Under steer advice wanted

[cliffy858]

Hi, I did my second track day with my 172 yesterday at brands since I rebuilt and modified the car. The car was going well but because it was damp and wet yesterday it suffered really bad from under steer that wasn't there before I did the upgrades. I was extremely lucky to win 30 mins tuition with touring car driver Tom Chiltern who was great and taught me how to load the front and make it grip and help turn in and to control oversteer. By the end of the day I was performing some decent controlled slides. He recommend raising the rear or dropping the front of the car.
I have set the car up to have a 15mm rake, measured from the sill, spax springs at lowest settings on rear and the front coil overs wound up to get the 15mm rake.
Damper settings are 10 clicks out of a possible 16 on the stiffer side
2 deg neg camber on front, 1.7 deg neg camber rear (using shims)
0 toe
tyre pressure are 28 front and 26 rear (hot)
Toyo 888's
Pure Motorsport Strut brace and top mounts
fully polybushed
stripped and lightened

Before the upgrades it was running standard worn out suspension, apex lowering springs, 1.5 neg camber front, standard 1.2 neg camber rear, budget tyres and although it didn't have as much overall grip it was was better balanced and inclined to oversteer.

My questions are what should I change first, raise the rear? Drop the front? How low on the front should I go? How important is the 15mm rake? More front camber?(but from what I've read that will make it worse in the wet). Can this be dialled out with damper settings although the spax kit only have rebound damping. I'm not looking for a race car just something to have fun with but the under steer is so frustrating. The car is not road legal and will only be used on track.

here are some photos to compare heights from before and after. Sorry there not the best but all I have.



Any help or advice will be appreciated before I take tom chilterns advice and wind up the rear, thanks.

 

[ilovewilly]

How stiff is the front? Have you done anything to the rear ARB wise?

 

[cliffy858]

It doesn't feel stiff at all. No ARB on the rear.

 

[ilovewilly]

What lb springs are they?

 

[Tony Hunter]

Toms right.

Without knowing a million other factors, the easiest thing to do is to raise the rear, these cars like rake. I would suggest getting it corner weighted first, then go from there. Mark Fish is down your way and he'll do a good job for you.

 

[cliffy858]

Thanks tony, what would recommend, 10 or 20mm? I was going to wait until I had a cage fitted until I had corner weighted. I would also like to have a go myself using the bathroom scales method not because I'm tight, it's just that I like to learn new stuff. Has anyone tried diy corner weighting?

 

[cliffy858]

I don't know what lb springs they are, there standard with the spax rsx kit. Can you buy different weight springs for that kit. It's not the new full coilover kit they do now anyway. Do you think a rear ARB help then?

 

[Martin.]

A rear ARB is a quick way to decrease under steer.

 

[cliffy858]

Looks like that's my next purchase then, thanks.

 

[Tony Hunter]

You would notice a big difference at 10mm, don't go more than that at first. Bathroom scales forget it. get it done properly or not at all.
Raise rear tyre pressure would help too, but do one thing at a time, then try it.

 

[underdog]

I would try and improve the grip on the front before you do work that will reduce grip on the rear. What about more neg front camber? Maybe -3 ? Toe out on front? Experiment with disengaging front arb if springs are to stiff on front? If these fail then adjust the rear last resort I'd say

 

[Fred@BTM]

rear looks too low to me! That will just snap and go sideways i reckon

 

[Tony Hunter]

I would try and improve the grip on the front before you do work that will reduce grip on the rear. What about more neg front camber? Maybe -3 ? Toe out on front? Experiment with disengaging front arb if springs are to stiff on front? If these fail then adjust the rear last resort I'd say

What, we have all said that the rear is too low, you can see that from the pic, so this needs sorting first.

 

[underdog]

What, we have all said that the rear is too low, you can see that from the pic, so this needs sorting first.

couldnt see pics on my phone so just went on the fact he had 15mm rake. while im at in my short time around here iv come to the conclusion your a miserable old man who thinks because hes a amatuer racer no one else opinion matters.

 

[Tony Hunter]

Lol,not at all. But he needs to do the basic things first before doing anything else.

Everybody's opinion matters if it's helpful and not misguided.

Anyway, you're from Wales, say no more.

 

[underdog]

Lol,not at all. But he needs to do the basic things first before doing anything else.

Everybody's opinion matters if it's helpful and not misguided.

Anyway, you're from Wales, say no more.

Gotta love the welsh aye. my intention was not to misguide so thats why i put ? marks after my suggestions.now i can see the pics on my pc but he did ask for suggestions before he raises the rear. so thats what i gave. im all for rake though so not dissagreeing with that.
to be honest the only reason i come on this forum is because theres more people with technical knowledge on handling and track cars than on my usual ford site.i dont even own a clio but love to learn and discuss handling.i dont know it all but its my favourite subject with cars to be honest so whatever i can learn on here is a bonus for me. just try and be considerate to people who are not as lucky as you to race but still love the track and cars. maybe iv got you wrong? maybe your not grumpy as you did put a wink in your last post?

 

[Tony Hunter]

As you say, you don't own a Clio, he's got to get the balance of the car correct before he starts messing with it.

And yes I am grumpy, fkn grumpy.

 

[underdog]

how low is too low on the front of a clio before the roll centre is to low? front looks very low if on standard ball joints. if roll centre goes to low front end goes horrible

 

[underdog]

As you say, you don't own a Clio, he's got to get the balance of the car correct before he starts messing with it.

And yes I am grumpy, fkn grumpy.

does it count if my brother has had 2 a 182 and 172 cup? am i still allowed on your forum tony? please?

 

[Tony Hunter]

Mr Northloop on here, would be able to answer that question accurately. Remember, I'm just an amateur racer.

 

[cliffy858]

Thanks for the replies guys, I will raise the rear 10mm for the next outing before I buy a rear ARB. It would be more like the same rake angle it had before. It's also free I am very interested in the answer to "how low is too low for the front" because would it be better to lower the front rather than raise the rear keeping the center of gravity lower?

 

[Tony Hunter]

Not necessarily, raise the rear don't lower the front. Please.

 

[underdog]

Thanks for the replies guys, I will raise the rear 10mm for the next outing before I buy a rear ARB. It would be more like the same rake angle it had before. It's also free I am very interested in the answer to "how low is too low for the front" because would it be better to lower the front rather than raise the rear keeping the center of gravity lower?

lower centre of gravity is the what we all want but to low messes up the roll centre. its quite complicated to explain roll centre so just google it and look at pics to show how its calculated. its based around the angle of your lower arm. it should always be slightly tilted down from its mounting point on the subframe to the outer ball joint. if you go too low its facingup and this will kill the front end. other than a roll centre underground you will be relying on the strenthgh of the spring to support sideways loads rather than the forces being transmitted to subframe. in short its really bad for handling. yours looks to me like it may be near the point of too low but check you lower arm angle. lower isnt always better

 

[Cub.]

does it count if my brother has had 2 a 182 and 172 cup? am i still allowed on your forum tony? please?

FLOL - dry your eyes.
NorthloopCup - Mark, the OP could probably do with your advice

 

[cliffy858]

I have read a bit on roll center before when I was researching suspension setup and to be honest I was completely confused but you explained it much better underdog, Thanks.

Cheers tony, the rears going up!

I might post a photo of the wishbones tomorrow if you guys care to share your opinions.

 

[underdog]

I have read a bit on roll center before when I was researching suspension setup and to be honest I was completely confused but you explained it much better underdog, Thanks.

Cheers tony, the rears going up!

I might post a photo of the wishbones tomorrow if you guys care to share your opinions.

no problem. have a look at this link for a better understanding. also the pics tell a better story than i can describe.

http://www.balancemotorsport.co.uk/main.asp?sitepages=suspension geometry

 

[cliffy858]

Interesting read, thanks.

 

[Tony Hunter]

does it count if my brother has had 2 a 182 and 172 cup? am i still allowed on your forum tony? please?

Lol yes, but when I meet you, I'm going to poke you in the eye.

 

[underdog]

Lol yes, but when I meet you, I'm going to poke you in the eye.

i see it going like this lol

http://www.youtube.com/watch?v=ScGPRsHSkaE

 

[Tony Hunter]

Classic.

 

[cliffy858]

Here you go, some shots of the front wishbones, my drives a bit pissed so I guess that's why one is higher than the other.

 

[Tony Hunter]

That is low, have you had the driveshafts knock on the inner bodywork by any chance?

 

[cliffy858]

No, I had no problems at all. I don't remember it being that low when I set it up. Maybe the suspension has settled? Am I right in saying that the top of the wishbones should be horizontal?

 

[Ph1 Tom]

It's low on the front but doesn't look too bad. Roll centre kit would help out so next time a group buy is on I'd jump on that.

In the pics the rear is too low as Tony has said. Just going off the photo I'd say raising the back about 10mm is a good idea. Then try it.

Get it corner weighted to keep it balanced.

I run a bit of rake and an ARB and it's very balanced, it will oversteer if you want it to. The ARB is on soft, I wouldn't run it on hard.

 

[underdog]

Here you go, some shots of the front wishbones, my drives a bit pissed so I guess that's why one is higher than the other.
View attachment 108161View attachment 108160

i think a big part of your problem is there in the pics. the arms are facing up.the shape of the arms makes it look worse but the point you should concern yourself with is think of a straight line from the centre of the subframe mounting bolt out to the ball joint.the very worst you want is parrallel to floor but for me id go for a slight tilt down to ball joint. the car will never handle well on the front until you correct this by raising the car or a roll centre correction kit. its free to jack the ride height up though so maybe thats your best option if your on a budget.

you need the car on a level ground though to make an accurate assesment of how much to raise it..

 

[underdog]

Classic.

shall we shake hands and be friends? i dont fancy a poke in the eye to be honest :cheers:

 

[NorthloopCup]

Here you go, some shots of the front wishbones, my drives a bit pissed so I guess that's why one is higher than the other.
View attachment 108161View attachment 108160

At a guess I'd say that's lowered about 45mm over standard. Anything over 20mm lowering compromises the roll centres BUT the chassis on the clios is very good at absorbing this, especially if the dampers are valved correctly and it's not under sprung.

First off you need to know what the spring rates are. I'd say that the rear is too soft which is causing the front end to push on, and the front is too soft so it's rolling over on itself. Set the rear to full stiff and you may even find you need to do that on the fronts as well. Depends on how well damped it is, and of course spring rates.

Run toe out up front - around 10 minutes maximum. I can translate that to mm if you want so let me know. Run toe out on the rear as well, but we are talking about 5 mins max as it will make the rear quite lively. It will however aid your turn in massively. You could set it to parallel on the rear too.

You need more camber up front - 2.5-3 degrees negative. You need more castor up front, so fit cup wishbones. You might even benefit from running a cup subframe and increasing the front track width - increased front end grip. Can't remember how much camber you said is at the rear.

Anything I've missed? Get the basics in place first.

^^^^^^All of that stuff listed above is tried and tested over months/years of faffing.
Cub. Tony Hunter

 

[Cub.]

And you said you wouldn't post

Sharing is caring x

 

[underdog]

At a guess I'd say that's lowered about 45mm over standard. Anything over 20mm lowering compromises the roll centres BUT the chassis on the clios is very good at absorbing this, especially if the dampers are valved correctly and it's not under sprung.

First off you need to know what the spring rates are. I'd say that the rear is too soft which is causing the front end to push on, and the front is too soft so it's rolling over on itself. Set the rear to full stiff and you may even find you need to do that on the fronts as well. Depends on how well damped it is, and of course spring rates.

Run toe out up front - around 10 minutes maximum. I can translate that to mm if you want so let me know. Run toe out on the rear as well, but we are talking about 5 mins max as it will make the rear quite lively. It will however aid your turn in massively. You could set it to parallel on the rear too.

You need more camber up front - 2.5-3 degrees negative. You need more castor up front, so fit cup wishbones. You might even benefit from running a cup subframe and increasing the front track width - increased front end grip. Can't remember how much camber you said is at the rear.

Anything I've missed? Get the basics in place first.

^^^^^^All of that stuff listed above is tried and tested over months/years of faffing.
@Cub. @Tony Hunter

how does toe minutes translate in degrees? i only work in degrees lol.

 

[McGherkin]

1 Degree = 60 Minutes.