i dont know much about the rear gears and all but dont the 4th gens have a limeted slip - posi. because when i was at the track a while ago both tires would spin for a burn out. last night i did a burn out and only the passenger tire spun. is my differental bad or is something wrong in there. i do have aftermarket gears but that was before i went to the track. any help is greatly appricieated.

 

All the V-8's have Positraction. If you are getting one wheel burnouts, it's time for a new Posi!

Rich Krause

 

thanks which posi unit do you reccomend and since i dont know much about rear end... is the differential the same thing as the posi unit

 

Referring separately to the housing ("pumpkin"), the ring and pinion, and the differential (whether it's a posi, on open diff, a locker, a spool, or whatever) makes the most sense. My personal choice for street/strip use is the Eaton "posi" with 800lb springs.

Rich Krause

Standard:
Whenever a vehicle negotiates a turn, the outside wheel must travel farther than the inside wheel. In order for this to happen, the outside wheel must turn faster than the inside wheel. This is accomplished by spider gears that allow the outside wheel to turn faster (this can be either the left or the right, but must be the outside wheel) than the ring gear, while the inside wheel turns slower than the ring gear. The net sum of the speed of the two wheels is twice as fast as the ring gear. That means if the outside wheel is turning 2 rpm faster than the ring gear, the inside wheel is turning 2 rpm slower than the ring gear. This differential action is very straightforward in a standard open differential and works great for more than 95% of vehicles on the road today.

When a vehicle with an open or a standard differential encounter a loose traction surface, it directs power to the wheel with the least resistance. The resulting action is the wheel on the loose surface spins while the opposite wheel on the better traction surface stands still or barely transfers power. The reason a standard open differential works this way is because it is designed to provide equal force to both sides. If the wheel on either side looses traction the other side suffers as well. If for example, the left wheel looses traction and can not provide a resistance force from the left wheel back to the differential side gear, then the right side gear can not transfer a force to the right wheel that is greater than the resistance force of the slipping left wheel. And vice versa. Re-read this a few times and it will make more sense. The main point to remember is that an open differential provides equal power to both sides, NOT equal speed.

An open differential works just fine for 95% of vehicles on the road since most people do not spin their tires often if at all. For those of us who like to burn rubber or go off the dry pavement, there are now too many limited slip and locking differentials to choose from.

Positractions & Limited Slips:
Transmits equal torque to both wheels when driving straight ahead. However when one wheel spins due to loss of traction, a patch of ice, mud, too much throttle, etc., the unit automatically provides more torque to the wheel that has traction. Recommended for daily driving, works well in ice, rain, mud and snow. However, in situations where absolute lockup is needed, a limited slip is not the best choice due to the fact that limited slips do slip in some situations.

Positraction is a type of limited slip and is a term that is used very loosely as another name or description for limited slip differentials. A positraction is not more aggressive than a limited slip or vice versa. The name "positraction" was used by General Motors for their limited slip differential and the name has been associated with limited slips for many years.

Automatic Lockers:
Lockers, mechanical locking differentials that is, provide 100% transfer of power to both drive wheels. This power can be lost if both wheels spin, but a locking differential will never let one wheel spin free by itself while the other one sits still (unless the unit is broken). Automatic locking differentials are engineered to keep both wheels in a constant drive mode, yet have the ability to unlock to permit a difference in wheel speed while negotiating turns. Recommended for serious off-roaders or serious hot-rodders, can be annoying for everyday driving. The main shortcoming of automatic lockers is the noise or banging and clunking inherent in their design. When getting on or off the throttle they tend to bang or clunk. And they sometimes make noise while disengaging when negotiating a turn. These characteristics are due to the design and a few locker manufacturers have come up with designs that make less noise, but no one has developed a perfectly quiet automatic locker yet. One more effect of lockers that hampers every day use, is, they only drive the inside wheel on a turn which can effect vehicle handling. The specific effects of driving the inside wheel is the vehicle tends to yaw from side to side slightly when negotiating a turn under power. When turning sharply while taking off from stop, the inside wheel will tend to spin easily. This is especially more prominent when taking off on a right turn for two reasons. The torque on the rearend housing due to the driveline torque un-weights the right wheel, and right hand turns are tighter because we drive on the right side of the road and we have to cross over the oncoming lane to make a left hand turn which makes it a lot less sharp.

On-Command Lockers:
Many people want the benefits of a locking differential, but do not want the handling characteristics or noise of an automatic locker. There are a few on-command lockers available as an OEM option. These include the 1998 & newer Toyota Tacoma & Land Cruiser. These EOM designs use an electric motor or vacuum diaphragm to engage the locker. When it is not engaged the unit acts like a standard open differential with no ill side effects aside from poor traction. When engaged, these units' lockup 100% and act like a spool with no differential action or difference in speed between the left and right wheels allowed.

Spools & Mini Spools:
For racing, serious off-road, or crazy hot-rodders, a spool is the ultimate traction differential. Actually, it can hardly be called a differential because it does not differentiate. Spools have several purposes in a differential. First, they lock both left and right axles solid together so that there can be no loss of power due to the unit allowing one wheel to spin faster than the other. Second, they usually support the ring gear much better than most other differentials. Last, they can be lighter than a differential, which saves rotating mass as well as un-sprung weight that the suspension has to contain. The main shortcoming of spools is the fact that the outside wheel has to turn faster when negotiating a turn if both wheels are to maintain traction. If the axles are locked together, one or both wheels have to slip in order for the outside wheel to travel farther than the inside wheel. This can cause the rear of the vehicle to spin out, fish-tale, or can cause a lot of noise that sounds like positraction clutch chatter as the axles twist and release. Sometimes these effects are not all that bad, and they are less severe when 35-spline or larger axles are used. For those people on a budget, there are mini-spools available for many rearend designs. A mini-spool fits inside the standard open carrier, replacing the spider gears, and locking the left and right axle shafts together just like a spool does. A mini spool drives exactly like a full spool does, but they are not as strong as a full spool and do not add any extra support to the ring gear like a spool does.

POSITRACTIONS / LIMITED SLIPS

Auburn Gear
The Auburn Gear limited slip uses a cone style clutch that wears directly against the carrier case and provides the friction force to make the unit work. This design is not rebuildable. Once the cone clutch or case wears out, the entire unit must be replaced. Even with this shortcoming, this design works well for occasional use where extra traction is needed. They have good impact strength in passenger cars and trucks up to 1 ton. They will hold up well to high horse power, but will not last long if there is a lot of tire spinning. (aftermarket ) 1 yr warranty

Auburn Gear PRO
Also cone style & not rebuildable. Designed with more lockup force than regular Auburn Gear limited slips. Will provide better high performance traction than regular Auburn Gear, but still wears out under extreme off-road use and heavy wheel spin. Tends to chatter a lot and not recommended if the customer is looking for a smooth unit. (aftermarket ) 1 yr warranty

Detroit Locker
Heavy duty. The most durable design available, the king of traction differentials. Causes banging and clunking, but gives 100% lock-up when traction is needed. Unlocks when negotiating a turn so that the outer wheel can turn faster than the ring gear is turning and the inside wheel are turning. New Sof-Locker design has damping device to reduce banging and clunking. Includes carrier case stronger than stock.

Eaton
Clutch type, similar to Trac-Lok in design, yet stronger and more aggressive and better lock-up similar to the Power-Lok design. These units came as an original equipment option in 65-72 12T (12 bolt GM truck), 12P (12 bolt GM passenger), 8.2" GM pass, 63-79 Cast Iron Corvettes. The original OEM 12T case was very weak, but the new design replacement from Eaton is very strong. 4 preload springs and 2 steel preload spring plates. Latest design uses HD nodular iron case, forged side and pinion gears, no-chatter, race-bred, carbon fiber clutches for extreme strength and longevity. Old design, all steel clutches which are still available in 18 or 22 clutch designs for those who need more lock-up and are not bothered by clutch chatter. For even more lockup customization, there are also 4 levels of spring pressure available (3 from Eaton and a fourth from GM) that can be used to vary the clutch preload from 200 lbs. to 800 lbs. Originally used in mid sixties GM muscle cars and trucks. This unit is now available for Ford applications and soon will be available for Dana Spicer, AMC, and Chrysler applications. They have a high tolerance for abuse in high horsepower vehicles. Recommended for everyday driving and severe off-road use (factory GM )

Etc. The rest can be seen at http://www.ring-pinion.com/tech/tech.asp

 

Great info Rich. Thanks.

 

Welcome

Rich

 

you forgot the Torsen's. torque sensing worm gear driven.. no clutches to wear out. I believe they come standard 99 and up on the V8's.. not sure about before.


http://www.torsen.com/products/T-2.htm

http://www.torsen.com/products/T-2R.htm

 

thank you very much. your help made things alot more easier to understand.

 

It says the Eaton is bad for wheel spinning? Would this be bad in the burnout box?