3.3TT Suddenly pulling left and right

[socalvn]

Hey all. Yep that is a common problem with the horsepower and the crank rotation under high torque. It pulls the car in that direction and when off the gas is an abrupt release of torque which feels like a pull in the opposite direction.

To correct this behavior you have to over compensate the front wheel alignment with a toe in. I will follow up with my exact alignment measurements that corrected the pulls if anyone is interested? Just know this will add an uneven wear on the outside of your tires. Since you can’t rotate 4 tires because of staggered front/back size, when you do rotate left to right front tires it doesn’t help the wear.

Quickest way to wear your tires is with toe

 

[Snicklefritz]

Hey all. Yep that is a common problem with the horsepower and the crank rotation under high torque. It pulls the car in that direction and when off the gas is an abrupt release of torque which feels like a pull in the opposite direction.

To correct this behavior you have to over compensate the front wheel alignment with a toe in. I will follow up with my exact alignment measurements that corrected the pulls if anyone is interested? Just know this will add an uneven wear on the outside of your tires. Since you can’t rotate 4 tires because of staggered front/back size, when you do rotate left to right front tires it doesn’t help the wear.

Ima not believing. Neither the 2.0L or 3.3L we have does a pull in either direction accelerating WOT and letting off. You don't let all the way off BAM anyway, just back off smoothly, no pulling happens, none. The last thing I would do is deliberately toe my front tires. I already get outside edge wear as it is.

 

[Drillwill]

Ima not believing. Neither the 2.0L or 3.3L we have does a pull in either direction accelerating WOT and letting off. You don't let all the way off BAM anyway, just back off smoothly, no pulling happens, none. The last thing I would do is deliberately toe my front tires. I already get outside edge wear as it is.

I'm not saying that changing the toe is the best thing. I'm merely saying that it corrects the pull. If you can't stand it then that's the option. Here are the adjustments made which allow the car to track straight during normal driving and under full throttle.

 

[Snicklefritz]

I'm not saying that changing the toe is the best thing. I'm merely saying that it corrects the pull. If you can't stand it then that's the option. Here are the adjustments made which allow the car to track straight during normal driving and under full throttle.

Ima no expert on alignment, but none of that looks to me extreme enough to cause undue tread wear. And the amount that front camber differs must be the sum total of suspension parts difference right to left, because the Stinger does not have adjustable front camber.

 

[Sdro_GT1]

@CBordies , took my car into the shop today after almost crashing it and found that the upper control arm on the rear left suspension was completely disconnected. The car's behavior became drastically worse today on the way home from work. It must have been loosening previously. Please have them check and torque all suspension bolts if you are still experiencing the problem. It will be very hard to drive if it comes loose at speed.

View attachment 37024

I found that both of mine snapped clean….. no accident or pot hole…. Weak ties!

 

[Snicklefritz]

I found that both of mine snapped clean….. no accident or pot hole…. Weak ties!

Holy cow! What am I looking at? Upper control arm? Stress fracture? I've read of them coming entirely unfastened, as described above, but never hear of, much less seen, a broken one!

 

[Sdro_GT1]

Holy cow! What am I looking at? Upper control arm? Stress fracture? I've read of them coming entirely unfastened, as described above, but never hear of, much less seen, a broken one!

Both lower control arms rear. Snapped like that. No clue why. The only thing I can think of is it was strapped down wrong on the dyno at one point.

 

[Snicklefritz]

Both lower control arms rear. Snapped like that. No clue why. The only thing I can think of is it was strapped down wrong on the dyno at one point.

This is something new, to me. I thought that when you put your car on a dyno that is it. I had never heard of needing to have it "strapped down." Is it literally that stressful that it could break the suspension like this?

 

[Sdro_GT1]

This is something new, to me. I thought that when you put your car on a dyno that is it. I had never heard of needing to have it "strapped down." Is it literally that stressful that it could break the suspension like this?

Any car gets strapped down when on a dyno.

 

[Snowwhite]

This is something new, to me. I thought that when you put your car on a dyno that is it. I had never heard of needing to have it "strapped down." Is it literally that stressful that it could break the suspension like this?

oh yes, you have to seriously strap the car down, to keep it from squirreling around while you're under power and in to keep it from getting off the rollers at speed. you don't want that.

 

[Snicklefritz]

Any car gets strapped down when on a dyno.

oh yes, you have to seriously strap the car down, to keep it from squirreling around while you're under power and in to keep it from getting off the rollers at speed. you don't want that.

Thanks. Why not grip the rims instead of the suspension? Seems it would be a lot more secure and no chance of breaking anything.

That's a joke question. Ha hah.

 

[Snicklefritz]

Seriously, though. Couldn't a dyno grip the car via the front and rear bumpers instead? Why does the suspension have to take it?

 

[Thomby]

Seriously, though. Couldn't a dyno grip the car via the front and rear bumpers instead? Why does the suspension have to take it?

You would potentially have several thousand pound feet of torque (after gearing & final drive) applied through your paint, body work, bumper support (including crash "circuit breakers"), etc. Plus if you were just nosed up against a barrier, you could have the back end (or front I guess) kick to one side, etc.

When you strap the car down, you're holding the car vertically as well as horizontally, which helps grip the rollers. If you were just holding it back horizontally, you could spin the tires under hard acceleration. Of course, you can overdo it and have the car strapped down so hard you load up the suspension, but an experience dyno operator shouldn't do that.

 

[Volfy]

I found that both of mine snapped clean….. no accident or pot hole…. Weak ties!

Meh... somebody f'ed up and did something to those control arms they are not supposed to. These multi-link suspensions are designed so that each of these arms (with single bolt end links) only primarily a tensile or compression load. For the steel beams to deform that badly, something applied a huge lateral force on the arm.

Can't quite tell from this single pic, but that rubber bushing appears to have a tear facing the broken beams. If so, that's yet another clue that something was pulling HARD on that arm sideways. And it ain't from driving.

 

[Snicklefritz]

You would potentially have several thousand pound feet of torque (after gearing & final drive) applied through your paint, body work, bumper support (including crash "circuit breakers"), etc. Plus if you were just nosed up against a barrier, you could have the back end (or front I guess) kick to one side, etc.

When you strap the car down, you're holding the car vertically as well as horizontally, which helps grip the rollers. If you were just holding it back horizontally, you could spin the tires under hard acceleration. Of course, you can overdo it and have the car strapped down so hard you load up the suspension, but an experience dyno operator shouldn't do that.

I wasn't thinking of the bumper covers, but the actual bumpers, the crash bars. Or possibly four corners of the main chassis. You might have to remove some undercarriage panels to do that. But you just said what happened to @Sdro_GT1 's car won't happen if the the dyno operator knows his job. So, this conversation boils down to an incident of incompetence, not a problem with the procedure.

 

[Thomby]

I wasn't thinking of the bumper covers, but the actual bumpers, the crash bars. Or possibly four corners of the main chassis.

I was thinking you meant literally just nosing the car up against a barrier, which in addition to being rough on the car could open up all kinds of rare but ugly scenarios if one side lost grip etc.

But if you just mean pulling the bumper cover and tying off somewhere on the frame, I'm sure many dyno operators would oblige. Most people would just consider it more work vs. using accessible points that work (except when they don't).

 

[Snicklefritz]

I was thinking you meant literally just nosing the car up against a barrier, which in addition to being rough on the car could open up all kinds of rare but ugly scenarios if one side lost grip etc.

But if you just mean pulling the bumper cover and tying off somewhere on the frame, I'm sure many dyno operators would oblige. Most people would just consider it more work vs. using accessible points that work (except when they don't).

Funny, and stupid. What's up with those floppy straps? Just have a couple of obese friends to sit in the trunk, that'll hold everything down. Uh huh.

The busted suspension parts now make more sense to me. To keep the car firmly anchored against the dyno, "they" put too much tension on the arms. Amazing.

 

[Thomby]

What's up with those floppy straps? Just have a couple of obese friends to sit in the trunk, that'll hold everything down. Uh huh.

Sometimes even straps & four friends aren't enough, like in the classic early-youtube Gojirra incident: