NA Suspension Upgrade, FM or FCM mounts?

Poida · Postby **Poida** » Tue Oct 08, 2013 4:48 am

Hi all,

I've been researching into an upgrade to my stock suspension, and I am probably going to go with Koni Sports (yellow) with Eibach Pro-Kit to put onto my 1990 NA.

What is the general consensus on this combination?

I'm also going to be upgrading the bumpstops and shock mounts, but can't really decide between the Flyin' Miata mounts and the FCM mounts.

From what I understand, the FM mounts don't drop the car any further, and increase travel.

The FCM mounts do drop the car, but doesn't add as much travel.

Can you provide some insight into what each offers so I can make a educated choice?

Thanks,

Peter

Magpie · Postby **Magpie** » Tue Oct 08, 2013 5:10 am

I can't help you with the mounts but the service from FCM is nothing short of brilliant. Get in contact with FCM and discuss your needs.

KevGoat · Postby **KevGoat** » Tue Oct 08, 2013 9:47 am

+1 on FCM's service ... absolutely brilliant.

I used FCM bumpstops on my NA with Monroe shocks & King springs. The improvement in the quality of the ride with just the FCM stops over the stock bumps was amazing.

Magpie · Postby **Magpie** » Tue Oct 08, 2013 10:17 am

I'm about to have FCM bump stops (including packers) installed. Whilst I did pay for FCM's customising service it was worth every penny to get the best solution (based on the data I provided). I will be testing the BC Racing bumpstops when they are replaced as it will be interesting to see how much they compress. I have a problem that when taking a tight right hander with 2 people in the car at track speeds the front left rubs. FCM's suggestion was to supply customised length bumpstops and fit at least 2 packers to the left hand side when there was 2 people in the car at least in the first instance and then adjust with further packers (if required). With 1 person just remove 1 packer, quick and simple solution.

However have you resolved your alignment, heights, sway bar, tire pressures, spring rates, corner weights etc first before moving on to mounts? You need to understand where you are and have a baseline to measure change from.

Postby **Boyracer** » Thu Oct 10, 2013 11:34 am

Why not just buy a set of yellowspeeds or similar?

sailaholic · Postby **sailaholic** » Thu Oct 10, 2013 12:58 pm

Boyracer wrote:Why not just buy a set of yellowspeeds or similar?

Why spend money on fancy bits like threaded bodies and adjustable ( crappy) valving when you can spend the money where it matters?

I've back to back dríven konis vs yellow speeds.... There was no contest (koni wins). On soft they felt nauseating, on hard they were jaring but still not as well controlled as konis.

Can't comment on other brands

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YanMa YatTai · Postby **YanMa YatTai** » Thu Oct 10, 2013 8:23 pm

Are Eibach pro kit performance or simply a "lowering" spring?
Are there more performance oriented springs that would be suitable?
Would a stiffer spring than the pro kit be better or worse with the Koni yellow?

I too am tossing up between a FCM mount+bump stop/Koni/some spring vs a cheap set of coilovers like YSR or BC Racing.

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sailaholic · Postby **sailaholic** » Thu Oct 10, 2013 9:57 pm

Eibach are a stronger spring rate as are just about any (decent) lowering spring as the have less travel to dampen the inputs.

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fcruz3r · Postby **fcruz3r** » Fri Oct 11, 2013 1:21 pm

personally am a fan of proper spring rates for desired application.

so if it's tracking the car and the suspension is rubbing, then I'd go for harder spring rates and thicker sway bars. i don't think custom bumpstops to compensate for shorter travel & weak springs will ever outperform the job of proper spring rates and somehow adjusting the rebound on koni's to harden the suspension makes the car feel really unsettled.

Will be ditching my koni/king combo for mid range (BC or HSD) coilovers as soon as funds permit

but please listen to the fast drivers/pros ...my opinions are based purely on personal driving style and experience (or lack thereof)

Magpie · Postby **Magpie** » Fri Oct 11, 2013 3:22 pm

Have a real good look at the FCM site
- Bump stops are also key to proper suspension performance. Which is ironic since many people (including me at first) considered them a necessary evil or afterthought.

Just putting a harder spring in and thicker sway bars to cure suspension rubbing is not a solution. If your increase rear sway you increase understeer, increase front you get more oversteer. If you increase your spring rates you may loose grip because the springs can not react to the surface and the wheel just skips. The spring and the shock work together, the spring is compressed by the car's weight and its rate dictates how far it is compressed, the shock controls how the force in the spring is managed. Is the weight transfered quickly rear to from when braking (bump) or is the weight released slowly from the front to rear when accelerating (rebound).

Proper bump stops especially in a MX5 NA6 in the rear are needed because of reduced travel. They can be customised with packers to adjust when they come into the equation as an intergal part of the suspension process.

This is not even getting into wheel motion rates, sprung/unsprung weight, vehicle height etc.

What is the main purpose of your car this will dictate your brand/choice? If road use then stock spring rates should be more than adequate and there would be no need for changing mounts. I would say FCM bumpstops but you will need to answer alot of questions if you want custom ones.

Poida · Postby **Poida** » Sat Oct 12, 2013 2:26 am

Magpie wrote:What is the main purpose of your car this will dictate your brand/choice? If road use then stock spring rates should be more than adequate and there would be no need for changing mounts. I would say FCM bumpstops but you will need to answer alot of questions if you want custom ones.

I would like the purpose of the car to be both road and track, with the majority being road, but having the suspension at a suitable level, when I need it at the track.

Mr. Keets · Postby **Mr. Keets** » Sun Oct 20, 2013 10:25 am

I contacted FCM and went with the custom coilover package which included the bump stops, I went for a similar plan...street / track use.

My preference is for more oversteer vs. push, My NA currently has an AVO kit fitted.

300mm /310 ride height F/R, 7.1kg/mm springs front, 5.3kg/mm rear with a 1" front tubular bar, stock standard rear. Custom length bump stops a 30mm medium density front and 35mm soft density rear to take up the travel to full compression while keeping the car in a neutral to slight oversteer balance. Frame rails and few other tweaks. The car handles as requested and rides well on the street/freeway/motorkhana...supermarkets take some thought though.

The service from Shaikh was excellent and the price was reasonable, save you money and go with someone who specialises in MX-5, you wont be sorry.