I mentioned this to JBT at Donington yesterday, but I do think a few people should maybe consider getting there viscous drives overhauled.

After browsing on the integrale forum, there has been a thread recently where a couple of people have sent there viscous drives to a specialist to get them overhauled. Below is a couple of photo's of the state of the plates that come out of the viscous drives :



As you can see in the first 2 photo's, lots of scorching on the plates, with also comments being made that the fluid coming out was like tar (when it shouldn't be). Whilst the viscous drives have been taken apart, new plates put in, the torque level it will start working at can be uprated too, handy for the bigger powered cars.

The price, well I have seen prices quoted from £200 to £350, depending on the number of plates that need to have been replaced. I'm sure Tricky will be along to comment, as the last 2 photo's are from his integrale viscous drive

The viscodrive on my Sprinty was completely fubar'd by the time I finally scrapped it. Due to running very good tyres and decent geometry, it wasn't too bad on the road, but when it had its last fling at TOTB, it was torque-steering all over the place and lighting up the inside wheel with ease. I reckon if I'd had a working viscodrive, I would have won the FWD handling (I only lost by 0.08 of a second)

It would be interesting to know more about uprated viscodrives and whether its a viable alternative to a Quaife ATB diff

Hey theres copy right on those !


You have an interesting point, I would say the best thing to do is phone bara himself just talking to him, he really knows his onions on VC units. He used to modify the units for Abarth grp A. I know he also does alot of stuff for cosworth lads as thier 4x4 uses an actual visco differential quite similar to what you lot have as opposed to the integrale unit which is a 'ferguson' unit acting on a seperate diff.

I would say there is an advantage for the coupe but VC's are not a full locking diff and there might be some side effects by going too far with the higher rating in a fwd setup. It is true that the fluid degrades as some of you have already seen, If you can afford it and your car is a well modifyed road car I'd consider a torsen diff (do quaife make them for the coupe ?)

I'd phone bara himself if you wan't some advice on what might work.

I think the Coupe diff is similar to the 'Grale diff (minus the prop shaft of course), ie. not a 'proper' lsd but an open diff with a seperate viscouse coupling connecting the drveshafts.



Everything I've read says that the Viscodrive can't be taken apart, but I've been thinking about buying one for ages to see if you really can't take it apart! Apparently viscoous fluid is only supposed to last <100k miles, which would mean that practically every Coupe on the road needs theirs overhauling!

Can someone tell what exactly is doing to Visco during this overhaul....and what fluid is used for refill????

...hydraulic oil mix, the viscosity of which plays the important role, given it's the correct quantity in the case. That's like the old "bremse" used to load engines for testing, and similar idea to the oil shocks.

Sorry if i sound silly, but will things gets better if only oil is changed....

I got a new visco for a bit more than 300 pounds from fiat.is it worth your while to spend the money for repair or getting a new one?
I bought mine about 1 year ago, and have the old one as a spare.

Oh yes, not seen a coupe one before. It just acts accross the diff ie; the two outputs. None of them are meant to be rebuildable, manufactures suggest buying a new one if it's found to be shot. This bara fella has the correct equipment to do that. I wouldn't recomend taking it apart yourself, as it's filled with very high pressure silicon fluid that might shoot in yer face. Once you have it apart theres not really much that can be one with it anyway.

Did it make much difference to the way it delivers power to the road?

Begbie, is there anyway of telling if it needs an overhaul?

I had mine on jacks at the weekend and could still feel the visco making life difficult to turn one wheel when it's jacked up.
Would a worn visco become more or less difficult to turn a wheel?

No idea Jimbo, just reciting information taken off the integrale forum. I was contemplating on it, but thought I would be better off spending money on getting the car finished, rather than the Viscous drive.

If anyone wants the contact details they are :

Bara :- 01527 880011
or email him on:- bara@baramotorsports.com

I would say more difficult. My own unit checked out at 140nm, the std being 120nm and it did need replacement discs fitted. This is because the fluid was stale and metal to metal contact was occuring, therefore a higher initial torque is needed to seperate the plates. A typical uprated version for the integrale is 300-400nm

The coupe Vc will be rated a lot lower than this probably around 20-40nm and an uprated version will probably not be a massive increase on it. This is because unlike the integrale which has the VC acting on the center diff where the wheel speed diference is not as variable across the two axles whereas the coupe has it between the two outputs of the front diff, where high axle shaft speeds exist and are constantly variable.
The VC's job is to promote equall drive, in a fwd car with this setup you might have to be carefull not to introduce too much equal drive otherwise it might start to effect the handling mid corner and under heavy braking.

Best speak to bara for advice.

This is similar to the delta setup just for referance.