| limited slip differential [message #87839] |
Wed, 09 June 2010 10:29  |
jayrabe
Messages: 509
Registered: June 2009
Location: Portland, OR
Karma: 0
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I've got a limited slip on my want list, but wondered about something and wanted some feedback to validate my thinking. Various people have posted that the LS improves traction on wet grass, for example, but I wondered about another mode. When accelerating, especially when it's wet (this is Portland, after all) and especially when driving over pavement grooves or paint strips, the wheels slip. If I'm under a lot of power, the front end can actually slide to the side a bit. I've learned to control it by backing off the gas, but it's disconcerting regardless. Will a LS reduce or eliminate this behavior?
Another way of asking this is, how "limited" is a LS? How much wheel rotation of a slipping wheel happens before the LS engages?
Thanks
J
76 PB
Portland, OR
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| Re: limited slip differential [message #87848 is a reply to message #87839] |
Wed, 09 June 2010 12:21  |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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Senior Member |
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Jay,
Limited slip differentials theoretically apply power to both wheels evenly. they operate under load and will sense a loss of traction on one wheel and 'transfer' power to the wheel that is getting the most traction. The affect of this transfer depends on the strength of the springs and the condition of the clutch packs in the LSD.
The situation you describe of a tire slipping on a wet road, especially when accelerating while on a painted stripe or a steel grate, will be improved if the other tire has better traction. My experience with limited slip diffs, on rear wheel drive cars, is that you will get much better traction under MOST conditions. The exception being a really slick condition like snow, mud, or ice. If you apply too much power under these conditions, you will break BOTH tires loose and loose directional control. That said, it will be harder to break the two tires loose than one as with an open diff. You just need to be aware of this and step on the gas accordingly.
My other main automotive hobby is Jeeps, and traction is always an issue in off road situations. One of my jeeps has a Detroit Locker in the rear diff and a Spicer Power lock (clutch type LSD) in the front. I don't get into snow or even mud all that often, but I understand that it would be a problem to have all four wheels spinning in those kinds of conditions, especially in an off camber situation. The result would be to slide toward the downhill side, as you have described with the GMC. People who operate their 4-WDs in that type of situation usually use selectable lockers, at least in front, so they can have one tire that is not spinning.
Here is some info on Wikipedia on limited slip differentials;
http://en.wikipedia.org/wiki/Limited_slip_differential
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles, Solar battery charging. GMCSJ and GMCMI member
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| Re: limited slip differential [message #87858 is a reply to message #87839] |
Wed, 09 June 2010 15:01 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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| jayrabe wrote on Wed, 09 June 2010 11:29 |
I've got a limited slip on my want list, but wondered about something and wanted some feedback to validate my thinking. Various people have posted that the LS improves traction on wet grass, for example, but I wondered about another mode. When accelerating, especially when it's wet (this is Portland, after all) and especially when driving over pavement grooves or paint strips, the wheels slip. If I'm under a lot of power, the front end can actually slide to the side a bit. I've learned to control it by backing off the gas, but it's disconcerting regardless. Will a LS reduce or eliminate this behavior?
Another way of asking this is, how "limited" is a LS? How much wheel rotation of a slipping wheel happens before the LS engages?
Thanks
J
76 PB
Portland, OR
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J,
If it actually sliding sideways while you hold the wheels straight ahead, then probably both front wheels are spinning. this is very common in front drives where the painted stop line kills the roads traction.
And no, my jeeps used to do that one end at a time as I pulled out of a light in wet weather. They both had a Torsen in the front and a Powr-Lock in the rear.
If the 4x was not locked, it would slip the rear, but if it was then it was still strang to drive.
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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