Thread: TC V Diff Locks

The TC system in the D3 is far more sophisticated than that in previous models.

I does not need speed to activate. It will activate at speeds lower than you can probably physically drive the car!

And, as far as I'm aware, the diff lock system in the D3 is capable of 100% lock up.

I've got both TC and centre and rear diff locks; so as tempest said, best of both worlds!

Originally Posted by gghaggis

difflocks can easily overload your drive train, especially when one wheel in the air comes down to earth rapidly. And I'd rather change brake pads than half-shafts or CV's.

Gordon,
I tend to disagree with this. While the wheel is in the air, greater stress will be put through the axle/CV on the ground while the diff is locked, but when the other wheels comes back to the ground, it is more likely to be spinning at a slower rate and closer to the ground speed than an unlocked diff, as the opposite wheel on the axle is transmitting power to the ground, thus less of a shock load, as only half of the power is going through it. An unlocked diff could have 100% of the power going to the axle/CV when it lands, this power will be instantly transmitted through the diff to the other axle as soon as the wheel gets grip, meaning more chance of breaking either of the axles/CVs or even the diff as the change in power distribution is transmitted through the spider gears.

Either way, you just need to remember the golden rule, bouncing equals braking!

TC is reactive. If you need to keep a bit of momentum, the delay in TC kicking in can be your undoing.

Difflocks are proactive, in that you need to anticipate the need & engage beforehand. Useless if half way across &....

Actually I'm surprised how often the light comes on in "normal climbs". You don't know how often you lift a front wheel.

One thing I don't like about TC is it changes your driving style - it goes against the grain to keep your foot in it when traction is lost.

Regards
Max P

Watching a 4WD with good traction control work its way up is slippery or rocky slope is quite amazing ( well to me anyway ). You can see it working - one wheel will spin a bit, it'll take a think, try another wheel and so on until its gets forward motion. I would presume TC and an auto would be a good comb.
I'd have to think seriously about the need for difflocks in my next car with the TC systems around now.

Heres's a bit of video that give a comparison ( although it's a bit doubtful if the TC in the Disco was working )

http://www.youtube.com/watch?v=elU2e7ZnNz8

Originally Posted by rrturboD

Also, consider when TC locks say left wheel, tailshaft is spinning at same speed, so right wheel drives at double the speed to accommodate the stationary left, .

No it doesn't, differential action doesn't half/double the wheel speed

In my experience TC works well at slow speeds, but not too well at high speeds. The link below shows how it works at slow speeds.
Note the on/off pulsing.

I was travelling with 2 Patrols on the day, one open diffed GQ, and one front and rear locked GU. After picking lines a little better the GQ got up, but the GU made very easy work of it with front and rear lockers on.

http://www.youtube.com/watch?v=D4-E6R0uXLQ

John

Originally Posted by rovercare

No it doesn't, differential action doesn't half/double the wheel speed

Yes it does! - lift one wheel of the ground and the ratio it turns at is about half that when both are on the ground (e.g. 2.35:1 instead of 4.7:1).

So much for your "practical" experience... Never noticed that when a 4x4 with an open diff lifts a wheel that that wheel spins faster???

Originally Posted by rovercare

No it doesn't, differential action doesn't half/double the wheel speed

Rovercare,
If one wheel is stationary, the other wheel will spin at twice the speed. If both axles are doing 50RPM with the prop shaft doing 100 RPM, if one axle starts doing 0 RPM but the prop shaft remains doing 100RPM, where does the 50RPM that the now stopped axle go? Out the other wheel, ie double the wheel speed.