MX-5 OC Forum

Guys can I have some advice please. I have a 1990 un-modified Roadster running on Toyo CF1 tyres on original 14 inch wheels. Friday was my first ever track day and I booked into Castle Combe for a taster session where I received some much needed tuition which was no doubt worth the £50 I paid on its own.

The car was balanced on track and quite easy to drift but I had to raise the pressure (under advice from the guys at the track) to 35 PSI as it was suffering a lot from sidewall movement. In its defence it was giving good feedback on grip and lots of warning of me going into corners too fast. And I have to say it felt a lot better from raising the pressure onwards. The tyres were getting a bit warm and showing signs of tread movement and they made me put more air pressure in as they were worried by the amount the tyres were bending in terms of the sidewall.

Their advice if I want to do this again was to fit stiffer dampers/springs and bigger wheels/lower profile tyres. Or leave well alone and just live with tyre wear and enjoy what they said looked to be a balanced and easy to control car. Or slow down  Is it possible to take a balanced approach because most of its life is spend on C and B roads where it rides the bumps and handles well? So could I keep it on standard springs with adjustable dampers I can stiffen for track days and larger wheels for track use? Or would I need to change the springs/lower the ride height to get a benefit?

Also what is the best way to check the shocks out, there is no double bounce etc but the car has done 168,000km and I have no records indicating any changes there.

Are there better tracks for me and my 5 to try out, Combe was great fun but felt fairly fast should I go for a more twisty circuit to keep the speeds down? Avon rise was good fun and the two chicanes the best place for catching-up. But the straights were becoming long.

 Once we got past the obligatory hairdresser jokes  I did hit the track and found I was not the slowest despite having the least HP on show, even managing to lap at equal pace to a 350HP Nissan and passed two caterhams plus was closing down an MG TF till it pitted. A track prepared MX5 flew past and a 911 serenely passed me at what my Speedo said was 90 and it did not make that much noise. I probably was cornering a bit too hard but the car was so easy to balance and very forgiving of me carrying too much pace in. Brakes were fine and the engine cope with being flat out in 3^rd and 4^th fine though it needed both fans and the heater on for a cooling lap to avoid a big jump towards red on leaving the track  so work required there. It was fine as long as I kept moving on track.

The other option I have been given is a newer but not so pretty looking MKI with 15 inch wheels cold air intake and lowered suspension. At £750 I am wondering if it is a better option but two 5’s sounds greedy and road tax and insurance….. And it needs sorting, steering vibration 60mph on and twitchier in wet than mine. Could be alignment/balance or something else….. And its sills had been given hasty sill repairs so I would be checking out those prior to spendng cash. 

Any advice welcome. I even wonder if the advice is just keep what I have and get a set of 15 Inch wheels/tyres from Ebay to trash on track. 

 Just get yourself 15" wheels. decent tyres are cheaper also.

CF's don't loke getting hot, they chunk

T1-r you can melt and they survive

First stop ARB set and kill the body roll

Hi can  I be thick and ask what you mean by ARB. Do you mean a new Anti-roll bar set? Or Anti Roll Bar brace? Or something else

Thanks John

 Anti Roll Bar set

i picked mine up on ebay for about £100

 I'm worried they told you to raise the pressures if anything i would have said put 28 psi or 26psi by the time you have done two laps they will be on the 32 psi and should have a very stable car.

if you were doing loads of track day i would say get a more focused Tyre. 

I wouldn't raise the pressure you get a load more wear and the rear end will want to step out more.  

Ollie_247:

 I'm worried they told you to raise the pressures if anything i would have said put 28 psi or 26psi by the time you have done two laps they will be on the 32 psi and should have a very stable car.

if you were doing loads of track day i would say get a more focused Tyre. 

I wouldn't raise the pressure you get a load more wear and the rear end will want to step out more.  

I can't agree with that. For standard 185/60/14 tyres you should increase the pressures otherwise the handling will be all over the place and you'll get increased scrub.

I took my heap on 185/60/14s to Goodwood a few weeks ago and didn't have time to put the pressures up (different story involving a Skyline...) and first time out the back end was way too loose. Put the pressures up to about 35lb and it was great all day.

 Where are the Goodwood track day sessions listed?

Ah, sorry, it wasn't a trackday at Goodwood it was a sprint. I don't know about the trackdays but I'm sure someone else will advise.

 I've done quite a few trackdays on 15/16 and 17 inch wheels and never raised  the pressures

Re tyre pressures. The thing I noticed is that the car was moving a lot on the sidewall at 26 psi and to be honest I prefer the feel at 28psi even on the road. On track I could feel it moving too much and the tyres were heating. I was told it was a combination of the sidewall size and stiffness and they said they were worried watching me from the trackside at the lower pressures. They showed me by leaning on the car how much side to side movement there was as I came off the track with warm tyres. 

With higher pressure the turn in was sharper and I did not notice any loss in rear end grip, it was fairly balanced and could be moved from mild understeer to mild oversteer by the throttle. I found it fairly easy to control, but then it is  standard car with the original LSD. 

They did say a lower profile tyre would work much better and not need as drastic a change. 

I am far from an expert so would welcome any other views. And it is quite softly sprung so no doubt stiffer dampers etc would help. 

Just thinking out loud here but if the tyres are still new the tread blocks will be at their tallest and more prone to movement and heat buildup. 

 Just to confuse the issue for you . All tyre makes have different characteristics and each rim width, diameter, and profile will change the characteristics again . Heat also changes the pressure in your tyres if pumped up with normal air, at cold you could have 28psi then come in after 10 laps and have 34 psi . Its not an exact science . Different combinations may also require different camber settings as some tyres tuck under a lot and others hardly at all .

Three differnt tyres that i raced in three different championships with the same car had very different optimum setups ( from my poor memory)

15" unirols needed 28psi cold to run at an optimum 32-34 psi hot and also a big 3.5degree negative camber.(fronts)...... they tucked under a lot.

17" falkens needed 24 psi cold to run around 28psi hot and only 1.5 degree negative camber.(fronts)

17" hill climb slicks 18-20 psi cold (hardly get warm in a hill climb) .5 degree negative camber

One of the best things you can buy is a TYRE TEMP probe as this will give you much needed info on what your tyre is doing. Come straight off the track and probe inside, middle, outside, as soon as possible . The ideal is all three temperatures about the same, if the middle temp is higher your over inflated, if the middle is cooler your under inflated . If the outside is hotest and the middle a bit less and then the inside a bit less still then you might need more negative camber to work the inside of the tyre more. They are not too expensive and do help you get the best from your tyres. Also the more track days you do the more you learn and just keep using common sense and don't forget its supposed to be fun . As for suspension geometry, springs, shockers thats a whole different thing,

 Just look at the side walls of the tyres, stick a couple of PSI in for every mm of wear past the tread that you see.

 I'd go with whatever Nick says, he speaks from loads of experience with racing / tracking MX5s!!  Next step, get yourself along to one of the Mazda on Track days and get some tuition from Nick, its the best thing I ever did... gave me real confidence to attack the rest of the track day I was on. 

Russell.

My favourite UK circiuts in order;

• Croft (closest to me!  Flat but good.  Work towards going through the Jim Clark bends flat out and still being able to brake in a straight line for Sunny In :)  I did my racing licence here.
• Donington (love the Craner Curves - when you can go flat through them you have balls)
• Oulton Park (great mix of everything but can be very difficult in the wet)
• Silverstone (the history...  Though more rewarding with a more powerful car)
• Cadwell Park (tight course suited to small light cars)
• Thruxton (Unsure about the new layout but I've done two 24 hour races on the old one)
• Anglesey (I've ony been on the old circuit but the new circuit offers a good range of options)
• Airfields such as Elvington (you just can't hit anything....!!!)

I've used Bookatrack.com or Javelin Trackdays.
BookaTrack can hire out cars (Caterham's) which are just amazing but can be frightening to a novice.