[DavS1]

Just wondering what diff my car is fitted with, I suspect open but had a suspicion of LSD the other night

[doughboy]

No LSD available from bmw.

is your car new?

[DavS1]

It's an 09, I read somewhere it's an E-diff? similar in feel to a viscous diff?

foot down off the lights, it stepped out a little before traction control kicked in

[doughboy]

An E diff (if yours has it) is the age old trick of applying brakes to the spinning wheel.

So instead of redirecting torque to the grippiest wheel, it just wastes the energy via heating the brake on the spinning wheel.

And its reactive so the wheel spins before the brake can act, wheareas the ATB LSD will spread the torque as the grip reduces thus pre-empting the spin in the first place.

Still better than nothing though.

[xenon]

Originally Posted by doughboy

An E diff (if yours has it) is the age old trick of applying brakes to the spinning wheel.

DSC individually brakes spinning wheels (and not just backs-off power).

What's the difference between DSC and an E-Diff, DB?

[DavS1]

So, anyone know what diff it has got?

[willhollin]

It's a shit diff.

[AlanQS]

It is very very unlikely that the first owner (or was it a Dealer car?) fitted a LSD to the car.

If I re-call, the easiest way to check it is to jack up the back end so that both rear wheels are off the ground (chock the front wheels) and, with the handbrake off and in neutral, turn one of the wheels by hand. Now the next bit, I forget which is the right way round but with one type of diff the other rear wheel won't turn and with the other, it will. Someone who knows which is a sign of an LSD, please help me out and post!

[DavS1]

Cheers, I was just curious if anyone knew off hand, It has the diff fitted by factory its not been changed it's a totally std car, thought it'd be easier to ask here rather than jacking it up or getting it sideways ......

Doesnt really matter either way I dont drive it hard or need an LSD, i've had my fun (and scared myself) with 400bhp RWD LSD equipped cars

[doughboy]

Originally Posted by xenon

DSC individually brakes spinning wheels (and not just backs-off power).

What's the difference between DSC and an E-Diff, DB?

I think DSC simply brakes wheels to help steer the vehicle in a straight line, as needed to help pass crash tests.

But the e-diff I think, tries to emulate an LSD by braking spinning wheel in as a separate function to DSC, to stop to torque loss.

[xenon]

Hmm, I was pretty sure DSC did that too.

[doughboy]

Originally Posted by xenon

Hmm, I was pretty sure DSC did that too.

I thought so too, but then BMW started selling 135i's with 'e-diff' which suggests it is another function...


or marketing BS?

[Skid]

Originally Posted by AlanQS

If I re-call, the easiest way to check it is to jack up the back end so that both rear wheels are off the ground (chock the front wheels) and, with the handbrake off and in neutral, turn one of the wheels by hand. Now the next bit, I forget which is the right way round but with one type of diff the other rear wheel won't turn and with the other, it will. Someone who knows which is a sign of an LSD, please help me out and post!

If it's an open diff when you spin one wheel clockwise the opposite will turn anti-clockwise.
An LSD the opposite wheel will turn in the same direction.

[YvesD]

Originally Posted by doughboy

I thought so too, but then BMW started selling 135i's with 'e-diff' which suggests it is another function...


or marketing BS?

Doesnt matter, will never be as good as our Quaiffe ATB's

The drive off traffic islands and tight corners is amazing. A thing of beauty.

Yves

[doughboy]

Originally Posted by Skid

If it's an open diff when you spin one wheel clockwise the opposite will turn anti-clockwise.
An LSD the opposite wheel will turn in the same direction.

Only a friction or clutch type LSD will tend to do this,

A geared ATB (automatic torque biasing) LSD (like quaife or torsen etc) spins in opposite directions under no load (i.e. jacked up) just like an open diff.

This is good as no one (i.e. BMW) will ever know you have fitted the quaife unit inside the factory diff housing.

As Yves says, its a thing of beauty

[Jamese93]

No, it's not got a LSD, but it does have traction which keeps things in line you really need a manual with revs piled on the get the rear wheels to step out - my old vert with full revs and traction off used to spin them all over the shop - not really easy with an auto

[YvesD]

Originally Posted by Jamese93

not really easy with an auto

Unless the road is slightly damp and you have Bridgestone RFT's fitted that is!

[m1bjr]

I'm typing this sat in Birds.
Whilst they stick the Quaife in

It's going to be a long day with the other bits on the list too.
Nice guys here. LIke home, but no TV.

Steve

[kaishang]

Originally Posted by Jamese93

No, it's not got a LSD, but it does have traction which keeps things in line you really need a manual with revs piled on the get the rear wheels to step out - my old vert with full revs and traction off used to spin them all over the shop - not really easy with an auto

I can activate the traction control no problems if I plant it around a corner and mine is an auto....

[DavS1]

Well as said, it did step out and traction light flashed when taking off from a set of lights in damp conditions.


I had my fill of LSD's with my old 200sx, rear wheels lighting up at 85mph in 5th gear on the motorway on a wet road.....brown pants!

[Jamese93]

Originally Posted by kaishang

I can activate the traction control no problems if I plant it around a corner and mine is an auto....

That's as yours is a diesel with stoopid amounts of torque (read: lucky man )

[Jamese93]

Originally Posted by DavS1

Well as said, it did step out and traction light flashed when taking off from a set of lights in damp conditions.


I had my fill of LSD's with my old 200sx, rear wheels lighting up at 85mph in 5th gear on the motorway on a wet road.....brown pants!

If you nail it in first you'll get it to step out - turn all systems off and it will light up a little while, but as some posters say that's due to the lovely run flats!