Understeer

[tomtikki]

So I've fitted Tein springs all round and replaced the front sway bar with a 22mm solid chromemoly jobbie, still have the stock rear (11mm i think on the '89?) including it's probably original shagged bushes but I'm still getting understeer out on the track (Hampton's) and the occasional roundabout...
Tyres are MY-01's by bridgestone all round.

I've reached the limit of my knowledge on the subject, what's next?
My new sway bar isn't adjustable so perhaps adjustable endlinks?
(Will WOF inspectors be ok with them I wonder??)

Cheers in advance!
-Please note that I'm a cheap bastard on a limited budget so expensive options will be interesting reading but probably not useful.

[Furai]

Wha tyre pressure are you running and what kind of shocks?

[Angreal]

(Will WOF inspectors be ok with them I wonder??)

Should be. The VTNZ WOF guys don't do a road test so they'll never pick it up...

[Mr. Shine]

A larger front swaybar will induce understeer.

[Keith Jones]

Assuming tyre pressures are OK, understeer normally means the front end is too stiff. Uprating your front sway bar to 22mm will increase the tendancy to understeer, but spring rates are also in the equation. What rates are the Teins?

[Keith Jones]

This guide is useful for sorting out handling issues.
You'll need to download the .pdf to see it.

[tomtikki]

Assuming tyre pressures are OK, understeer normally means the front end is too stiff. Uprating your front sway bar to 22mm will increase the tendancy to understeer, but spring rates are also in the equation. What rates are the Teins?

Ahh, crap! I could have sworn i read/told it was stiff front bar will induce oversteer, stiff rear will induce understeer!
(stiff front bar *chuckle*)

Springs are S tech's, 235/168lbs, I can't remember what to divide that by to make it in kg's...

Have tyres at 36psi on the road and I try to use that as my when hot temp on the track too.

[tomtikki]

This guide is useful for sorting out handling issues.
You'll need to download the .pdf to see it.

Ha! The basic handling guide for dummies. Perfect for the caveman track hacker.
Cheers Keith.

I actually have a 16mm rear swaybar (came as a set) that i'll put on and see what that does -i hadn't even bothered to put it on coz (im lazy) & i''d been told it would only make the understeer worse! -Its hard to know whose recommendation/opinion to trust and don't even get me started on the conflicting info on the interweb!

[Keith Jones]

Spring rate ratio looks OK (a bit towards the oversteer end if anything).
What are the tyres - make and size?
36psi hot seems a bit high, particularly if you are running a low profile tyre. Does the car feel loose through the 2/3 corner complex (or anywhere else)?

[Mr. Shine]

I actually have a 16mm rear swaybar (came as a set) that i'll put on and see what that does -i hadn't even bothered to put it on coz (im lazy) & i''d been told it would only make the understeer worse! -Its hard to know whose recommendation/opinion to trust and don't even get me started on the conflicting info on the interweb!

Stiffening it up makes it less compliant with the driving surface, so bumps will be felt harder and effect the handling more, so stiffer = more prone to losing grip, but sharper response for handling purpose.

[tomtikki]

Spring rate ratio looks OK (a bit towards the oversteer end if anything).
What are the tyres - make and size?
36psi hot seems a bit high, particularly if you are running a low profile tyre. Does the car feel loose through the 2/3 corner complex (or anywhere else)?

Bridgestone MY-01, 205/45/16. All even, all with about 7mm.
Hmmm, not loose in my opinion but don't have much experience to give you an accurate discription.
All I can say is through the S bends she feels good, the hairpin after that it feels like I'm in a front wheel drive.
The 'corkscrew' and the big sweeper before the straight I can feel the front washing out a little aswell but perhaps I'm just asking to much?!

Oh and I know when the end of the session is coming coz my tyres usually give up about the lap before cooldown and get some great oversteer - usually after the straight which is a sweet corner to 'drift' through. If a little worrying the first time!

[Angreal]

Too much entry speed? Yep... I have not much to offer in terms of knowledge regarding this conversation

[Keith Jones]

I'd suggest dropping your tyres pressures to 32psi hot and seeing if that is any better.
If I am doing training at Hampton the next time you are down there I'd be happy to jump in the car with you.

[Donovan]

I have been playing around with my suspension settings a lot on the last couple of track days. I take it you don't have coilovers in your car with adjustable damping, if not, get some. Makes life so much more easier for dialing out understeer/oversteer, given that the balance is not way off the mark to start off with.

On Wednesday the difference between how the car handled in the morning, and how it handled midday was like chalk and cheese, and it was just in the changing of the damper settings, I didn't touch anything else. I guess this is where the joy of these things come in, cause it is just a simple adjustment to stiffen up or soften up an end of a car without having to fiddle around with other things, once the suspension settings are sorted, then can start fine tuning other things.

In the morning the car was a complete nightmare to drive, and I came close so many to wiping out it wasn't funny, in fact it was pretty scary, it would understeer, then change to oversteer part way thru a corner (no it wasn't power oversteer ), it would even try to spit me off into the wall along the straight if I took my foot off the gas. Fiddling with the settings got the oversteer dialed out, but still had cronic understeer, and then just stiffing up the rear just a little bit more and leaving the front alone made the turn in crisp and clean, with just a bit of oversteer poking it's head in part way thru the corner, and I reckon I could have got rid of that if my god damn brakes didn't give up on me again.

As for the tyre pressure, I was running 22psi cold, and that would get me up to about 30-31psi which seems to be about right for my tyres, which are Toyo R888 205/40/17

[WideOpenThrottle]

My sugggestions based on what i have done to my car...15 x 7 wheels with Toyo R888's 205/50/15 at 30-36 psi....lowered on Koni sport shocks set on firm with King springs...wheel alighnment somewhere between road & track...1800 NB front brakes with EBC race pads all round...manual steering rack...no issues at all at Hampton apart from occaisional lack of concentration! .

And the bits that made my car go faster was the race seat & 5 point harness...youd be amazed what these two items gives to your driving confidence. {thanks Keith for so many parts & guidence along my journey}.

[Mad Kiwi]

Hi Tomtiki

I agree with the others.

More sway bar decreases overall traction at that end, so by adding more rear bar you will be taking away steady state grip from the rear...i.e reducing rear grip and adding "balance" to the car.

Stiff bars in general help turn in etc but if you ever want to balance front to rear you add bar to reduce cornering grip but dont forget you could conversley reduce front bar to increase front grip....

Having just fitted 22mm fr and 16 mm rear to Wee1 I have to say the difference is amazing (incredible turn in) and the balance very good.

From all my study, this is a recommended setting on most MX5 forums around the world so as a platform to start from you would be on the right track.

I also agree your tyre pressures are too high, this is born out by the fact you lose grip towards the end of the session (usually due to tyres overheating). I had the same problem on wednesday starting with 27 psi cold and ended up at a cold of 22-23 to maintain grip through out the session...

This is dificult to understand for me as motorbike racing (my backgorund) is the reverse, you reduce pressure to INCREASE temp.....

Also, reading pressures on each tyre after the session will allow you to adjust each tyre to get a 30-32 hot pressure (info also from our fairygodfather - Keith!). Meaning each tyre at the end of the day could be quite different to each other cold.....

Did you manage to get any laptimes inyour car?

[tomtikki]

I'd suggest dropping your tyres pressures to 32psi hot and seeing if that is any better.
If I am doing training at Hampton the next time you are down there I'd be happy to jump in the car with you.

Cheers Keith, I hope I can take you up on that offer!
I'm going to get a decent tyre gauge for my next session and make sure those pressures are lower and more acurate.

Did you manage to get any laptimes inyour car?

Unfortunately not, i would love to know! I think it's time to get a lap timer and take closer note of things!

Cheers for everyone's input, can't believe I had been given crap setup advice in the first place! Should have known better than trusting a Skyline owner perhaps...

Going to book a spot for March 29th I think, hopefully catch some of you there!

[Mad Kiwi]

Donovan and I have had good runs with the iphone and android gps based laptimers on our cell phones.....i beleive the android ones are considered slightly better but they both work (usually).

Mine played up on wednesday but I think it was a dodgy update..

[Donovan]

Donovan and I have had good runs with the iphone and android gps based laptimers on our cell phones.....i beleive the android ones are considered slightly better but they both work (usually).

Mine played up on wednesday but I think it was a dodgy update..

Mine was working fine on Wednesday (iphone), so just goes to prove Mark was wrong again.

[Mad Kiwi]

snippy....