LSDs revisited

[hoshy]

Hi all,

This is my first post so be gentle with me

I've just got myself my first BM!!! 350gbp for for a '89 318i (M40) Needs a few bits doing here and there to the body work, preferably a new off-side wing if anybody knows a good source, but I digress...

The first thing I'd like to do is fit in an LSD, my current plan is to take a 325i diff and swap the pinion to keep the final drive the same. My father who's owned a few e30s over the years, and is a mechanic, seems to think this shouldn't be too much of a problem but I'd like to get your opinions.

Just to check, do all 325i, auto and manual cars have an LSD as standard? The local scrappy has both of these cars, one of which I'm hoping to use as a doner. Of course, if anybody else knows a source please let me know.

I'm just a lowly uni student so I have little money but plenty of tinkering time. And access to ramps, tools, mechanics and rolling road

Thanks in advance,

Ashley

P.S. My last car was a 1.2 Corsa... I'm loving the beemer!!!!

[E30Adam]

The only E30s that came with a LSD as standard were the sport models.

You'll be lucky to find one on a stock 325i.

Contact Jimbob on this forum, he has an ultra rare 4.10 big case LSD for sale which is perfect for your engine size.

[DawieM3]

Hoshy,

First determine what ratio your existing diff is. The E30 LSD come in a variety of ratios from the M3, with 3.15 & 3.25 as standard. The 325 and sport variations had 3.64, 3.73 and 3.91 options. Not all 325`s had LSD diffs.

It would be far cheaper to install a complete lsd than to match parts from your standard open diff. I also think that you cannot simply exchange crownwheel and pinion gears between open and LSD diff`s.

The LSD diffs also have differences depending on the carrier that was installed at the time. When ordering parts for my track car I always have to quote the carrier serial numbers as there are differences between the LSD`s.

Given the above , and if you really have to have one, I would settle for a ratio change over trying to put a puzzel togather of pieces that do not fit.

The going price for a good LSD should be between Ԛ£200 to Ԛ£250. The Lsd also use a special oil and you just cannot simply fill it with standard hypiod oil.

Goodluck.

[johnono]

which are the "best?" ratios to have for a 2.0 liter

[CaesarBob]

I'm not sure the internals from a 325i lsd will swap into a 318i open diff. For a start the 325i has the large case diff and the 318i a small case. If it was easy i'm sure others would have done this already.

Then you have the ratios. Most 325i's will run a 3.64 or 3.73 which will make your 318i a bit slow. Even with a sport 3.91 your gonna notice the difference. Really the 4.10 lsd Adam mentioned would be perfect ... in fact i fancy the but i've got no spare cash.

Johnono - would think you'll need a 4.10 or maybe a 3.91 really altho didn't davetouring say he's got a 3.38 which seemed to work well on his 320i (or has he done the engine swap now as well??)

[kevin316i]

I have a 316i and went from an open 4.10 ratio diff to a 3.91 ratio LSD and didn't notice much difference. You are talking about 5% lower revs for a given speed, e.g. if you engine was doing 2,500 rpm with a 4.10 ratio diff then it would be doing just under 2,400 rpm with a 3.91 ratio diff. The proper replacement would be a small casing LSD but these seem to be impossible to find in the UK. The large casing LSD will fit. I got a 3.91 ratio small casing LSD in the US, but shipping and taxes worked out more that the unit itself! It came from California and was so clean, with no rust on the casing.

[hoshy]

Thanks for the info guys. I'm gonna pm Jimbob now. In case I've no luck with him does anybody know of another source?

Cheers

[CaesarBob]

If your after a 4.10 slipper you'll have to trawl the scrappers and breakers. Hope you get lucky.

Otherwise you could try and source a US M3 4.10 large case diff but like Kevin said - shipping will be expensive.

[E30Adam]

4.10 slippers are like Gold dust... the only one I've EVER seen is the one Jimbob managed to buy. You'll probably never see one again.

[Jimbob]

This diff will soon be making it's way to 325tracky aka Driftlearner soon!

[Guest]

Hey it may be for you but it's for me!!!

[E30Adam]

Fantastic, the perfect diff for a bit of drifting, get those wheels spinning!!!

[CaesarBob]

Thought the perfect diff for drifting was 100% locked up - or so TBMW wrote in this months mag.

[Jimbob]

Perfect for drifting yet still drivable in every day use

[CaesarBob]

Fair point jimbob. I just thought it was for trackdays/drift comps so that wasn't a big issue.

[Jimbob]

In which case you're right, 100% lock up all the way

[Gi]

Hey!
I'm new to the site...stumbled across it whilst looking for an LSD!
I have a 325i se. I changed the diff oil when I got it 5 years ago.... I've just found out the hard way that you can NOT use normal EP90!!
I have a whirring noise and rear wheels are hard to turn when lifted, I think the clutch plates have burnt out and the diff is locked... Any advice on what action I can take would be appreciated!
Methinks it will be an expensive Ԛ£4-500 refurb.
In this state, is it possible to cause any damage to the gearbox/engine if i drive it?

Thanks
Gi
Herts

[Guest]

Nah it's not for drifting, was gonna but not now hence the name change....2006 Kumho is in the pipeline though, with a 4.1 final got a chance of out dragging the Group D opposition I guess who are all mainly running on 3.91 (am I sly or what ).

Gi,

I'm no expert but I would flush it out, stick in proper LS oil and you may be lucky...certainly worth a try it before stripping it down.

[kevin316i]

Proper oil for limited slip diff is available from the main dealers. You need to bring along your own container for it as it only comes in 25L drums. It's called Castrol SAF XJ. I had the same problem, put the wrong diff oil after the LSD was fitted but realised after a couple of days when I could hear the clutches making groaning noises. Didn't do any lasting harm as far as I can see.

[CaesarBob]

Kev - there's a bit of a difference between a couple of days and 5 years.

Gi - i wouldn't be too hopefuly that your diff will survive. The oil should be changed every Insp II as well.

[kevin316i]

Sorry, didn't read the post clearly. Five years of not having the proper diff oil would probably cause terminal damage alright! The problem about the limited slip diffs is that there is no reference to the correct oil in the owners handbook or any workshop manuals that I have come across(Haynes, Bentley) so it is easy to put the wrong stuff in without realising.

Thats why forums such as this are so useful

[E30Adam]

The diff will probably be okay, the LSD specific oil just has a noise suppressant in it so I would have thought it would be okay.

If you've been running low on oil then you might have siezed the bearings which can make it hard to turn the diff.

I would suggest swapping the oil to begin with and see how you go, if it's knackered then I have a spare LSD that's on evay at the moment, have a look in the for sale section.

[Gi]

The oil wasn't low, as I thought it may have been - and it was quite clean.
Diff is still in the same state after changing the oil...
Ive been ill so havent got round to getting it sorted yet...this week...

Yeah, I regret not knowing about these forums 4 or 5 years ago - there was no mention of using a different grade oil in any handbook I looked at.

Adam, I saw your diff last week but haven't have internet access since, its gone now...
Kev, Did I spoke to you on the phone - Specialist Cars?? the guy there had the same story!

Thanks for your comments.

[kevin316i]

Gi,
No it must have been a different Kevin, but given the lack of information in the various handbooks and workshop manuals available it's probably a common occurrence, especially for someone who buys an E30 doesn't know their car has an LSD fitted.