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Understeer Problem

Philip Male

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Just had 4 wheel alignment done to sort a vague feel to the steering and reduce understeer ( looking back on it fairly well balanced understeer ) on tight turns in the damp ( not wet ), roundabouts and things

this was caused by a hard hit on a kerb trying to avoid a car coming the other way a year ago.

it was crisp, responsive and well mannered before that. I had a garage check it out afterwards, but they said it was all fine, it braked and tracked ok too.

after driving an identical focus last week i knew mine wasn't fine, infact it drove like my old 97 astra!

anywhos, with it done the car felt a little better at first coming out of town, but when doing A roads at A road speeds in the damp i've got a car that jinks and feels nervous with ruts and imperfections in the road, can feel that through the seat rather than steering.

Steering is less vague but now where on a roundabout i might have of just had understeer i could hold and live with the car now just gives up and plows straight on, that was scary first time thinking it'd be better not worse!

full acceleration in 3rd from a roundabout onto a dual carriage way with a slight left bend in this mornings damp had it understeering into the outer lane all on it's own with hardly any lock on from me, 20-30 degrees maybe

i've never had it do that before

i'm totally lost as to why apparently the ideal settings have made my car unsafe at anything above boring speeds

driving sensibly is one thing, but theres those corners that catch you out, and you always just trust the car will sort it out.

now i think it'll just try mating the hedge and thats making me drive very nervously just making things worse.

1.6 petrol hatch

fronts, something called a focus 2000, used to have them all round and grip was pretty good, 31.5psi 5mm tread, no uneven wear.

rear michelin primacy, 33.5psi 6mm tread no uneven wear

mileage 53k

heres the alignment sheets.

cheers, phil.



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well first off tyre pressures for the 1.6 hatch are as mine fronts max 30 psi so youre over there and rears fully laden 33 psi i find if its just you and a passenger 28-30 front 31 psi rear try that and see how it goes

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If your tracking is fine, your pressures are fine, what you're looking at is either tyres gone beyond their optimum grip or the conditions are no longer good enough for them to work sufficiently.

I watch a lot of Nascar, the biggest reason for cars becoming 'loose' or oversteering, or 'tight', understeering, is due to tyre wear. Having had a quick google, these are what are known as budget tyres, no offence intended as you could've had these fitted before, but tyres are the only thing keeping your car straight on the road. The reason your car felt different to the other because possibly the tyres were of a better make or compound.

My advice would be to swap around the front to the rears. As the rears only really get dragged and the fronts do all the work, it would be one way of seeing if the missing feeling is the tyres.

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since the pressures are wrong at cold by the time they warm up they will be well over fronts will be around 33.5 and rears around 36 or more

as said above you have michelin rears cheapies front different tread patterns for a start so the rear will likely be gripping a lot more than the fronts

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I must agree with the other guys. First of all get those budget tyres on the rear.

The only other thing if that doesn't improve things dramatically is I wonder if the steering track control arms or similar were slightly bent in the impact with the kerb. The tracking may be set up to correct this when in a straight line but the turning angle on each wheel could be different and one of the wheels is turning further than the other causing the under steer.

This is just a hypothesis and is no way based on any experience.

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First thing i did when i got home was check pressures after letting the tyres cool for a couple hours, they were actually 29.5 front and 32.5 rear

i've never found the ford sticker easy to understand, but it seems to suggest for 205/55 R16 lightly loaded 30 front, 33 rear

gave it a little extra thinking like previous cars a slightly harder tyre feels better to me, responds better.

to be honest with this set up trying to throw me in hedges there's far too much going on to notice 1psi

( don't you just hate it when you get new tyres and the garage bungs 36psi in there for you! )

yes, the fronts are older, but came fitted to the car when i got it a year/14K ago and were pretty new

these used to be on all 4 corners, and while you don't expect slicks grip, for normal road use they seem to offer reasonable grip.

when the fronts wore out i had the primacys fitted, but they made the car feel unstable, and not consistent in cornering, turn, lean, ah thats how much you want to turn, ok, have some more, which then you have to counter correct

rule of thumb has always been stick your best grip on the back, because it's easier to loose the front than back and correct

so thats where they went and the car went back to it's normal behavior. that was in september

I also want to wear them out so they can be replaced with something better, they'll live forever more on the rear.

the other car is a works one, so trust me, it has the cheapest black round things they could find, and checking pressures? he's only washed it once since he's had it, to him a car is A to B, if it manages that it's fine.

the difference is it's a TDi, so the nose feels a bit heavy in corners

but more to the point it has the crispness i remember from mine pre numpty on my side of the road.

let me clarify how i feel the different understeer types between old and new alignment

the old issue was mostly vagueness and loss of crispness.

the understeer was what you'd expect when your being a bit of a kevin on the accelerator at a road speed you wouldn't have an issue at otherwise, the wheels are spinning, the cars drifting out wide, but your still taking the line you intended because of the extra lock

if speed was the problem, ie, big roundabout at the end of a dual carriageway you'd get the more traditional pushing on, but letting off would bring it back in line, and sometimes the grin inducing focus happy tail.

that understeer is generated by the nut behind the wheel

this understeer is the kind of thing that has you introducing yourself to the livestock the other side of the hedge you're plowing into before you've worked out why

there is no holding it, it's happening at lower speeds, and even high speeds with modest lock ( accelerating from a roundabout in 3rd on a damp dual carriageway on a slight left bend had me drifting into the outside lane, it's never even hinted at understeer here before )

you can also get it to happen at low speeds, tight turns and mini roundabouts, first time i went straight was at a mini at what would be considered a fast but normal speed

the car more nervous in a straight line too, or at least rut and bump following.

this i think is set-up understeer, although yes you can still drive slow enough to avoid it, but thats slower than you were going before, thats not an improvement.

i'd be more tempted to blame the tyres if it wasn't fine when driving fast but normally on the old setup

nothings changed but the toes and it really has been a before/after thing, it's why this set is bad thats confused me

forums seem to suggest a little toe out is good for focus's, but the range is -0.02 to 0.08, so that'd suggest toe in is what ford want

it might well be better with the higher grip from the primacys, but thats not solving the issue really, esp when you get those corners that catch you out and you just trust the cars better than whats left in your bag of tallent

at the moment it's really not

it'll also be better once the roads dry up, but i don't like this scary handling in the damp

the tyres haven't changed so total grip, and difference in front/rear levels should also be the same shouldn't it?

side note, i don't have any driving aids other than ABS

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It does sound pretty weird. Personally I prefer a loose back end (excuse me vicar) than the front. That's in both front and rear wheel drive cars as you can drive out of a sideways slide but not out of a straight on plough when attempting a corner.

I have had some cars do some odd things due to tyres. I had one car that for no reason used to start squirming all over the place when driving on a dead straight piece of road at 50mph. I would literally be fighting with the wheel to keep it in a straight line and then it would be fine for another 200 miles before it would do it again for no reason. I thought it was possessed. After getting the shocks changed and everything checked to no avail I just swapped the tyres around and it was fine. The car had Pirellis all round.

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i did have the first garage check everything after the hit and they did say it was fine.

i did note a knock from the steering if going from left to right lock when stationary, this would happen at any point in travel

however i was looking for problems and this might have already been there.

theres no knock when moving

they reported no slop or issues, but suggested i could of rounded off a tooth on the pinion and this is what was making the noise.

a new rack was £250 and unlikely to change anything. s

sounded more like a knuckle to me, but thats based on what does what when i used to race RC cars, heck if i could did out my old instruction book for the touring car and a 3.5mm spanner i could tweak it to do what ever i wanted. it always was handling over outright speed for me

anywhos, it still pulled, braked and tracked perfectly straight.

The second garage knew of the kerbing and also found no issues

then again the 1st garage also couldn't find an issue with the old astra after rough winter roads left it feeling unstable mid corner at speed on right hand bends only.

told them it was a front left issue, gave them feedback J button would be proud off, first tracking, no effect, then a front right?! new wishbone, still nothing, told me thats how astras drive, i expect too much and drive too fast for the car.

only i know how my astra drove, the RC thing really does let you know whats doing what on a car when the only feedback you get is an imagined one through your thumb!

it's a kind of input vs result expectation that can tweak out the smallest set up changes

couple of months later in the MOT a cracked ( but not totally sheared off ) anti rollbar mount was found front left

£19 and the car was transformed. it wouldn't lap the ring in 8 mins, but you knew what it'd do, and it'd do what you wanted

this is what the focus has now lost, the smack lost the crispness that everyone raves about, this alignment has lost it's predictability

how do those result numbers look tho?? most set up guides suggest neutral toe in, or even a hint of toe out

miss my old fester, that was set up on purpose slightly out, fun on B roads around here, but also good on motorways

nothing i've driven since can get from redruth to helston quicker

i'll swap the wheels around anyway, i've got a hundred miles inc some fun bits to do this weekend, and i know the road well, so will notice any changes.

if i don't report back monday eve i died in a hedge

cheers for the advice so far, phil.

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loose back ends

the end game idea was to wear out the cheapies on the front, then get something better than the primacys, which i really didn't like, so then i would have more grip at the front, but more overall than the cheap rubber

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Sometimes Phil its best to cut your losses, and just bring forward the purchase of four optimum tyres, that way you get more trustworthy performance, but unless your steering is shot and not responding correctly, the rubber is the last piece of the puzzle.

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I have to say Phil (and I know tyre choice is a very personal thing) but mine is fitted with Michelin Primacys all round, and it handles an absolute treat.

Its quite often over looked by tuners and people who want to better the performance of their cars, but tyres really are such a key part, not only having 4 matched ones, but have 4 that are right for the car.

Some grip patterns maybe great for light cars, while others offer better grip when loaded up more, others are best when fitted to lower profilers while some steering setups maybe designed to allow a little side wall sway in the corners.

Who ever told you about having the best tyres on the rear, well personally, I would slap them. The fronts in a front wheel drive car do the steering, deliver the power and about 60-70% of the braking. The rears are followers, their purpose is to take any load over the rear axle and keep the car moving forward straight line. However as has been posted above a matched pair on all four wheels is great. It gives you confidence that the grip should be somewhere even over all four contact patches. This depends on weight transfer and cornering speeds, but will at least give the car more of a fighting chance of being stable throughout the corner.

Compounds also make up a huge part of the tyres working, as Stoney posted budget tyres are just that, budget. The manufactures won't do as much research into the design as Michelin, nor will they research their rubbers grip abilities over the course of the tyres wear and environment change.

From reading your posts, I wondering if perhaps there could be a level of you've had a knock and now it doesn't seem to feel right, but added to that, the cold weather has brought out how the budgets fitted a really out of their depth for the conditions.

Anyways, hope you get the car feeling better soon, report back any findings as well.

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Phil, if you have a tread depth gauge if you would measure the tread of each tyre in 3 places (the middle,or just off the middle on some tread patterns the inside and the outside- approx 20mm in from the edge)

This will tell all sorts of things

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I agree with Andy, got primacy HPs on mine all round and happy with it. The pressures being too high, only by a few psi, were making mine feel like a dog. I even posted on here about it as I thought it was busted!

I thought all sorts could be wrong. I think often when you think there's a problem we tend to over-analyze everything.

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a few psi on mine with just me in it can make a big difference as can the type of tyre ideally all 4 should match

in winter normal tyres the rubber goes hard and the tyres take a long time to soften up while the tyres are hard the grip is very poor so you will understeer easily i think its just that and once the weather warms up the problem hopefully will have stopped

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in winter normal tyres the rubber goes hard and the tyres take a long time to soften up while the tyres are hard the grip is very poor so you will understeer easily i think its just that and once the weather warms up the problem hopefully will have stopped

Exactly what i was going to say -

the type of rubber in modern "summer" tyres does not grip well under 7 degrees centigrade, - under 4 degrees,c they are worse, in my experience


winter (tarmac) tyres have a special rubber compound that stays pliabie/ grippy at low temps- i run vredstiens - you would not believe the differece they make

it is difficuly to get heat into the tyres at these temps, they start off with 8mm tread, once you have rounded off the front "shoulders" of the tyre, or worn the tyres down, the blocks of rubber can't move around so much to generate heat

im sliding around a bit more now - i think its the salt on the road (as well as the low temps)(no ice/ snow where i live now)

roundabouts are notorious for spilt diesel and can be very slippery with the slightest hint of moisture or low temprature, bumps, the state of the roads, camber (usually running to the left) all compound the lack of available grip (with the low temps/ tyres that are not good at low temps)

The pressures are critical, don't just stick the recommended pressures in - try different pressures (within reason)

the "for high speed/ heavily laden" pressures may be more appropriate for you

the diesel has a heavier engine, probably stiffer springs, more torque, (the torque and the weight helps to put heat into the front tyres) most of the steering, braking etc is all about the front end on these cars

I think you drive / corner faster than most drivers on the road, and have a "feel" for your car that, many drivers, do not have, most drivers do not find/ explore the limits of their cars handling, you owe it to yourself to invest in decent rubber, (the Michelin is an "eco" tyre, ive never heard of the other ones )

As others have said - a decent set of tyres would transform your car, 4 is best, but at least 2

Ive tried Pirelli, Michelin, Dunlop, Avon etc , i run Goodyears (my favorites) in the spring/ autumn, i have a couple of "no brands" i am trying to wear out (i stick them on the nsf in the warm summer) they seem to last forever, (3 years+) but very little grip

There is a possibility that something else has been knocked/ twisted - subframe bushes, wishbones etc etc - tracking cannot pick up everything, i have personally have trouble with tracking that was supposed to be "ok" - remember, you are expected to drive it like a tea trolley like everyone else :) if you know what i mean

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some great answers there and you've all got a piece of what i think is the answer.

at the weekend i broke out the trolly jack to swap tyres around, but i thought before that i'd just double check the pressures again.

reason thinking, it was fairly cold when i did them, and i put a little much in then

now it was 14c outside the fronts were 32.5 and the rear 35.5

so that explains alot!

whats weird, in my experience of other cars pressures, is the lower pressure has made the steering lighter and more responsive, pretty much how i remember it being the first few drives, it's lacking a little feel, but thats probably cold winter driving as mentioned above lowering grip.

2nd, the scary roundabout was only 1.5 miles from work, again it was cold, and there's no heavy braking really to get the temps up, by the time i got home it was better, but i had that me as me treating it like crystal glass.

tyre depths were taken from a service end of last year, i checked them with a borrowed, and somewhat crusty depth gauge at the weekend, actual depth was 4mm, not accurate enough to tell if it was different across the tyre because it was too stiff.

a new gauge and pen style pressure reader are in the post.

i've only ever heard your best rubber should be on the back in a FWD car, you'll loose traction at the front first and know to back out before the rear tries to overtake, and as a side, it wears out the old rubber first.

my intention is to wear out the budgets first, but i could try swapping again, see if the michelins are better now the tracking's sorted, as said, i hated the feeling before.

these tyres were nearly new when i got the car, and they needed replacing after about 7k on the front, so these i have now should be ready to swap over in the summer so long as i leave them on the front, they have too much tread and my wallet too little money to just bin them for a new set right now.

and i'd rather not have the grip difference the other way around, esp when it's cold and the rears would be slippy

to be honest when reading about correct pressures, primacys were mentioned as the ford test drivers choice, but that was on a diesel and they were comparing what tyre makes need what pressures.

so, the next issue i need to sort is this knock.

i don't know if i had it before the kerbing

but every time you turn right from any position you get a click/knock, it's not very serious but it's there, it's passed an MOT with no notification. it's been checked and was told it's maybe the pinion rounded off?? you can feel it on the track rods as a vibration, left side more than right.

with the car jacked up and someone holding the wheel you can't feel it rocking the right wheel, but can just about feel it if pushing with arms and knees on the left.

couldn't get my head up far enough with the wheels on the floor to see if the rod ends were moving at the power steering unit.

don't think it'd be enough to change the steering angles during driving but you never know.

any ideas??

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I think you drive / corner faster than most drivers on the road, and have a "feel" for your car that, many drivers, do not have, most drivers do not find/ explore the limits of their cars handling, you owe it to yourself to invest in decent rubber, (the Michelin is an "eco" tyre, ive never heard of the other ones )

you're probably right, i'd say i'm a very average driver, i have no extra level of car control or skill ( unless i can translate what my right thumb can do with a RC car to full size on a track ), but i can sense what a cars doing i guess more so than other normal people i know, they think i'm mad when i talk about how it feels, and there they are with 19psi in the tyres and the only comment when i put it right is, umm the steering's lighter.

you mention over/understeer, cornering balance, turn in ect they think you're talking BS, or drive like a t**t, which i guess as they pootle along ( admiring the end of their bonnet ) i must seem.

even a garage can't take handling comments seriously to find a cracked antiroll bar link.

don't know where the primacy sits in the range, after reading reviews for focus/tyre combos i wanted eagle f1's? which were only about 15 quid each dearer, but they didn't have on stock, and give the normal, they know best, bs that these are fine unless you want to do trackdays.


front or rear?? from the fat bloke himself


The AA also agree:

New tyres to the front or rear?

Check the handbook first as some give vehicle specific advice.

Generally it's good practice to fit the best/newest tyres on the rear – in wet conditions, this favours understeer rather than oversteer.

So if you have the front tyres renewed it's best to have the rear ones moved to the front and the new tyres fitted to the rear.

Tyres with deep tread are less likely to puncture and it's more difficult to control a car with a damaged rear tyre.

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She would if they werent all rear drive cars

...and they weren't two different types of car.

I've never heard this before, and to be honest, I'm finding it hard to believe at all. If you keep the tyres at the recommended pressures for the weight of the car, and at the tread depths which the manufacturers specify, you'll find you won't suddenly spin out.

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it's having a difference of tread thats the problem, and given my difference in tyre, the quality of the compound, so the cheapies will stay on the front till their more like 2.5-3mm

see if Vicki can sway you in a FWD


i've only ever know this advice, and i don't know why, given a large difference in grip levels, you'd want the worse at the back

rotating to keep them the same is different

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