Quaife/Q2 LSD know-how needed

My 16VT Coupe is in the 300+hp club now. I use it only for fun (Sat/Sun driving on track or twisty roads). Viscodrive is not up to the job anymore I decided to change the stock diff and to put Quaife or Q2 LSD in the 5-speed stock gearbox.

I've read some posts here (fccuk.org) but I can't find a clear answer to the question : "WHat exactly is needed to put Quaife LSD into Coupe 5-speed gearbox?" I am with the impression that everyone who knows exactly what have to be done is keeping it "in secret".

I will be very thankful if somebody would share some know-how with me so that I can change the diff by myself. I am not a mechanic so I will not steal your job or customers. Please send me PM if you don't want the information to be public

I have only 2 questions:

1) Which is the correct part number for the quaife LSD that must be purchased? According to the quaife official site QDH2K-21 is for Fiat coupe and QDH6E-2 is for Alfa 156 GTA. I am a little bit confused because I have read that Coupe owners are using GTA Q2/Quaife diff?!

2) What kind of "long" drive shaft are you using (from what car) after deletion of the original drive shaft with viscodrive on it? Maybe from N/A 16v Coupe ?

Thank you in advance

Standard diff not up to job? Theirs plenty of use in the 300-500hp range, using the standard diff with no problems what so ever so I am supprised but then again im talking about the 20v version but surely they cnt be to much difference??
Are you sure your diff wasnt jst worn out rather than not being able to cope? As a warn diff would give same symptoms as over power for your diff...

Yes. Maybe it's worn. My Coupe is one of the first produced in 1994 so viscodrive is old enough and not performing at its best. However I prefer to put Quaife or Q2 rather than new or second hand viscodrive.

Quaife over viscodrive is like night and day , had mine for a year and a half and wouldn't go back to viscodrive .

Did you install it Nismo?

it was installed by me , marco and a mate of his from autolusso who installs quaife's to alfa's so he knows what he was doing .

Oh, yes......Quaife makes real difference.....


Alfa 156's QUaife can be used on Coupe 16V, driveshaft is the only problem......As far as i know Autolusso sell it for 550 pounds........Guess you had my mobile .....

So the Alfa 156 GTA is the one to buy.

This is some info about the driveshaft but still not mentioned what exactly was modified to fit...

we used the drive shafts from the coupe with no problems at all , the only thing I changed was the drive shaft seals for new ones and mine is a quaife for a 156gta .

In this case is the drive shaft long enough after deletion of the viscodrive unit?

yes but you need to use the o/s gta seal cover and a different seal . if you need any info or the seal and cover plate then give marco a call @ http://www.torqueautomotiveltd.co.uk/

Hi nismo, any chance you can explain just what benefits over the stock unit? Only issue i have is in the wet i do get wheel spin when i get to full boost around 5/6 k, always jst put it down to the wet rd, not thought about the diff not up to the job..

Im running around the 360 hp with my 20vt and the one thing i would like is better handling, done all the usual mods but not thought about the quafie but if their realy is such a BIG differance thats the next item to purchase on the never ending list of mods! Lol..

Quaife diffs are not plug and play, they need to be pre-tensioned correctly along with the right seals otherwise your crown wheel will float in the bearings and it'll leak all your gearbox oil.

I've been running my Quaife for a few years now and the difference between Visco and Quaife is as Ian has already stated, night and day and loads of fun, especially in the wet left foot braking when on boost

If anyone goes for a Quaife make sure it's correctly fitted by someone who knows what they're doing. Quaife themselves cover these with a life times guarantee from memory but read the small print as it states a recognised garage/specialist needs to install.

totally agree with you Joe , its not something I would have installed on my own , a specialist is required for install and one who knows what he's doing .

Nigel's review

Today I have installed quaife diff into my gearbox.

I have used my original long driveshaft (28mm diameter). Viscodrive is removed and custom gearbox oil seal (28x50x10mm) is used + seal cover from jtd gearbox(diesel).

It's not as hard as people think are they

I did mine last year and has been faultless

Yes. If you have all the parts and the tools you need it is 2 1/2 - 3h job

I have driven the coupe with the new diff during the 3 day alfisti.gr event(150km at the track).

My impressions :

- almost no understeer and no spinning of the inside tyre while cornering. A lot of grip through the front wheels!
- rear end of the car became very sensitive and it wanted to oversteer most of the time. I am using 22mm whiteline rear ARB if this fact does matter.
- the steering feels strange when I first drove the car with this diff. I can describe it like driving with low pressure in the tyres compared to what was before. The steering wheel always "wants" to make the front wheels to point straight ahead. Even when I steer left or right I can feel some kind of force that pulls the steering wheel to the central position. Is that normal?

I agree about the oversteer - ever since I had my Quaife fitted, the car feels more nervous in very high speed corners - I'm using a Novitec 23mm rear ARB

I'm trying to reduce it by playing with the geometry, but I haven't fully sorted it yet. I've already set the tracking to 2mm toe-in and my next change will be to reduce the camber (currently at 1.3 degrees negative - I'll probably go back to about 0.75 degrees negative)

I don't want to rise discussion, but IMHO fitting stiffer rear ARB, without changing front with stiffer as well, on a heavy-weight-front-end FWD car as Coupe will produce a lot of oversteer.....
Have front 26mm Eibach bar from my Alfa 156's, and i plan to fit it to my Coupe, and did a try with and without 23mm rear bar....
Below is a simple quote from "Competition car suspension" book.....a great resource.....

I was on Per's car, with uprated ARB and camber bolts on the front, and by passenger, I think that the car has got very great handling.

Mine T20 (full stock) seems it doesn't want to turn, instead of Per's car that seems to have rear wheel steering!

Hi Ferrarist

I understand your point, but seeing as the Coupe suffers from understeer as standard, uprating the rear ARB will simply reduce the understeer - it won't automatically push it into oversteer

On my Sprint Blue Coupe, I originally tried uprated front AND rear ARBs - roll was reduced, but understeer remained. I then had the front ARB returned to standard and kept the uprated rear. It transformed the car - it was totally planted at ridiculous speeds, yet nimble through twisty bits.

However, after the Quaife was fitted, the balance was disturbed - it has the feeling of falling into oversteer (but never actually does, although I'm not sure I'd like to have to jump on the brakes at high speed on a gentle curve - feels like it will let go)

FWIW, this thread has prompted me to take action - I've emailed Quaife to ask if they can give any advice - will keep you posted

Is it possible that any of these symptoms are caused by the lack of viscodrive, rather than the addition of the Quaife? ie is the Quaife more free in normal driving than the visco which might somehow affect the balance or make the handling feel different?

Maybe it is like driving fwd car with full race slicks at the front wheels and normal street tyres at the rear wheels. You have so much grip at the front that you are confident to push hard into the corners but then suddenly your rear can't reach this level of grip and it just let go...

So IMO quaife makes the front end of the car too grippy but then you don't have the same grip at the back and the thicker rear ARB makes the things even worse causing oversteer...

Agree with above......
We discuss very car-to-car specific matter......personally for me FWD car must be prone to bit of understeer, because it's easier to correct.....if fwd car oversteers mid or in corner entry - it's nightmare to avoid spin.....
And vice versa - rwd car wont suffer from bit of oversteer.....
And it's matter of car balance, weight transfer, suspension setup and a lot more.....
I drove same car fwd, then it was rwd, lot of weight in front when fwd, perfect 45-55% balance when was rwd and mid-engined, did not tried twin-engine car still .....Did trackdays only with full slicks - nothing can change car's behaviour most than ARB and tire pressure, assuming that suspension and springs works fine.....
And i'm pretty sure that WE ALL can make wrong assumption about car's behaviour when on track - sometimes i had a feeling that the car handles worst than before, but laptimes and available telemetry state otherwise......
We may try to be very addicted amateurs, but way too far from profis......


Guess no - Quaife can make things only better....


When your car oversteers - after braking in corner entry, mid corner, or when throttle applied on exit?

Rear end feels twitchy and prone to oversteer :

1) in fast and long corners while 70-80% throttle is applied. For example at the Serres circuit sections: K2-K3-K4 and K11-K12-K13

2) after braking in corner entry (especially when is damp)

So - we have some differences - when I'm accelerating, I have no feelings of oversteer at all. At very high speeds (120+) in long corners while simply maintaining speed, it starts to feel a little loose at the back end. If I lift off the throttle, it needs a corrective input on the steering wheel.

I think I have a combination of factors contributing - a bit too much camber, a very stiff front end and also different tyres (Continental on the front, Toyo on the rear).

I think I'll do a front-rear swap on the wheels to see if it makes a difference - its a no-cost experiment, so definitely worth trying

Also - I've had an email reply from Quaife - we are arranging a time for a chat on the phone

Update - just got off the phone to a techy chap at Quaife - he's very much into his motorsport and is used to having to play with settings to get a car to handle correctly

He's said that a Quaife'd car will generate so much more front end grip that any car that has had handling mods to reduce understeer will quite likely tip into oversteer once the diff is fitted

As I mentioned above, I've been recommended to back off the handling mods, by reducing camber and possibly even removing the uprated rear ARB

Before I remove the ARB, I'm going to back off the camber to standard, put the Contis on the rear and play around with the tracking a bit more. If its still over-steery, I'll then put a standard rear ARB on

Fingers crossed....

This is exactly what I found after fitting camber bolts on my car and I don't even have a Quaife! I'm only running a 22mm rear ARB but it subsequently generated so much more front end bite at 1.25 degrees that the rear would step out for too easily for my liking. I had them removed soon after.

To be honest, I suspect that the bushes (along with several suspension components) may be a bit tired on the rear and contributing to this.

I like my coop handling nice and neutral so I can hoon around regardless of tricky cambers or the possibility of lift off oversteer due to 'unforseen circumstances'...

Oh Looks like the Rear anti roll bar thread could be redundant if everybody got quaifed!

I found the rear on the LE to be twitchy after fitting mine but I put it down to needing to refurb the rear subframe which is on the cards over the next few months but as you say it maybe caused by the diff.

Il be awaiting updates on this thread that's for sure

Nigel, I'm surprised a man with your experience of handling cars has mismatched tyres fitted!! My first option would be to fit a matching set before I adjusted anything in the geometry. Different traction at either end of the car is going to be a nightmare set up.

I found that on track in my old car jimbo, it Yokohama parada 2s on the front and toyo p/t1r on the rear.
It was a beautiful warm day at donnington and the car just under steered,
I came in after six laps and swapped the (expensive) yokohamas onto the rear and the transformation in handling was amazing, turn in was great and throttle steering was so controllable.

LOL - very true

I bought the Contis because they were a bargain. I seem to have worn them out pretty quickly though - probably more than half worn after 5k miles

My Toyos on the rear are still very good, so I have a choice - put new Contis on and take off a perfectly good pair of Toyos, or replace the Contis with more Toyos

Whilst I think Toyos are a brilliant tyre for the money, I have to say I've been deeply impressed with the grip of the Contis - £19 more per tyre though...

I think a front-rear wheel swap will confirm or eliminate the tyre difference as a contributor to the oversteer

Nigel, I had Conti 5p all round and they were a great tyre in the wet and dry. Before that I had Falken 452 as alot of people use rave about them, all I can say about them is.... NEVER AGAIN, average in the dry and terrible in the wet and they were rock hard.

My Dad has Toyo t1r all round on his 450bhp plus, not bad, miles better than the Falken but for the sake of 38 quid a pair you have to get the conti's!

Nigel, thank you for this info

So my suggestion was correct. As I said before - too much grip at the front compared to the grip at the rear after I've got quaifed...

I will also try with reducing the front camber and I will put 26mm eibach front ARB because I want to keep my 22mm rear ARB.

What about trying to even the weight up more so bring weight fro. The engine bay to the back like relocate battery, washer fluid and anything else you can move to the boot area, possibly GRP bonnet aswell

Will be good idea, anyway GRP bonnet is not cheap, but with that you can remove about 30 - 35kg from the front end.....

My battery is already relocated into the boot where the spare wheel usually is (the lowest point).

Air con compressor, pipes and radiator - removed

Washer fluid tank - removed

I am dreaming for GRP bonnet since I've bought the car but it is too expensive. However when I have the money I will change it for sure!

Auto ds are doing a bit of a deal on grp bonnets at the moment......