Another coilover topic - which for track use for MX5?

[Paul Tomb]

Hi, I'm after a set of coilovers for my MX-5 Mk2.5 1.8 Sport. Car is intended as a track toy and it's the primary focus when choosing the right coilovers. It is being driven daily, however I don't care too much if it's uncomfortable. The car other than uprated brake pads/fluid and lightweight alloys with Federal RS-R 205/50 R15 tyres is bone stock.

 

I have narrowed down my options to Gaz Gold Pro, MeisterR Zeta-S/Zeta-R and BC Racing BR Series.

My main concern regards correct spring ratios. As I mentioned, I lean towards performance and I will be going to Nordschleife which is quite bumpy compared to most modern tracks, so need to take this into account too. I suppose I need harder than average (around 6kg front / 5kg rear), but the hardest (10F/6R or 10F/8R depending on brand) would be too stiff because of the Nordschleife, the fact I actually drive the car on public roads and the tyres which do not generate enough grip to justify the hardest springs. I'll probably turbocharge my car and fit some sticky 225 R888 in a distant future, but it's another story and I'll worry about stiffer springs then.

I'm afraid that MeisterR's Zeta-S would be too soft (6F/5R), and Zeta-R (should be available soon - 10/6 springs) too hard.

I think BC BR with 8/6 kg springs would be best of both worlds, am I right? Also they come with pillowball top mount which is nice thing.

What puzzles me is GGP ratios. Why medium and hard use the same rear spring ratio (400F/300R and 500F/300R lb/in)? Doesn't it unsettle car's balance to change relationship between front and rear spring ratios? Also they're single perch design, does that mean that in order to change ride height I have to change spring preload?

I'm planning to get the coilovers in September and have WIM to do the geometry alignment (which I doubt has ever been done to my car).

Another matter is corner weighting. Do you do it at WIM? I've heard it's very important on track car. How is it done on single perch coilover like GGP, does it involve messing with spring preloads?

Sorry about the lengthy post and obvious lack of experience in that matter. Been reading a lot, narrowed down my options as far as I can but need some advice before I make a final decision.

 

Regards,

Paul

[Tony]

Hi Paul

The BC BR with 8/6 kg springs is definitely the way to go in my opinion ever more so since you can adjust the height without disturbing the pre-load like the GGP. Another negative with the GGP is they don't come with top mounts, they can supply racing top mounts but i tell you they knock like a bugger.

 

We don't corner weight. Reason being is domestically there is no point, simply filling up the washer bottle would destroy the weight balance. Out of the box the MX5 has a 50/50 balance so the only issue would be to watch the rake when the coilovers are fitted. When we had a centre in Milton Keynes we did do corner weighting there and of the 5's weighted there after fitting coilovers the only weight balance needed was diagonal correction and such a small amount it was a wast of the owners money if i'm honest.

 

My advice to you is be sure the drivers weight is added during the geometry calibration and go in with half the amount of track day fuel, "HALF", yes if you intend to use half a tank then go in with 1/4 of a tank, this means the geometry's perfect position will be there during your hot laps.

[Paul Tomb]

Thanks Tony for your invaluable advice, I'm glad your opinion confirms my conclusions. I'll go for BC BR type RA coilovers then. Will give you a call in near future to book my car in after my holiday in September

[Tony]

Wise choice