Sorry, not being from a mechanical or motorsport background, could someone explain how an LSD works and how is it better than a normal diff and what is a straight cut gearbox - in english.
Cheers,
Pat...

Lsd transmits power to both rear wheels to increase drive. Staight cut gears are noisy.

helical gears are used in road cars due to quieter turning, but they have greater transmisison losses. Straight cut (also dog tooth?) are noisy as hell but have less drag.

Limited slip diffs would rather that both wheels turn the same amount. they slip enough to go round corners, but they wont let the unloaded wheel spin freer, as will happen in open diffs.

was gonna post earlier but was afraid i didn't know anything

normal diff diverts power to the wheel with lest resistance(i.e. a spinning wheel)

lsd diverts power more equally to both wheel regardless of grip or speed

i hope thats right??


i think straight cut gears are stronger

What sort of slipper? Plate, viscous or ATB?

Have a look at the Quaife site, it might help.

This is one reason why it is advisable not to use straight cut gears in a road car...

http://www.kimini.com/Video/index.html

(then click on super car challenge BMW)

Right, got the LSD bit - I think. It limits the slip on the wheel that wants to slip (spin) and if it was a normal diff, the slipping (spinning) wheel would just slip (spin) more...
As for the straight cut - it is just the patern of the teeth, so rather than sliding in gradually, they have to be forced in hard and then off you go???
Pat....

that is ear splitting good vid though

The selection (i think) is the same on a 'dog-box' as it is in a gearbox with helical gears. It is merely how the gears are cut which is the difference. As mentioned above, they are more efficient then helical gears with a lower power loss.

Some video that, but those pesky kit cars took some catching!

An LSD is better cause I've just sorted one out for mine!

Your not keeping up with the Jones'! Remember the advert!?!?

lol good vid and what a noise it makes ,i thought only dogs could hear such a high pitch

The word dog seems to have several meanings here.
Regarding gearboxes, you can have a 'dog-leg' pattern box which refers to the gear lever positions, usually 1st is on its own, bottom left, 2nd is forward centre (hence the dog-leg kink), 3rd is behind 2nd, 4th is top right. this, I think also applies to Hewlands on s/seaters. The other use of dog, refers to the engagement of driven gears. Where two gears, on a common axis need to engage/dis-engage, they are typically meshed together by a matching set of castellations, known colloquially as dog teeth.

Straight cut boxes are more efficient at power transfer, as they do not have the frictional losses of the 'sliding' helical gears. Down side is they are bu**ers to mesh once moving. Motorcycle gearboxes (sequential) use both straight cut teeth, and dog teeth.

To clarify, dog teeth, are on the side of the gear, to 'join' the two gears on the same shaft. Straight cut and helical are on the periphery to transfer power from one shaft to another. I'll shut up now!

as kissy says, a dog box is to do with the meshing of the gears, a dog ring (looks like a castle battlement) meshes with another on the relevant gear shaft to engage the gear. they are faster and transmit power quicker/easier and are i believe stronger.

straight cut gears are stronger, but clatter and whine like the sound a car makes in reverse which uses an idler gear

a dog leg box is where first is bottom left and 2,3,4,5 are like 1,2,3,4 in a 4 speed box, so on track you rarely use 1st, so the other gears are easier to shoft between. obviously sequential is better still.

Ned.

[Edited on 30/9/04 by ned]

quote:

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Originally posted by andylancaster3000
This is one reason why it is advisable not to use straight cut gears in a road car...
<snip>

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helical (not straight cut) gears
Rescued attachment image010.jpg

If you need to know how just about anything works, you should visit:
http://www.howstuffworks.com

Endless reading!

/Johan