Differential Choices

#1

Our LSD is a little on the weak side right now (35ft-lbs breakaway).

Should we:

  1. just change fluid? Does this improve the torque? or just the heat induced slip later in the race?
  2. rebuild the current LSD?
  3. put in a welded diff? Local diff builder was trying to talk me into this as he has one on his 2002 race car. Does this add understeer at turn in? track out? Anyone have experience with both a strong LSD (not weak like ours) and a welded diff? Likes/dislikes? Problems?

Opinions? Personal experiences?

Thanks for sharing.

#2

I would also like to know if anyone is running a welded diff.

As i am trying to save as much money so i can get on track sooner. I would expect that the welded diff would have more of an affect on tight turns (as in an auto x) than it would on longer turns. but i have never driven a car with one so that is all speculations.

#3

I would advise 1) and 2). I know of only one car in MA that has run a welded diff and not sure he was that happy with it. I also observed him trying to navigate through the paddock - needless to say, wide turns and dragging the inside wheel was apparent. Check out factory3 performance for replacement disks and instructions. The rebuild is relatively easy and inexpensive (about $100 assuming the bearings are in good condition).
Ed

#4

Thanks for the quick response

if the rebuild is only $100 i guess i will hit the junk yards looking for a good core.

What is a good price for one? Ebay has lots of them in the $250 to $300 range.

Also did the e30 have the same rear end as any of the other bmws from the 80/ early 90s? for example can i get an LSD out of a Z3 and just swap ring gears and put it in my non LSD housing.

now that i wrote this i realize i should have searched first but since it is already writen… lol

thanks again

Daniel Graybill

#5

Not sure about Z3, but those from 80’s 5 series will work. I have purchased 2 from ebay - for $150-175.
Ed

#6

I paid $50 for my Pick N Pull (junkyard) 130k mile LSD. It’s a 45 ft lb breakaway. I’m probably going to snag another one and do the rebuild over the “winter”.

#7

Nice…. $50 is a good price for my budget. Question for people near Pennsylvania, I have heard roomers about an all BMW salvage yard near Carlisle PA. Has anyone heard of this place or something like it in the mid Atlantic region