I'd be interested to see how you get on Marco - I'm beginning to think that a standard viscous coupling isn't beefy enough to work properly with 400bhp - in the current damp weather, I'm spinning up the inside wheel a lot more easily than I remember doing last winter - maybe I've cooked the viscodrive unit?

Either way, it would be interesting to consider a proper LSD

Think you might have done Nigel - in the current slippy conditions, i'm finding if i give it too much of the loud pedal in a corner it just wants to go straight on as both wheels spin up...

Alfa Q2 fit in 20VT 5 speed?

Good question.

Any feedback on this chaps?

You could get the fluid uprated also as cheaper option. This is done on a lot of other cars.

I have a friend with an MX-5 saying he needed to replace the viscous coupler every 100k km. Viscous fluid is known to degrade over time. For all you BIG BHP guys you should really look into a mechanical LSD (though more aggressive).

I didn't know you could replace the fluid... I would be surprised if you could.

Hi fella's ( and any female members !! ),

Just joined tonight after searching for tuning tips/ideas for my Marea 147 20v.I came across this thread and thought I would add to the discussion.

I bought a Turbo box with a view to fitting it to the Marea for the benefits of the Visco drive, hence to say it's a completely different box and the gears would not be to the Marea's liking anyway .

Something good came of it however, as my brother has a 155 V6 with a 156 6 speed box ( fitted with a quaife LSD ) and he wanted to check out the turbo box.

He brought his standard 156 diff and final drive down to mine. I took the diff/final drive out of the turbo box and we checked the teeth on both final drives and they where the same, as was the cast number 7783659. So where the cast numbers on the diffs - 7783660.

So, apparently, a standard Alfa 156 V6 Q2 LSD should fit into the turbo 5/6 speed box .

Hope this helps someone

Is there any way of telling if the viscous diff is working properly?

you can replace the fluid in rs turbo diffs I know that, theres a fella in birmingham that does it makes one hell of a difference

Tonight I've fitted Alfa Q2 on Fiat 20VT 5speed. I'm just looking the way to fit shaft without viscous coupling.

So, if you could figure out the cancelation of Viscodrive then the Q2 LSD fits the 20VT 5speed??

This is a great finding.

I'll try finding some 20V N/A shaft. In case there are the same from the differential to the near shaft then problem is 100% solved. If not, I'm sure there is solution, I read somewhere that some sort of sleeve was made for 20VT to remove viscodrive. I also wonder how much power this Q2 LSD can handle?

Q2 diff is good for around 400bhp and around 300 pounds feet torque from what I have seen and heard in tuning circles.

There are quite a few drive shaft companys that will make you a bespoke drive shaft.
My friend had one made by a company in Luton for his Mk2 Escort cosworth conversion.

What about using the Alfa 155 V6 2.5 shafts?

I think they will fit properly.

Alfa 155 V6 are 20-25mm shorter:( Tried them today...

Umm, did i mislead you ?!!

Please forgive me. i didnt mean it.

But that was close.

300ft/lbs doesn't sound like a massive amount by modern coupe standards (ie there seem to be alot of people running over 300ft/lbs now)

Have there been many failures over 300ft/lbs or is this a (conservative) manufactures rating?

You didn't:) It was just another idea, it was close. I gave my shaft to people who will make some sort of sleeve. Will keep you posted

Supposedly its what Alfa "rekon/claim" it can handle.

The KAAZ 1.5 LSD is a better diff to the Q2.

I know someone who had both diffs fitted and he rants and raves about the KAAZ,its the best thing since sliced bread.

Kaaz part number is 2510? Kaaz is much expensive anyway.

Any update on subject?
Conclusion is - Alfa Q2 fits 20vt 5/6 speed boxes?

Alfa Q2 fits 5 speed for sure. My 20VT is 1997 manufacturer year

Yep the q2 will fit the coupe 'box,

Sorry to drag up an old thread, but does anyone know if the v6 final drive will fit the 5 speed box