Pulls hard right on acelleration

[Gregorio]

Under moderate to hard accelleration, myLR4 pulls hard right. When lifting the throttle, it reverses this trend. The dealer has looked at it twice. First time they adjusted the rear alignment but second time said everything was OK. My friend's LR4 tracks true and does not exhibit this dangerous behavior. I've had the car for 6 months and 6500 mile. Does anyone else have this problem?

Greg

 

[Count Laszlo]

That's strange, I don't have this problem. Do you think one of the suspension airbags is misaligned on one side of the vehicle? A bad suspension airbag sensor? For something like this, from a physics perspective, one side of the car has to be either leaning, off-set weight in the vehicle, or the alignment and/or tyre air pressure is low on one side (which the dealer/yourself would have already ruled out.) You could try measuring the distance on each side of the vehicle, left side road to lowest body part, right side to lowest body part, front and rear, and see if all four sides match. I have a sneaking suspicion one side of the car is off-set, due to airbags or something else out of whack.

 

[Gregorio]

Tire pressure is spot on. That is the first thing I checked but wasn't holding my breath that it was going to be the problem. A body lean due to offset weight or air bag pressure differences will not cause this. The physical geometry of the suspension (toe, camber, caster, etc.) has been adjusted and verified twice. The problem is likely a drivetrain design flaw or malfunction that would cause an excessive amount of torque to be delivered to one wheel under accelleration. Due to drivetrain design and engine rotation, one wheel in a rear wheel drive vehicle will get more torque than the other. The problem can be worse in a front drive vehicle where axle shafts are unequal lengths. In an all wheel drive vehicle, manufacturers can neutralize this effect somewhat through the use of viscous axle couplings and electronic contols, among other things.

Less likely problem would be loose or defective suspension contol arm/locating link bushings that are deflecting under accelleration. However, this would also exhibit other poor driving characteristics.

The issue I have is that my vehicle has this problem and my friend's identical LR4 does not.

 

[Count Laszlo]

Sounds like you have thought all of this through - and my sincere apologies for my assessment, as I thought this was happening at acceleration as well as breaking.

If you're getting torque steer due to some software issue (which controls the amount of torque each wheel is getting?), or major frame/suspension flaw, I'm not sure there's anyway you can convince the dealership of this. At least it's only happening when you stomp on the accelerator and drive the LR like a race-car. ;-)

I feel bad you're having this issue because convincing a dealership of a flaw like this (which they'll say is completely in your head,) to get into a replacement (new) vehicle, is going to be a very long road. Got a lawyer who's also an engineer? I guess you could probably try to go through your State's lemon-law process, but convincing both parties that this is a true issue, will likely be impossible.

Good luck!

 

[crewcabrob]

I would say it is due to torque also, but maybe not torque steer as in a front wheel drive car.

Have you ever driven a 70s era muscle car? When you romp on the gas pedal, the engine would want to twist the car; violently in some cases. I have noticed 1 time in my LR4 the same sensation. when you let off the gas, the twisting motion is negated and it feels like the truck turns ever so slightly to the left.

Do you think this is the senasation you are feeling?

 

[Gregorio]

I would say it is due to torque also, but maybe not torque steer as in a front wheel drive car.

Have you ever driven a 70s era muscle car? When you romp on the gas pedal, the engine would want to twist the car; violently in some cases. I have noticed 1 time in my LR4 the same sensation. when you let off the gas, the twisting motion is negated and it feels like the truck turns ever so slightly to the left.

Do you think this is the senasation you are feeling?

I am very familiar with 60's and 70's muscle cars. I have several very high HP cars in my stable from 1932 to 1969.

Torque is what causes the problem. My issue is that not all LR4 cars exhibit this behavior. Two others I drove tracked true under full throttle. This leads me to believe that there is something amis in my vehicle. It is back at the dealer right now and I told them if they could find 2 other LR4s that pulled like mine, I would chalk it up to a poor design and move on. If not, I want it fixed. This is not an unreasonable request for a $60,000 vehicle.

My previous vehicle (GMC Denali) was about the same size, weight and power and did not do this. Same with my X5 V8 and Touareg V8. My E55 has 50% more power and torque and does not do this even with 2 wheel drive. None of my newer cars do it.

Thanks,
Greg

 

[Gregorio]

Sounds like you have thought all of this through - and my sincere apologies for my assessment, as I thought this was happening at acceleration as well as breaking.

If you're getting torque steer due to some software issue (which controls the amount of torque each wheel is getting?), or major frame/suspension flaw, I'm not sure there's anyway you can convince the dealership of this. At least it's only happening when you stomp on the accelerator and drive the LR like a race-car. ;-)

I feel bad you're having this issue because convincing a dealership of a flaw like this (which they'll say is completely in your head,) to get into a replacement (new) vehicle, is going to be a very long road. Got a lawyer who's also an engineer? I guess you could probably try to go through your State's lemon-law process, but convincing both parties that this is a true issue, will likely be impossible.

Good luck!

Thanks. The dealer rode with me and saw first hand how it pulls. He even said it was odd. Not driving it like a race car but like it would be driven in the real world. Imagine being on a two lane road behind a slow vehicle and need to pass it in a short distance. Here in the USA, that means going around on the left under heavy accelleration. During this move, the car is pulling back to the right very hard so I have to fight it to keep it from hitting the vehicle I'm passing. Since I have left steering input to the wheel at this point, lifting the throttle when moving back into the right lane causes the car to **** to the left and off the left shoulder of the road. All in all, a very dangerous situation.

We'll see how this goes.
Greg

 

[suvowner]

Have you driven it in 4 lo on some slick surfaces , spinning the differntials around a bit, also to make sure the center diff is transferring good torque to the rear.

Does the behavior change with dsc off

Whatvabout a bad front cv joint

 

[Gregorio]

In theory, I guess a bad CV joint could impart more friction to one axle shaft but would it be so great, especially at such a neutral angle to cause that much torque loss?

I have not taken traction control off nor have I been able to take it off road yet but if the dealer can't figure it out this week, I'll give them both a try. At this point, I am open to just about anything.

 

[Count Laszlo]

Thanks. The dealer rode with me and saw first hand how it pulls. He even said it was odd. Not driving it like a race car but like it would be driven in the real world. Imagine being on a two lane road behind a slow vehicle and need to pass it in a short distance. Here in the USA, that means going around on the left under heavy accelleration. During this move, the car is pulling back to the right very hard so I have to fight it to keep it from hitting the vehicle I'm passing. Since I have left steering input to the wheel at this point, lifting the throttle when moving back into the right lane causes the car to **** to the left and off the left shoulder of the road. All in all, a very dangerous situation.

We'll see how this goes.
Greg

Sounds very dangerous! Isn't some of the torque managed by software as well? By your more detailed description I'd want it fixed as well. I would make them eat it.