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LSD advice please!


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As in diffs, not drugs (man!).

I'm thinking of putting LSDs front and back on my Tomcat rather than a locker on the back. Has anyone tried this and if so, what sort of results have you had?

Cheers

What's you're motivation for going LSD rather than locker? Not saying one's right / wrong but I'm just interested.

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What's you're motivation for going LSD rather than locker? Not saying one's right / wrong but I'm just interested.

I wasn't particular fond of the auto locker that I had and would prefer something that worked more in harmony with the vehicle if that makes sense! Oh, and I have a spare one!!!

Read an article in Total Off Road where one chap had done the very same thing.

I guess if the wheel is in the air, the diff would work the same as an open diff and would only perform really well with at least some traction. Or maybe with a little use of the brakes.

I also want something I can fit and forget - don't want on-board compressors, or cable lockers, etc.

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I've driven vehicles with an LSD in the back and they do make a differance but, in some situations, they don't get you as far as a locker. I also know of people who use them in fairly serious vehicles and like them. However, I use ARBs and like the control of them.

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LSD or torque-biasing diff? There's a difference. If you can get your head around how a Torsen torque-biasing diff works it's a beautifully elegant piece of engineering. The effect on the vehicle handling depends on the bias ratio, but if you've got all your wheels in contact with the ground it's very predictable. Under heavy cornering when a wheel is on the point of slip, torque is transferred to the wheel with the most weight. With a high bias ratio this transfer would be quite pronounced, but with a moderate bias the effect is to shove the vehicle forwards, hard, from exactly where you want to push. With a wheel off the ground the diff behaves as if it was open, although you can use the inertia of the roadwheel or gentle dragging of the brakes to 'help' the mechanism work for you.

Is there nothing that can't be done with Lego©?

torsenDifferential28.JPG

Limited slip diffs use friction plates between the halfshafts to transfer torque across the diff, and are like a half-locking diff. I don't have time for them because I don't like friction plates - I mean, who put a wearing component in the bellhousing anyway, stupid place for a clutch, you've got to take the engine out each time :rolleyes.

To be honest, if you install them instead of lockers you'd probably be disappointed. I like the 'fit and forget' ability and the engineering theory. It also massively outperforms an open diff.

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i know a bloke with a tru-tracs both ends in his ltwt, he loves them. he tends to play in bogs & mud so the wheels are always on the floor. which tru-tracs need to function as anything other than an open diff.

id suspect that for racing LSD/tourqe bias would be nicer than lockers as they wouldnt force you sideways as much on the corners.

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LSD or torque-biasing diff? There's a difference. If you can get your head around how a Torsen torque-biasing diff works it's a beautifully elegant piece of engineering. The effect on the vehicle handling depends on the bias ratio, but if you've got all your wheels in contact with the ground it's very predictable. Under heavy cornering when a wheel is on the point of slip, torque is transferred to the wheel with the most weight. With a high bias ratio this transfer would be quite pronounced, but with a moderate bias the effect is to shove the vehicle forwards, hard, from exactly where you want to push. With a wheel off the ground the diff behaves as if it was open, although you can use the inertia of the roadwheel or gentle dragging of the brakes to 'help' the mechanism work for you.

Is there nothing that can't be done with Lego©?

[/img]

Limited slip diffs use friction plates between the halfshafts to transfer torque across the diff, and are like a half-locking diff. I don't have time for them because I don't like friction plates - I mean, who put a wearing component in the bellhousing anyway, stupid place for a clutch, you've got to take the engine out each time :rolleyes.

To be honest, if you install them instead of lockers you'd probably be disappointed. I like the 'fit and forget' ability and the engineering theory. It also massively outperforms an open diff.

If anyone has had their apetite whetted by the excellent LEGO diff - there is quite a good explanation of the Torsen diff (including pics/diagrams) at http://www.2kgt.com/item.php?itemid=76

I personally love the concept of 'torque-sensing' or lockers better than slipping clutchy things (actually anything would be nice as long as it's free ;) ). BUT - If I had a spare LSD at the back of the garage I know where it would be headed :)

Rog

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I have tru-trac, torque bias centres, front and back in my disco (air lockers in my rangie and manual lockers in my bushie).

So far I am pleased with the tru-tracs. Advantages include automatic operation and better directional control than true lockers.

Ultimately, they will not be as good as a true locker when a wheel lifts, but this has not been a problem yet (early days).

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there is quite a good explanation of the Torsen diff (including pics/diagrams) at http://www.2kgt.com/item.php?itemid=76

Except that he's wrong:

Well, when worm gear drives worm wheel, they will be locked up. As a result, the left worm gear and right worm gear are actually locked together, thus wheels on both side will rotate at the same speed and get the car out of the lose of traction.

Because the angle of the involute (worm) gear is quite steep, torque is transmissible back through the involute and it is this angle which gives the different torque-biasing ratios. Thus the wheels don't have to rotate at the same speed when the diff is biasing torque - it's not a locker. Nice pics though :)

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A TruTrac is a Torsen-type diff, and indeed is what I have in the back axle of my Ninety. If you want to see it in action, I might be able to cross-axle it for you somewhere around Bristol or Stroud on Sunday?

Basically it keeps going when I don't expect it to. It got here without the centre diff locked...

18112006072.jpg

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Hi all just new to forum on this subject

Had a Detroit locker fitted in rear of my 90 but found it to aggressive as it would lock in when not expecting on conners and roundabouts so now got True Trac`s front and rear .Work well just have to learn how to left foot brake when one wheel in air (stop`s wheel in air from spinning and transfares torque to wheel on ground )

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I have a Detroit on the back of my 110 and am happy with it on road. Just don't turn the wheel with the clutch in, ie I 'drive' into parking spaces else it clonks at the back a lot.

And yes, in a Bowler or a 90" the wheelbase is too short for a Detroit, causing it to unlock and lock all the time. The manual says that the locker should not be used in short wheelbases, which they define as < 127" :o

The Disco/RR 100" wheelbase is also a bit short. I know a guy who took one out cos his wife didn't like it.

On that point, a Detroit in a 127" LR is not noticeable, according to a guy I talked to.

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A TruTrac is a Torsen-type diff, and indeed is what I have in the back axle of my Ninety. If you want to see it in action, I might be able to cross-axle it for you somewhere around Bristol or Stroud on Sunday?

Basically it keeps going when I don't expect it to. It got here without the centre diff locked...

18112006072.jpg

Cool! Sorry, didn't get to my computer this weekend, but I might be able to catch up with you next weekend. TruTracs looking more popular than I expected!

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I have a Detroit on the back of my 110 and am happy with it on road. Just don't turn the wheel with the clutch in, ie I 'drive' into parking spaces else it clonks at the back a lot.

And yes, in a Bowler or a 90" the wheelbase is too short for a Detroit, causing it to unlock and lock all the time. The manual says that the locker should not be used in short wheelbases, which they define as < 127" :o

The Disco/RR 100" wheelbase is also a bit short. I know a guy who took one out cos his wife didn't like it.

On that point, a Detroit in a 127" LR is not noticeable, according to a guy I talked to.

Might be why it wasn't great in my 80 then! Didn't seem to lock all the time, or rather it unlocked more often.

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so if there was a Torsen torque-biasing diff in an axle, could/should you put it on a rolling road to test the brakes? :unsure:

probably a dumb question.........

So long as the handbrake's off, no problem. No load at the diff pinion means that (excluding the inertia of the prop and handbrake drum) there'll be no load seen at the undriven wheel. In practice, the inertia shouldn't be enough to let it climb out of the roller... although I wouldn't stand behind it!

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