torque pull

dzag · December 2002

Just bought a 2002 mazda protege 5 hatchback with 12,000 miles. Right front tire tread = 3/32 and left = 4/32. Rear treads were 6/32.

After rotating, balancing and alignment the tire dealer tells me the car's pronounced pull to the right happens in some cars as a result of "torque pull".

Assuming everything is now to spec what permanent fix is available and who should do it?

zueslewis · December 2002

and it's common with front wheel drive cars. Today's cars are much less pronounced than older front drivers.

There's no real "fix", it's just a characteristic.

If you're rotating at 12,000 miles, you should rotate much more frequently.

vidtech · December 2002

i wouldn't expect great handling with tire tread depths of 3/32 and 4/32.those should be replaced.i wouldn't drive on those in the winter time.a new tire measures atleast 10/32 and a lot of traction is lost when the tire even reaches 50% worn.

zueslewis · December 2002

and 2/32 is minimum legal depth in most states - those buggers are bald!

tboner · December 2002

Maybe not in rain or snow, but on dry pavement, I prefer about 2/32nds of tread, LOL

TB

zueslewis · December 2002

And I'm totally scared of them on anything but dry pavement - they're downright squirrelly.

dzag · December 2002

My original question seems to have been left in the dust. Thanks to all for your thoughts on tires, but please note the 6/32 treads are now on the front and balanced and 4 wheel computer aligned. What can be done to correct the heavy right oversteer?

swschrad · December 2002

individual FWD vehicles have different engine support, computer/transmission settings, balance of components, and the like. the theoretical engineer can well make a case that a RWD car also has a torque shift when you punch the engine as it shifts its weight due to friction in the drive train. probably won't tell it unless you have either hopped up the engine considerably for stock car racing, or are on ice.

but on a FWD car, when you punch it up and the engine lays over to the side, generally to the right, it is also putting that extra weight on the driven wheels, not on the passive wheels. this will greatly exaggerate the effect, as you have discovered. I am told that in some cars, using counter-rotating camshafts and balance shafts reduces the torque shift of the engine, and in others the effects of torque shifts in the engine and transmission seem to add up for a greater side pull.

short of massive redesign and reconstruction efforts, there is little way to minimize this torque steer effect in a particular model of car. you have to decide if you can stand it in a particular vehicle during the test drive.

methods of living with it once you're stuck and decide you don't like the torque steer effect are driving like granny with eggs taped to the pedals, or cranking the wheel X amount left before pushing the gas down, X being dependent on your own reaction times and the amount of torque steer in a particular car.

sorry, but there is no real neat answer, and no "mechanic-in-a-can" that can correct this.

dzag · December 2002

swschrad thanks for the erudition. latter suggestion most helpful.

swschrad · December 2002

if you have worn springs or struts it will be more prone to have the steering "roll over" with the torque. so there is that possibility to improve the control.

alcan · January 2003

Sounds good except fr one minor point; most fwd engines are transverse mounted and torque roll is fore and aft.

Mr_Shiftright · January 2003

Doesn't the right front wheel get most of the initial power in a FWD car, or are they all posi now?

I distinctly recall the r/f tire in my Saab turbo wearing at a far greater rate than the l/f tire, regardless of how I drove or rotated or whatever.

zueslewis · January 2003

but "torque steer" is the problem the guy is describing, and yes, the right front wheel shows more usage and wear inflection because the drive shaft is usually a little longer on the right side. Also, with the rotational direction of the engine, the side of the shaft that gets turned from the top to the bottom, versus the bottom to the top (as in the driver's side) will get more torque.

8u6hfd · January 2003

You can minimize torque steer in FWD cars by using equal length (left and right) driveshafts.

alcan · January 2003

That's why Chrysler used an intermediate shaft on the right side with higher torque engines, and GM has an extension of the diff to the right. Makes the shafts equal length, which in turn makes the CV joints operate through the same angles. Other strategies include one side shaft a solid rod which will allow some torsional twist, the other side a rigid tube.

oldharry · January 2003

All FWD cars have a little, especially on hard accelleration. Later model cars a designed to minimize the effect. If it did not do it before rotating the tires, the you probably have a tire problem. Cross the fronts, and see if the effect reverse or goes away. If it goes away, leave them there and use up your tires. if it reverses, you are in the market for a new set.

Harry

P.S. Zues? Huh? Top to bottom/bottom to top? Axel length and angle have some effect, and a couple years on the "X" cars GM was putting a shim under one engine mount to minimize it. No 2002 automobile should have noticable torque steer at light throttle.

zueslewis · January 2003

because of the way the engine rotates - that's what I meant if I wasn't clear.

torque pull

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