Tell me about Hydratrak diffs...

[pupp]

How do they differ over the 'conventional' version, and why is this 'better' (I'm assuming it attracted a premium because of some claimed benefit), and are they interchangeable.... ie could a BTR HT be slotted in instead of a BTR regular, all else being the same?

Cheers

[andyoleary]

Good question, I have one on my Tusc and would be keen to know the answer so thanks for bringing it up....all we need now is someone who knows to show up...

Andy

[Wildfire]

There is a really good post a while back by GreenV8S who explained the differences. Try a search. Can't remember the title thoug,

[andyoleary]

(bump)

Can't find anything specifically relevant on the search option. Anyone able to answer this or is GreenV8S about perhaps??

Cheers

Andy

[satman]

Wildfire said:

There is a really good post a while back by GreenV8S who explained the differences. Try a search. Can't remember the title thoug,

GreenV8S said:

Like what he said, but I think the difference between Hydratrack and a 'proper' LSD is more fundamental. An ordinary friction locker transfers a constant amount of torque from the faster wheel to the slower wheel, the amount of torque transferred is a constant (defined by the diff preload) plus a component that is proportional to total prop shaft torque (defined by the taper angles in the diff). This sort of diff is nicely predictable, transfers torque the instant either wheel starts to spin up, and makes power oversteer (relatively) predictable and controllable. However, it also means you get a significant torque transfer in normal cornering due to the variation in wheel speeds, so it suffers a little more push-on understeer in slippery conditions and tends to spin the inner wheel sooner when powering through a corner. However, the amount of wheel spin is limited due to the friction connection between the wheels, so niether wheel will spin up on its own.

HBydratrak is a viscous diff which beaves completely differently. With these diffs, the amount of torque transferred is propertional to the speed difference between the two wheels. Two consequences: (1) in cornering, there is no wind up between the wheels so no push on and no tendancy to spin the inner wheel, you can push harder before it starts to let go, (2) when either wheel slides, it has to spin up quite a lot before the torque transfers to the other wheel. This can mean that in slippery conditions or under hard acceleration you sit there smoking one wheel before the diff transfers power to the gripping wheel.

Searched and found this...think the answer you are looking for!

[Figgis]

In short a Hydratrak Limited-Slip Differential provides improved handling and enhanced safety for drivers by incorporating a cartridge-type fluid coupling, which progressively and smoothly increases torque transfer to the wheel with traction.

This is in direct response to the reactive speed difference between the wheel with traction and the opposing, faster rotating wheel, the wheel that is slipping. So, the more one wheel slips, the more
useful traction that is transferred to the opposing wheel.

The benefits of the Hydratrak LSD is that it improves stability and handling, progressive build-up of torque transfer as wheel speed difference increases and is speed sensitive with innovative fluid coupling.

As to whether they are upgradeable, there are some areas you can mess about with. Mainly the Racing Tuscans and T440R and T400R's had some modified Hydratraks in them. Your question would be best posed to someone from BTR or a Gearbox/Differential rebuilder.

Hope this helps.

[andyoleary]

Cheers Satman/Figgis - most helpful. This might explain then why I have never (not once) spun out the back end of my Tuscan in 3 months and 2K miles of driving.....I have Toyo's fitted and have to say that the grip is phenominal - I thought it was just the tyres but sounds like the hydratrak diff is doing a good job too. Of course, it could be that I have just never pushed past the limits (yet)

Cheers again

Andy