| [GMCnet] differential types [message #88066] |
Fri, 11 June 2010 12:17  |
Gary Worobec
Messages: 867
Registered: May 2005
Karma: -1
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Just wanted add a note to the discussion regarding limited slip differentials. I think there might be a little confusion on the two unique types of limited slips.
The Detroit Locker or Richmond Locker type diff uses gears with teeth on the faces of the gear that are pushed together by coil springs. (just like putting your hands together like you are praying) As long as you are going in a straight line the the teeth stay meshed together. When you turn a corner since one the outer wheel wants to go farther than the inner wheel the pressure on the two gears increases to the point that the springs let them disengage and they slip teeth making a noticable click, click, click, click sound as the gears disengage at low speed. Once you are going straight again the springs push the gears together and you have traction on both wheels.
All NASCAR racers are mandated to use the Detroit Locker type of rear end. It is surprisingly strong, needs no adjustment and works pretty darn well. I have a Richmond Locker in the rear of my GEO Tracker.
The downside is that they are noisy with the click, click, click sound when you going slow in a parking and making turns. There is also an issue of axle wind up as while the axle is twisting the teeth are unlocking which is probably not an ideal situtation.
Detroit Lockers and Richmond lockers are relatively cheap, the Tracker was $265 and for a regular sized vehicle maybe less than $500.00
The second type is a Positraction or clutch based limited slip. This system uses actual clutch packs that are attached to each axle and pressed together by coil springs just like the Detroit Locker. The same type of clutch material you would find in a manual shift car. When you are going in a straight line the clutches are pressed together and both wheels have torque. When you turn a corner the clutches slip smoothly to allow the outer wheel to roll farther than the inner wheel. The obvious benefit of this is a much smoother transfer of power than with the Locker and no noise. Probably easier on the entire drive train.
The down side for a clutch based limited slip is that the clutch discs can wear out and need to be replaced. These clutch packs are like a motorcycle clutch with many smaller discs and plates to fit inside the diff housing. Also these types of diffs cost a boatload of money, probably double the cost of a locker. Most all pro road racers use clutch based limited slip diffs because of the smoother transfer or power in wet conditions.
Hope this helps some folks understand the two types.
Thanks
Gary and Joanne Worobec
1973 GMC Glacier
Anza, CA
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| Re: [GMCnet] differential types [message #88083 is a reply to message #88066] |
Fri, 11 June 2010 14:59  |
Bob de Kruyff
Messages: 4260
Registered: January 2004
Location: Chandler, AZ
Karma: 1
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Senior Member |
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There are several more as well--there is the gerotor type that is similar to an engine oil pump. As it sees a speed variation between the input and output it forces a clutch pack to start to lock both sides together. It is smooth and infinitely tuneable. Then there is the Torsen gear driven units that more or less operate on the principal that you can't backdrive a worm gear.
Then there are variations such as airlockers and electronically lockable clutches. Most common today is an open diff controlled by antilock braking which slows the spinning wheel and forces the wheel with traction to accept more torque.
Bob de Kruyff
78 Eleganza
Chandler, AZ
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