Fiat Coupe Club UK

Too much understeer !

Posted By: Sean_C

Too much understeer ! - 24/04/2013 20:50

On Monday I went to Snetterton for a track day. As I have suspected for a long time my car suffers from lots of understeer. So what is wrong ?
My set up is :

Bilstein shocks
FCSS lowering springs
Uprated front ARB ( Lancia Dedra ?)
22mm uprated rear ARB
Front upper strut brace
Toyo tyres

The lack of front end grip is so frustrating.

Opinions anybody ?

Sean
Posted By: Anonymous

Re: Too much understeer ! - 24/04/2013 21:26

I've heard on here mentioned that a front and rear uprated ARB counteract each other. I think its best just to have the uprated rear ARB without the front but i'll let someone with more experience comment as i may be wrong.
Posted By: deannn_20VT

Re: Too much understeer ! - 24/04/2013 21:40

General rule is that to reduce understeer on FWD cars you only fit stronger rear ARB.

As I told you on the day, practice trail braking, add to this 'heel and toe' to match engine revs to those of the transmision and it will pretty much sort your understeer and improve your exit from the corners. It did certainly help me in the corners a lot thou I got still a lot to improve.
Posted By: charlie_croker

Re: Too much understeer ! - 24/04/2013 21:40

I suspect its your uprated Front ARB, basic rule is on a RWD have an uprated Front ARB on FWD have an uprated Rear ARB.

My setup is almost the same as yours (I have Eibach springs and Poly Rear subframe bushes) and I have almost zero understeer.
Posted By: andyps

Re: Too much understeer ! - 24/04/2013 21:49

Stiff front end with a softer rear will always lead to understeer, FWD or RWD. If you want to reduce the understeer you need to change the stiffness balance to stiffen the rear compared to the front.

Or, reduce the weight percentage over the front substantially. That means making the rear heavier (probably not ideal!!) or reducing front weight. A carbon bonnet probably helps, about the only other idea I have had is to move the battery to the boot, and possibly the washer bottle too, but that won't make much difference.
Posted By: Per

Re: Too much understeer ! - 24/04/2013 23:11

Also check your toe, too much toe-in is fatal.
And add a bit of camber, that's done the most of it for me. I use H&R bolts set to -1.5deg.
Another thing that helped me was relocating the battery to the rear (yes you can certainly feel the difference).

All these mods adds up to a neutral, almost oversteering, Coupe! smile
Posted By: Hovedan

Re: Too much understeer ! - 25/04/2013 00:59

Camber is key.

Charlie I hope you don't drive that hard on public roads confused shocked
Posted By: charlie_croker

Re: Too much understeer ! - 25/04/2013 08:09

Originally Posted By: Hovedan
Camber is key.

Charlie I hope you don't drive that hard on public roads confused shocked


Dan, I drive like an old lady, smile I certainly would not be pushing things on the public highway.
Posted By: Hovedan

Re: Too much understeer ! - 25/04/2013 09:59

That's true, I remember the convoy to the tunbridge wells event the other year laugh
Posted By: gj88

Re: Too much understeer ! - 25/04/2013 10:17

Originally Posted By: deannn_20VT
As I told you on the day, practice trail braking, add to this 'heel and toe' to match engine revs to those of the transmision


How is heel and toe going to reduce understeer? Regardless, you want to have completed your down changes before you enter the corner, not upon entry. confused
Posted By: phil_20VT

Re: Too much understeer ! - 25/04/2013 15:57

Maybe driving style, slower in, faster out.
I think i found maybe being a little slower in but with an aggressive turn in, then power through the corner gradually increasing throttle to 100 % once the front wheels are straight. I find if I’m too fast in I always get uncomfortable understeer.
Try different techniques out for yourself, a slight lift or left foot jab on the breaks can transfer the weight of the car too.
Posted By: deannn_20VT

Re: Too much understeer ! - 25/04/2013 18:25

Not saying that heel and toe will reduce your understeer but trail braking will then add to it heel and toe and you have just competed nice smooth corner.
Posted By: Ferrarist

Re: Too much understeer ! - 25/04/2013 19:19

Why don't just use 2 second hand(if new too expensive)full race slick tyres......you'll be amazed how much difference can make no matter how good your Toyo is......
Coupe too heavy front end....
Posted By: Anonymous

Re: Too much understeer ! - 25/04/2013 19:59

Originally Posted By: gj88

How is heel and toe going to reduce understeer? Regardless, you want to have completed your down changes before you enter the corner, not upon entry. confused


Not driven on a track before? Accelerate flat out to the corner hard on the brakes - if you changed down before you'd wipe out your engine, since you want to turn in on the brakes you'll either change down during braking like Deannn said (heel toe) or change down in the corner (usually only done in error). If you don't heel and toe you'll create a braking reaction from the engine and the car will understeer more.

I second the 2 used slicks comment, save your decent road tyres and beat the hell out of some slicks. plenty of negative camber will help.
Posted By: andyps

Re: Too much understeer ! - 06/06/2013 14:37

Originally Posted By: Per
Also check your toe, too much toe-in is fatal.
And add a bit of camber, that's done the most of it for me. I use H&R bolts set to -1.5deg.
Another thing that helped me was relocating the battery to the rear (yes you can certainly feel the difference).

All these mods adds up to a neutral, almost oversteering, Coupe! smile


Any pictures of the way you did the battery move? I know it is pretty logical in some ways but I have thought about this to help balance the weight slightly.
Posted By: gj88

Re: Too much understeer ! - 06/06/2013 15:15

Originally Posted By: sediciRich
Originally Posted By: gj88

How is heel and toe going to reduce understeer? Regardless, you want to have completed your down changes before you enter the corner, not upon entry. confused


Not driven on a track before? Accelerate flat out to the corner hard on the brakes - if you changed down before you'd wipe out your engine, since you want to turn in on the brakes you'll either change down during braking like Deannn said (heel toe) or change down in the corner (usually only done in error). If you don't heel and toe you'll create a braking reaction from the engine and the car will understeer more.


I'm aware of what heel and toe is and how you use it. I never drive without using it. As I said, complete your changes before entry to the corner i.e. under braking but you've seemed to back me up with your comments.
Posted By: Per

Re: Too much understeer ! - 06/06/2013 23:17

Originally Posted By: andyps
Any pictures of the way you did the battery move? I know it is pretty logical in some ways but I have thought about this to help balance the weight slightly.

I did a guide on here but I can't find it. The pics for it was here..;
http://sfk.ibk.se/depa/index.php?sub=viewcar&car_no=123

A few completing, later, pics here:
http://sfk.ibk.se/forum/showthread.php?5311-Coupe-projekt-batteriflytt&p=134638#post134638
Posted By: andyps

Re: Too much understeer ! - 07/06/2013 12:24

Thanks Per - interesting that you have used the wheel well, for balance the weight of the wheel could also be helpful!!
Posted By: Nigel

Re: Too much understeer ! - 08/06/2013 17:27

Sean - I may have the answer for you - a 24mm rear ARB - just about to come off my car, as it's a bit excessive with a stock front ARB - going back to my 23mm Novitec
Posted By: Anonymous

Re: Too much understeer ! - 09/06/2013 09:43

Sean, like others I would say add some negative camber, sticky tyres (I recommend the federal Rsr as a cheap option) and work on your driving style.
Posted By: Anonymous

Re: Too much understeer ! - 10/06/2013 06:49

Slightly off topic but everyone should get on at least one track day. The best way to safely learn how your car reacts when you corner too rapidly. My cars pretty much standard bar lowered springs and was slightly suprised by the amount of understeer a near OE Coupe has designed into it (though that is probably safer for road use). I'm sure there would be fewer accidents if everyone learnt more about how their vehicles react under speed in this way....
Posted By: Per

Re: Too much understeer ! - 10/06/2013 11:22

Track days are indeed both good and fun.
And obviously a terrific way of validating your recent mods!

Originally Posted By: andyps
Thanks Per - interesting that you have used the wheel well, for balance the weight of the wheel could also be helpful!!

No problems! Well, I want as little weigth as possible (with sustained comforts that is) so away with heavy spare wheel etc. Dead weight, also - 1. The battery sits much lower than otherwise, and 2. A flat untouched luggage space with sustained flat floor, i.e. How Fiat Would've Done It.
smile
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