How to ruin the handling of an MX5.by Norman H Gar

[gslender]

Another obvious point is the clubman. So either the stock NA6 is crap, or the clubman is.... They can't both be perfect!?

G

[Patrick Bramston]

So JEO, just to prove norman is wrong, how many KPH faster were you in any of the slow corners than Guran with similar tyres. I assume you were not on semi slicks..being 2 seconds faster over a lap may be more to do with having more power than handling.. If you were in a similar powered car to Guran the lap time may mean more.. I hope for us all that modifing your car is worth the effort, after all my white car has had $60,000 spent on it over the years, I would like it to be faster through the corners than a standard car on similar tyres but I doubt it, after reading the book in question...Patrick

[Guran]

Corr! I suppose I ought to comment in this thread. Down at Wakefield supersprint at the moment, but will try to look up the data requested when I get home. For starters, tyres are a major factor on a stock NA6:

RE001s 1:16.80
R888s 1:16.22 (best so far)
Star Specs 1:15.80
RE55S 1:14.98

I won't be buying another set of R888s as they're rubbish on a stock MX-5.

[Basho]

Corr! I suppose I ought to comment in this thread. Down at Wakefield supersprint at the moment, but will try to look up the data requested when I get home. For starters, tyres are a major factor on a stock NA6:
I won't be buying another set of R888s as they're rubbish on a stock MX-5.

Ah Ha --and the best tyres for street are ? - yes seriously.

[Guran]

For my car, with the tyres I've tried in 185/60R14 ... RE001 are my ideal choice for street use. Star Specs are a better tyre in the dry and especially in the wet, but I don't think it's worth paying nearly double for them as an everyday street tyre. Track is a different story.

[Jeo]

So JEO, just to prove norman is wrong, how many KPH faster were you in any of the slow corners than Guran with similar tyres. I assume you were not on semi slicks..being 2 seconds faster over a lap may be more to do with having more power than handling.. If you were in a similar powered car to Guran the lap time may mean more.

Biggest difference is on the fish hook at ~7km/h faster, most corners are more like a 4-5km/h difference.

Power certainly makes a difference though. With less power and a slower mid corner speed, Guran makes a bit of distance on me coming out of practically every corner, then I catch and pass him shortly after.

[manga_blue]

Just home from Wakie a little while ago. The track was pretty cold so grip was a bit low.and most people were about 0.5 sec off their best. I think the idea of presenting comparative data is a great idea. Maybe Vmin is not the best measure but at least it's something easily collected and objective.

Here are my Vmins for each corner compared to Patrick's on a 1:13.5 lap today (Patrick first, manga second):
turn 1 190 ... 153.9 (which is also my Vmax for the whole circuit, no turbo and about 80rwkw )
turn 2 94 ... 87.5 (fluffed it )
turn3 120 ... 113.8
turn 4 95 ... 96.4
turn 5 88 ... 82.9
turn 6 120 ...118.7
turn 7 69 fishhook... 67.6
turn 8 95... 95.4
turn 9 115... 113.7
turn 10 66... 56.8

This is for a very porky NA8 (no lightening, with A/C, P/S, etc) and no aero. Tyres are 195/50r15 r-specs on 6.5" rims, 10/7 springs, stock sways. Not much difference, is there, for an 8 sec laptime difference?

[Guran]

Here you go. A comparison of Vmin in turns (eg. T10 = turn 10) and Vmax on straights (eg. S1 is near turn 1 on main straight). My best laps for each tyre choice were:

1:16.81 with RE001 on 4/9/2011 (run 6, lap 2)
1:16.20 with R888 on 26/8/2012 (run 8, lap 4)
1:15.78 with Star Spec on 29/7/12 (run 3, lap 5)
1:14.99 with RE55S on 30/7/2011 (run 3, lap 4)

The above times are from my Performance Box data and are with the Club's fishhook start/finish for RE001 and Star Spec, or the normal start/finish for R888 and RE55S.



I don't have Vmin for turns 1, 6, 7 and 9 because I'm accelerating constantly through all of them. I'm not sure why you guys are calling the fishhook "turn 7". I use the following numbering system:

[Patrick Bramston]

This is what I suspected..Coilovers/sway bars/bracing/diffs/you name it and really no increase in corner speed over a stock car. They made this little car pretty god dam good in the first place. Don't get me wrong, I love my 300 rear wheel horsepower weapon big budget MX5 but it's no quicker around corners than a good standard car with the same driver I believe..What I would like to see is Guran put some 15x7 wheels and comporable tyres on his car and see how much slower it goes to prove the point...Top Gear put big brakes and wheels to go over them on a Renault Aventime and went 7 seconds a lap slower..

[davekmoore]

Following the theme of performance modifications slowing cars down, the ECU on mine is going to have the lower boost map on it as soon as I can work out how to do it. This is so I don't kill the tyres and brakes as much on the track. Hopefully it'll make me brake less, which will be kinder on the tyres, which will give the coilovers more chance to get me quicker round the corners, which will increase exit speeds, which will mean higher speeds at the end of the straights, but oh bu**er, that'll mean more work and heat for the brakes and tyres ...........

[manga_blue]

Vmin is not the real measure though. Guran and I were talking about it this arvo. He was saying that the important KPIs are how long it takes you to get from a defined point before a corner to a defined point after a corner and what speed you have at that second defined point.

Hellmun logged a few laps at EC on my GPS a couple of years ago. He had the same Vmins and acceleration rates as me but was 6 secs quicker. He'd done a lot of work on that setup and I still don't know it could do it but his transition time from full braking to full acceleration in any corner was often close to zero, equivalent to only a meter or two on the track. Mine was more like 5 to 10 meters, but with the same Vmin. My car simply refuses to do what his does.

The other factor is repeatability. A good laptime depends on you hanging 10 good corners together on one lap. It's much easier for me to be consistent like that that on my stiff set-up than it is for Guran with his car waving all over the place. He's just cheating by using skill and applying rigorous analysis. In other words, a stock car is capable of high corner speeds, but only occasionally in the hands of an average driver.

[Hellmun]

Like Bryan I'm disregarding points where I'm full throttle. Otherwise heres best V-mins on one 4 lap session (accounts for driver variance a bit). One of these is a 1:09:65 and worst 1:11:37. Peak G was 1.527 on T5.

Peak speed 155.6kph
t2 93.06kph
t3 127.2kph
t4 98.68kph
t5 99.72kph
t8 70.39kph
t10 66.55kph

Racelogic DL1 with the 20hz upgrade is what I'm using.

[Mick93]

I think some of his comments are generally correct.
You can't expect to put swaybars on and it improve your handling or coil overs and it be better. When my stock shocks were shagged I did what everyone on the web said to do. Put in Konis and King Springs. Biggest mistake ever, it destroyed the handling. the reason was the springs were too hard as they are lower and the Konis couldnt control it. I then bought a set of Aragostas they are awesome fully adjustable made of duralumin so the complete units are 2/3rds the weight of the originals (less un sprung weight) best of all the springs were perfect for the shock to control. Wheels can wreck an MX5 I bought one with 17inch chrome mags on it they heavy and made the handling clumsy I took them off bought a set of Ray GramLights for it and massively improved the handling. The wheels I searched high and low for were 15" BBS RC's (it took 9 years) they are the lightest 15s put on a production MX5 and the only 15's lighter than them are Watanabe and Volk race magnesium wheels, but they fatigue crack badly. The RC's are only 330 grams heavier and lighter than the stock hollow 14's.
Sway bars should be mated to a spring, when you see how many suspension engineers for race teams work on suspension dynos to get it right I don't think you would believe that something that an aftermarket company could make would improve it. Afterall a sway is more reliant on the low body flex to perform and MX5's flex. You would be better trying to eliminate the flex but even that isn't easy
Unsparing mass is everything especially in an MX5 as they are light and not powerful. Don't get me wrong I love the look of flared out MX5s with deep dish rims but they are style over performance but I love them all the same.
Ultermately make the MX5 you wanted. Some want to cruise others corner hard some want a bullet. I love seeing everything people make in MX5 land it's all good

[Aussie Stig]

Don't see how dropping it an inch and getting a wheel alignment would be detrimental.

[Hjt]

I would love to see a comparison of all models in the stock form, similar driving conditions, tyres and driver.

I know the later models would be faster p 2 p, but the corner speeds would be interesting.