Mk3 Track Day Improvements

  1. My model of MX-5 is: NC (2006)
  2. I’m based near: Wiltshire
  3. I’m looking for technical help or recommendations on: Further suspension improvements?

I recently started doing trackdays in my Mk3 and after my last day at Castle Combe and looking at the pictures I’m thinking of some further suspension improvements…

So the spec of the car is basically:

  • Basically stock engine, ‘cold air intake’ with the filter down in the bumper and backbox, I believe it’s been remapped but I suspect it won’t have much/any more than stock.
  • Brakes I’ve got braided lines and Roddisons pads in the front (stock/pattern in the rear).
  • Suspension I’ve had MeisterR coilovers fitted by Roddisons and setup at that time (was a while ago so maybe worth re-doing the geometry) but stock ARBs and not polybushed.

So my last two trackdays were at Castle Combe (local circuit), I put some overlays on from the GoPro GPS and my fastest lap looks to be a 1:24.6 which I’m pretty happy with, the video onboard is here:

But after looking at the pictures afterwards I feel like there’s a fair bit of body roll visible…

In terms of handling it feels pretty good, as I’ve been pushing a bit harder it’s been understeering a bit, especially in the final corner (Camp).

Not sure it’ll fix the understeer but guessing either ARBs and/or polybushing the suspension can’t hurt :smiley:

Any reccomendations for the ARBs? I’ve heard the RX-8 ones but also looks like there are whiteline and a few other aftermarket ones available?

Also are ‘all’ polybushes the same or is it worth paying the premium for the likes of Superpro/Powerflex?

Hello NoSkill
I think you need to speak/visit Roddisons, get Paul to corner weight after he has checked the geometry. He can of course advise on ARB’s, in fact you name it Rodders is the man!
Cheers
Keith

I have used whiteline ARB’s before on other chassis with good success. Having pretty much the same setup as you on my NC it’s also my next planned mod.

I was going to go adjustable ARB’s along with a chassis brace stiffening package.

‘Unfortunately’ Paul is waaaaay up north :stuck_out_tongue:

Was planning to fit the ARBs and maybe bushes myself and probably get the Geometry setup by somewhere a bit closer really…

Yeah, I’ve heard good things about whiteline, mostly regarding the Mk1 MR2 slowly rusting away in the garage :stuck_out_tongue: never actually used them personally

Not sure on the benefit of the chassis bracing kits really? I think I was advised to actually remove the stock front strut brace…

Hi
Please remind me what spring rates you have and what tyres you are using?

Hi Paul,

Not sure on spring rates, I think I told you at the time it was mostly road with maybe some track stuff so if there’s an option I’m guessing you went more road than track spec?

Tyre wise I’m on Yokohama AD08RS

So if you have ‘moved the goal posts’ you may need stiffer suspension and better tyres if you want better lap times.

It’s all down to what you want???

Some body roll can be beneficial…

That’s fair :slight_smile:

It has changed from being a daily driver for a 20-mile each way commute to work but that’s now gone forever so it is/can be much more track focussed.

I’ve ‘expertly’ modified a couple of pictures to remove my number plate showing the worst of the body roll:

Not exactly full-on boat levels but seems more than ideal?

Would you recommend keeping the stock ARB and stiffening the springs? or upgrading/changing both?

Also what tyres would be a good choice? I’ve seen some using the Nankang NS2R… I’d still like to drive to/from the tracks and hence not need to change tyres for cold/wet conditions…

What I like about the chassis stiffening braces is that if they seem to make no difference they can easily be unbolted and sold :slight_smile: - I figured I would give them a shot and see.

Federal RS-R work on track and on the road.

First thing I would do is increase spring pre load, corner weigh and set up again…yes you have some ‘roll’ but let me explain…

I’m 16st if I stand upright I have 8st on each leg, now if I stand on one leg I move all 16st on to that said leg…with me so far???

It also works with braking too…you need weight onto the wheels to stop them locking. That’s the ‘black art’ of setting a car up.

If I was able to post pics I’d show some of my race car, we use kerb to rotate car and move weight…

Paul

1 Like

If you’re concerned about roll you can add stiffer anti roll bars, or less grippy tyres. If you add more grippy tyres it’ll lean over more as the inertia produced by the higher G levels caused by more grip has to go somewhere.

I did heaps of sprints in Australia and the guys with unmodified NA6s with no grip seemed to have as much fun as the guys with turbo/aero/9" slicks etc.

It depends if you want to have cheap fun or if you want to go fast. If it is the latter, then you need to decide how much you want to spend per second you can save. The faster you go the more each second costs.

2 Likes

True, worth a try I guess :slight_smile:

Cheers for the tyre recommendation, are they available in the standard sizes or do I need to go slightly wider?

I do get that some roll is not just inevitable but also desirable, and I guess I’m not even sure if what those pictures shows is ‘too much’ roll or ‘the right amount’… It seemed a lot as a layman looking at a static picture.

I thought spring preload was largely used just for ride height and had little/no effect to the actual handling?

The whiteline arb kit seems to have a 24mm front and 16mm rear, and I believe the soft-top NC1 has 22mm front and 12mm rear, so all else being equal a decent amount more affect to the rear than the front. And from my limited understanding that would have some affect on the balance towards oversteer/away from understeer. But obviously I’m no expert.

I guess springrates and/or other geometry could achieve the same things, if the roll exhibited in those pictures is indeed within what you’d expect/want?

I wanna go fast! :smiley: This car is largely now just a trackday car, with some sprints likely in the future, for me improving lap time on subsequent visits is the fun in doing that, and I know there’s still time to come from improving my driving obviously but also looking at the next steps to hopefully improve the car and maybe tweak the balance slightly to help me out…

So if you wanna go fast rather than just have fun you’re into spending ££,£££s, and for every £1,000 you spend on one improvement you’ll be spending the same or more on other items that are now letting down the most recent improvement. I did that for a decade and spent a fortune and ended up with a 400hp car that was about twice as quick as I was as a driver. Fortunately, for all the expense and frustration I also had a great deal of fun with a great bunch of MX5ists.

Enjoy the journey!!

Haha, yeah, thanks :slight_smile:

Although I guess if it was just numbers I could just slap a turbo/supercharger on the car and gain far more lap time than any suspension tweaks would give me :stuck_out_tongue: so maybe it’s somewhere in the middle…