E30 Differential making noise- help!

[e30mitch]

Hi everyone,

I recently purchased a 1990 e30 5 speed coupe and it’s doing this weird howling/hissing noise from the back. It gets louder as you speed up. At first I thought it was a wheel bearing, but my mechanic drove it to hear it and he said he’s pretty sure it’s the differential. The previous owner says he had a 3.73 LSD installed on the car...

What do you suggest to fix this issue? What solution will be cheaper? I really don’t care about having or not having lsd on my car...so I was thinking of just hitting up the junkyard and getting a stock one, but I’m not sure. Please advice, what should I do? The noise REALLY bothers me!

Thanks!

[e30davie]

Diff needs new bearings and probbaly either a diff gear lap or new diff gears.

My advice is remove the diff from car and drop it at a reputable diff shop. Get an indication of condition and repair costs. Fixing diffs is a precise science ive tried it once and its very difficult to get it perfect. And if its not perfect it will just destroy itself.

[agent]

^ This.

I'd wager that more than half the E30 diffs out there are in need of at least a partial rebuild, yet folks buy and sell them like they're not 30 year old mechanical assemblies full of wear parts.

We offer this service; if you'd like to talk about a rebuilt unit feel free to PM me.

https://www.r3vlimited.com/board/showthread.php?t=292966

[Wanganstyle]

time to spend some money and get something properly built.

cheap is not the optimal when rebuilding differentials.

[e30mitch]

^ This.

I'd wager that more than half the E30 diffs out there are in need of at least a partial rebuild, yet folks buy and sell them like they're not 30 year old mechanical assemblies full of wear parts.

We offer this service; if you'd like to talk about a rebuilt unit feel free to PM me.

https://www.r3vlimited.com/board/sho...d.php?t=292966

Thanks, will do. As I mentioned above though, I really do not need the LSD...so I'm thinking of just going the stock route-i just want the noise gone. However, if this one can be rebuilt at a fair price I will do it.

Let's say that I do decide to buy a stock non LSD or buy another LSD, what year and model do i need to look for in terms of fitment? I know this is a noob question, because it is lol...but what stock differentials/LSD's will fit my e30? (1990 325i 5 speed).

[e30davie]

The LSD is not the thing that is making the noise. the LSD is most likely a stock item. dunno in the US but my understanding is that IS models came with them, and it was an option on all the others.

The thing making the noise is the bearings or the gears them selves, the LSD unit sits inside of these. An LSD should not make any bad noises as it wears out, all that will happen is that it will stop locking up both wheels as it should.

The bearings and gears will wear out/be damaged weather you have an LSD or not.

What i rekcon has happened is someone has shoe horned an LSD into the housnig, stuffed up the shims or the pinion depth that has led to the bearings or gears being worn out.

As mentinoed your best bet is to take the whole unit out, drop it off somewhere. and if its re built professionally and properly it will last another 30yrs.

Its worth spending hte money. as mentioned DIY job of this is quite difficult. I diy everything myself except machine work and differential gears....its just not worth spending money on bearings and gears for them to be destroyed cause your pinion depth is out by a fraction of an inch.

[TobyB]

True.

But in California, try a few yards for a cheap diff. If it works, bonus, and you
can sell the LSD, or get it rebuilt. We still get enough E30s in the u-pull-it yards
that a $50- 100 diff can be had for the hour under the car with wrenches.

Condition unknown, of course.

Reshimming a diff will be a couple hundred, if that's all that's needed, but figure
on bearings for an added hundred or so.
Unless the gears are too worn, in which case a used diff is the way to go.

t

[Wanganstyle]

E30 Differential making noise- help!

True.

But in California, try a few yards for a cheap diff. If it works, bonus, and you
can sell the LSD, or get it rebuilt. We still get enough E30s in the u-pull-it yards
that a $50- 100 diff can be had for the hour under the car with wrenches.

Condition unknown, of course.

Reshimming a diff will be a couple hundred, if that's all that's needed, but figure
on bearings for an added hundred or so.
Unless the gears are too worn, in which case a used diff is the way to go.

t

Much cheaper to buy a complete used several DECADES YOUNGER z3 6 cylinder unit if gambling with secondhand junk.

Labor and service costs in California are not the same as they are elsewhere; Bay Area bmw shop labor is quite often over $150/hr here.


Nobody with a brain or budget is just going to re-shim a worn out sloppy diff and pray; if going in there the ball of worms gets much more expensive with the actual parts count in these units and using actual new parts.

R3vtards will try to do anything though to avoid reality.

[e30mitch]

UPDATE: I took out the LSD diff two days ago and replaced it with a non-lsd I picked up from craigslist...and noise is gone!!! I sold the bad LSD...thanks everyone for their feedback!

[agent]

Hopefully the buyer knew what they were getting.

[Wanganstyle]

Hopefully the buyer knew what they were getting.

This is the land of r3vtard. Usually a buyer is getting screwed on a used part or e30 like op.

Chance of op screwing someone else per r3vtard norm is high although I hope he just threw it in the recycling bin or sold for scrap value.

[e30mitch]

Hopefully the buyer knew what they were getting.

Oh yeah I made sure to disclose that it was going to need a rebuild! No funny stuff here...:tsk: