LSD rebuild and ratio change

[gareth]

as i belive my LSD is fairly tired ('sometimes' doesn't lock up properly), i'm wondering about rebuilding it while i do a total rear suspension refit and also if possible swapping the rato for something better suited for my M30 while i'm at it (mine is a 3.91 at the mo.)

what is involved in a LSD rebuild?

can a better suited open diff be cannibalised for a more suited ratio?

i've read somewhere in the past that a 2.8 capri LSD rebuild kit can be used for the clutch plates or something... i believe the reasone being that one capri kit will do 2 E30 diffs and cost a lot less


does anyone know anything useful?

[Templ8e30]

Don't know about the capri parts

You can remove the LSD clutch pack from your diff and fit it to another open diff.

I'm doing this job soon, got an LSD that has knackered input bearings dirt cheap that'll be fitted to my existing open diff of a different ratio. You'll need to fit the ring gear from the new diff to your LSD unit and re-shim the output bearings (not an easy job).

Cheers,

Iain T

[liam012]

sorry Iain i am slighty misunderstanding -
is the swap of clutch packs dead easy and will convert your open to lsd without hassle with no mucking about with ring gears or shims?
its the rebuild of the diff thats the tough one as you have to mess with the input bearings/shims etc...?

[Templ8e30]

Liam, if you swap the clutch unit from an LSD to another diff you need to swap ring gears and still need to shim up the output bearings. Ideally you should remove the inner bearing races from the LSD and fit the inner races from the open diff, the bearings are made as a matched set and mixing inner/outer races from different bearings is not a good idea.

It's a whole load of work basically

Cheers,

Iain T

[stuartgallafant]

i was going to attempt this too, by using my 3.91 slipper clutch pack and putting it on a 4.27 open diff. i would of changed all the bearings too, but then i realised how big a job this actually is, so im thinking i might just send it away to get rebuilt...

does anyone know of any good companies near SE London/Surrey that can do this?

[liam012]

damn and i only just got new clutch packs 1000 miles ago before she went on the road
how do you know the correct ammount of lash is there?
ie if i turn the prop how far should it turn without turning the output shafts?
AND if there is too much lash what is involved in setting that right?

[Royalratch]

i was going to attempt this too, by using my 3.91 slipper clutch pack and putting it on a 4.27 open diff. i would of changed all the bearings too, but then i realised how big a job this actually is, so im thinking i might just send it away to get rebuilt...

does anyone know of any good companies near SE London/Surrey that can do this?

This would be really usefeul to know - if there are any out there that people can recommend?

[stuartgallafant]

liam, i believe there should be no lash what-so-ever...

its a long drawn out affair that takes a lot of time using feeler gauges, other measuring equipment, engineers blue, etc

thats why i think i'd rather just hand it over to a company and let them do what they do best!!

[Dr Firefly]

I've heard that Hardy Engineering are very good - I've been in email correspondence with them before about rebuilding a diff and gearbox and they replied very quickly and seemed to know what they were talking about... unfortunately I didn't have the money to afford the £500 they quoted me. I don't know if that's a decent price or not.

[stuartgallafant]

apparently iain haynes got his done for about £250??? but i dunno where from!!

[stuartgallafant]

BUMP

anyone else know of any companies?

[gareth]

cheers lads. that's a start anyway. now at least i can look for an open diff of about the right ratio.

regarding measuring and shimming etc, this is no problem for me whatsoever.

does anyone know of a guide on rebuilding a lsd anywhere, obviously i'll need to know the clearance specs etc. also, where to get the bits?

[stuartgallafant]

gareth, why will the measuring/shimming pose no difficulty to you? are you an engineer? if so, do you fancy doing mine too?! :winkeye:

also, i may possibly be able to get you the clearances and measurements that you need

[gareth]

i am indeed an engineer! i also have limited use of the surface grinder at work which can mean free shim modifications!!!

i also have plans for playing with the ramp angles....

if i get on ok, i may have a pop at a few more. it seems there is nobody doing this and a shortage of information about it.

[stuartgallafant]

i am indeed an engineer! i also have limited use of the surface grinder at work which can mean free shim modifications!!!

:winkeye: is that in return for the tech spec?!

i also have plans for playing with the ramp angles.....

excuse me....

if i get on ok, i may have a pop at a few more. it seems there is nobody doing this and a shortage of information about it.

im sure you'll soon be everyones best friend!!

but seriously though, do you fancy having a go at mine if yours turns out ok?

[gareth]

if i suss it and it doesn't take me months to achieve then i may be up for it not promising anything yet but it seems like a decent sideling for a few extra £'s in the mank

regarding ramp angles, it's something i've read about. there are ramped sections within the LSD that drive the clutches together during a torque split and it is this that locks the diff up hard. changing the ramp angles will (afaik) make the clutch bite harder and increasae the bite and lockup rates. this is all purely based on 'i've read it somewhere once' info though so i could be very wrong. pulling one apart is the way forward though...

[Brianmoooore]

i've read somewhere in the past that a 2.8 capri LSD rebuild kit can be used for the clutch plates or something... i believe the reasone being that one capri kit will do 2 E30 diffs and cost a lot less

This is true, as the LS units are the same make and type. Also, with a bit of simple machining, I've read that all the clutch plates from the Ford kit can be fitted to the E30 unit.

[gareth]

i'm not going insane! result!

don't suppose you know wher you read this do you brian? i can't find anything on it...

[Andy335Touring]

There was a bloke on here called M3compact(?) who was very knowledgable about this kind of thing but i've not seen him post for while ?

Try searching posts with his name might bring some of it up ?

[Andy335Touring]

LOL, he probobly gets bored of the constant LSD threads on here

[stuartgallafant]

2.8 Capri gear it is then!!

what kind of machining brian?

[M3Compact]

Yes, use the Altlas axle repair kits.

The Atlas units use 4 plates where the BMWs only use two, you need to machine 50 thou from the end plate and leave the flat washer out from the other end, it works superbly and makes them much more durable.

changing the ramp angles will (afaik) make the clutch bite harder and increasae the bite and lockup rates.

It makes the clutches bite more readily and you can adjust them to work differently with power on/over-run.

Drawing for the 2-way ramps...

[Andy335Touring]

Speak of the devil

How are you doing ?

[M3Compact]

Speak of the devil

How are you doing ?

Good thanks. Not been around this forum much - but might be again with regard to an M42. Sorry I never managed to collect the bust diff. Still got it?

We're well happy with these diffs.

Had one out on the hottest day of 2006 in July in the S50. 130C+ engine temps on 14 mile stages, not a peep from the diff and it's been stripped/ is fine.

Even sacked an unrequired diff oil cooler.

[Andy335Touring]

No, that old diff of mine has gone.

I saw that for sale thread of yours and thought that set up was cool, like you say you need to be using it for drifting/track work/ect to get the best use out of it.

I'd settle for a Z3M cover for the mainly road use my car gets.

[M3Compact]

... you need to be using it for drifting/track work/ect to get the best use out of it.

I'd settle for a Z3M cover for the mainly road use my car gets.

Drifting use would benefit hugely from the 4-clutch conversion. For prolonged track use a cooler would be handy imo.

We can't even use the breadvan finned cover as it's too vulnerable, the standard E30 cover and oil capacity has proved good enough for our shortish period abuse.

[stuartgallafant]

where do you get these kits from simon and how much are they?

im definately gonna have a go at this now!

is it easy enough to swap all the bearings too? and setup up the pre-load and things like that too???

[Templ8e30]

Had my LSD apart today, one of the clutch plates is in a bad way

As stu asked, where can we get these parts ?

I've been on C3's website and they do a group N 40% lock up kit with new plates and different profiled pressure rings for £170 ish.

Cheers,

Iain T

[stuartgallafant]

...I've been on C3's website and they do a group N 40% lock up kit with new plates and different profiled pressure rings for £170 ish...

thats good!!! i've been searching for ages for stuff, but couldn't really find much. Even the stuff that i did find was mega-bucks!!

[tee]

Have you rung nige yet stu?

[stuartgallafant]

Have you rung nige yet stu?

yeah, he spoke to JP Race for me, they said about £70 just to strip down and look at it, but i gotta have a proper chat with the bloke

iain, those lock up plates can be made from original ones, as M3Compact/simon was saying

i'd rather do that than spend nearly £200 on them!!

i need the actual lock-up clutch discs i think. and new bearings for the sake of it, and i'll change the ramp angles on the end plate whileits all apart

[M3Compact]

I've been on C3's website and they do a group N 40% lock up kit with new plates and different profiled pressure rings for £170 ish.

Cheers,

Iain T

Is this a 4-plate pack?

We use genuine ZF Atlas kits at £120 for the clutches.

There's a place here that supplies them for less, I haven't used them - but T1000 on E36coupe has without any problems.

[stuartgallafant]

Simon, the parts that Iain is talking about are only the pressure rings and not the discs aswell

im gonna browse through the link you supplied! how easy is it to do?

[stuartgallafant]

Simon, just had a look at that site. What kit are we talking about needing???

Atlas LSD Plate Repair Kit. Consists of 4 steel external drive plates and 4 coated internal drive plates


Atlas Gp4 Plate Repair Kit. Consists of 2 steel external drive plates, 4 coated internal drive plates and 2 external lug wavy plates for added preload.


Atlas LSD Gp4 Wavy Plates. Manufactured from profiled carbon steel, formed, and heat treated.

and how much are these???

and also, are these...

Pinion Bearings


Side Bearings


Crush Spacer


Pinion Flange Oil Seal

included in the kit or are they seperate? if they are seperate, how much?

thanks for all this info dude

[Templ8e30]

Have a peek at this link http://www.metricmechanic.com/pdfs/Differentials.pdf

Gives a good idea of the internals of our LSD's, however our standard E30 LSD's have only 2 sets of plates rather than the 3 illustrated.

A good tip if you're rebuilding one, when fitting the end cover make sure you use strong (green) loctite on the 8 bolts. I've got an LSD here that had unwound 7 of the 8 bolts and snapped the head off the 8th. All the bolts have been chewed up by the crown wheel and pinion damaging the gears and chewing up the bearings with the swarf and metal chippings

The bolts are difficult to get hold of, metric fine M8x1.00x16mm reduced height socket heads in high tensile 10.9 steel

Fortunately I've rescued the clutch unit so I can fit it to another good diff.

Cheers,

Iain T