Question....hhr ss with 5sp manual without the posi option means one wheel spins, does the computer or is there a computer control that will will try to apply power to the other wheel but power is only going to one wheel, switches back and forth to wheels?

with the J56 posi option both wheels spin (burnout) full power to both wheels all the time, no switching from wheel to wheel?

automatic there is no J56 posi option, does traction control apply full power to both wheels (burn out) or is computer switching back and forth to one wheel and trying to stop wheels from spining?

automatic with traction control off ,one wheel spins? no switching of power

 

While somebody better versed on the technical workings can answer all your Q's regarding this, from my real world experiences is that I leave a match set of stripes on the road with traction control set to competitive mode with my automatic.

 

A LSD is designed to apply power to both wheels. With equal traction, both should sping aobut the same speed. On slippery roads where one wheel may have less (ice for example) traction, power is more applied to the wheel with traction.

Traction control, usually applys the brakes (or just cuts power) to the wheel that is slipping to regain traction.

ON a FWD with neither of the above options, dunno. Cause both of mine spin...... Expecially on wet roads.

I'm sure someone will come in with a better answer, but that's the way I see the differance between LSD and traction control.

 

To my knowledge, if a wheel on an open diff is slipping, the T/C applies brakes to the wheel, forcing torque back to the wheel with traction. On an LSD, if one wheel is slipping, the axle locks the wheels at the same speed. I guess it has to be a little fancier for LSD on FWD or AWD (since front axles are separate), but it seems to work. It's sort of a poor-man's LSD, much cheaper to implement than a true LSD (assuming T/C is already present, and T/C is cheap if ABS is present).

If you're gonna get the 5-speed, and you're even considering the LSD, definitely spend the extra couple hundred bucks to get it.

 

Now that is not to say you can't at times spin both tires on a open diff with out LSD. It can and will happen but usally the right front will over take and spin if more power is applied there is a limit it can or might do it but usally there is no performance gain.

LSD gives you two tires pulling even to the two front tires It will spin under heavy loads . While Traction Control just helps prevent the tire or tires from slipping or spinning no matter if it is two or one tire that is pulling.

LSD transmits power to the two wheels but it still can spin.

Traction control does not control the power as LSD but it controls the tire spin to give better traction with the use og the Anti Lock brake unit pulsing the front calipers to induce traction. Kind of just a reverse of a skid.

In FWD the LSD is more to help reduce torque steer or you SS making a hard right turn under hard acceleration and give perfornace to the two tires for better traction. It may pull a little to the left and right but is kind of keeps things in check and going straight in the SS LSD's I have driven.

The bottom line is LSD controls power for traction and TC helps give traction but are two totally different systems that do different jobs for similar results. Having TC is good and having LSD with the TC is just better.

Note most LSD are just a spring loaded diff with clutch packs that keeps both sides locked together and pulling the same till enough torque like turning a corner breaks it lose so it slips since the out side tire is rolling faster than the insider tire.

 

When drive wheel slip is noted while the brake is not applied, the Electronic Brake Control Module (EBCM) will enter traction control mode.

First, the EBCM requests the engine control module (ECM) to reduce the amount of torque to the drive wheels via the serial data. The ECM reduces torque to the drive wheels by retarding spark timing and turning off fuel injectors. The ECM reports the amount torque delivered to the drive wheels via the serial data circuit.

If the engine torque reduction does not eliminate drive wheel slip, the EBCM will actively apply the drive wheel brakes.

 

Just for the record, the HHR SS LSD is a gear mechanism, torsen style differential, which has advantages in FWD by being able to supply torque to both front wheels even while the wheels are turning at different speeds. IE as in turning and accellerating under power, which would be difficult with FWD and a clutch plate style diff, as the added power would tend to lock the front together and prevent accurate turning. A clutch style diff lockes tighter as power is added, as the pinion gear's torque presses the clutch plates together tighter.

 

Does anyone know if we can go back and get an LSD installed after purchase or if one is sold aftermarket for our ss???

 

i was researching and it seems the quaife lsd may be used, an EXCELLENT piece quaranted under racing conditions, i had one installed in my 01 turbo jetta $1000 parts $900 labor at the stealers, the porsche mechanic installed it at a vw audi porsche dealer in harrisburg, it prolly is cheaper in a hhr since prolly the same unit used on cobalt ss, they use the same code, if anyone knows this as factual let me know