Bloody understeer and strange handling.

[raptor95GTS]

practice, practice...

It took me about 3 months of practicing before i could do it and a bit more honing of it to get it nice and quick rather than just for show.

I find i can do it in any car pretty much these days as i find i tend to drive heel and toeing normally so like anything with driving if you do it enough it becomes second nature eventually.

yup indeedy - will continue lessons when the weather allows

[jonno]

the idea that bigger wider wheels = more rubber on the road is a common myth. The amount of rubber on the road is affected by the cars weight and the tyre pressure. e.g. a tyre inflated to 30 psi and carrying a load of 450 lb will have a contact patch of 450/30 =15 sq in.
If you don't believe me do a web search.

Dont believe everything you read on the web...

If what your saying is true why do Lamborgini's run 325 wide rears? and why does my girlfriends Vauxhall corsa run 165's? Why do F1 cars run wider rears than fronts?

Tyre width makes a *huge* difference. We all know that pressures and the weight of the car affect the contact patch but the biggest single factor are the tyre dimensions.

Neil.

if you spread the same weight over a wider area the pressure per square inch goes down but this is offset by having a gripper rubber and more of it.

But remember on ice the rally cars use narrower tyres as do f1 cars in the wet

ALso the fronts only steer whereas on f1 cars they also transfer the engine load to the ground hence doing more work.

Think how easy it is to drive ford ka in snow in comparision to an mr2? The Ka is lighter and has skinny tyres that dig in and grip.

Exactly my point, they modify the tyre sizes to maximise grip - dry road they use huge wide tyres and wet road they use skinny tyres - why dont they just keep the stock tyres and wheels and change the tyre pressures if it doesent make a difference?

[raptor95GTS]

Exactly my point, they modify the tyre sizes to maximise grip - dry road they use huge wide tyres and wet road they use skinny tyres - why dont they just keep the stock tyres and wheels and change the tyre pressures if it doesent make a difference?

yea almost 2 right answers by me already this week. Must be a record

[John Rees]

In all honesty, and don't take this the wrong way, its not normally the cars fault.

Yes the MR2 suffers with drop link wear bla bla bla, and most of the twos in the uk have done high mileage and are about ten years old so a shock change is a good thing but thats about it.

The thing is they're not the same as other cars because of the weight lay out.
You can't steam in to corners like front engine cars, slow in fast out, use the extra traction on the rear.
This is also not the best time of year to be learning to drive the your car, unless of course you want to take advantage of the slippery roads

You'll find most MR2's get smashed up in the winter months

Your best bet is to wait till the weather gets better and go from there.
Just make sure your shocks are ok and you have an suspension alignment check and good tyres and you should be ok, any problems big handling issue and there could be a bigger problem.
John

[Paul R]

Thanks all for the pointers, to answer some of your questions -

The tyres are standard sizes with correct tyre pressures.
The car is a rev1 turbo which would of originally been fitted with 14" wheels.
Yes the weather whilst I'm cornering is wet, bloody horrible cold and wet - one of the 'perk's of living in England!
I read the tyre reviews on the old site and I think I will try the Bridgestone SO3's next - I didn't read about the F1's and the site is no more , with all the sliding around I'm doing it shouldnt take long to finish off the Yoko's.
I havn't had the alignment checked at all since owning the car so I think that will be my starting point.

I understand that the whole suspension was revised around '92, what are the differences and is it worth upgrading to later spec? Also what is the best (cost effective) aftermarket suspension set up i.e. lowered springs / new shocks / nicking a roadroller and re-surfacing the roads.
Also what wheels / tyres will fit the car? Can I put 285/35/19 & 225/40/19 on and have more rubber touching tarmac than a car park full of clio's? (I guess it would still be pretty crap in the wet / snow but would climb walls in the summer )


Cheers,
Chris.

hiya mate,

If you have a Rev1 with standard suspension, then you should have the option of rebuildable shocks. there are some Nice Koni inserts out there that are fairly cheap - A worth while option IMHO!

Thats certainly the route I'm taking!!

Paul.

[CJ B]

In all honesty, and don't take this the wrong way, its not normally the cars fault.

Yes the MR2 suffers with drop link wear bla bla bla, and most of the twos in the uk have done high mileage and are about ten years old so a shock change is a good thing but thats about it.

The thing is they're not the same as other cars because of the weight lay out.
You can't steam in to corners like front engine cars, slow in fast out, use the extra traction on the rear.
This is also not the best time of year to be learning to drive the your car, unless of course you want to take advantage of the slippery roads

You'll find most MR2's get smashed up in the winter months

Your best bet is to wait till the weather gets better and go from there.
Just make sure your shocks are ok and you have an suspension alignment check and good tyres and you should be ok, any problems big handling issue and there could be a bigger problem.
John

I drove my mates '91 NA which behaved a lot better up front. He did have SO2's on the front and SO3's on the rear but the kind of speeds my tubby is letting go at are so SLOOOOOW.
I also have plenty of experience driving a certain similar car (I'm not saying what 'cause of the 'flames' I will get on here) which is sitting out the winter in the garage. That one has 205/55/16 front and 225/50/16 rear as standard and takes a hell of a lot more abuse before it unsettles.
I really think mine is somewhat shafted up front but its too cold and horrible to go lie down in the road to investigate.

Does anyone know a trusted wheel alignment place up here in the NW?
I'm based in Northwich Cheshire (not Norwich - yes it is different)

Cheers,
Chris.

[Paul R]

In all honesty, and don't take this the wrong way, its not normally the cars fault.

Yes the MR2 suffers with drop link wear bla bla bla, and most of the twos in the uk have done high mileage and are about ten years old so a shock change is a good thing but thats about it.

The thing is they're not the same as other cars because of the weight lay out.
You can't steam in to corners like front engine cars, slow in fast out, use the extra traction on the rear.
This is also not the best time of year to be learning to drive the your car, unless of course you want to take advantage of the slippery roads

You'll find most MR2's get smashed up in the winter months

Your best bet is to wait till the weather gets better and go from there.
Just make sure your shocks are ok and you have an suspension alignment check and good tyres and you should be ok, any problems big handling issue and there could be a bigger problem.
John

I drove my mates '91 NA which behaved a lot better up front. He did have SO2's on the front and SO3's on the rear but the kind of speeds my tubby is letting go at are so SLOOOOOW.
I also have plenty of experience driving a certain similar car (I'm not saying what 'cause of the 'flames' I will get on here) which is sitting out the winter in the garage. That one has 205/55/16 front and 225/50/16 rear as standard and takes a hell of a lot more abuse before it unsettles.
I really think mine is somewhat shafted up front but its too cold and horrible to go lie down in the road to investigate.

Does anyone know a trusted wheel alignment place up here in the NW?
I'm based in Northwich Cheshire (not Norwich - yes it is different)

Cheers,
Chris.

hiya Mate,

I live in Nantwich - not too far from you! Last time I had a 4 wheel alignment I went to ABP Motorsport in Shavington. They can do a full geometry setup!

Paul.

[SimonPearse]

dont just believe me, do a search on tyre manufacturers sites e.g.bridgestone. Then learn some basic physics and use your brain.
There are three main reasons for high-performance cars using wider tyres.
1. cos it looks 'better'. This is why lots of people spend lots of cash putting big wide (heavy) wheels on ,for example MR2's. OK so it buggers up the handling and produces a slower car, but it looks fast.
2. A bigger wider tyre has a greater surface area. It can be made using a softer rubber compound and still last as long as a narower tyre. softer rubber can mean better grip, so if two different size tyres are each designed to last say 10000km the wider one could provide more grip because it can use softer rubber.
3. The shape of the contact patch is different. A wide tyre has a contact patch which is a long narrow oval. A narrow tyre has a more circular contact patch. A long narrow contact patch (wide tyre) has quite different grip characteristics, its can provide higher grip, but its relatively unstable. It's more prone to sudden break-away and is less predictable under break away, but the break-away point is raised compared to a narrower tyre.

It's quite a good idea to 'not belive everything you read on the web', but it can be a good idea to read a lot and give it consideration.....

[Dave Burke]

Had a similar problem on my mk1. The handling had been degenerating gradually, tons of understeer, very odd steering behaviour under braking, and some odd creaks and groans.

I'd put it down to the balljoints, which I was about to replace - so I replaced them, then took it in to get the alignment done. Turns out the alignment was a mile out, and had worn the inside 1/3 of each front tyre completely bald. I guess I should check my tyres with the steering on full lock in the future eh?

Anyway, a new pair of tyres later, and the alignment straightened out, it's like a new car, very "pointy" when cornering, even in the wet. The odd creaking has gone too, which I'm going to say was cured by the new balljoints so the day spent replacing them wasn't wasted

[^Trickster^]

I run koni adjustables with H&R 40mm lowering springs and polyurathane bushes all round on my mk2 and it still understeers, there been a few medium sized roundabouts ive tried to fly around at about 60 and the car likes to go in a striaght line. Im going to readjust my dampers this week, going to soften the back up and stiffen the front.

What settings are you people with koni adjustables running?


Graeme

[Bry]

[quote="^Trickster^"]I run koni adjustables with H&R 40mm lowering springs and polyurathane bushes all round on my mk2 and it still understeers, there been a few medium sized roundabouts ive tried to fly around at about 60 and the car likes to go in a striaght line. Im going to readjust my dampers this week, going to soften the back up and stiffen the front.

What settings are you people with koni adjustables running?


If you want less understeer,stiffen the rears and soften the front,this will allow the weight to transfer to the front better when braking giving you more front end grip and less understeer,also check your tyre pressures
Bry

[^Trickster^]

Thats what i meant to say actually, they are set the other way around at the moment!

Cheers

Graeme

[crazylegs]

the tyre contact patch cant be that simple.i agree that tyre pressure and weight will be a factor.the tyre width and diameter must come into it.you cant tell me you get the same grip from a 20cm wide tyre as you do from a 40cm wide one.if the pressure is the same you must get more friction from more rubber its simple physics.

[BenF]

I run koni adjustables with H&R 40mm lowering springs and polyurathane bushes all round on my mk2 and it still understeers,

Hmm, the lowering won't really have helped the alignment that much - mine is completely neutral normally can can easily be made to oversteer with too much throttle on a wet roundabout.

If the aligment is OK, you tried playing around with tyre pressures at all?

If you're getting understeer, I'd add more air to the rear tyres.

[raptor95GTS]

the tyre contact patch cant be that simple.i agree that tyre pressure and weight will be a factor.the tyre width and diameter must come into it.you cant tell me you get the same grip from a 20cm wide tyre as you do from a 40cm wide one.if the pressure is the same you must get more friction from more rubber its simple physics.

um but if the same weight is spread over twice the area then the pressure per inch^2 or cm^2 is halved - that's simple physics

Think F1 - take away the wings front and rear and replace the weight loss with some ballast, the cars are hugely slower round the corners. Why? the weight seen by the tyres is far less as there is no downforce adding to the weight of the car

hence lower pressure forcing the tyres into the tarmac hence lower grip

bottom line

but if the same weight is spread over twice the area then the pressure per inch^2 or cm^2 is halved - that's simple physics

[CJ B]

Quick update!
I still havent managed to find the will to crawl under the car but a couple of times now when I've been parked (removing stereo front etc. )the front end has clunked / pinged as if something under tension finally slipped!
I have also been paying more attention whilst driving and noticed that the steering deflects over road bumps.
Hopefully I will get this looked into before the wheels fall off on a bend

Thanks for all the help with the F1 tyres but for the time being I'm gonna concentrate on getting the '2 right before challenging Schumacher
Cheers,
Chris.

[DeusMR2]

the tyre contact patch cant be that simple.i agree that tyre pressure and weight will be a factor.the tyre width and diameter must come into it.you cant tell me you get the same grip from a 20cm wide tyre as you do from a 40cm wide one.if the pressure is the same you must get more friction from more rubber its simple physics.

contrary to popular belief, frictional force is not proportional to area, only to the coefficient of friction (which is constant for a particular material) and the force applied normal to contact area i.e. the weight

[^Trickster^]

I put 30psi all round, ive never looked into what they should be, something ive always put aside and maybe shouldnt have!

Graeme

[BenF]

I put 30psi all round, ive never looked into what they should be, something ive always put aside and maybe shouldnt have!

Graeme

The fronts should be 2-3 psi less than the rears. That alone will give you understeer.

Get a proper pressure gauge (pencil /interia ones are cheap and quite accurate) and sort the pressures out.

Clunking - get under the car and check everything that should be tight actually is.

[John Rees]

Bry is correct here, soften the front and stiffen the rear will make the front turn in better. The same as having the front end slightly lower than the rear has the same result.

Try running 3/4 stiffness on the rear and 1/2 on the front and go from there.
When you make changes be sure you try it for a few days before you make more changes, give your self and chance to get used to them.

John