Ok that confirms what I was starting to suspect. The HLSD, Quaife, etc., MUST have a certain amount of resistance on BOTH wheels in order for it to work.

When one tire is off the ground and the engine is in motion there IS a certain amount of torque being applied to the ring gear which is why we attempted the test in the first place.

Now we need to determine how much resistance is required to make the unit lockup and work. If slick ice or mud can't provide enough resistance to the torque then what would be the point of even having the unit?

You can do this by using the two 2x4 method. I personally don't want to start prying on my wheels while the car is on stands.

As far as the usefullness of this, any benifit you get while both tires are on a slick surface is a bonus. It will not only give you the ablity to launch harder while keeping wheel hop down and give you better traction during luanch. But will allow you to corner much harder. The only porblem with our car is the front can handle hard cornering well beyond what the rear can. Adding SFC's to your already modded suspention should help that though.

Also remmeber that this ultimate test your doing is not something that will be seen often in real use. Both tires will usually be on the same surface. With ice there is usually snow or sand/salt down. In any case if you're ever in that situation you'll be glad you have it.

Have a good one guys. :)

This is what I've been saying all along. Put a wheel on wet mud/grass, dirt, ice, etc with one wheel on pavement. Launch hard and see what happens. Will someone please do this test and tell me what happens? Mine spins the wheel with low traction and it didn't used to.

Another test you could do is to find an '02-'03 6sp Non-HLSD equipped car and drive them back to back. I did this when I was shopping for my '03 6sp and there is NO DOUBT that the HLSD is there when you drive the two back to back. The best way to tell if it is working(when using my 'patented' back-to-back test) is to start the car from a stop into a 90 degree left or right turn. The HLSD will barely lose traction while the non-HLSD will require judicious right foot work not to spin the front wheels.

Yes, yes, this is all nice. I am 99.9% convinced my HLSD doesn't work. My issue is that I'm going to have to prove it to the dealer. So far no one here other than SR20DEN has helped me get any proof. The test I'm asking for is pretty simple.

Today on a nice smooth tarred parking lot, very little grain to the asphalt due to the tar, I did a few hard launches. 2 were done with water under the passenger tire while the drivers side was dry. Nice clean patches from both tires every time.

If yours isn't working I feel for you. If laying patches doesn't prove anything to you, you may want to jack your car up again and try the your test again with 2 2x4's as described above.

Maximaman777 thank you for finally confirming my testing. In that situation my car would only spins the tire in the water.

The plot thickens...

Today the roads were wet (I got back from China early) and I was able to spin both wheels together in 1st, 2nd and 3rd on several occasions. I don't know what's going on anymore.

Nissan dealers suck, I used to work for them. They have had a few good techs, but most of them didn't know **** about performance ! I was told by a "master tech" for 10 years now- that putting a UD pulley on a Maxima will destroy the engine. I was just a mechanic- not a master tech, but I been around Nissan SR20s for longer than some might imagine, and the VQ engine always interested me- but all Nissan engines are internally balanced thus do not need a harmonic balancer pulley like the "master tech" claimed to have. I'ma have to go visit my old store and have em good will my coil packs at 70K miles.

Have you changed the trans fluid or checked the level since you got the car? If not that may cause the effect your seeing if the car has more that 15k on it.


The HLSD/Quaife is not the traction cure all. If there is ever not enough resistance on one of the wheels it will unload. In situations where you have the car on wet grass or ice and you are easy on the gas the HLSD should still work, but if on that surface you punch the gas you will probably have a wheel start spinning. Again this is not what it was designed for but you will get the added benefit if this ever occurs and you take it easy on the gas and use a little brake if you get wheel spin. High speed turning and hard launching is what this is for. Unfortunately in stock trim the suspension/frame can't handle the high speed turning as well as the diff can and you'll loose the rear of the car with out upgrades.

I highly recommend getting SFC's as the 1st suspension upgrade. But if all you’re worried about is winter driving in MI the just remember to use the brake.

If you want to do further testing it shouldn't be long till you have some ice on the roads up there :D (we'll be we'll be lucky if it happens at all down here ;) ) then you can try driving on a sheet of ice, hopefully with some snow or sand on it for traction, then you can try out using some brake and see if it kicks in.