Torque steer

DavieGravy · #1 06-15-2003, 12:28 AM

I noticed a bit of torque steer today under heavy acceleration. It only happened twice and I couldn't duplicate it after. I took the car on a dirt road immediately after. The front wheels didn't slip at all nor did I hear thunk sounds. The RWD seemed to be working fine. Also, I put the two front wheel against a slanted curb and they didnt slip at all.

A while back (several months) I had to have the thing towed. Upon unloading the car from the bed of the tow truck, it would only roll far enough such that the back wheels touched the ground. This was because my back wheel had seized up due to bearing failure. Against my better judgement, I let the tow truck driver move the tow truck forward to roll the front wheels off the bed of the truck, all while the back wheels weren't turning and lay still on the ground. I know I should have put the FWD fuse in, but the battery was dead and the truck driver was being an complete asshole. I've read a lot about long distance towing, but would that short distance of rolling the front wheels have fried anything? Transfer clutch? I noticed a quick wafe of smoke yesterday.

Also, can torque steer be normal on the SVX under certain circumstances?

#2 06-15-2003, 10:00 AM

i've been noticing the same thing in mine.. i'm not positive what it is, but it's gotten a lot worse since i put summer tires on.. my thought is maybe that my summer tires are a bit flatter and wider than my snows... i have no idea, really, but you're not alone..

-adam

gl1674 · #3 06-15-2003, 12:17 PM

Don't worry, a short distance like a few car lengths does not do any harm.

The damage comes from lack of oil circulation to rotating parts - you need to be going rather fast to overheat them (normally oil flow cools) or rather far to lose the residual oil that is there in the clutch and bearings.

gl1674 · #4 06-15-2003, 12:21 PM

Re torque steer - no, I do not even remember how torque steer feels like. My SVX does a fair bit of "gravity steer" - it does pull sideways whenever there is a dip in a road, and steering is generally on the heavy side, but torque steering is something it never does.

DavieGravy · #5 06-15-2003, 02:23 PM

Quote:

Originally posted by gl1674
Don't worry, a short distance like a few car lengths does not do any harm.

The damage comes from lack of oil circulation to rotating parts - you need to be going rather fast to overheat them (normally oil flow cools) or rather far to lose the residual oil that is there in the clutch and bearings.

That's good to know. I've been worried about that for a while. As for why the car is torque steering, it's strange. The AWD appears to function flawlessly. In instances of snow, there may have been a bearly audible thud, but I'm not sure. It could have been the tires gripping the snow. I didn't hear a thud on the dirt road though. I'll probably take it in to have the AWD system inspected thoroughly. I don't know my head from my ass when it comes to cars.
Thanks.

DavieGravy · #6 06-15-2003, 02:46 PM

Quote:

Originally posted by alacrity024
i've been noticing the same thing in mine.. i'm not positive what it is, but it's gotten a lot worse since i put summer tires on.. my thought is maybe that my summer tires are a bit flatter and wider than my snows... i have no idea, really, but you're not alone..

-adam

Is your AWD functioning correctly?

Mr. Pockets · #7 06-15-2003, 03:55 PM

Quote:

Originally posted by DavieGravy
I know I should have put the FWD fuse in, but the battery was dead and the truck driver was being an complete asshole.

The FWD fuse does nothing while the car is off. The car has to be turned on and running for that fuse to do anything. Putting the FWD fuse in disengages the transfer clutch so that you can run the car on a 2WD dyno, for example. Or, if you happen to discover that you've got a Legacy tranny in your car that doesn't match the rear diff, you could drive the car to VT for a meet.

Still, I don't think that short bit of dragging did any real damage. Oh, and I recommend getting a AAA membership. Every tow truck driver dispatched to me by AAA has been nothing but completely helpful and accomodating.

Quote:

Originally posted by DavieGravy Also, can torque steer be normal on the SVX under certain circumstances?

I say no. Mine has never, ever exhibited torque steer. I couldn't explain to you why yours would, though. I suspect the transfer clutch.

DavieGravy · #8 06-15-2003, 04:25 PM

I do have an AAA membership, but I think the guy was cranky from driving 6 hours at night in the snow.

Although he did have a bit of an attitude from the start.

DavieGravy · #9 06-15-2003, 10:10 PM

My back right tire was at less than 10 PSI.

#10 06-16-2003, 12:28 PM

Quote:

Originally posted by DavieGravy

Is your AWD functioning correctly?

yeah.. i'm nearly positive that i need a front-end alignment, but i'm waiting until i lower the car..

-a

DavieGravy · #11 06-16-2003, 03:10 PM

You might want to check your tire inflation. That's what it was for me.

#12 06-16-2003, 04:31 PM

Quote:

Originally posted by DavieGravy
You might want to check your tire inflation. That's what it was for me.

just got new tires put on.. they're all good.....

it's like they lead the car as it passes over bumps and stuff.. weird.. like the steering is just a little too loose..

-a

oab_au · #13 06-16-2003, 05:49 PM

"Torque steer" is more of a problem with wide tyres. If one side of the tyre has more grip that the other side, due to uneven road surface or such, the wheel will try to steer around the center point of the steering axis.

While the grip is the same on the inside and outside edge, the forces on each side of the steering axis are the same, so it will steer straight.

Using different wheels with a different offset will move the center of the tyre in relation to the center of the steering axis. This will cause Torque steer.

Harvey

DavieGravy · #14 06-16-2003, 11:30 PM

oab_au, I'm a bit confused as to what you mean by the steering axis.
When you say the wheel will steer around the center of the steering axis, do you mean that the tire will be forced in some direction such that the friction with respect to the road is equal on either side of a tire? Or are you referring to the difference in friction/grip from one side of the car to the other?

oab_au · #15 06-17-2003, 05:37 PM

Quote:

Originally posted by DavieGravy
oab_au, I'm a bit confused as to what you mean by the steering axis.
When you say the wheel will steer around the center of the steering axis, do you mean that the tire will be forced in some direction such that the friction with respect to the road is equal on either side of a tire? Or are you referring to the difference in friction/grip from one side of the car to the other?

I'll explain it better. Looking from the front of the car at the right side wheel. The steering axis or kingpin inclination, is a line drawn down from the top strut bearing, down through the bottom ball joint, to meet the ground in the center of the tyre contact patch. This is the line that the wheel steers around.

When we had narrow tyres, there was not much tyre on ether side of the center point. Now we have tyres that are twice the width, so there is a lot more leverage on ether side of the center point.

If you are accelerating the tyre is pulling the car along, if the outside edge has more grip that the inside edge, due to the uneven road surface, the outside edge will try to pivot around the center point to move into line with the center point. End result is the wheel steers to the other side.

The wider the tyre the more pronounced the effect. The same effect happens when cornering, the load is on the outside edge of the outside wheel, so it wants to steer in more the wheel is turned. Hard breaking on uneven surfaces will also produce this, as the grip moves from one wheel to the other, the steering will pull from one side to the other.

This is the effect when the steering axis point is in the middle of the tyre. If wheels are fitted with a different offset, than the 55mm, it will move the center of the tyre to one side of the steering axis point, to increase the leverage that the edge of the tyre has to torque steer the wheel.

While the road surface is smooth and the grip is the same on both tyres, the car will steer straight, power it through a corner, the weight moves to the out side wheel and it will, either steer in or out depending on whether it has positive or negative offset.

I'll stick a diagram in my locker " steering offset." .

Harvey.