Reducing understeer in AWD
Discussion
Ok, so I know that most all wheel drive cars are characteristally built with abit of understeer designed into them, Im just looking for some tips on how to maybe reduce the effect? I drive a 2002 Impreza WRX, which is stock
Im not talking massive understeery slides here, just the kinda average speed, roundabout type drivng the just feels like the front of the car wants to press on rather then turn in.
Is it just a case of being more assertive with the steering?
Getting on the power earlier and letting the differentials do their thing?
Minimising weight transfer? Going slower in/faster out?
Could it just be something as simple as having four tyres of equal wear?
Or is it just something you have to live with? 'cus dont get me wrong, its still such a fun car to drive!
Any tips would be very much appreciated
Im not talking massive understeery slides here, just the kinda average speed, roundabout type drivng the just feels like the front of the car wants to press on rather then turn in.
Is it just a case of being more assertive with the steering?
Getting on the power earlier and letting the differentials do their thing?
Minimising weight transfer? Going slower in/faster out?
Could it just be something as simple as having four tyres of equal wear?
Or is it just something you have to live with? 'cus dont get me wrong, its still such a fun car to drive!
Any tips would be very much appreciated
Pretty much every car has a tendancy towards understeer in tight radius curves like on roundabouts. IME the feeling of the front end 'pushing on' in low speed corners is usually a technique thing- namely carrying too much momentum in. Are you in too high a gear? Are you holding an unnecessarily tight line? Are you turning in without relieving your brake pressure? Play around with this before you spend money on the car IMO.
This all sounds a bit race tracky, but a car doesn't have to be on the limit for the driver to benefit from smooth and well co-ordinated inputs.
This all sounds a bit race tracky, but a car doesn't have to be on the limit for the driver to benefit from smooth and well co-ordinated inputs.
Just get the geometry looked at. Most cars will have very little negative camber front and only a touch more rear. Without starting to look at other settings i have found these two are the main ones.
Dont have more negative on the front though as you will likely end up with what you have now but with oversteer.
A neutral set up is what your after.
Dont have more negative on the front though as you will likely end up with what you have now but with oversteer.
A neutral set up is what your after.
Classic Grad 98 said:
Pretty much every car has a tendancy towards understeer in tight radius curves like on roundabouts. IME the feeling of the front end 'pushing on' in low speed corners is usually a technique thing- namely carrying too much momentum in. Are you in too high a gear? Are you holding an unnecessarily tight line? Are you turning in without relieving your brake pressure? Play around with this before you spend money on the car IMO.
This all sounds a bit race tracky, but a car doesn't have to be on the limit for the driver to benefit from smooth and well co-ordinated inputs.
Just to clarify, I think you mean the opposite of the bit I've put in bold This all sounds a bit race tracky, but a car doesn't have to be on the limit for the driver to benefit from smooth and well co-ordinated inputs.
The idea of balancing a car on the way into a corner is to exchange the brake for the steering, just like you exchange the steering for the accelerator on the way out. The timing of this exchange effects the balance of the car through weight transfer. If you relieve brake pressure and turn in afterwards, any car is going to just want to plough straight on.Your closing statement deserves repeating because it's just so true, and so often mis-understood:
Classic Grad 98 said:
a car doesn't have to be on the limit for the driver to benefit from smooth and well co-ordinated inputs.
Thanks guys. I have tried a few different approaches in similar conditions on the same roundabout, and it does seem that by being in a lower gear and getting ont he power abit earlier, therefore letting the back wheels come into play rather than just overloading the fronts, with the weight going forward and steering at the same time, tends to dial it out abit. At least I think thats whats happening :P
RobM77 said:
Just to clarify, I think you mean the opposite of the bit I've put in bold The idea of balancing a car on the way into a corner is to exchange the brake for the steering, just like you exchange the steering for the accelerator on the way out. The timing of this exchange effects the balance of the car through weight transfer. If you relieve brake pressure and turn in afterwards, any car is going to just want to plough straight on.
Absolutely. The brake to turn-in transition is a blurred one and foreward weight transfer is what you want- but keeping a consistent brake pressure from the braking zone to after the turn-in point is also conducive to understeer. It is very much a transition. The idea of balancing a car on the way into a corner is to exchange the brake for the steering, just like you exchange the steering for the accelerator on the way out. The timing of this exchange effects the balance of the car through weight transfer. If you relieve brake pressure and turn in afterwards, any car is going to just want to plough straight on.But your dead right Rob- abruptly releasing the brakes at/before turn-in causes all kinds of issues!
bejc said:
Thanks guys. I have tried a few different approaches in similar conditions on the same roundabout, and it does seem that by being in a lower gear and getting ont he power abit earlier, therefore letting the back wheels come into play rather than just overloading the fronts, with the weight going forward and steering at the same time, tends to dial it out abit. At least I think thats whats happening :P
If you're on the power then the weight won't be going forward, it'll be going back and off the fronts, thus tending the car towards weight transfer understeer. What's probably happening is you're increasing the rear slip angle through power application, which won't work as well at higher speeds and depends on the road surface. It's best to learn all about controlling weight transfer initially - as this is what 90% of car handling is all about.RobM77 said:
If you're on the power then the weight won't be going forward, it'll be going back and off the fronts, thus tending the car towards weight transfer understeer. What's probably happening is you're increasing the rear slip angle through power application, which won't work as well at higher speeds and depends on the road surface. It's best to learn all about controlling weight transfer initially - as this is what 90% of car handling is all about.
That interesting, power on just past the apex definately reduces understeer in the quattro, (I have been playing with it to establish this) you can even sort of sense the drive moving around the wheels. I think it may be because the front comes under less load that more drive moves to the rear so the fronts are driving less and turning more? Its very hard to explain. I tend to brake smoothly into a bend so no sudden brake release.ScoobyChris said:
We let Powerstation in Cheltenham (http://www.powerstation.org.uk/ ) loose on our old classic Scooby and they managed to dial out a lot of the understeer and make the car much more neutral. Happy days 
Chris
They are pretty good, they did a decent job with my G33. Not a budget option though Chris
blueg33 said:
ScoobyChris said:
We let Powerstation in Cheltenham (http://www.powerstation.org.uk/ ) loose on our old classic Scooby and they managed to dial out a lot of the understeer and make the car much more neutral. Happy days
Chris
They are pretty good, they did a decent job with my G33. Not a budget option though Chris
Get them to remove the factory standard bumpsteer - this alone has a huge effect on understeering tendency of Imprezas
They will also give you a geometry set-up as mild or as radical as you wish.
It is possible to remove the understeer, but it costs you in other areas of chassis behaviour.
Wow thanks for the responses.
I was pretty sure that by applying the power and therefore moving the weight back to the centre/rear would reduce understeer, not increase it, becuse you're freeing up the front wheels to do their job ie. turning, but maybe im wrong?
Lots of interesting stuff there though, I'll probably work on my technique firstly before looking at geometry and such like. And swap the steering the wheel for a smaller item (they do tend to be abit bus-like) :P
I was pretty sure that by applying the power and therefore moving the weight back to the centre/rear would reduce understeer, not increase it, becuse you're freeing up the front wheels to do their job ie. turning, but maybe im wrong?
Lots of interesting stuff there though, I'll probably work on my technique firstly before looking at geometry and such like. And swap the steering the wheel for a smaller item (they do tend to be abit bus-like) :P
bejc said:
Wow thanks for the responses.
I was pretty sure that by applying the power and therefore moving the weight back to the centre/rear would reduce understeer, not increase it, becuse you're freeing up the front wheels to do their job ie. turning, but maybe im wrong?
Lots of interesting stuff there though, I'll probably work on my technique firstly before looking at geometry and such like. And swap the steering the wheel for a smaller item (they do tend to be abit bus-like) :P
It's the other way round. When you accelerate the downward pressure on the front tyres reduces, and this decreases their grip. When you drive a racing car fast all you're doing is trimming the balance to maintain the slip angle that gives max grip, and you do this by making small movements of the throttle as described. Ideally it's not necessary if your turn-in and setup are good, but in reality you always need to in small amounts.I was pretty sure that by applying the power and therefore moving the weight back to the centre/rear would reduce understeer, not increase it, becuse you're freeing up the front wheels to do their job ie. turning, but maybe im wrong?
Lots of interesting stuff there though, I'll probably work on my technique firstly before looking at geometry and such like. And swap the steering the wheel for a smaller item (they do tend to be abit bus-like) :P
The effect you've noticed is almost certainly because you're below the optimum slip angle (aka "the limit").
A common mod by Impreza owners is upgrading to a thicker rear anti-roll bar. I've recently gone for a 22mm Whiteline ARB. Made a huge difference to my understeer problems. Coupled with Eibach springs+alignment setup I've largely solved the issue.
Could go for a set of coilovers but they are a lot more expensive
Could go for a set of coilovers but they are a lot more expensive
Impreza are undesteery things as the engine is forward of the front axle line.
When I had one I found on track that you need to be careful on the way in to a corner. Carry to much speed in or get on the power to early and the front will just wash out. Very much a point and squirt car.
You can cure its built in understeer with a thicker rear anti-roll bar and an 'anti lift' kit which controls camber changes at the front while cornering.
When I had one I found on track that you need to be careful on the way in to a corner. Carry to much speed in or get on the power to early and the front will just wash out. Very much a point and squirt car.
You can cure its built in understeer with a thicker rear anti-roll bar and an 'anti lift' kit which controls camber changes at the front while cornering.
blueg33 said:
In my A6 quattro I find power on earlier helps a lot.
Used to work on my Legacy too, till it died 
(broken engine not a crash)I found the car just wanted to go straight on without power, as soon as a gentle press on the throttle was given the front just tracked round fine. Oddly enough if you went fast enough lifting off gave oversteer, where as it gave understeer at lower speeds.
Hooli said:
Used to work on my Legacy too, till it died (broken engine not a crash)
I found the car just wanted to go straight on without power, as soon as a gentle press on the throttle was given the front just tracked round fine. Oddly enough if you went fast enough lifting off gave oversteer, where as it gave understeer at lower speeds.
I could have written that entire post! (broken engine not a crash)I found the car just wanted to go straight on without power, as soon as a gentle press on the throttle was given the front just tracked round fine. Oddly enough if you went fast enough lifting off gave oversteer, where as it gave understeer at lower speeds.
Did you ever have BIG lift off oversteer with it?
I have an original style Impreza turbo. It does understeer a bit more than I would like but, much less than the old Leggy.
A little slower in and a good bit of just pre-apex power seems to keep it on a tight line.
Going to get the geo on mine looked at. I want to have it closer to the Pro Drive setup.
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