E30 Zone

Hello everyone

Another question
I decided to electrolysis my diff to remove the rust. It did that fine. I blocked up the the breather hole. Unfortunately some/all of the oil came out. That means that water went in.

What do I do? Hope I haven't fooked it up. I guess it's a lsd because I have a 325i sport.

Thanks for any help.

I would wash it out with kerosene/paraffin/petrol to remove any water then refill with the correct LSD oil.

Should I do this through the fill/drain holes or should I remove the back cover and flush around like that.
Problem with taking the cover off is that I will need a new deal. Where would I get on free of those.

Diff gaskets ate available from the dealers. I'm sure the last time I bought one it was £1+VAT

Ideally, you should remove the back cover to do it, and to enable you to inspect the gears to ensure all traces of water are removed.

But if you can't get a seal, swilling it around after filling via the normal filler will be OK. Then drain and refill with oil.

The idea is to leave the vent just above the water level!
A bit of water in there for a couple of days isn't going to do any harm, so just drain it out and refill. May be an idea to fill with ordinary diff. oil, run the car for a few miles (avoiding sharp turns), before draining again and refilling with the expensive stuff.

Should I do this through the fill/drain holes or should I remove the back cover and flush around like that.
Problem with taking the cover off is that I will need a new deal. Where would I get on free of those.

maxfield and myself already answered that above!

Sorry accidentally pressed the back button on my piece of s**t android which then makes my last entry come up again.

Thanks for the information. At least I can sleep in peace now.

So I took the diff cover off. No water .
Another concern though. On wiki it says that it should not be possible to turn the output shafts of a lsd in opposite directions by hand. Well in mine you can. I have a 325i sport all kosher logbook and all. Has someone nicked the real lsd and swapped a normal one in

I took some photos inside and outside of the diff

Thats an open diff.

And small case by the looks of it!

Definitely an open diff., although any original E30 LSD that hasn't been rebuilt is likely to have output shafts that can be turned in opposite directions without too much effort.

An LSD should have a little tag on with an 'S' followed by the ratio, e.g., S3,91 = 3.91:1 LSD.

As above, that is 100% an open diff and worse still a small case.

Whack the backplate back on, (£1 gasket from BMW, p/n 33111210428) don't put £25 worth of expensive oil in it, it doesn't need it!

Throw it on the car again and keep your eyes peeled for a LSD

So I take that my car was raped of its lsd before I bought it. What other things should I check ie the gearbox etc

Jatin wrote:So I take that my car was raped of its lsd before I bought it.

That's the 'best case' scenario. Worst case is that it isn't and never was, a 'Sport'.
What colour is the headlining?

I'll check and get back to you

I went to the stealer with my car registration. He said it was a sport .
Ps the headlining is black - is that consistent with a sport.

Another question
Bearing in mind that most lsd`s around are 25 years or older and have never been overhauled, they have probably lost most of their LSD properties. It is really worth it to buy a used LSD and then overhaul it just for a 2.5 litre engine. I`m not sure if I want to part with the best part of 600 quid for a lsd and overhaul.

 

Would it be that much better than the diff that I have at the moment.

Yes black headlining is consistent with a sport.

A used LSD will be fine in my opinion from reputable sellers, ie pacerpete bmw-mad etc..
a 3.91 ratio is what you would be aiming for and expect to pay around £300 for one.

What meant was is it really that much better than a non lsd given the limited power of a 325i

Having owned both a 325iSE with open diff (3.64:1) and a Tech 2 Sport with 3.91:1 LSD, I would say not, for general everyday driving on the roads.

In fact, the handling on my 325iSE was more predictable than the Sport, which seemed to suddenly dig in when going around sharp bends, and punt you off in unpredictable directions, but then it was the first car I'd ever owned with an LSD.

In the real world, you would hardly notice any improvement with a LSD, especially a 20+ year old one that hasn't been rebuilt. I'd be more concerned about the small case diff. you have and its ratio.
The torque produced by the 325 engine is marginally more than this size diff. was designed to take, so there's a possible reliability issue, and since it probably came from a smaller engined car, its ratio is possibly less than ideal, costing you money in increased fuel consumption.
Was there a steel tab under one of the rear cover bolts? If so, it will have the ratio diff. stamped into it, and should be readable after the application of some emery cloth.

There is but the writing seems rusted beyond recognition. Is there another way of checking the ratio ie actually turning the the input vs output (might give me just enough info for me to figure out which one I have

Yes. Turn the input shaft and count how many turns are needed for one complete rotation of an output shaft.

Most common is 3.64:1 ratio.

If you still have the rear cover off you can count the teeth on the crown wheel and the pinion gears. Dab of tipex helps.

Brianmoooore wrote:If you still have the rear cover off you can count the teeth on the crown wheel and the pinion gears. Dab of tipex helps.

Yep the stealer said the new gasket will take a couple of days to come, so doing that should be easy enough.

You could also try using Jenolite rust remover and wire wool or a fine wire brush on the tag, which should reveal the numbers...

Will try a good dose of electrolysis to see if that works

Jatin wrote:
Yep the stealer said the new gasket will take a couple of days to come,

If you ordered the 'correct' one for your car, then it isn't going to fit when it does. Only six bolt holes in yours, and the diff. that should be fitted has eight.

The P/N i gave was for the correct small case one, so fingers crossed

I took the diff cover with me

Did the Electrolysis - nothing- the tag is too far gone to read anything. Looks like I'm gonna try the teeth counting method