Looks like the truth to me Bob. May be too much but I'd add/replace "It does this to prevent useless wheel spinning" with "It does this to prevent damage to the drivetrain which can be caused by aggressive wheel spinning". I'm talking of course of MG1.

 

Ok, I think we have a winner:I'm always open for improvements and updates to the FAQ. Hopefully this covers the subject well enough. It is hard to briefly cover the material in a FAQ and I appreciate everyone's help.

Bob Wilson

 

Yeah I would say to protect the electric motor. On hybridsynergydrive.com, it is listed as a "Motor TRAC".

 

Bob, we may have to add the 2007 models (at least) as well.

I have three 2007 models currently used as company vehicles. One that I had bought in the October 2006 for my wife (later became the third company Prius) was very susceptible to slow speed climbing of our driveway. She experience the phenomenon in two separate occasions even with Michelin X-Ice winter tires on.

The other two were bought in November 2006 and also have evidenced almost similar behaviors when climbing the parkade ramps, especially when the ice is packed on the surface. None of the events were heart stopping but if the car briefly stops on the incline, getting it to move again requires some care. My guess from talking to other Prius owners in my area is that the 2007 is still less vulnerable to Trac issues than the earlier models.

Cheers;

MSantos

 

For legal reasons in the United States, many retail businesses will not mount two snow tires and two non-snow tires on any vehicle. This includes those of you who only want to put on your two winter tires on your vehicle.

 

Thanks,

I'll see if I can merge these in. The problem is a FAQ needs to be a series of brief but complete guidelines. Let me think about this over night and see if I can come up with better wording.

Bob Wilson

 

Well MY 2007 is fine in ice and snow. In fact, it does better than most other vehicles around me. In snow and ice country - Alberta Canada. Of course, I have "real" tires on it (Nokian WR), not "rim protectors". Msantos, I think your company had better brake down and get some tires! Before someone is killed!

 

No, quick, QUICK, activation of Trac on a FWD or F/AWD vehicle is of the utmost importance. When wheelspin/slip develops due to drive torque, too much drive torque, on the front wheels then you not only do not have enough traction for forward (or reverse) motion, but you have also lost all ability to maintain directional control of the vehicle.

Think of Trac as being an inverse form of ABS. Rather than being designed to shorten your braking distances as some folks believe, ABS is actually designed to keep your wheels rolling, rolling ever so slightly, so that should you need to provide directional, stearing, inputs during severe braking there is the possibly of them being effective.

So, "drifters" use RWD vehicles exclusively, you can "spin" both rear wheels continously and still have (perverse) directional control. Not so with FWD or F/AWD vehicles.

So, the very instant even one of your front wheels begins to spin, Trac will activate braking instantly. So what, you say, I'll just stay on the throttle and "pull" myself out of this mess.

NOT..!!

If the front brakes are FORCED to restrain the wheelspin/slip against a high level of engine torque you will have over-heated brake rotors in very short order. Later, WARPED brake rotors, maybe even severely so.

Trac applies braking because otherwise you would/might have NO directional control. Trac also instantly dethrottles the engine because, basically, most (all??) drivers cannot be relied upon to lift the throttle in order to moderate the level of wheelspin/slip to something within reason.

I use the Trac on my '92 LS only as an indication of slippery conditions for which I might have otherwise been unaware. Once Trac activates I turn it off manually and then do my own "feathering" of the gas feed.

 

Legal liability reasons arising from the VERY REAL THREAT to the safety of your passengers and yourself with higher traction at the front vs the rear.

Every FWD or F/AWD owners manual states this.

Also applies to tire studs.

And then we have so many manufacturers of FWD and F/AWD advising, requiring, the use of tire chains ONLY on the front wheels but absent a WARNING of the extreme hazards arising therefrom.

 

"MORONS.."

NOT...!!!!

It is NEVER a good idea to have the system in 4WD while traveling along the highway. Almost all 4WD systems disable ABS in 4WD mode, plus when you enter a turn/curve you DO NOT want engine drive torque or any level of compression braking on those front wheels. Too easily, 'way to easy, to miss the curve due to understearing, "plowing", and end up in the "borrow pit".

Now, if you simply CANNOT get up and going initially in only RWD mode, that's an entirely different matter. And keep in mind that the blazer, unlike your FWD hybrid, could easily maintain directional control, and obviously did, with a "controlled" level of REAR wheelspin/slip.

With RWD there is an argument, a fairly good one and a SOUND one, for getting the vehicle slightly "sideways" on the slippery stuff for gaining initial speed vs "straight-ahead".

Traveling "Sideways" those rear "driving" tires actually have more "bite" on a snow covered roadbed.