what sort of power will brake a diff ?

[ross2009]

abit of a random question
but id like to know has anyone broke a medium case 188 lsd diff
or anyone know what sort of peak power or tq that said diff would hold??

[penton08]

I have seen them cope with 500 whp, drive shafts and propshafts normaly let go first.

[ross2009]

my drive shafts will not let go i can tell ya lol there rated at 1500 bhp lol
reason im asking is that the next engine im going to be putting in will have a serious amoung of tq and i really dont know what to do diff wise

[penton08]

I've seen your shafts a large case e36 m3 evo diff should take a shed load of grunt, might be an issue getting it fitted though. You will need a meaty prop too!

[ross2009]

there big and chunky
yeah i was thinking of maybe a e28 large case which has the same bolt up as the 188...... but
theres no real way to hold the bk up on them with out a twin eared rear cover but i dont believe they made such a cover for a large case
the e36 one has no bolt up place like the 188 but does have twin ears rear cover so its abit of a bummer as in what to do
yeah the prop will will be compleatly re designed as it will have a different box in it also

[jmc330i]

my drive shafts will not let go i can tell ya lol there rated at 1500 bhp lol

A guy at work does a lot of off roading 4x4 events. He was telling me about a guy with a land rover of some kind, who got fed up with breaking half shafts (apparently they are easy to change on the side of the road, just unbolt, remove broken bits and slide new one in), so he fitted uprated/unbreakable ones.... got stuck and instead of breaking a half shaft, he tore the diff apart and that was weekend over. Next event he was back with normal half shafts lol


Unless you've seriously strengthened the boot floor, I'd be more worried about ripping the diff mount off the car. I've seen that happen with a standard M20

What ratio diff will you need with the new gearbox? A Z3M 3.15:1 LSD bolts into an E30 and is built with 321bhp in mind and I'm sure will take much more than that. But its still only got one mount to the boot floor.... Might be worth a search on here, because I'm sure I remember a post on here about the twin ear E36 diff being fitted.

[ross2009]

ill be getting about 321 bhp on about 3 or 4 cylinders of what ive got in mind
dont need to worry about ripping the floor out im not a stranger to building chassis to take to power

well ideally i want a twin eared rear cover but on a large case diff but i dont think they ever made a twin eared cover for a large case diff
im not 100% sure on ratio yet i think it might have to be low or i might even have to go quaife diff etc to hold the power
but if not then ill have to stick with a medium case and see what happens

[jmc330i]

ill be getting about 321 bhp on about 3 or 4 cylinders of what ive got in mind

Well I'm hoping you're looking at doubling that cylinder count??.... Sounds like my kind of plan


If you're happy with modding the rear end to suit, I see no problem with getting any diff to fit. Just a case of finding a diff that will cope and fit with a sensible amount of work. I'm sure the E36 M3 diff has been done...

Maybe look at some of the big power E36s and see what diff they run? Or the S50/S38 turbo E30s - there's a black 2dr with M3 arches and a blue M3 both running near 1000bhp, from one of the Scandinavian countries I think.

[ross2009]

yeah indeed it is going to have 8 cylinders lol all at 4 inch diameter a pop

the modding isnt a proplem im just trying to make things a little easier

well i know limmets e30 ran a e28 large case at over 1000bhp on a m20 but he had a proper cnc machined rear cover on that which looks the mutts nuts but to try and get some thing like that wil cost a prettty penny like soo


which is were i got the idea from but i suppose i could make some thing to hold the e36 diff or what ever i choose

[Kos]

It all depends how you treat it

[ross2009]

It all depends how you treat it

true but its going to have silly amounts of torque so i want to over engineer it so i know if i do plant it i know its going to hold

[redcar]

What sized tyres are you using? Drag slicks?

[ross2009]

What sized tyres are you using? Drag slicks?

im not using anything yet this is all for an up and coming project that im trying to get my head around for when i do it but at the moment ive 225s on 9js but im also thining of changing wheels at some point so again i couldnt tell ya as that might change

[Rav335uk]

Boys over on R3V have had over 550rwhp running through them, no issues.

[youtube][/youtube]

[ross2009]

rav im looking at alot more than that not to mention double the amount of torque lol

[Rav335uk]

Best get a largecase one and bolt it up.

[maxfield]

I know a man that makes custon diffs etc. Although not cheap.

That machined case is nice, maybe the way to go if your running serious power?

[ross2009]

Best get a largecase one and bolt it up.

thats the idea mate
having said in a previous statement about a large case rear cover i have found that the e39m5 rear cover is from a large case and does indeed have a rather fancy twin ear rear cover i wonder if i could get it to fit on a e28 large case

[ross2009]

I know a man that makes custon diffs etc. Although not cheap.

That machined case is nice, maybe the way to go if your running serious power?

i mean if it comes to it i could just put a quaife set up in a medium case and brace everything up but then im looking at 1k for that

im thinking of a way to do it well but cheaply as poss

[Rav335uk]

Surely, if going to all this trouble, you could have Quaiffe?? internals fitted into a medium casing.

[ross2009]

Surely, if going to all this trouble, you could have Quaiffe?? internals fitted into a medium casing.

just said that rav come on keep up lol

[maxfield]

Building big power cars doesn't come cheap

Agree with rav get the large case bolted up and look where you can go from there

[ross2009]

Building big power cars doesn't come cheap

Agree with rav get the large case bolted up and look where you can go from there

i know that mate look what ive ploughed in to mine as is youve seen it at pod you can see how much money ive put in to it

[Rav335uk]

Surely, if going to all this trouble, you could have Quaiffe?? internals fitted into a medium casing.

just said that rav come on keep up lol

I posted it just after you, thinking alike.

But I would be going largecase, no messing about.

[ross2009]

lol ha yeah rav that was my intention to start with but i was concerned about the rear cover and being able to fix it up well enough to hold as most only have the little slot as that isnt going to be good enough

[maxfield]

I know mate, I've started building my car, the costs are rising already, will be all worth it in the end.

You may have spent a lot of money and time, but I'm sure it puts a massive smile on your face!

[ross2009]

I know mate, I've started building my car, the costs are rising already, will be all worth it in the end.

You may have spent a lot of money and time, but I'm sure it puts a massive smile on your face!

o it does as soon as i sit in it i start smiling i love it
even more so its got 400 bhp on tap

but what im thinking of doing next is a whole different ball game mate

[maxfield]

Well what ever your doing I imagine it will be awesome if you're bored of 400hp.

[ross2009]

Well what ever your doing I imagine it will be awesome if you're bored of 400hp.

what im doing will more than likely be the only one in the country

[maxfield]

Individuality is the way to go

Especially when it involves lots of horsepower

[ross2009]

Individuality is the way to go

Especially when it involves lots of horsepower

yep indeed it will be some thing special i can tell ya

i have got my eye on a e28 m5 diff on the bay at the moment its only on for 99p lol

might be worth a punt

[HairyScreech]

Do i sniff a charged SBC?

If so there may be no replacement for the extra wheel/pinion contact that a large case provides.

However the diff will only see as much torque as the tyres can hold.
If the tyres just spin at 300lb/ft then you wont really be putting 900lb/ft through the diff.

Whats more likely to kill it is the gear chatter caused by continuous slip and grip of the tyres under high loads.

[ross2009]

Do i sniff a charged SBC?

If so there may be no replacement for the extra wheel/pinion contact that a large case provides.

However the diff will only see as much torque as the tyres can hold.
If the tyres just spin at 300lb/ft then you wont really be putting 900lb/ft through the diff.

Whats more likely to kill it is the gear chatter caused by continuous slip and grip of the tyres under high loads.

you do indeed smell what im cooking

but there you do have a good point about how much the tyres will hold before they spin but im quite sure im puttng more than 300lb/ft thro it now and i dont have not one sign of losing traction which is a good thing i think ive set it up pretty well to handle it chassis wise
just looking to upgrade a little to take the extra grunt

[HairyScreech]

Oh yeah, just picking figures from the air.

If your looking at what i'm thinking get yourself over to the speed talk forum.
(link by pm)

[zaust]

Think a med case diff is stronger than you think. I'd be more worried about your diff mounting points and prop and the choice of gear box.