Help from the track day/race guys here.


S

Struggle

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Jun 3, 2009
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110
Hi,

Right so little background.

Me and my mate run an EK4 track car as a budget build.

Car has S80 box, good coileys, rear EK9 arb, rear asr brace and full front ITR subframe and rack setup.

Last year the car had a very good ballence of front and rear grip.

This year we have introduced the front ITR subframe along with ARB and rack.

The car now understeers loads. It takes a massive flick to get the back going.

We run r888 in 225/45/15 all round with 21psi front and 20 back when HOT. (this equates to 16psi front 18psi back when cold)

the setup is
front camber 3ish
toe out total 10 minutes

rear camber 1
rear toe in total 10 minutes.

The back grips really well but my question is how can we get more grip on the front? and why have we lost front grip or gained from last year? is the ITR front arb thicker than the ek4 one??

I did think about an air dam on the front but that wouldn't help with corners and would take a little straight line speed. Im looking for an easy answer to this without removing rear grip.

just to note. we haven't used front camber arms as any we have used have hit the top turrets and started to bend so we didn't go down that route as it would have ruined a good track day. (kinda tempted to cut and weld them shorter to get to 4 degrees neg.

anyway any advice would be lovely.

ed
 
Have you tried playing with the suspension a bit? Try to soften up the front and see if that helps? Initially just changing the damping rate should give you an idea, if that works then softer springs. I dont know whether ek4 arb is less stiff than dc2 arb, but if that is the case it certainly would decrease front end grip.
 
id try pulling the camber back on the front to like 2degrees, you need to see the tyre wear to judge really.
I know you don't want to remove rear grip but what if the net gain is a faster laptime?
I've found simply adding like 2-3psi hot in/out of the rear tyres makes a massive difference to the car.
 
Oifovo
The front damper is only on 3 clicks and is pretty soft. The back is already pretty hard. I'd definitely say the rear is a lot stiffer than the front. I run 10k front 8k back and with no weight over the rear it's a lot tougher. An uprated rear arb would be a costly way of testing out the theory.

Jessy
Less camber? I'd have thought more would have given us more grip. I guess I could add some rear end Psi's in the tires and see what happens. I just loved the rear grip and wanted some front grip without aero.

Cheers for the help BTW.
 
Remove the ITR arb and refit the ek4 one seems the obvious way?
Or.can the ek4 one not fit the ITR subframe?
 
Is there a reason why your tyre pressures are so low?

I always use the guide of coming in somewhere with between 28 and 32psi when HOT for the tyres was about right. 21psi hot seems really low
 
I don't think it will fit the subframe Murray. We chucked the old one anyway so I couldn't compare now.

I've always thought that lower tire pressures means more grip. 28 to me sounds really high but maybe I need to give it a go. No idea where to look for advice on tire pressures tbh. I'm just going off past experiences with cars.
 
Struggle said:
Oifovo
The front damper is only on 3 clicks and is pretty soft. The back is already pretty hard. I'd definitely say the rear is a lot stiffer than the front. I run 10k front 8k back and with no weight over the rear it's a lot tougher. An uprated rear arb would be a costly way of testing out the theory.

Jessy
Less camber? I'd have thought more would have given us more grip. I guess I could add some rear end Psi's in the tires and see what happens. I just loved the rear grip and wanted some front grip without aero.

Cheers for the help BTW.
Click to expand...

If your not leaning into the whole width of the tyre whilst cornering then you've got too much camber. I've recently pulled my camber back since swapping from 195s to 225s.
I'm agreed the pressures are abit low aswell, I tend to run about 26-28 hot front and rear and then balance the oversteer out with less rear tyre pressure, tends to work for me most times
 
jesse888 said:
If your not leaning into the whole width of the tyre whilst cornering then you've got too much camber. I've recently pulled my camber back since swapping from 195s to 225s.
I'm agreed the pressures are abit low aswell, I tend to run about 26-28 hot front and rear and then balance the oversteer out with less rear tyre pressure, tends to work for me most times
Click to expand...


Also good advice ^^

I found that with too low a tyre pressure, the car would move about on the side walls, steering would be heavy/not sharp and you will also loose speed with lower tyre pressures

I would say between 28-30 hot depending on the tyre would be about right but a better way to judge this would be to use a temperature gun and check the temperature across the width of the tyre. The general rule would be if its too warm in the middle of the tyre then lower the pressure a bit, if the outside and inside of the tyre are warmer then the tyre is under-inflated and needs more air


Also when you mention about the thicker front ARB, stiffening the front in relation to the rear will cause more understeer and you can change that by either stiffening up the rear more, adding a few psi to the rear tyres or changing camber or toe settings
 
Having put a bigger/thicker ARB on, you have caused it to under steer. Either remove it for a smaller one or start stiffening up the rear, so it makes the front dig. Also what rake are you running?
 
I did a track day by accident with 16psi last year - it was absolutely horrible and the worst time ive had on track - car just didn't behave how I wanted it too - I always run 28-26 hot too
 
Is an ITR front ARB ticker than an EK4 one? I'm not sure.

Rake is good. 5 to 10mm lower at the front. Really the way its setup with a relatively soft front end and a pretty solid rear is SHOULD be oversteering.

As for tire pressure i WILL give it a go. However i tend to disagree with what people are saying. Last track day we did (last year before changes) we set out at 22psi all round. Car handled well and was ballenced. After 5 or so laps the front tires had gained loads of heat and the car understeered massively. Pulled into the pits and found the tires at 30ish psi. Dropped them back down to 22 and it ballenced the car out again.

Don't forget these cars are pretty light. My dad runs an Ariel Atom and they reccoment 16psi all round.

I'm not saying you guys are wrong i will give it a go but generally i've found less pressure means more grip. And as tires have gained heat so they have lost grip.

Are people running same psi all round in the tires? no difference between front and back?
 
Last year on track i ran spec2's 36psi hot all round. I had immense front grip, could push into corners at 90mph with zero understeer however i couldnt get any grip in the rear and felt unstable. This time round on track going to lower the rear tyre pressure and play around with it till its perfect as got 3 hours of testing!
 
Right bit of an update.

Checked the breaks last night as they feel aweful from the track day. Think the pads and disks are nailed.

Anyway took a few pictures of the tyre wear. If you look at the tyre from above and divide the tread across the tyre into 4. With 1 being the outside tread (wheel face side) and 4 being the very inside tread (coilover side) the majority of the wear is in section 2 and then section 3. This to me actually shows the signs of wear similar to that of an OVER inflated tyre not underinflated. Sections 1 and section 4 are actually not very worn at all. I'd say maybe 20-30% worn whereas the centres are way over 50% worn. The tyre pictured was measuring 16PSI cold and 21PSI hot on the track day.

Pictures are below. Like i said previously i WILL try and run 26PSI front and 30PSI rear to make the car ballenced and fall inside what toyo actually reccomend. I will also e-mail Toyo with the pictures and see what they come back with.

So what do people think?









 
I have found that semi slick tyres, and esp the R888 Design tends to wear like that on the front of the car. I guess that when you are going through a corner and putting the power down on a FWD car with a diff, the tread deflects the direction the force is being applied and makes it wear like that

With my 15" full slicks I was coming in with probably 32psi and they have very slightly wore more in the middle but not much. 32psi is def a bit much and I'm going to aim for 26-28 hot next time out and see what it feels like

21psi hot would definitely not be too much for the weight of your car imo
 
Just a theory here,
Too much camber and too little pressure has resulted in that tyre wear.
Doesn't look like your even catching the outer edge of the tyre in these pics.
I'd pull like a whole degree off the front and correct the pressures.
 
The cars running like 2 1/3 degree neg front camber. Thats not aggressive at all. I'd be saying it needs more to give it more grip. To add to this we don't have front camber adjustment as we found every kit we fitted collided with the top turret and started to bend the arm. We went back to OEM to rule out these issues. CBA messing around on a track day fixing broken stuff.

SPek9 i know what your saying. I'm just curious as to the solution and thinking behind it. Are you saying that 21PSI is far too low? Have you tried really low pressures?

At the end of the day I'm going to play with pressures to ballence the car. Run probably 4PSI more in the rears than fronts HOWEVER i really need to know where to aim with pressures.

I've e-mailed big boss man at Toyo with pictures and info and questions so it'll be interesting to see what he comes back with.

Just for info for you guys I've come from drifting. And in drifting the lower the pressures the more the cars grip. The Driftworks AE86 actually runs just 7PSI cold in the rears to get grip. So this is why my experiance is questioning the reasons behind high pressures for more grip.


EDIT: what settups are you guys running then? as in geo, pressures, tire sizes, spring rates, ARB's ETC???

Thanks
 
I have tried about 24 PSI warm and without power steering it was seriously hard to turn, I also felt like the car wouldn't change direction as quick with really low pressures. Lower pressures will improve grip in a straight line in a FWD car but I can't see anything lower than about 26 PSI hot doing much for a fwd Honda on a circuit


Really as low as 7 psi!! I have seen the driftworks AE86 a few times here at the Irish drift championship and its impressive but you would think that the tyre would come off the wheel with that little pressure and so much power going sideways! I try to get to as many rounds of the IDC as I can and my mate competes in the NI drift series. Great form of motorsport imo and its only going to get bigger



Setup wise I use OEM front and rear ARB's, 16k spring rates, about - 2.5 front, -1.5 rear camber and zero toe to keep things well behaved, my local circuit is quite fast with 1 x 120mph corner and not too twisty so I don't want the rear to be too lively. For a more technical circuit I would probably add a small amount of toe out on the rear
 
You mention having 3 degrees camber upfront in your first post, now it's about 2 and 1/3.
 
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