I race a 1967 MGB, here's what I have found out about the clutch type and the
gear type Limited Slip Differential (LSD).
The gear type LSD only works if there is some resistance on *both* wheels. If
one of the tires is up in the air, or has zero resistance, then the gear type
LSD sends the power to the lifted wheel, not very effective. Some how the gear
type recognizes it needs to move power to the wheel with traction until the
point one wheel has no traction, then it moves the power to that wheel.
The clutch type LSD is just the opposite, if a rear wheel has lifted, the power
goes to the wheel on the ground. Unlike the gear type, generally the clutch
type is adjustable. The adjustment allows you to set how much slip is allowed
before lock up. This type LSD continues to move power to the wheel with
traction even if one of the wheels lifts.
Bottom line? Lift a rear wheel with the gear type LSD, and it becomes
ineffective. Lift a rear wheel with the clutch type, very effective.
Maintenance? Gears don't wear, clutches do.
Which is better? Depends on what the vendor you are talking to sells.
What do most road race cars use? Clutch type.
What about steering? Both will cause under steer.
What do I use on my race car? Nothing, so what the h_ll do I know??!!
Larry Hoy, who will be driving his V8 within 10 days.
>Folks,
>
>Let me step up to the plate here, and impress y'all with my ignorance.
>
>As I understand it, there are basically two type of posi units available for
>street use, clutch type, and gear type. The clutch type is suited more for
>drag racing and snow or ice conditions than for road racing applications. The
>clutch type locks up both wheels if powered heavily coming out of a corner.
>With both wheels locked, the car tends to go straight, as Ron mentioned. The
>gear type will allow differential action under these conditions, while still
>eliminating wheel slip on the inside wheel.
>
>At least that's my understanding, but I could very well be all wet, as this
>is well outside my area of expertise. I bought one of the gear type posi
>units from Currie, so I'll let you know when I finally get the car on the
>road. The good folks at Currie recommended that type to me for my particular
>application, which is the same as yours - not drag racing, but fast road use
>on curvy roads. With in excess of 300 HP, I feel like I will need the posi
>unit (OK, I admit it, I'll do a little drag racing).
>
>Only time will tell, and I should know more after I drive the car a while.
>
>Currie Enterprises is one of, if not the, largest dealer in rear axles to the
>Hot Rod/Street Rod crowd in the country. They sell 8", 8.8", and 9" Ford
>units, and about a half dozen different types of posi units, so they can
>advise you on the best choice.
>
>
>Dan Masters
>Triumph TR 250 - TR6 Electrical Maintenance Handbook
>http://members.aol.com/danmas6/
|