Car shifts attitude under hard cornering and gear shift

[jimk04]

As the title says, if I'm cornering pretty hard whilst accelerating, when I change gear the car tightens its line. Pretty obvious really, but what is the main cause.....Im guessing engine/trans mounts?

All suspension on the car is new except the dampers themselves.

rear toe is pretty much parallel.

thanks

[jsceash]

You shouldn't do that, your asking for the rear to come round.

[Porsche9]

Originally Posted by jsceash

You shouldn't do that, your asking for the rear to come round.

That's what I was thinking but I guess it depends on how tight/at the limit you are in the corner. If you are feeling it jimk04 you are getting close and asking for it. It's not a good idea to upset the balance of the suspension mid turn and that includes shifting. You are best holding the gear through the turn and either shift before of after executing the turn. The tires only have so much grip and asking them to do more then turn can get you in trouble when close to the limit.

[particlewave]

The front motor mount would be the first thing I'd check/replace, then trans. If you can feel the stick move under acceleration or when letting off, that's most likely your problem.

[jsceash]

I thought other would chime in but the car is probably fine. Under acceleration in a corner the front end is light causing an under steer. If you push in the clutch to shift, the car attitude shifts adding weight back to the front giving forward bite. The car start to have full grip again, turning sharper, you unwind the wheel a little. At that point leaving out the clutch, it can balances the car returning some under steer but still not as bad as accelerating in the lower gear. The way you hit the gas at that point can do a number of things several of which are not good depending on your driving ability and tires and radius of the turn.

If your pushing your tires the rear will brake loose and come around. Or the front will start to slip and as you turn to catch up and leave off the gas the front will bit hard and the rear will come around fast.

[jimk04]

Thanks for the input.

I understand fully the dynamics of lifting mid corner, and I am no where near to provoking the car into a hairy moment. It is a long bend with only a small amount to of steering lock that I particularly refer to .

Will change mounts as matter of course.

[Joe B]

Originally Posted by jsceash

I thought other would chime in but the car is probably fine. Under acceleration in a corner the front end is light causing an under steer. If you push in the clutch to shift, the car attitude shifts adding weight back to the front giving forward bite.

+1. It happens because you lift your foot off the accelerator and push the clutch in. Weight on the front, the car will tighten up the turn (oversteer). When weight shifts towards the rear, the car will run wider (understeer). It all has to do with weight transfer. Same happens on my motorcycle at the race track. That's why I try to maintain a steady throttle through the middle of a turn, and never shift gears while turning hard.

[woodsman]

I think they call it a 'responsive chassis' and it's considered to be a desirable trait. I understand that it's not always wanted and wonder if adding a little rear toe-in might improve things.

[Pominoz]

Originally Posted by jsceash

You shouldn't do that, your asking for the rear to come round.

+1

Get in the right gear before the bend.

[kk2002s]

Originally Posted by Pominoz

+1

Get in the right gear before the bend.

+1
Trying to shift in a turn is to much, takes both hands off the wheel
Higher gear before the turn gives you more lifting the gas response with better exit acceleration
I have found that the car tells me (Seat meter) when it's time to accelerate out of a turn.
When I feel the meter right (Not all the time) and accelerate at the right time, everything plants, weight distributes and the grin on my face widens