[R330dx]

The Drexler diff seems very good for me so far, although havnt tried other lsd's in bmw's as a direct comparison, used quaife lsd before in rwd and fwd and there fine if both driving wheels are on the ground, if you lift a driving wheel you loose drive, which isn't usually a problem of course in road use but can cost valuable time in racing. Plated diffs keep the drive even with a lifted wheel.

[moff]

Originally Posted by dirkules88

At least they have a LSD. Part of my next round of mods as my 443bhp 340i can absolutely not get it on the road many times haha. Great to break traction and drive sideways but not fast off the line until it grips.

I ran a C63 with 457hp for 2 years and never had an issue with traction. Obvsiously when wet and cold it was challenging but no different to my 440 now.

Also, not running sh1tty RFT's is a huge help.

[BMWiltshire]

Originally Posted by Lorcan

That would be the one to go for then, as BMW sell you a complete boxed diff which leaves your standard one spare and is an easy swap over (and back later, if need be). The Schnitzer one has slightly more locking action but you have to send them your diff and wait for it to come back modified, which is a PITA to be frank, and you can't easily revert back to standard if you sell the car.

Any and all mods I do I want to be able to reverse at some point, so sounds like the M Performance diff may be the way to go - will price it up with fitting once I've got the suspension done in the new year. Thank you for your advice!

[BMWiltshire]

Originally Posted by moff

I ran a C63 with 457hp for 2 years and never had an issue with traction. Obvsiously when wet and cold it was challenging but no different to my 440 now.

Also, not running sh1tty RFT's is a huge help.

Yeah I want to get rid of the rft but can't bring myself to ditch them when they've got a load of wear still in them, as soon as they're shit though it'll be proper tyres all round

[moff]

Originally Posted by BMWiltshire

Yeah I want to get rid of the rft but can't bring myself to ditch them when they've got a load of wear still in them, as soon as they're shit though it'll be proper tyres all round

Stuff the wear lol

I sold mine and got MP4S's after about 5k when I could take them no more!!!

[BMWiltshire]

Originally Posted by moff

Stuff the wear lol

I sold mine and got MP4S's after about 5k when I could take them no more!!!

Haha, yeah I should really, I curse them daily!

[rossm]

Originally Posted by R330dx

The Drexler diff seems very good for me so far, although havnt tried other lsd's in bmw's as a direct comparison, used quaife lsd before in rwd and fwd and there fine if both driving wheels are on the ground, if you lift a driving wheel you loose drive, which isn't usually a problem of course in road use but can cost valuable time in racing. Plated diffs keep the drive even with a lifted wheel.

Plated diffs are also noiser at low speed and require regular maintenance unlike the Quaife which is fit and forget. How often do you drive with your wheels off the ground to make it worthwhile having the other one?

[t5pilot]

Originally Posted by M2Andy

Don’t M3/4’s have a reputation for exactly that... difficulty putting their power down?

Yes, they do mate. The GTS diff & TC software helps though. Quite a lot. But with 550hp you still have to be careful. Let's just say it's 'challenging'. Keeps you on your toes though! You HAVE to be fully aware at all times, which, is a good thing.

It's the biggest thing I miss from my tuned 35d X-drive, planting your right foot without a care in the world...

[Watsey]

I've had a Quaife diff in my 330D for the past 3 years or so and it's been utterly reliable. It can feel a little open at times, but the upside is that being gear rather than plate the torque shift to the tyre with more grip is very progressive. There is still some over-rotation of the inner wheel but the TC system does not feather the throttle (unless TC is on and you break traction with both tyres) - the traction benefits from the diff really make a difference to daily driving and when pushing-on.

I've not had a plated diff on my cars so don't know whether they 'snatch' as they lock-up - can't offer you a direct comparison on that.

[BMWiltshire]

Originally Posted by Watsey

I've had a Quaife diff in my 330D for the past 3 years or so and it's been utterly reliable. It can feel a little open at times, but the upside is that being gear rather than plate the torque shift to the tyre with more grip is very progressive. There is still some over-rotation of the inner wheel but the TC system does not feather the throttle (unless TC is on and you break traction with both tyres) - the traction benefits from the diff really make a difference to daily driving and when pushing-on.

I've not had a plated diff on my cars so don't know whether they 'snatch' as they lock-up - can't offer you a direct comparison on that.

@Watsey & rossm

Thank you both for the Quaife info, lots of food for thought and great to get advice from people who've already gone down this route - this is the whole reason I use this forum!

[dirkules88]

Originally Posted by moff

I ran a C63 with 457hp for 2 years and never had an issue with traction. Obvsiously when wet and cold it was challenging but no different to my 440 now.

Also, not running sh1tty RFT's is a huge help.

My mates C63 507 Edition gets the power down really well but that came with an LSD already.

I'm running reasonably new 275 MPSS in the rear obviously that tyre lives of being at the right temperature and that's an issue in the cold.

[GermanWhipped]

Originally Posted by BMWiltshire

@Watsey & rossm

Thank you both for the Quaife info, lots of food for thought and great to get advice from people who've already gone down this route - this is the whole reason I use this forum!

Hi there mate, sorry to
Bump an old post/thread but I have followed your journey with the BMW 440i upgrades and was really impressed.

Did you end up upgrading the suspension? What did you go for.

Still have the car?

Cheers

[winther1]

Curious too as I might be hitting same numbers soon with BM3

[Quantox]

Originally Posted by Wills2

Apart from the M3/4 is built to take and deliver that power through its bespoke rear axle/solidly mounted sub frame/electronically controlled mechanical LSD/wider track/suspension and sticky 285 section tyres, the 440i is effectively one wheel drive with an open diff going into a 255 section run flat with the same suspension/sub frame and axle set up as a 320i.

Oh Crap, Now I'm so disappointed with my F36, glad it's not a 20i though.

Q

[chris-c]

I know I'm not the OP but I honestly thought the car was "okay" suspension wise up to stage2 (450-480hp) but once I added ethanol and it was into the 500's it was obvious the car had shortfalls. The traction is problematic and the suspension just isn't capable with that power.

I've recently gone to a hybrid turbo and after a month I've had enough of the suspension so it's getting a Quaife ATB LSD and Birds suspension as soon as they can fit me in.

The other thing is brakes. The car NEEDS decent brakes and I found that the mperformance big boy brakes (370mm) just were not cutting it so had to upgrade the pad compound as I was getting massive brake fade and judder from them leaving deposits.

[winther1]

Under hard acceleration I sometimes feel the car pull to the right. On a few occasions I was well on the way to the opposite lane before lifting the pedal. Tyre pressure is even. Is this a common effect of power vs open diff? This happens at the current 395bhp - not sure I would enjoy 450 if this gets worse without LSD

[Tengocity]

I've got the MP diff and BM3 on our 340 tourer, along with full ACS sports suspension. I think it's perfect for us as a discreet performance oriented family car. The traction is very good with PS4S, certainly not traction limited. The suspension is a good balance of ride and handling and significantly better than stock. However, it's only any good up to 8/10ths for me. The steering is a little too vague for my liking, and it doesn't quite have the roll control I'd want to really enjoy pushing it hard as an out and out sports car. If it was my only car I'd definitely fit Coilovers, as my 335d with coilovers handled better. But it's not, and I've got other cars for that kind of driving.
I was more aiming for an Alpina type of character rather than Mcar, and it can certainly do that very well.

[ValleyBMWs]

These are nearly my exact numbers ...... Yet, I got so much shit on my post

F33 xDrive B58B30M0 w/Mppsk & MHD Stage 1 93Oct ..... 444 whp | 480 lb-ft

https://f30.bimmerpost.com/forums/sh....php?t=1721857

[ValleyBMWs]

Originally Posted by chris-c

I know I'm not the OP but I honestly thought the car was "okay" suspension wise up to stage2 (450-480hp) but once I added ethanol and it was into the 500's it was obvious the car had shortfalls. The traction is problematic and the suspension just isn't capable with that power.

I've recently gone to a hybrid turbo and after a month I've had enough of the suspension so it's getting a Quaife ATB LSD and Birds suspension as soon as they can fit me in.

The other thing is brakes. The car NEEDS decent brakes and I found that the mperformance big boy brakes (370mm) just were not cutting it so had to upgrade the pad compound as I was getting massive brake fade and judder from them leaving deposits.

Great post - Would like to point out suspension refers to vehicle handling. You are talking about the drivetrain.

[chris-c]

Originally Posted by ValleyBMWs

Great post - Would like to point out suspension refers to vehicle handling. You are talking about the drivetrain.

No, I'm talking about suspension AND drivetrain if you read what I put.
I swapped to a Quaife LSD and I also swapped to the Birds suspension setup.

[dizzy619]

Originally Posted by ValleyBMWs

Great post - Would like to point out suspension refers to vehicle handling. You are talking about the drivetrain.

I wouldn't have bothered🤦*♂️

[chris-c]

Originally Posted by dizzy619

I wouldn't have bothered🤦*♂️

I'm really not sure what the issue is. When increasing power many things became apparent as a shortfall. The whole car felt unsuitable.

The transmission needed mapping to handle the extra power and the transmission is starting to slip. Here I am talking about the HP50 gearbox.

The car found the limits of the suspension a lot sooner so upgrading to the birds setup helped

The car lost grip sooner so the Quaife was needed.
The car needed more stopping power hence brakes.

Over the last year I've done too many modifications to the car now. I know it's various limits in different states of tune.

Currently I'm fighting simple physics as I'm at the limit of mechanical grip down to power.

Oh and handling would be an overall characteristic of a car so that would be suspension, brakes and pretty much everything else that makes the car go how it goes.