Initial track setup for NA6

[ianoz]

First post here so be kind Sorry about the length..

Just bought my first MX5 from an old mate - an NA6 (Oct 1989 build). 170,000km, currently totally stock – even the original purchase receipt. But showing it’s age.. with original suspension, tired paint and original timing belt!

I’ve done lots of reading around the forum (and UK,NZ, US forums) – with the result that I’m better informed but also a hell of a lot more confused than before, so please forgive the basic nature of my questions ... Any comments on if I'm heading down the right/wrong track would be great. Based in Melbourne, so subject to VicRoads regs.

Target is a track day club car, road registered but not a commuter. I’m definitely in the ‘flat cap’ demographic, and haven’t been on a track since clubbing with RX2/RX3 coupes back in the mid 80’s.. Really focusing on the handling this time round rather than power, want to keep the handling sweet and avoid creating a twitchy oversteering mongrel (like ported RX3’s). Not worried about comfort – just predictable cornering. Aiming for ‘clubman’ class with only limited mod’s allowed – until the red mist descends then that’s open to revision...

So – my questions;
Coilovers - Yellowspeed seem a fair balance of cost/performance, but not sure about the standard ‘sport’ vs the 'competition' choice. Their spring rates of 12/12kg seem high and from what I’ve read would tend to oversteer?? Would the standard model with 8/6kg be a better choice for club level track work? Or competition valving but with softer springs? Ohlin's would be nice of-course, but I'd rather spend that extra towards a better seat/harness/helmet/tuition etc.

Sway bars – any suggestions on a suitable match to the coilovers? A heavier adjustable front (22mm?) and stock rear?

Diff – is an LSD really worthwhile on a stock (tired) 1600? What ratio would be best compromise for Victorian tracks (Sandown, PI, Winton).

Wheels - was planning 15x7 +40, with 205/50 AD08R’s to fit within the Supersprint 'standard' regs – but there seems to be a lack of suitable 15x7 around. Would 15x6.5 +40 with 195/50 suit a tracked NA? or would it be better to keep hunting for 7's?

Brakes – thinking NB8A brake upgrade as NB8B I understand would need minimum of 16” wheels. Is that correct? or are there some 15's that are known to work with the NB8B brakes?


Any comments gratefully received. Some of this is going to have to be done prior to getting a roadworthy, rather than buy stock parts to be turfed out straight away.. so like to get it right first time (plus avoid the explanations to the financial controller...)

Cheers, Ian

[manga_blue]

I suggest you read all about Guran's Little Ready first. viewtopic.php?f=57&t=39676

I wouldn't be thinking about any mods except safety ones until you're beginning to get competitive in SNA in the Vic MX5 Club.

[bensale]

Hi mate,
I've been down the same road, initially on a very tight budget in Clubman class.. and now with some nicer parts fitted to the car...

To start with, after fixing the service items I would suggest just getting the car out there as is with whatever tyres you have on it and see what you think need changing. If you're targeting clubman class my personal order of mods would be something like the below which comes out at the 4 allowed mods. You'll be going to be up against it in an NA6 anyway... You just have to drive it harder

Tyres / wheels (nb8a 15'' wheels are cheap and will do the job - wider wheels do help but it's not the be all and end all) ADO8s or Dunlop Starspecs would be the two best options.
Safety (seat, roll bar, harness)
(mod 1) 24mm adjustable Whiteline Front Swaybar (stock rear)
(mod 2 &3) Suspension (look into Weitecs - they're KWs (think Ohlins but better) with a smaller price tag & a really, really good bit of kit for roughly the same money as yellow speeds)
Wheel alignment
(mod 4) Cat back exhaust, 2.25" (might as well sound good - it's a track car!!)

Personally I don't think an NA6 needs an LSD at any of those tracks providing you know how to drive... The standard 4.3 is pretty much spot on too so I wouldn't change it.

1.8 brakes won't hurt at all, NB8B will be overkill. Most important is good pads ( TWRs are a great budget option - hawks, ebc yellows, QFM if you have more to play with) and some good fluid.

[manga_blue]

If you are entering in Standard NA in Vic then the 2.25" exhaust is a free mod for an NA6 and it helps to give you some power parity with NA8s. Nevertheless I still say just give it fresh fluids, filters and pads and drive it as standard until you're competitive and ready to move up.

[93_Clubman]

Brakes – thinking NB8A brake upgrade as NB8B I understand would need minimum of 16” wheels. Is that correct? or are there some 15's that are known to work with the NB8B brakes?

NB8A 15" rims, as well as a few others, will fit over the NB8B brakes.

[david_syd_au]

I use the Yellow Speed competition coilovers in a dedicated NB race car, although with the alternative 10/9 spring rates (special order, same price) rather than the default 12/12. The initial install of the coilovers was done with the original std sway bars and the result was lots of oversteer, regardless of the shock settings. Once the swaybars were replaced with Whiteline adjustables front and back, the result was very good.
Also the Yellow Speed competition coilovers are very harsh, even with the reduced spring rates, and I would not recommend them for road use, even if it is just to the track and back.

In a nutshell:
Suggest the street Yellow Speeds if the car is used on the road, or you don;t intend to change the sway bars.
The competition Yellow Speeds would require also changing the swaybars, and you would have to be a masochist with a physio on staff to use them on the road.

[ianoz]

Thank you all for your help Got to say that this is a very friendly forum

To be honest I'm not aiming to be up the timing charts - just on having some fun while trying to improve PB's, and doing regularity runs. Speed takes skill (nope!) so I'll be in the one down the back with the bifocal windscreen


manga_blue - that is an epic thread at 49 pages.. but a great read! (working my way thru it). I appreciate what you mean by keeping it stock and moving up in the future, but don't want to double-dip where I can avoid it. Not really keen about taking it out on the track with the original 1989 shocks... and the tyres & pads (and probably shocks) are going to have to be replaced for the roadworthy anyway. What counts as 'standard' in the regs? non-adjustable pedders/kyb/koni , etc or strictly OEM? I assume anything adjustable would be regarded as a mod?


bensale - thanks - great guides there. haven't come across Weitec before, but will check them out. What spring rates are you using with them? I didn't really intend to do the LSD, but there seemed to be a big focus on them and final ratios around the various forums - good to see that it's not so important. They don't list AD08's in 14", hence looking at 15" rims (can get a good deal on Yokohamas).


93_clubman - thanks, seems like NB8A brakes are enough for me, but the NB 15" wheels sound like a cheap (and good looking) option anyway...


david - that confirms what I thought - that the 12/12 full competition set was maybe OK for a full on serious racer, but probably a step too far for me.


Thanks everyone for your advice & PM's. Hope to have this up and running soon

Cheers
Ian

[bensale]

Sounds like you've got the right idea.
I'm running KW competitions (high end setup with adjustable high & low speed, compression + rebound adjustment) so not really relevant to the Weitecs. I'm not sure what rates they run in the MX-5 setup. However, KW control the suspension more through the damper compared to the others who rely more on spring rates.

4.3 is a really good ratio for an NA6, not worth changing it out. Most of the discussion is probably from guys with 1.8 diffs which usually have 3.6s or 4.1s fitted.

[speed freak]

If your going to upgrade the brakes slightly Id highly recommend getting some braided brake lines especially since your using it on track. Iv done that mod in my nb8b and the difference it makes in pedal feel is amazing, Im using Hawk HP+ street and track pads so with these and those braided lines make for huge stopping power in a light car.

Also Im running BC BR street and track coilovers and they are great, not harsh on the road but firm and great handling. Good price too.

[ianoz]

Agreed on the brake lines. Will be replacing them with braided, along with replacing all the other 25 year old fluid hoses around the car with fresh rubber as part of the maintenance work. The Hawk pads seem a popular choice, so will give the HP+ a go.

Great that the stock ratio's suit! One less thing to worry about