be the tiniest bit short geared for regular lazy town driving
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Most large case diffs fit the 8 from E34's,E32's and E23's usually the back plate is all that is different
i believe although not verified the guts of the E38 and E39 are also compatable
John if you need an extra set if hands with the install let me know
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