Huge understeer

Huge understeer

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Discussion

anonymous-user

Original Poster:

61 months

Tuesday 3rd January 2012
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As per title, in any conditions that are slightly damp the mini likes going straight even when I turn.
I have good tyres and I'm not taking a 30 at 60 but it is crazy, any cures for this people?

Mini1275

11,098 posts

189 months

Tuesday 3rd January 2012
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Learn left foot braking...



hehe


Seriously though, what tyre pressure are you running?. Could they be too high (on the front)?.

anonymous-user

Original Poster:

61 months

Tuesday 3rd January 2012
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I can't remember off the top of my head but they were checked recently.

rawkyjnr

259 posts

178 months

Tuesday 3rd January 2012
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Them being checked doesnt matter an awful lot. Most garages these days won't know about what your Mini needs best and will have probably put 40psi in the front tyres like they would on a modern hatch...

Next time you fill up with petrol, pay the 20p to check the pressures yourself, I am running c.28psi on the front and 30 on the rear....

anonymous-user

Original Poster:

61 months

Tuesday 3rd January 2012
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I have 12inch tyres, know what PSI I'd need?
Garage did say it was okay but I'll double check like you said.

1point7bar

1,305 posts

155 months

Tuesday 3rd January 2012
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Garage pressure gauges get horribly abused and often read inaccurately.
Buy a decent one.
Tyre pressures are a personal taste thing.
The higher the pressure the more feedback you get at the steering wheel, but less grip (smaller contact patch) and longer to get heat into them.
The lower the pressure the larger the contact patch but obviously the feel can become really jellylike if you go too low and they will overheat on long, fast journeys.
Minis suffer understeer if power is used mid corner. Try to seperate cornering from accelerating.

Furyblade_Lee

4,112 posts

231 months

Tuesday 3rd January 2012
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I once had a trackday in France ruined by a local pressure gauge reading 30psi but when I got home with an horrific handling car realising it was closer to 50 than 30...

Halfords do half decent electronic ones for £10. IF you find they are way too high, as in 35 or more psi, drop them back about 28 all round and try them. If pressure is your problem, and you have the time and inclination, have a play by dropping them to 25 and then raising them up into the 30's again. You will get a "feel" for what tyre pressures do then. Obviously, don't drive like a donut if you have wrong pressures in, but I am sure you know what I am getting at. You will feel with low pressure that the car is soft, comfy, bouncy and when you turn the steering you will feel "squidge" in the steering, like you can feel the rims moving immediately but the tyres not. With too much pressure, the car will feel harder, skittish over bumps, a few crashes and bangs and the steering will feel very light. And the car will probobly wheelspin far to easy, and understeer.. Find yourself a good compromise and balance.

anonymous-user

Original Poster:

61 months

Tuesday 3rd January 2012
quotequote all
I think my granddad has one of those halfords ones. I'll give him a call and check on the weekend.

haynes

370 posts

249 months

Thursday 5th January 2012
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The suspension on the front end may be too stiff, ie if the rubber cones are very old and become hard and compressed. Do you have adjustable shocks, are these set too high at the front?

To reduce understeer you need to increase grip at the front, to increase grip you need to soften the suspension at that end so theres greater weight transfer on to the tyres.

anonymous-user

Original Poster:

61 months

Thursday 5th January 2012
quotequote all
haynes said:
The suspension on the front end may be too stiff, ie if the rubber cones are very old and become hard and compressed. Do you have adjustable shocks, are these set too high at the front?

To reduce understeer you need to increase grip at the front, to increase grip you need to soften the suspension at that end so theres greater weight transfer on to the tyres.
Its adjustable suspension and its quite stiff.
As low as it can go without scraping though.

DanGT

753 posts

233 months

Thursday 5th January 2012
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There are 3 things that effect front grip suspention shocks springs, suspention set up wheel camber tow in etc and tires. If the Tires has hard rubber (Some times just down to age) or has littel tred left and the road is wet (Less tred gives you more grip in the dry).

anonymous-user

Original Poster:

61 months

Thursday 5th January 2012
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They are newish tyres but to be honest I've been looking at those semi slick yokos for a while now.

haynes

370 posts

249 months

Thursday 5th January 2012
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PSBuckshot said:
Its adjustable suspension and its quite stiff.
As low as it can go without scraping though.
Is it so low its hitting the bump stops? That'll stop it going around corners!

After checking you have sufficient clearance on the bump stops, You could try softening the front shocks, see if that cures it.

Just re-read your OP, you say it heppens when its damp, does that mean you can corner really really hard in the dry no problems?



Edited by haynes on Thursday 5th January 13:25

anonymous-user

Original Poster:

61 months

Thursday 5th January 2012
quotequote all
haynes said:
Is it so low its hitting the bump stops? That'll stop it going around corners!

After checking you have sufficient clearance on the bump stops, You could try softening the front shocks, see if that cures it.
Its all good.
Shocks could be too stiff though, I'll check sometime soon.

haynes

370 posts

249 months

Thursday 5th January 2012
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good luck and hope you get it all sorted, a 75bhp mini that handles well and goes round corners like its on rails is far far more fun that one with 120bhp that corners like an oil tanker.

Reminds me of the top gear India special, Hammond was grinning like a loon in his min, well until they trashed it.

nick1275

1,272 posts

177 months

Thursday 5th January 2012
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PSBuckshot said:
They are newish tyres but to be honest I've been looking at those semi slick yokos for a while now.
unless your tracking it i wouldnt bother to much, ive got them on my car. there great on track, but do take some warming up for road use, driving them in the wet is interesting too

anonymous-user

Original Poster:

61 months

Thursday 5th January 2012
quotequote all
nick1275 said:
unless your tracking it i wouldnt bother to much, ive got them on my car. there great on track, but do take some warming up for road use, driving them in the wet is interesting too
I've just saw your car.
It looks like my car's brother hehe

Cooperman

4,428 posts

257 months

Thursday 5th January 2012
quotequote all
Try raising the car back up to standard ride height all round, softening off the front dampers and having the suspension tracked both front & rear. The rear should toe-in between 1 mm & 2 mm, front should toe-out 1 mm.
Then set the tyre pressures to 30 psi all round and try it.
With the suspension set low the suspension can't work properly as there is too little suspension travel available.
What tyres are you running?

anonymous-user

Original Poster:

61 months

Thursday 5th January 2012
quotequote all
Yoko asomething.
Do you know what the standard ride height is?

Cooperman

4,428 posts

257 months

Thursday 5th January 2012
quotequote all
Don't laugh, but I work on three fingers between the top of the tyre and the bottom of the wheel arch front & rear! It seems to work.
For road use a lowered Mini does suffer from lack of suspension travel. It really doesn't improve the quality of the drive or even the overall roadholding. It's the suspension settings which are critical.
To be more specific, the best settings for the road, with standard ride height, are:

Front: 1 mm toe-out, 3 degrees caster, 1 to 1.5 degrees negative camber
Rear: 1 mm to 2 mm toe-in, zero to -0.5 degrees negative camber.
Damping: Slightly harder at the front than the back.

Tyres: No wider than a 165 section with presure at around 30 psi all round.