LSD predicament (lots of reading)

[Guest]

well, according to a local shop, my LSD is about to take a shit. It is really wailing bad. About 3/4 months ago i changed the fluid with a full synthetic but that seemed to make the noise worse, especially on the freeway. And when I do slow turns in parking lots, something just doesn't sound right. I suspect that when i changed the fluid, it was the first time this car had had it done. But, honestly, my diff is really sounding like crap. If I can manage it, i'd like to get a replacement before winter hits. At a local junkyard is an '89 325is that still has its LSD, except that it's been sitting in on the ground in the dirt for probably 7 years.

Should i change the fluid again with some additive to get me through the winter? Or should I see if i can get the junkyard one? I"m just concerned that the one in the junkyard may be no better than mine. Also, any replacement i get i would like to one suited for better top speed. Or am I overreacting? the other day i did some donuts in the rain, which was probably a stupid thing to do, but i was able to do them...

thanks.

[permit]

Damnit, I thought this was going to be about drugs.

[Axxe]

Get rid of the synthetic oil, and pour in regular 80W90 with LSD additive. I had the same noise and you are killing your diff until you change it.

[Jordan]

I've got a very good condition 3.73 LSD (out of my car) available. ~137,000 miles. No rust. No noises. Just smooth quiet operation.

[E30 Wagen]

I've got a very good condition 3.73 LSD (out of my car) available. ~137,000 miles. No rust. No noises. Just smooth quiet operation.

i'm hoping to get whatever is the best for higher top speed. so would a 2.93 be better? i just don't want to be at 3000 rpms at 70mph.

i have to cough up the cash and pay somebody to intall it, so it would really have to be worth it.

anybody know a good place where i can buy remanufactured?

[permit]

3.73 with a Getrag 260 would get you around 3850rpm in 5th at 90mph. Top out 4th at 120, 5th at about 151.

[Addissimo]

but none-the-less, he's still about 3k rpm at 70...

i wouldn't go any lower than a 3.46 thruthfully- I had a 2.93 in my m50e30 and it was only a little tiny faster than my car before i did the swap. Stick with the 3.73 or buy a 3.46- you'll regret going lower.

-Addis

[E30 Wagen]

but none-the-less, he's still about 3k rpm at 70...

i wouldn't go any lower than a 3.46 thruthfully- I had a 2.93 in my m50e30 and it was only a little tiny faster than my car before i did the swap. Stick with the 3.73 or buy a 3.46- you'll regret going lower.

-Addis

i don't understand exactly what you mean. 2.93 is too low because...?

[permit]

It'll take to long to get the rpms up with a 2.93 because the M50 doesn't have that much power. With an S50/52, you could consider it.

[erik325i]

i don't understand exactly what you mean. 2.93 is too low because...?

2.93 is too low because it would be in too high of a gear. It would almost be like starting in second gear every time.

The only benefit would be a low highway cruising RPM

[Addissimo]

I think with a boosted s50/2 it'd be great. My friend with the twin turbo m52 is putting my old 2.93 in his car next season. He hopes to be able to use first and second gear.

-Addis

[StereoInstaller1]

Buy Jordans diff...but be careful. He gets mad and posts bad things if you don't pay him after only like 6 or 8 months....

Seriously, you will never find a more honest seller.

I run a 3.73 on 215/40/17's with a M20B25. I think it an excellent combo overall.
I also ran a 3.43 on 245/60/15's on my Nova....that had the torque to spin taller gears, but the M20 does not.

Unless I wanted to get my ass spanked my the average delivery van, I would never go lower than 3.43

Luke

[alex]

well, according to a local shop, my LSD is about to take a shit. It is really wailing bad. About 3/4 months ago i changed the fluid with a full synthetic but that seemed to make the noise worse, especially on the freeway. And when I do slow turns in parking lots, something just doesn't sound right. I suspect that when i changed the fluid, it was the first time this car had had it done. But, honestly, my diff is really sounding like crap. If I can manage it, i'd like to get a replacement before winter hits. At a local junkyard is an '89 325is that still has its LSD, except that it's been sitting in on the ground in the dirt for probably 7 years.

Should i change the fluid again with some additive to get me through the winter? Or should I see if i can get the junkyard one? I"m just concerned that the one in the junkyard may be no better than mine. Also, any replacement i get i would like to one suited for better top speed. Or am I overreacting? the other day i did some donuts in the rain, which was probably a stupid thing to do, but i was able to do them...

thanks.

Did that synthetic oil have an LSD additive (aka fricktion modifier)? If not you need to put it in there. Not sure how it works with synthetic.

I also have LSD for sale:

http://www.r3vlimited.com/board/showthread.php?t=57279

[Axxe]

The problem is your fucking oil. Change it and be happy.

[E30 Wagen]

Did that synthetic oil have an LSD additive (aka fricktion modifier)? If not you need to put it in there. Not sure how it works with synthetic.

I also have LSD for sale:
http://www.r3vlimited.com/board/showthread.php?t=57279

i've decided to change the oil as soon as possible. i've decided any new lsd i buy will be a direct replacement: 2.93. i really do enjoy the low rpm highway cruising.

thanks for everyone's help, this is why i like this site, although nobody seemed to care i have an eta, and not an m20b25, or s50, or m50 which were all referenced...