Before we started the install, we wanted to see just how inadequate the stock open differe
We all love horsepower, but having a lot of it isn't going to be much good if you can't get it to the ground. Common sense tells us that the best way to do this is to get as much power transferred through the tires to the ground as possible, and to do this both tires need to be utilized. Once both tires are spinning, then we can play with bigger and stickier tires and other suspension mods to help plant them better. Another situation where having reliable power transfer is important-that those of us in the fair-weather states forget about-is in adverse weather conditions when one tire might be affected by snow or ice. Horsepower and torque are not big factors here.
A large percentage of cars are running around with an open differential that provides engine power to the wheel with the least amount of resistance or traction. This means that the wheel that's spinning gets the power-we'll demonstrate this later. The cure for this is usually to install some kind of posi or limited-slip unit, but in most cases this requires special tools and knowledge that most of us don't have to set the rearend up properly. A few years ago Powertrax developed a traction solution called the Lock-Right Locker which can be easily installed in less than a couple of hours with no special tools.
The Lock-Right worked on the street but had been developed with off-road as the primary use. As a result it had a light clicking noise that could be heard when turning during normal cruising which many people didn't want for their street cars. To solve this and to take care of the street guys Powertrax recently introduced a new unit called the No-Slip Traction System which provides the maximum traction of a locking differential combined with the smooth and quiet operation of a limited-slip device. A precise synchronization mechanism eliminates the ratcheting sounds typical of other locking differentials, and a special gear-and-spring design reduces the backlash. Units are available for just about any mainstream vehicle and cost around $400.
The Powertrax No-Slip unit is very compact and comes out-of-the-box assembled, as seen her
Continuing on our foundation building for our '70 Monte Carlo, we contacted the folks at Powertrax and went through an installation with one of its engineers, Valentine Cucu. The installation is so easy and quick we had to have Cucu slow down so we could take our pictures. But even with his pausing for photos, the time it took from when the Monte Carlo was lifted up on the hoist to when the rearend was filled back up with differential fluid was less than 40 minutes.
At the time this is being written we have had a couple of weeks and about 600 miles with the No-Slip unit and have found it to perform very well. The car pulls around corners much better thanks to better power transfer and seems to handle better. The unit is noticeable, however, while performing slow maneuvers such as parking we can hear a light click as it disengages, but this is generally with the radio off and the window rolled down. There is also a little bit more back lash than the original open differential when shifting between Reverse and Drive, but other than that the unit is quiet while cruising and seamless in its operation. One thing to note with the installation is that the use of the grease to help hold the unit together will make the unit disengage hard for the first 100 miles or so until the grease is dissolved and the parts seat during the break-in period.
It was now time to start the transformation. The rearend cover was removed and the gear oil drained. The pinion shaft was pulled out after the 1/2- inch retaining-bolt was removed.
The axles were then pushed in enough so we could remove the C-clips from each axle end.
Both spider gears and their thrust washers were then removed. The passengerside axle was pulled out about 6 inches, and the side gears and their thrust washers were removed. it's very important that the thrust washers come out, so make sure that they are not stuck to the case.
The rearend is now ready for the No-Slip unit. The installation was started by verifying that the gaps in the coupler teeth were aligned with the synchro ring. The passenger-side coupler was installed first (it won't go in through the opening in the case if the ring gear side is on) making sure that the widest gap in the synchro gear (arrow) was facing towards the rear of the car. The driver's side coupler was then installed making sure the widest gap in the synchro ring faced the front of the car.
Some wheel-bearing grease was applied to the drivers' teeth and to the saddle springs before installing them to hold them in place. This grease will hold the drivers to the couplers while the unit is being installed.
The C-clip was then reinstalled on the passenger-side axle, and the driver and spacer were installed onto the coupler making sure that the paddle was facing towards the rear of the car. if the spacer paddle and the synchro gear paddle opening are aligned properly, the teeth should be fully engaged all the way
The slotted spacer was inserted into the slotted driver, making sure to align the paddle and paddle opening, as well as the slots.
There are two drivers, one has a slot to slide one of the C-clips through and the other does not. The non-slotted driver goes on the passenger side. The non-slotted spacer was then inserted into the passenger-side driver making sure to seat the paddle in the opening on the driver (missing extended
It was then installed onto the driver's side coupler with the paddle facing the front of the car. Verify that all the teeth are fully engaged all the way around the unit.
Two pairs of springs (inners and outers) hold the two drivers apart. The long, thin springs were inserted through the short ones as shown.
The two drivers were held apart with a screwdriver, and the passenger-side wheel was rotated about a quarter turn until the spring slots were exposed. The springs were then carefully inserted using a screwdriver to ensure that the inner spring was fully seated. While again keeping the drivers apart with a screwdriver, the wheel was rotated a half turn until the other spring slots were exposed. The second set of springs was then installed.
At this stage the gap between the drivers had to be checked. Powertrax provides a check block with the No-Slip unit to check this. The narrow side of the check block must be able to be insert between the drivers, but the wide side of the check block should not. if the gap is too wide or too narrow, something is most likely wrong with either the installation or the differential case. Either way, it needs to be checked. Ours checked out okay, so the ring gear-side axle was then pushed in and the C-clip installed through the opening in the driver.
Both wheels were then carefully rotated backwards about a quarter of a turn to expose the pinion shaft opening and Cucu felt through to ensure that all eight saddle springs were fully seated and that the spacers and drivers were fully engaged with the couplers. Everything checked out, so the case was rotated a quarterturn forward to align the pinion shaft opening with the driver saddles. Then, using the retaining bolt as a handle, he inserted the shaft into the differential. it takes a little pressure to pass the shaft by the springs but no more than you should be able to do by hand. NEVER use a hammer, if one is needed, something is wrong.
Once the shaft was installed, the retaining bolt was installed to hold it in place. After a couple of quick tests to confirm the unit was working properly, the differential cover was installed using silicon in place of the gasket and some new fluid was added. No special oil additives were required because the unit is all gear: There are no frictional clutches.
We then took the car back out, strapped it to the pole and scale, and placed the right wheel and tire back onto the zerotraction rollers. What a difference this time: The left tire was smoking and trying to pull the pole out of the ground. The scale reading this time was 980 pounds of pulling force. That's 48 times the pulling force of the open differential. If only all of our modifications were as easy to do as Powertrax's No-Slip Traction System and had improvements like that.Not bad for less than an hour's work.
P.O. Box 909
245 Fischer Ave., Bldg. B-4