Torque steer from the rear

I have a V6 drivetrain from a 2010 Impala in the rear of a Ferrari Dino kit.  Not running - yet.

I have been driving a 2010 Impala for the past couple of days and that thing is squirrely as heck under full throttle.

How can that not create issues when it's in the rear?

I realize that conventional wisdom and innumerable posts say it doesn't, but how can it not?  That action has to be transmitted into the chassis.

The first time I tried to pass a car I almost ended up in a ditch.  On 2 lane highways basically you don't give it full throttle unless you are in a straight line and are being very careful.

TIn reply to carguy123 :

As long as you’re using something more stiff than the stock suspension bushings I think you’ll be ok. Axle windup shouldn’t be much of an issue, given it’s a much lighter car than the Malibu. 

On a FWD car, any difference in traction between the front tires means one tire is generating more acceleration force than the other one and that difference is what tries to turn the car.   Wheel/Tire combo's where the steering axis isn't in the center of the tread pattern at the ground provide a lever to steer the car.  The first of these still affect RWD setups, but the second doesn't because the back wheels don't steer.  They both affect FWD cars to cause torque steer.

Any time I've had that anything feel like rear torquesteer in a rwd car it's meant that something is loose, bent, worn, or otherwise Not Right Nor Proper in the rear suspension. Invisibly worn bushings in the rear toe control links being the most recent.

It can't steer wheels that don't steer. The only give will be in bushings and ball joints, and hopefully they're tight enough that it's not an issue.

Torque steer will be negligible if it can't impart an actual steering angle because the 'steering' is locked.  Make sure those engine mounts are ok, though.  It's really hard to talk about torque steer on the internet because driving enthusiasts talk about torque steer in the same way that professional athletes fly off of each other from incidental contact.

The most that can happen, you will light up one wheel and the car may lurch away from it some. 

Might need a limited slip?

Might need a limited slip?

Funny thing is, a torque biasing diff in a rear end basically creates 'torque steer' by design (maybe torque thrust is a better term for the rear?) but because noone associates it with that negative term, nobody sees it as a downside.  

I have driven solid axle cars that would torque steer.  Damndest thing.

And yes, loose parts.

Jay_W said:

Any time I've had that anything feel like rear torquesteer in a rwd car it's meant that something is loose, bent, worn, or otherwise Not Right Nor Proper in the rear suspension. Invisibly worn bushings in the rear toe control links being the most recent.

I have a feeling my MX-5 has something in the rear end that's doing this now.  An aggressive run up through higher gears and you'll feel the ass kick around when you clutch in to shift.

In reply to KyAllroad (Jeremy) :

My 99 NB does this as well when accelerating and up shifting on curves.  I assumed it was the Torsen differential.

outasite said:

In reply to KyAllroad (Jeremy) :

My 99 NB does this as well when accelerating and up shifting on curves.  I assumed it was the Torsen differential.

It's stuff gone sour in the suspension.  It should not go all cattywompus and/or gollywobble.

carguy123 said:

I have a V6 drivetrain from a 2010 Impala in the rear of a Ferrari Dino kit.  Not running - yet.

Is there a build thread? 

In reply to Knurled. :

The car has 60,000 miles and I inspected it before adjusting 4 wheel alignment angles to factory spec. I does not go all cattywompus/gollywobble. It feels like the car wants to go straight when accelerating hard thru sweeping curves which stops when disengaging the clutch and shifting up only to return to the condition upon hard acceleration thru the curve. It is more of a feel than actual changing direction. Does not happen when accelerating on straights .

I had a 2005 Impala that was given to me by my Grandmother when she stopped driving. Hated that car, I was very glad to sell it on to a friend. Regardless though, it was a torque steering monster, especially in bad weather. Having said that, I bet your dino replica will no more torque steer than a Fiero, X 1/9, MR2, or any other transverse mid-engined car does

outasite said:

In reply to Knurled. :

The car has 60,000 miles and I inspected it before adjusting 4 wheel alignment angles to factory spec. I does not go all cattywompus/gollywobble. It feels like the car wants to go straight when accelerating hard thru sweeping curves which stops when disengaging the clutch and shifting up only to return to the condition upon hard acceleration thru the curve. It is more of a feel than actual changing direction. Does not happen when accelerating on straights .

Sounds like you're describing understeer, not torque steer.

dps214 said:

outasite said:

In reply to Knurled. :

The car has 60,000 miles and I inspected it before adjusting 4 wheel alignment angles to factory spec. I does not go all cattywompus/gollywobble. It feels like the car wants to go straight when accelerating hard thru sweeping curves which stops when disengaging the clutch and shifting up only to return to the condition upon hard acceleration thru the curve. It is more of a feel than actual changing direction. Does not happen when accelerating on straights .

Sounds like you're describing understeer, not torque steer.

Well, limiting the speed difference between the drive wheels limits how much the car wants to turn, but generally that is a side effect that's pronounced with clutch type limited slips but not with helicals or torsens and it would generally only come into play at slow speeds when you are both turning hard and have enough torque to light up tires. If it's sweeping curves I'm inclined to agree it's just unloading the front tires with weight transfer and getting understeer. 

I'd suggest this is an image of the results of torque steer in a rear wheel drive vehicle.  I very much doubt you will notice anything unless you are hard on the pedal, and I think if it has enough power, it will feel completely normal when you are hammer down.

I realize that the steer part of the equation is limited when it is in the rear, but unequal, and I mean very unequal, power/torque inputs can cause a car to change direction.  I realize the effects would be limited in the rear, but the effects were much more pronounced than I've experienced before and I worry that under power and adding in a bend or corner that it will upset the rear more easily.

I should have the engine wired back up semi-soon so I can drive it again, but it's still a way from being able to test it with 100% power.  The holidays are upon us and I have next to no car time.

I've had little car time this whole year.

outasite said:

In reply to Knurled. :

The car has 60,000 miles and I inspected it before adjusting 4 wheel alignment angles to factory spec. I does not go all cattywompus/gollywobble. It feels like the car wants to go straight when accelerating hard thru sweeping curves which stops when disengaging the clutch and shifting up only to return to the condition upon hard acceleration thru the curve. It is more of a feel than actual changing direction. Does not happen when accelerating on straights .

That sounds like what a Torsen does.  Under neutral throttle, the handling characteristics are entirely chassis-based.  Under throttle, it applies more torque to the wheel that is turning less, which is the inside one, and the thrust vectoring pushes you to the outside.

It took me a while to noodle out why a tight clutch diff or spool does the opposite - applying throttle thrust-vectors the nose to the inside.  I think what is happening there is that due to the tires' always slipping to various degrees, applying throttle changes the main slip agent to the inside tire, so the outside tire becomes the one to thrust-vector the chassis.

In reply to Knurled. :

Suspension geometry (partiuclarly anything that gives you roll steer) will have an effect as well.  If the car roll steers the rear end outwards, it'll tend to point into a turn tighter when you get on the power, as the rearward weight transfer will compress the outside rear and steer the rear end out.  

In reply to Knurled. :

Yes, my first experience with a Torsen and assumed it is normal.

rslifkin said:

In reply to Knurled. :

Suspension geometry (partiuclarly anything that gives you roll steer) will have an effect as well.  If the car roll steers the rear end outwards, it'll tend to point into a turn tighter when you get on the power, as the rearward weight transfer will compress the outside rear and steer the rear end out.  

While all that is true, and a large part of why '84-85 RX-7 handles like a wallowy mess compared to the '79-83, and why they all handle awful if you lower them (mass amounts of roll understeer in the rear suspension), the effect I am describing doesn't require any real suspension travel to be noticable, just rolling back and forth between neutral throttle and maintenance throttle in a corner.