Hydratrak : low perf??

[zidmie]

Hi all,

After 2 years of ownership of a nice 4.5 Cerbie, I decided to try it on a track (La Bresse, in France).
It was great! Easy to drive, good chassis, good engine...

But I had a problem : I had the feeling to have absolutely no LSD! The interior wheel was always spinning, I couldn't even get the car to oversteer under full acceleration. So it was quite slow after each turn...
I looked at the 1998 4.5L models, I should have a hydratrak diff. Does anyone know which is the good sentence?
- I have a classic diff, not a hydratrak?
- I have a hydratrak without oil anymore? (could it be refilled?)
- I have a broken hydratrak? (could it be repaired?)
- The hydratrak is a very bad LSD?

Did anyone fit another lsd? Maybe Quaife have lsd for this car?

Thanks a lot for your always useful answers!

Yves

[scotty_d]

The 4.2 cars had the hydratrac as a option, mine has a standard friction style set up lsd and it is great on the track. Might be worth finding out why our diff is not doing as it should then look in to your options then.

[jamieduff1981]

I'm not a huge fan of the Hydratrak so far as it's a little inconsistent for my liking, but it can definately spin both wheels. They can be worn out, and stop working if they overheat too.

[zidmie]

The diff has 65000 miles so I guess it is worn...

[jaydom]

Hi Zidmie,
Maybe you will recognize me as i'm a member from the french tvr car club too...
I never used my cerbera on a track, so i can not share any informations about this point.
I think Quaife (i'm sure even) has a diff that can be fixed ; quite a huge amount (nearly 1000€) without the fixing that seems to be quite difficult...
I have some problems with my Hydratrack too with big noises sometimes, especially when i use reverse gear and just after the first one when my front wheels are turning...
I've checked the brackets that are perfect...
And, another symptom, when i drive at high speed (more than 240km/h), the car is shacking quite a lot...
I think the diff is responsible of everything.
Next step : have it checked or directly change by a Quaife...
When i will have some money cause the diff of my old M just broke !
See u on the french forum soon !
Jay D

[jesfirth]

if you are using the car on track bin the hyrdatrack, if that is what it is and get a standard diff. having used both types in anger sprinting the cerb hydratacks are unpredictable and IMHO generally crap.

[julian64]

I like mine

[FUBAR]

Im not good enough a driver to tell the difference

[dean_ratpac]

i have inconsistent results with mine...

But i can tell you that the hydratrack certainly lights up both rears and you can hold the back out easily.

However on a corner when powering out every so often... the inner wheel can go. SOmehting on the list to replace.

[Brummmie]

The Hydratrack locks when it senses a wheel spin, so this is in effect too late, the cone diff locks as torque is increased so locks before spinning, or so thats the theory.
Mine got weaker and weaker (cone type), in the end was also totally open, i had it rebuilt with an extra spring to increase torque on the cone friction surfaces.
Much better.

[BCA]

They do break and become open.. ours did at 70k(ish?)

It's one of the worst things about the car IMHO - get it changed for something that locks properly and quicker. Ours felt/went/gripped much better with a Quaife ATB, it's something I'll do first when I get another.

[zidmie]

OK thanks to all for the good info, I think I'll get a Quaife.
I won't change it by myself and there isn't any garage who knows TVR around, so I'll bring it to a "normal garage". I hope it is easy to replace? Nothing needs to be modified?

By the way, my 420hp Cerbie was estimated... 320hp! A friend gave me his "driftbox", which uses GPS to estimate lap times, and also calculates car power when fully accelerating. The powers calculated for other cars were quite accurate, so I guess these 320hp are quite accurate too . I know I lost a lot of power when I put the catalysts (they are maybe too little). But I didn't expect such a low value!

Still enough hp to have a lot of pleasure

[pmessling]

No cars really left the factory with the quoted figure, 320 does sound low, perhaps get it on a proper dyno and find out for sure. Mine currently stands at 380.