Mashing the throttle, taking a tight corner aggressively, or working through loose gravel trails will result in the limited slip differential limiting wheel spin across the drive axle by permitting the axle shafts to spin at different speeds while continuously trying to balance the application of torque between the two axles.
This results in transferring more power to the wheel with the best traction which enhances the grip, control, and the predictability of the vehicle.
In their static state, when traveling in a straight line where wheel speeds are identical on both sides, all limited slip differentials provide equal traction to both tires. The difference between LSD types is how each unit applies torque when additional traction is needed.
In regular circumstances a clutch-type unit , like the Yukon Dura Grip, uses an array of springs to apply pressure to the side gears which puts pressure on the clutch packs in the outer part of the carrier.
Both axles get equal pressure and both tires get equal traction. When a tire starts slipping, the clutch packs are engaged with differing resistance. In a positraction differential, the unit senses which wheel has the greatest traction, when one tire is slipping or stuck, and sends power to that wheel.
Power to the other wheel continues until equal control is returned to both tires. Positraction is beneficial when road conditions are wet or muddy. Thanks for the pic showing the clutches, that makes sense now. My understanding is it's super rare. Most 'experts' I've talked with in trying to get info on it, as i mentioned missing clutch disc guides, say they've heard of never seen. Just got off phone with royal purple and their tech said their 75w90 is fine in everything I have and does have the additive in it, but no issue for the g80 locking rear.
Joined: Dec 6, Posts: Profile Page. I remember a Impala with a"positraction' emblem on the glove compartment door-from the factory-that would be the 55 to 64 passenger car rear end. Joined: Jan 30, Posts: 2, Profile Page. Joined: Feb 1, Posts: 58 Profile Page.
Heavy Old Steel , May 1, Truckdoctor Andy likes this. Joined: Dec 10, Posts: 5, Profile Page. Some pretty comical. As stated there are two main kinds of traction enhanced rear ends. The clutch type and the mechanical locker. There are several versions of both. Marketed under a variety of factory names. The most common are the clutch type , as they help with traction and have little bad habits Most clutch type enhancers depend on the angle of the gear teeth, to compress the clutches.
But the problem with this is ,with more power , more locking action is needed! The angle of the gears is rather steep, in order to maintain strength, so the clamping action is compromised Dana solved this problem with their version , by the utilization of a two piece spider gear shafts, for four spider gears, anchored on a approximately 45 degree slope, there by applying a lot more clamping action than the approximately 60 to 70 degree angle of the teeth on the gears.
So with this version you get better traction and no bad habits. Last edited: May 1, Boneyard51 , May 1, With a clutch type traction enhancer, resistance is needed on both axles to activate the clutches. With no resistance, there is no force trying to separate the spider gears, therefore no force to apply the clutches. There is a spring in most , to apply some pressure. My point being, you take a perfectly good clutch type traction enhanced rear end, put one tire on wet grass, the other on dry pavement Nothing wrong with the rear end.
With these rear ends, it is imperative that you have somewhat equal traction , before it will operate. I repeat However, the axle is mounted to the vehicle frame, so it can't move. Cars without Positraction units would spin one wheel, but those with Positraction rear ends didn't have that problem.
Some owners of muscle cars today are retrofitting their cars with equipment including the Duragrip Posi Differential. This equipment enables drivers to keep both wheels on the ground, achieve better traction, and avoid one-wheel burnouts. As limited-slip differentials became more popular, other makers got in on the brand name game in the 50s and 60s.
If you're shopping for a car with an OEM Positraction rear end, look for a tag on the right lower cover bolt.
There is a two- or three-digit axle code or a production date if the car has Positraction. If the rear end has an open differential, the tag is on the left lower cover-mounting bolt. Another way to check for Positraction is by jacking up the rear end, blocking the front wheels, and putting the car in neutral.
Ask another person to hold one rear wheel while you try turning the other wheel. If you can turn the wheel on your side while the other wheel is held still, the rear differential is not a Positraction unit.
If you cannot turn the wheel on your side while the other person is holding their wheel in place, then the axle is a Positraction. Original gear ratios for GM bolt 8. Another type of differential, called a locking differential, uses dog clutches instead of friction plates to send power to each wheel. A dog clutch transmits power by pressing the tooth of one side of the clutch to the tooth of the other clutch.
Generally, this type of clutch is used in manual transmissions. When one wheel turns faster than the other, the differential disengages the appropriate clutch automatically and delivers power to the wheel that has greater traction. Instead of sending power in a smooth, progressive motion as with Positraction, the locking differential operates with a ratchet-like movement.
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