Hi, I would like to know if the Quaife ATB limited slip differential with the code QDH2K will fit the Coupe turbo gearbox either the 5 or 6 speed.
The other question I have, if it fits what do I do with the viscous drive.
When I asked Quaife they said that it can work with the viscous.
Thanks

yes it does as I have one fitted to my 20vt and bin the visco drive as you wont need it .

QDH2K is for the C510 gearbox (non turbo coupe)

Then which one is for the turbo?

Did you fit it on a 5 or 6 speed?
What have you done with viscous drive? How did you replace it?

its fitted to a 6 speed box and the visco is removed as its not needed with the quaiffe diff , you will need a different driveshaft seal for the drivers side shaft .

Can you please guide me?
Do you keep the same shaft or use another one?
Replace the seal with what seal?
Thanks

Keep the coupe shaft but with the visco removed and ill have to check what diff seal we used but I think it was from a fiat bravo .

Hello,

Maybe a dozen of people here know the answers of your questions.

Although I have noticed that when somebody asks "What exactly is needed to bin the viscodrive and put the Quaife into the gearbox", nobody gives accurate answer!?! Maybe it is some kind of secret or know-how that they don't want to share...

So let me get straight to the point :

I am a pharmacist not a mechanic but I have some basic skills and I have "Quaifed" my coupe by myself and 10 000+ km later - no problems at all!! The whole thing is not complicated but you will need some tools and car lift (preferably).

1)Do you keep the same shaft or use another one? - YES, you keep the same shaft but you have to remove the viscodrive.

2)Replace the seal with what seal? - WHen you remove the viscodrive, you will see that if you use the original driveshaft((28mm diameter), you will need different seal cover (from jtd or alfa romeo V6 gearbox for example) + custom gearbox oil seal (28x50x10mm).

Here I found something that could be helpful for you (with pictures) :

http://www.totallyalfa.com/blog/index.cfm/2015/3/1/How-to-fit-a-Q2-or-Quaffe-Diff-to-your-V6-gearbox

What is the part number of the Quaife to fit a 20vt?

Errr, see OP

Sorry dw,I thought the answer was there already. According to Quaife catalogue, it's QDH6E

To: digitalundgrd
Which Quaife diff did you use (QDH2K or QDH6E)?
On which gearbox did you install it (5 or 6 speed)?
Thanks

Did same and i can confirm it.
I used Quaife that previously was fitted to 145's 1.9JTD.....it's same as 156's 2.5V6 and 166's 3.0V6.......
Quaife number was QDH6E

QDH6E

My coupe is 16VT with 5-speed gearbox. Also I didn't remove the whole gearbox. You must unbolt the front subframe and then just unbolt the rear differential casing and take the differential out.

But 5 or 6 speed gearbox IMO there is no difference. The installation procedure is the same.

Ferrarist, The QDH6E is not listed for 145 1.9JTD, for this model is listed the QDH2K, as per Quaife catalogue.

The problem is, I have contacted Quaife and ask them a couple of things regarding the QDH2K and I have clearly mentioned to them that I was going to install it on a Fiat Coupe 20v turbo and they didn't tell me that it doesn't fit. They have only said that as far as they are aware this fits the 5 speed not the 6 speed, so I ordered it. Now some people are saying it fits and some are saying it doesn't. When I asked Quaife again they said that they haven't heard of any issues with this fitment.
I believe that in the end the best solution for me is to give a try and see by my self. If it doesn't I will contact Quaife and try to return it and get the correct one.
Thanks all of you for the feedback.

For 6 speed you need qdh6e that's what I can understand as quaife aren't sure . But gearbox company have measured and looked at diagrams and that's the diff which should fit .

Order from auto lusso lot cheaper and you order kit with seal and bearings .
It's the custom oil seal auto lusso said you can buy it but no one knows what it is.

Matching up a seal from another Fiat/Alfa should not be too hard. There is no surface on the Coupe drive shaft for a seal to seal against however so you'll have to fit/weld a collar or machine one.

There is likely a plug and play solution. My first guess would be to use a Croma/Thema drive shaft and seal.

QDH6E is what's fitted to my early 20vt with early 5 speed gearbox

I don't know if it's listed or not, but i bought 2 very same P/N Quaife diff's from Autolusso UK, one was fitted to my 3.0V6, other one to my friends 145's 1.9JTD '99.....QDH6E.
After year or so he abandon the car, i removed his Quaife and fitted it into my 20VT.....
P.S - now i have 2 same Quaife diffs, one is on 5 speed early GB, other one on 6 speed GB from Alfa 166 3.0V6(same as 156's 2.5V6.....

There is nothing special and magical about this oil seal. If you use oil seal from other fiat/alfa/lancia it would be with 29mm diameter and it will leak quite a lot!

So the easiest thing you can do is to use the original drive shaft + jtd or v6 gearbox seal cover + custom oil seal (28x50x10mm) which costs 1 EURO!!!

Is there any need to check bearing pre-load or do you just re-use the original shim pack?

I re-used the original shim. No strange sounds, no leaks, no broken gearbox

IMO in 99% of cases the original shim can be re-used without problem. Still you can measure and check the preload for your own comfort

Thanks for the feedback

By measure you mean check end float before removing the original diff from the gearbox?

Here it is what the book says for 16vt gearbox :

I understand the custom seal is not special it's just a seal . I have the measurements and once it's all back together I will show what I used and where the parts came from .