Fitting a limited slip diff

M

mcbutler

Senior member
Hi All,

General opinion is that a standard diff is fitted to the 35i car.

As I am sure most 35 owners with mapped/modified cars will agree the standard diff fitted to the car is completely incapable of dealing with the rest of the powertrain. I know my 35i on anything but a good grippy dry road will be scrabbling for grip in 1st/2nd/3rd gear changes and in the wet is getting close to dangerous.
So, talking to a local indy and a mod specialist I was told very quickly that a LSD will 'transform the car'.

Next question, has anyone fitted one, what do you think?

Pricing seems extreme, the diff from Quaife is around £1000 but I also need a crown wheel and pinion, around another £500 - £600 and then of course fitting, probably around £350.
 
Hi Mark, my Quiafe diff is being fitted at the moment by a subbie to B for BMW in Glasgow.

It will probably take a few hard charging trips out to see what the effects are..

I noticed on mine with the remap when accellerating hard that when the wheels unload over a bump that she can break traction quite easily then struggle to recover..I haven't provoked the car mid corner wet or dry so can't comment on that..

Others have fitted these to E85/86 eg PH001.

Birds (who market the Quaifes) wax lyrically about the benefits, most are what you seek..

So I'll see how she feels and maybe I'll be able to get round corners quicker in future..
 
mcbutler said:
As I am sure most 35 owners with mapped/modified cars will agree the standard diff fitted to the car is completely incapable of dealing with the rest of the powertrain. I know my 35i on anything but a good grippy dry road will be scrabbling for grip in 1st/2nd/3rd gear changes and in the wet is getting close to dangerous.
Click to expand...
Manual?
Which tyres?
 
mcbutler said:
Hi All,

General opinion is that a standard diff is fitted to the 35i car.

As I am sure most 35 owners with mapped/modified cars will agree the standard diff fitted to the car is completely incapable of dealing with the rest of the powertrain. I know my 35i on anything but a good grippy dry road will be scrabbling for grip in 1st/2nd/3rd gear changes and in the wet is getting close to dangerous.
So, talking to a local indy and a mod specialist I was told very quickly that a LSD will 'transform the car'.

Next question, has anyone fitted one, what do you think?

Pricing seems extreme, the diff from Quaife is around £1000 but I also need a crown wheel and pinion, around another £500 - £600 and then of course fitting, probably around £350.
Click to expand...

A LSD won't help your straight line grip, the ediff in the E89 will apply the brakes to the wheel which loses traction so you don't just spin up 1 wheel like old cars with open diffs. Even with the Quaife fitted you will still struggle putting power down in the lower gears.

The best way to gain traction is tyres and rear suspensions components like stiffer bushings.

On a warm dry day I can open it up in second without any slip, that's with 275 width Michelin Pilot Sport 4S. In these wet winter conditions I still sometimes slip in third gear.

There's a chap on another forum who has a highly modified E89 which he uses for racing/track work and this was his feedback on the Quaife LSD:
We installed a quaife core on mine, and after a few thousand miles the diff bearings were done due to faulty installation. Got a scrap yard diff and had the actual quaife importer do the install with the same old core. So far no problems. Point being, don't cheap out on installation if you go for an ATB core.

However one wheel peel is not really a thing on the Z4 except in the rain. Seems most people get LSDs just because it is cool. Im sure you know what you are getting, but I just want to mention it to others reading.

I do not recommend getting an ATB LSD for the Z4 unless you
1a) want to practice drifting in the rain and/or
1b) care about lap times on a track, looking for a more planted rear end when exiting onto curbs etc.
2) Drive with DSC=off. In good conditions, there are really no benefits to be had if you drive in normal mode imho. Traction control will have already decided to kick in, when the diff starts to react, no matter open or LSD. That is my experience.

Know that the OEM diff is absolutely usable for drifting in the dry. If you want more grip on the street try better tires first. If that doesn't work, try even better tires. A diff wont really increase straight line grip in normal conditions.
Click to expand...
 
A company marketing a product is unlikely to decry it or highlight its limitations..

However the write up from Birds contradicts R.E92 posting, at least in part..

https://www.birdsauto.com/content/what-quaife-atb-limited-slip-differential
 
Pbondar said:
A company marketing a product is unlikely to decry it or highlight its limitations..

However the write up from Birds contradicts R.E92 posting, at least in part..

https://www.birdsauto.com/content/what-quaife-atb-limited-slip-differential
Click to expand...

Birds have just copied the sales blurb from Quaife. Not a shocker considering it's a big earner for them.

Asbjorn was the chap who made that post. He's done some serious track time in his Z4 so I would take his word over anyone selling it!

Here's some of his postings: https://bmw.spoolstreet.com/threads/the-grand-track-tour-of-china.4001/
 
R.E92 said:
Pbondar said:
A company marketing a product is unlikely to decry it or highlight its limitations..

However the write up from Birds contradicts R.E92 posting, at least in part..

https://www.birdsauto.com/content/what-quaife-atb-limited-slip-differential
Click to expand...

Birds have just copied the sales blurb from Quaife. Not a shocker considering it's a big earner for them.

Asbjorn was the chap who made that post. He's done some serious track time in his Z4 so I would take his word over anyone selling it!

Here's some of his postings: https://bmw.spoolstreet.com/threads/the-grand-track-tour-of-china.4001/
Click to expand...

I read his blog, clearly put a lot of effort into his racing, however..

He has twiddled with so mnay things its difficult for anyone to quantify any one change..

A racetrack is a wholly different enviroment from hooning down unfamilar roads in variable /unpredictable conditions

So I would respect /like to hear from someone who has road based experience of this..if possible..

Ironically just heard from the diff expert that Birds shipped the wrong variant, on the Z4 there are two versions and despite a full VIN number check they got it wrong..so will me middle of next week before I can use my favourite Moffat-Selkirk test track checkout..
 
Just thought I would reply to mcbutler now I have had chance to use my private test track (Moffat to Selkirk) on the way back from B for BMW who, in the end used a subbie to fit the Quaife diff as they said its a very specialised job, and he spotted asp, that Birds had supplied the wrong diff!

Anyway for reference the car is running (today)
Zito 935 8.5/9.5 wheels with 235/40/18 and 255/35/18 Continental Sport Contact 5P tyres (about 1/2 worn on back, 1/3 worn on front)
MSport springs with Bilstein B8 dampers
H+R front rear anti roll bars (rear on middle position)
Celtic stage 2 tune (alledged 285bhp)
And now Quaife QDF14N LSD

Today it was 10c and the road was mostly damp, wet in places and a fair amount of mud from logging lorries.

I've been up and down thsi road quite a few times, its a challenging road with mixed surfaces, severe bumps, tight and sweeping bends,soem good straights..

I tried the car in Sport Mode Plus, Comfort Mode and Comfort Mode with DSC off

Whether I was in happy mood or the gods were with me,a nd without 2 cars back to back here's a few observations..

The car just felt happy, despite hooning down some very damp/bumpy roads the traction control (when on) hardly flashed a light, which on dry days down there happened a few times..

Switching from full on to a 'whoops the bend is sharper than i remembered' training throttle was calm under any circumstances..

Pulling out of a junction ona damp day which with a boot would result in wheel spin, then bog, then lurch off was much smoother and quicker.

With Sports Mode Plus with DSC disabled I pondered on the explanation I would give to the officer when I explained I was enjoying 'the looser stability' round bends..before I went off the corner into hyperspace..

So very pleased with the result, B for BMW gruppen fuhrer was very glowing about how it felt..took some time to get out of the driving seat as he demonstrated perfect dougnuts in the industrial estate..

So to your question..

You have a lot more ponies..more weight, different tyres, suspension etc..will it work for you..I'm sure it will make things better..

Is it worth £1200 ish , thats your call!
 
Pbondar said:
Just thought I would reply to mcbutler now I have had chance to use my private test track (Moffat to Selkirk) on the way back from B for BMW who, in the end used a subbie to fit the Quaife diff as they said its a very specialised job, and he spotted asp, that Birds had supplied the wrong diff!

Anyway for reference the car is running (today)
Zito 935 8.5/9.5 wheels with 235/40/18 and 255/35/18 Continental Sport Contact 5P tyres (about 1/2 worn on back, 1/3 worn on front)
MSport springs with Bilstein B8 dampers
H+R front rear anti roll bars (rear on middle position)
Celtic stage 2 tune (alledged 285bhp)
And now Quaife QDF14N LSD

Today it was 10c and the road was mostly damp, wet in places and a fair amount of mud from logging lorries.

I've been up and down thsi road quite a few times, its a challenging road with mixed surfaces, severe bumps, tight and sweeping bends,soem good straights..

I tried the car in Sport Mode Plus, Comfort Mode and Comfort Mode with DSC off

Whether I was in happy mood or the gods were with me,a nd without 2 cars back to back here's a few observations..

The car just felt happy, despite hooning down some very damp/bumpy roads the traction control (when on) hardly flashed a light, which on dry days down there happened a few times..

Switching from full on to a 'whoops the bend is sharper than i remembered' training throttle was calm under any circumstances..

Pulling out of a junction ona damp day which with a boot would result in wheel spin, then bog, then lurch off was much smoother and quicker.

With Sports Mode Plus with DSC disabled I pondered on the explanation I would give to the officer when I explained I was enjoying 'the looser stability' round bends..before I went off the corner into hyperspace..

So very pleased with the result, B for BMW gruppen fuhrer was very glowing about how it felt..took some time to get out of the driving seat as he demonstrated perfect dougnuts in the industrial estate..

So to your question..

You have a lot more ponies..more weight, different tyres, suspension etc..will it work for you..I'm sure it will make things better..

Is it worth £1200 ish , thats your call!
Click to expand...
I have asked around a dozen mod companies including my preferred supplier Celtic, my local indy (one of whom is all about on BMW performance as he races them). ALL of them agree that a quaife LSD is the way to go and that it transforms the car, result being more noticeable as power increases. We discussed the electronic controls fitted to the Z4 but as anyone with a tuned 35 knows the lights are on and off all the time and it frankly does very little that is really effective.
So, yes its my next mod.

Can you give me a break down of costs parts - labour and the supplier please.

Regards
 
I drove a 110bhp MX-5 with an open diff for 8 months or so, then installed a TorSen diff to it and the difference was noticeably better whenever I was driving spiritedly. The MX5 had no traction control, so maybe you won't feel the same difference I felt as DTC tries to mimic an LSD by braking the wheel that loses traction, but oh my was it the best thing I had done to that car. So much more predictable and fun to drive.

I paid £300 for that diff, which I thought was quite a bit then and I was working and earning relatively well then. I miss having an LSD so much that now, even as a student, I'm saving all I can (read eating CupNoodles every other day) to buy an LSD for my 3.0si... It is worth it.
 
Pbondar said:
Hi Mark, my Quiafe diff is being fitted at the moment by a subbie to B for BMW in Glasgow.

It will probably take a few hard charging trips out to see what the effects are..

I noticed on mine with the remap when accellerating hard that when the wheels unload over a bump that she can break traction quite easily then struggle to recover..I haven't provoked the car mid corner wet or dry so can't comment on that..

Others have fitted these to E85/86 eg PH001.

Birds (who market the Quaifes) wax lyrically about the benefits, most are what you seek..

So I'll see how she feels and maybe I'll be able to get round corners quicker in future..
Click to expand...
i suspect you will notice the difference in the first bend in the first drive! I did with my e85
 
lucasxdiniz said:
I paid £300 for that diff, which I thought was quite a bit then and I was working and earning relatively well then. I miss having an LSD so much that now, even as a student, I'm saving all I can (read eating CupNoodles every other day) to buy an LSD for my 3.0si... It is worth it.
Click to expand...

Well an LSD would probably have made your drive in the field at the Black Swan even more fun! :rofl:

Good luck with your saving. :thumbsup:

And if you get bored with Cup Noodles there's always beans on toast!
 
Mr Tidy said:
lucasxdiniz said:
I paid £300 for that diff, which I thought was quite a bit then and I was working and earning relatively well then. I miss having an LSD so much that now, even as a student, I'm saving all I can (read eating CupNoodles every other day) to buy an LSD for my 3.0si... It is worth it.
Click to expand...

Well an LSD would probably have made your drive in the field at the Black Swan even more fun! :rofl:

Good luck with your saving. :thumbsup:

And if you get bored with Cup Noodles there's always beans on toast!
Click to expand...

Yes, it wouldn't have made it so pathetic :rofl: That was just to check whether TC would kick in if it completely off based on what something someone had said here (that it would).

Baked beans :sick:
 
Mr Tidy said:
How can you not like baked beans? :o
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I'm not British, so baked beans was not something I had come across until I was 16, specially not for breakfast - my normal breakfast is what you guys call 'continental breakfast'. The first and only time I had a full English breakfast I was sick for two days, and since I have not been able to even smell baked beans.

Mr Tidy said:
Maybe try cheese on toast or poached eggs instead. :lol:
Click to expand...

That's more like it!

This is me when I'm out with friends and the waiter asks if I'm also having English breakfast :rofl:
 
Mark,

Prices I was quoted /actual were as follows:

Birds supply Quaife LSD £893.65 +vat

Birds fully fitted £1670 inc VAT ..as you say the 35i series has a welded crownwheel..

I was charged £165+VAT for a specialist to fit in Glasgow with 3 hours labour to remove and replace at B for BMW, labour rate as about £75 per hour.

So about £150 cheaper than Birds doing it..

From what I heard its a pretty specialised job as even the B for BMW guys contract it out.

Out of interest, had to take the car for its MOT and the roads were teh most treacherous I've seen yet here in the Scottish Borders.

A couple of hills, one with a very sharp, steep turn.

Both the zed scampered up on summer tyres with only a very little flash on the DSC on the first steep hill where quite often, non AWD cars just get stuck with one wheek spinning..I was taking it very very carefully but anyway..there you go!

Enjoy
 
I could not imagine Z4 ownership without my Quaife diff. It was my very first mod and especially with a tune, it’s a must have.

Also, an RWD car should really be able to light the rears up without any one tire fire. Disappointed they didn’t have it as a factory option.

I can highly recommend it if you are anywhere above 300 hp or like to kick the back end out every now and then.

This sums it up:

https://www.reddit.com/r/BMW/comments/f3dcn1/warming_up_the_tyres_35i_dct_mhd_tune_and_quaife/?utm_source=share&utm_medium=ios_app&utm_name=iossmf

:rofl:
 
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