Rolling when changing lanes

[Wabbitkilla]

Might be worth getting a proper 4-wheel alighnment check.
Mine did a similar thing also when i had a droplink failing.

[ChrisGB]

Could it be a tyre carcass has gone bad? Maybe on that looks more bulged out where it meets the road than the other?

Chris

[Chris 180SX]

Cheers for the replies guys, the problem started a few weeks after getting new Bridgestones all round, and it happens on all road surfaces/conditions to varying degrees.  I've had the wheels off and can't see any tyre irregularities.  Could it be engine mounts or somehow something is allowing the weight of the engine to move around?

[ChrisGB]

Cheers for the replies guys, the problem started a few weeks after getting new Bridgestones all round, and it happens on all road surfaces/conditions to varying degrees.  I've had the wheels off and can't see any tyre irregularities.  Could it be engine mounts or somehow something is allowing the weight of the engine to move around?

Did this happen immediately after the tyre change, or was it OK on the new tyres to begin with?

Chris

[Chris 180SX]

It was OK to begin with though curiously when I got the tyres fitted the steering wheel is off centre to go dead straight.  Brakes dead straight and drives straight though....

[Ilogik]

It was OK to begin with though curiously when I got the tyres fitted the steering wheel is off centre to go dead straight.  Brakes dead straight and drives straight though....

Sounds like it was probably done by cock handed tyre jockeys who think all cars are set up on a fwd machine. Think your issue is heavily based on alignment, it sounds like they did the tracking for you, but fubard it up more.

You need full wheel/geometry alignment that will sort out your bonked steering wheel. Could of hit a pot hole too. Where are you located?

[ChrisGB]

Hmm..

I wonder, did you have RE040 on before this? The RE040 do like to tramline a bit once they start to wear and it gets worse with increased wear. Regards the tyre fitters, if they did not touch the alignment, you could still have odd steering offset to go straight. The coloured bands around the treads are indicative of carcass layup and bias. If you get a strong offset to the same side on both fronts, that can cause the steering to be over to one side while the car is going straight, however, this is usually accompanied by some degree of pull.

Only other thing I can think of is to check the rear chassis mount points as we know the rear subframe can turn to wheetabix on some cars.

EDIT: What area are you in? Maybe someone with RE040 experience can drive your car and indicate if it is normal.

Chris

[Chris 180SX]

Thanks guys, they were RE040s on the back and Kuhmo KU31s on the front, now they're all stones...

I'm in blackburn by the way...  Will have to check subframe and book myself for an alignment, any recommended places?

Cheers   s:) s:)

[Ilogik]

Thanks guys, they were RE040s on the back and Kuhmo KU31s on the front, now they're all stones...

I'm in blackburn by the way...  Will have to check subframe and book myself for an alignment, any recommended places?

Cheers   s:) s:)

Shame your in blackburn, if you were in birmingham I would say take it to A line in Dudley, can't fault them, they do all the set ups for the drift cars and touring cars and best of all its only 40 quid.

[Ilogik]

Thanks guys, they were RE040s on the back and Kuhmo KU31s on the front, now they're all stones...

I'm in blackburn by the way...  Will have to check subframe and book myself for an alignment, any recommended places?

Cheers   s:) s:)

Shame your in blackburn, if you were in birmingham I would say take it to A line in Dudley, can't fault them, they do all the set ups for the drift cars and touring cars and best of all its only 40 quid.

[Chris 180SX]

Hi chaps, just another update, I tried some 99-02 wheels from my mate's roadster last weekend, but the rolling was still there.  I noticed how much smoother the ride was with the earlier wheels though...

Am going to get an alignment check next I think, you can adjust the rear toe, right?...  I will keep this thread updated as I attempt to eliminate things...

[Chris 180SX]

It seems the rear toe is toeing out by 0.5 degree (same both sides) doubt this would be a such a big problem though?

[ChrisGB]

It seems the rear toe is toeing out by 0.5 degree (same both sides) doubt this would be a such a big problem though?

Toe out on the rear will make the car turn in and load up the rear end faster in slow, tight turns. However, in fast turns and direction changes the car will feel less stable. Toe out at speed can lead to oversteer too.

For a stable setup I run 0 toe at the rear. If I wanted something more aggressive, I would be running some toe in for stability in fast corners.

Chris

[Chris 180SX]

Thanks, I thought as much   s:) s:)  

As another update I tried various toe settings -va and +ve.  They affected handing as per Chris' descrption, as you would expect, but the wallowy roll was still there.

I then stuck a bar down to prize the bottom engine mount side to side a bit.  I noticed a fair amount of movement in the top right of the engine.  Though I'm not too sure if this is to be expected, or how much movement you would expect.  Do the mounts often go on 2's?

Cheers   s:) s:)

[cclarke99]

ChrisGB - thats really interesting what you wrote regarding rear toe in/out. Would I be right in saying that with toe out, the loaded wheel (outside of the turn) is tending to steer the the rear of the car towards the outside of the turn, whilst with toe in the reverse is the case?

I suppose this explains why the standard set up is always toe-in (0.1-0.5 degrees), making the car moere stable and promoting understeer on tight corners

[ChrisGB]

I then stuck a bar down to prize the bottom engine mount side to side a bit.  I noticed a fair amount of movement in the top right of the engine.  Though I'm not too sure if this is to be expected, or how much movement you would expect.  Do the mounts often go on 2's?

Cheers   s:) s:)

The engine mounts do allow a fair bit of movement. Check for splits or tears in the mounts, if they are looking healthy they generally are.

Chris

[ChrisGB]

ChrisGB - thats really interesting what you wrote regarding rear toe in/out. Would I be right in saying that with toe out, the loaded wheel (outside of the turn) is tending to steer the the rear of the car towards the outside of the turn, whilst with toe in the reverse is the case?

I suppose this explains why the standard set up is always toe-in (0.1-0.5 degrees), making the car moere stable and promoting understeer on tight corners

It is to do with slip angles and yaw rate build up. If you have a rear outside tyre that is toeing out, when you first turn, the front wheels turn in and start the rotation, the rear wheel that is starting to load up is pointing ever so slightly toward the outside of the turn, so the rear tyre does not induce much slip angle and does not prevent the tail from swinging as much. If it is toed inward, as the front wheels turn, the rear wheel that is loading up has a larger slip angle and will resist the rear end moving outward around the front. From the drivers point of view, toe out makes the rear end lively and the car feels like it is helping turn in. Toe out makes the car feel like the rear end does not want to help with turn in.

BUT, when the car is loaded into the turn, it is a different story. Once turned into the curve, if you have toe out, the rear tyre that is loaded (the outside rear) is not producing much slip angle so the rear will be out at a steep angle to produce cornering force. Toe in has the opposite effect of making the rear generate more slip angle and thus the rear will not sit out at such a steep angle for the level of grip generated. This then relates to the front wheels. If you have toe out at the rear, when you turn the front wheels into the corner, the rear that is loaded is facing away from the inside of the turn, this makes for fast turn in, however, once the turn is generated, the front tyres need to stay at a big slip angle relative to the rears to keep the front loaded. Because of this, the tyres have to run different slip angles and one pair will be at less than optimum throughout the steady state part of the turn if the other pair are to be at optimum. If you have toe in at the rear, once you are loaded up into the corner, the front and rear tyres are much closer in angle and this allows both tyres to run closer to optimum slip angle. So for a short track autocross type of circuit, you would run rear toe out, for a race track with big fast sweepers, you would run some rear toe in.

So how do manufacturers make a car that turns in and has good balance in fast turns? A typical way it is done is via a rear toe arm / track rod. This works on the rear hubs to turn the rear wheel inward as the suspension compresses. As you initially turn in, the toe at the rear is pretty much neutral, but as the loaded wheel moves up in the arch, the track rod is mounted either higher or lower on the shell than on the hub, so it turns the wheel slightly inward making toe in build up on the loaded wheel. This is one reason why cars that are lowered too far feel inert and also a reason why a too stiff rear roll bar can lose rear grip. Suspension setup is a huge interdependent set of variables and is really difficult to do properly. Personally, for a road car I am happy to sacrifice a little turn in for a car that has a neutral high speed behaviour. My objective when setting up is a car that will keep as small a difference in slip angle front to rear as possible. This works for good corning speed and makes it possible to steer the car on the throttle without drifting it. Just my personal taste in setup, but I got this with a 20mm (from stock) rear drop and 0 rear toe.

Chris

[cclarke99]

Thanks for your fulsome reply, gave me so much food for thought I nearly got knocked over whilst out for my lunchtime walk today. I suppose that Fords 'Control Blade' rear suspension is one example of a suspension linkage designed to control toe-in as you describe

I can see how toe in would promote stability as the more highly loaded wheel will always be tending to steer the car back to it's original path. I was imaging a force (side wind) on one side of the rear of the car causing a yaw and also increasing the load on the tyre opposite to the force. With toe-in the loaded tyre tends to steer against the force thus steadying everything. With toe out, things will be unstable.

In steady state, it would seem to be best to have the wheels set straight ahead, so that the slip angles were the same side to side. With toe in/out, the wheels on opposite sides will always be fighting each other thus reducing the overall available cornering force. However I suppose some toe-in is advisable in a production car to avoid the unstable toe-out condition developing as a result of wear, tolerances and distortion of the suspension under load.

As far as getting the best balance front/rear in steady state, I am still a bit uncertain as to how toe in would help. The toe angle will affect the angle the car body makes with it's track on the ground by effectively steering the back of the car, but the front wheels will be steered to compensate for this. So the car will be in steady state with the front and rear wheels at whatever angle gives the right slip angle to generate the cornering force and the body aligned accordingly. The cornering force (and hence slip angle) will depend on the distribution of the weight front/rear, so for an MR2, the rear wheels will always be working harder.

[Anonymous]

Hi! Just had exactly the same thing happen with me recently - the car (2001 stock roadster) handled beautifully but the steering wheel was a tiny fraction off centre when gong in a straight line so I had a full 4 wheel alignment done and everything was set well within Toyota recommended tolerances.

About 1 day after this I got a nail stuck right in the edge of one of the right rears and had them both replaced (at the same place that did the alignment) as the puncture was unfixable and they were approaching the limit anyway.

As I don't drive the car much, and never very hard or fast (I have a very fast motorbike to quell those urges) it took me a few days to realise that it had started handling like a a piece of sh1t (technical term!) and it was making me nervous going around bends that were normally comfortable at a very minimum of 70 - 80 mph when I was only doing 50 - 60 mph, also, if I tweaked the steering wheel slightly whilst going straight it felt like the car was going to turn in and under on itself and just flip!! There was more than a few occasions that I thought I was going to be seasick with all the rolling about!

At first I thought it was just me but checked all the tyre pressures (twice!) and I played around with it every time I drove it and was convinced that something had been broken or come loose after the set-up!!

Took it back to the garage (Elite in Rainham, Essex - highly recommended) and they were really cool, no fuss at all and didn't think I was a nut-job, checked it all out underneath and check the set up again (all free of charge) - all good underneath and no changes or problems with set up. The mechanic (Lee) said it could be a couple of other things that had gone wrong or become apparent after the set up (like my cheap front tyres that were on when I bought it and still going strong after 3 years) but still got their driver to take it for a quick spin so see what he thought. We went out and I explained and after less than a minute he knew exactly what I was talking about.

Went back to the garage, he made a few suggestions to the mechanic who then re-aligned the front wheels slightly - we took it out again and although it was only a brief test it felt just like it used to do again!

I haven't had the time to give it a full work out yet but I feel confident that it is back to, or even better than where it started from and hopefully this will be proven when I get it around some familiar bends...

I will let you know if I later change my opinion after extensive testing but I feel comfortable that it's sorted now!

If anybody is curious please ask and I shall post the detailed settings etc but the basic principal (on my car at least) is that the back wheels are pretty much dead straight and central within Toyota recommendations and the fronts (which were central within the recommendations when I was having problems) are now ever so slightly toe-out yet still on the edge of Toyota recommendations (i.e. green on the print out!)

Result!

Hope that helps somebody like these forums have helped me from time to time....

[loadswine]

Interesting Andi,glad to see Elite making the effort to sort things for you.
Best advice on here is to have same make and type of tyre all round ( in stock sizes to maintain stagger)for safe handling, so would be good to get those fronts matching as soon as you can and you might find things are better.
A decent alignment makes a vast difference to the handling on the 2 for sure.

[Ilogik]

I need to get this sorted, having the same issue again, I had lowered it a bit more, im waiting to buy some new tyres and hit everything at once though. Will keep you posted.