Please Help!!!!

[EVOthis]

Hello All.....I was just wondering if torque bind occurs both in automatics and manuals?...Also I have read a little bit in previous threads about it but still dont get exactly what happens.....Is there anyone who could explain it to me in detail?.....thank you in advance for your time and knowledge....

[NOMAD327]

When a car goes around a corner, all four tires travel a slightly different path, and each path is slightly longer or shorter than the others. This is why there is a standard differential on two wheel drive. The same principal exists on all wheel drive, where the front driveshaft and the back driveshaft need to spin at slightly different speeds. On dirt or snow, the tires slip slightly on the road surface which is how old fashioned four wheel drive trucks managed, but modern systems need a system where the front and rear drives turn slightly different speeds when turning. The Subaru manual transmission models use a clutch of sorts consisting of small discs encased in very thick silicon grease. The Subaru automatic transmission models have an oil wetted conventional multi-disc clutch to divide the torque and allow mismatched output shaft speed. Both systems have to deal with any speed variation between the front and rear axles, and both can lock up which is what causes torque bind, same as an old fashioned four wheel drive truck trying to steer on dry pavement with the hubs engaged. On a Subaru, automatics seem more vulnerable to torque bind, but it's more trouble to fix on a manual transmission model.

[OB99W]

NOMAD327 covered the topic pretty well. The problem can be caused by tire size mismatch. See: http://www.endwrench.com/pdf/drivetrain/RearAxleBindingInfoF99.pdf

 

If you haven't seen this thread, it includes some pics of what can happen:

http://www.ultimatesubaru.org/forum/showthread.php?t=78467

[nipper]

When a car goes around a corner, all four tires travel a slightly different path, and each path is slightly longer or shorter than the others. This is why there is a standard differential on two wheel drive. The same principal exists on all wheel drive, where the front driveshaft and the back driveshaft need to spin at slightly different speeds. On dirt or snow, the tires slip slightly on the road surface which is how old fashioned four wheel drive trucks managed, but modern systems need a system where the front and rear drives turn slightly different speeds when turning. The Subaru manual transmission models use a clutch of sorts consisting of small discs encased in very thick silicon grease. The Subaru automatic transmission models have an oil wetted conventional multi-disc clutch to divide the torque and allow mismatched output shaft speed. Both systems have to deal with any speed variation between the front and rear axles, and both can lock up which is what causes torque bind, same as an old fashioned four wheel drive truck trying to steer on dry pavement with the hubs engaged. On a Subaru, automatics seem more vulnerable to torque bind, but it's more trouble to fix on a manual transmission model.

 

 

 

What he said.

 

Check tire size (even if they are all the same brand). Circumfrence is 1/4 of an inch max variation. Check tire inflation (that they are all properly inflated).

 

nipper

[idosubaru]

try using descriptive titles, that helps you, helps others, and makes the board better.

[EVOthis]

thank you all very much.....i have spoken to a few master techs and they have never heard of the phrase "torque bind"..????? nonetheless i appreciate your knowledge and time.....

[nipper]

thank you all very much.....i have spoken to a few master techs and they have never heard of the phrase "torque bind"..????? nonetheless i appreciate your knowledge and time.....

 

 

Odd its a very common AWD phrase.

 

nipper