TC V Diff Locks

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Originally Posted by isuzurover

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???

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Maybe I'm ignorant, but that doesn't make sense.

The drive shaft drives both axles in an open diff setup. It doesn't split the drive in half. The revs of the driveshaft should be altered by the gearing ratio so it should only half if the ratio says so.

If, for arguments sake, the ratio is 1:1, then if the tailshaft is rotating at 100 revs, then both axles should be rotating at 100 revs.

If in an open diff setup, the wheel in the air spins faster than when on the ground, it should only be because there is no longer the frictional retardation of the ground itself, thus reducing the load on the engine.

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Originally Posted by Aussie

Is it worth fitting Difflocks if you have TC? also to ppl who have TC in their vehicles, Wot are your thoughts on it?.

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In a word...

YES

:D

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Originally Posted by Jamo

Maybe I'm ignorant, but that doesn't make sense.

...

If in an open diff setup, the wheel in the air spins faster than when on the ground it should only be because there no longer the frictional retardation of the ground itself this reducing the load on the engine.

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The reason it happens is because of the gears in the diff. When both wheels are turning at the same speed, the pinion turns the crownwheel, but the side and spider gears in the diff remain stationary compared to one another. When you lift one wheel, the side gear on the axle (halfshaft) that is connected to the wheel on the ground now remains stationary (or rolls along with the speed of the vehicle), while the diff centre revolves around it... The change in ratio comes from the fact that the internal diff gears are now turning.

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Originally Posted by Redback

Wayne that's excactly how the TC works in a Disco, it keeps the car going even with 1 or 2 wheels off the ground, made that hill look easy.

I love the TC in mine.

Baz.

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The posts on diff ratios and spinning wheels is making my head spin :angel:
specially on a Friday nite !

Anyway ..Baz ... yes I agree ...I've personally experienced much the same situtation as in the video ...my car with rear difflock (as per the Rangie in the vid ) and a jap car with TC ( as per the Disco in the vid ) ..I got up with a bit of scramble and fuss but the TC car got up with much less "fuss". Mind you my driver skills ( or lack thereof )might have been a part of that too !!

Oh well, as I said, I've got both.: TC and two diff locks. I think I'll keep up with the rest off road, but I'm not sure if they'll keep up with me!;)

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Originally Posted by cmurray

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.

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I'll eat my words, the joys of posting when you haven't slept after night shift:(

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Originally Posted by isuzurover

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???

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Now Now Ben, this isn't OL:D

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Originally Posted by Aussie

Is it worth fitting Difflocks if you have TC? also to ppl who have TC in their vehicles, Wot are your thoughts on it?.

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It depends on the type of driving that you're doing.

ETC is totally under rated in my opinion, even in sand.

I drive a disco2 with ETC, centre diff lock, front and rear diff lock. My thoughts are ETC is better than no ETC. ETC is better than a LSD. ETC with CDL is better than ETC without CDL. ETC with CDL with 4 wheels on the ground is better than No ETC, but with CDL and a rear locker. CDL and a rear locker is better than ETC and CDL with less than 4 wheels on the ground. ETC with CDL and rear locker is best for climbing offset and angulated terrain and steps. Twin lockers with CDL is the best for crawling extremely difficult terrain but can induce front end movement if wheelspinning. Twin lockers with no CDL is stupid.

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Originally Posted by rovercare

Now Now Ben, this isn't OL:D

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I know, there is no finger:Dfinger icon :D - but it was on here you had a go at me for saying that an LT230 CDL was vacuum operated :p

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I'd have to think seriously about the need for difflocks in my next car with the TC systems around now.

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I have front&rear lockers & love them but,financially speaking the above quote makes alot of sense 2 me.

Cheers Dean.