General LSD question

[losichu]

Is there a way to tell what years/models have what differentials? Do the cars with traction control autmatically have an open diff? Is there a way that I can tell if my car has an LSD?

[DustenT]

Originally Posted by losichu

Is there a way to tell what years/models have what differentials? Do the cars with traction control autmatically have an open diff? Is there a way that I can tell if my car has an LSD?

Jack up the back of the car so both wheels are off the ground, put the jack under the differential. Once both wheels are off the ground, spin one wheel forward (the e-brake needs to be off and the tranny in neutral). If the wheel on the other side spins forward its an LSD, if it spins the opposite way it's an open differential.

[losichu]

Lets say I have an open diff, if I decide to change the diff to an 3.73 LSD, would that have any affect on the traction control?? Will I have to disconnect the traction control? Can they coexist? How would I go about readjusting the speedometer?

[DustenT]

Originally Posted by losichu

Lets say I have an open diff, if I decide to change the diff to an 3.73 LSD, would that have any affect on the traction control??

No. They are two seperate systems. LSD is mechanical, completely contained in the diff. housing. The traction control uses a throttle plate to stop air flow to the engine, thus controlling engine power, and it also uses the brakes to control wheel spin.

Will I have to disconnect the traction control?

No, they can coexist together. In fact, they work better together. I've had both setups and I prefer TC and LSD.

How would I go about readjusting the speedometer?

Not sure about this one. NickG can probably fix it in the ECU, but that'll be pricey. Eric (Cali-ti) on this forum has a 3.73, send him a private message.

[1996 328ti]

A LSD will work with traction control.
Where are you going to find 3.73 gears that fit in a ti diff?

I don't think it will effect the speedometer.
Tire sizes do.

[CirrusSR22]

Look at the rear differential cover on your 318ti. It'll have a metal tag attached to a bolt. If the text starts with an "R" then it's an open diff. An "S" should be a LSD. Like this open diff....

[1996 328ti]

Originally Posted by losichu

Is there a way to tell what years/models have what differentials? Do the cars with traction control autmatically have an open diff? Is there a way that I can tell if my car has an LSD?

Only the 1995 Club Sport has a LSD and I believe it was an option in 1995 and part of 1996 until ASC was available.

Hmmm? I guess that answers your question. Unless the previous owner installed a LSD, you don't have one since I don't think you have a 95 Club Sport.

[losichu]

Thanks for all the responses, was just thinking about going with an e30 diff that had an lsd and was curious if the different diff would throw everything off.

[1996 328ti]

Originally Posted by losichu

Thanks for all the responses, was just thinking about going with an e30 diff that had an lsd and was curious if the different diff would throw everything off.

I don't believe changing the ratio throws the speed off.
It does change your top end though.
At 80 MPH my tach is almost at 4K with my 3.46 diff.

[L84THSKY]

Yeah, I think this question has been asked before, and the answer was the speedo is not affected.

Originally Posted by 1996 328ti

I don't believe changing the ratio throws the speed off.

[losichu]

Is it normal not to have a letter in front of the numbers on the LSD? I haven't jacked it up yet to check if I have the LSD or not, hopefully it will be warm enough to do tomorrow.

[oakley]

A real dumb ass question wots the advantages? Y would u bother with the hassle?? Sorry i know its gonna be stupid to most of u but if i dont ask i wont learn!!

[DustenT]

Originally Posted by oakley

A real dumb ass question wots the advantages? Y would u bother with the hassle?? Sorry i know its gonna be stupid to most of u but if i dont ask i wont learn!!

LSD = both wheels spin
open diff = only the easy to spin wheel spins

Going around corners your inside wheel will spin, making acceleration difficult. With an LSD the diff locks up and forces power to BOTH wheels, thus you can push the car a lot harder without losing traction.

[oakley]

ahhhh fair enough sorry to block the thread with my stupidity!! (Must say its pretty rare u lose traction in these cars, if not modded anyway..im sure its different if ya running ya dasc, no matter how hard u push it..especially since i put bigger wider tires anyway!)

[DustenT]

Originally Posted by oakley

ahhhh fair enough sorry to block the thread with my stupidity!! (Must say its pretty rare u lose traction in these cars, if not modded anyway..im sure its different if ya running ya dasc, no matter how hard u push it..especially since i put bigger wider tires anyway!)

I guess it depends how you drive. 80hp cars can have traction problems if you push them hard enough. When you have a low power, lightweight car it's very important to be able to carry speed through a corner, so you need every bit of traction you can get.

Most people that just daily drive their cars will never know the difference.