Help with Koni yellows + GC setup
 

Hi

I have koni yellow shocks + stock springs with flying miata front and rear sway bars on my 1990 NA miata.

Just ordered GC ground control 375/250 from goodwinracing to replace the stock springs. Also purchased the Sport FCM bump stops. I have 15x8 6uls for wheels. What is a good ride height i can go and have performance at the same time? I was recommended by Brian from goodwinracing to go 12.25f/12.5r and remove the fm rear sway bar to get a decent suspension setup. Do i need nb shock mounts? Am i missing anything else? I just want to get as much information before we install the ground controls and bumpstops next weekend. Thanks!

I'd aim closer to 12.5/12.75 and install the rear stock bar.

what length rear spring are they sending? konis are really short and you'll might end up with coil bind if it's only 7" long. Although, maybe that's why they suggest 12.5" in the rear...

NB mounts will exaggerate the issue, so it's unneeded really. Just helps to go lower, you wont have that issue.

what is your goal with the car?

hi

i will be mostly street driving, but sometimes id like to drive faster on twisty roads and later try some track days. I want it set up for performance.

Right now i only have koni yellows + stock springs, and it has alot of body roll which is something i really dont like. Im hoping the ground controls 375/250 and fcm sport bumpstops and being lowered to 12.25f/12.5r will eliminate alot of the body roll?

braineack: brian from goodwinracing said i could take out the FM rear sway bar, or even put the stock sway bar back on. I dont know if i even have the stock bar but i guess i could find one. Savington told me long time ago, to get the RB tubular front sway bar, and take out the rear. Is that alot better? Suposely the FM front sway and RB front sway is not much difference?

I have no idea what length springs im getting from goodwin, I just got the 375/250 rates ground controls.

So basicly, the NB shock mounts just allow me to go LOWER and still have good suspension performance?


I posted on Clubroadster, and some guy was mentioning, if i get NB mounts, i need to get NB konis as well for the rear? Is this true? Im pretty sure i have the 1990-1997 koni yellows, so it would be the NA konis. Kinda confusing

If the nb mounts just allow me to go lower with performance, then maybe i dont really need it, and my NA mounts NA konis should be fine?

thanks

The FM front sway on full stiff would be close, IIRC. But I'd still want at least the stock sway on the rear. I don't like how the car feels without one.

i will see if i can find a stock rear sway bar

So i want to know, what does the nb shock mounts actually do? what does it improve? Is it really worth the upgrade?

I want to make sure i have all the parts before i get it all installed this coming weekend. I want to get my suspension setup and do it right the first time.

thanks

You can mount the NB top hats to NA shocks, you just need special nuts to get the top hats mounted. Fatcat will sell you the nuts seperately. I ended up making my own out of some coupling nuts.

If you use NA top hats and lower the car, make sure that you have enough shock travel.

The nb top mount gives additional compression travel to the damper body by allowing it to travel further past the plane of the mounting surface (unibody).

A rear anti-roll bar (swaybar) is going to decrease body roll, quickening transitions, helping to reduce camber loss, and shift some grip bias towards the front. All of these things could be good. A rear anti-roll bar is also going to hurt your ability to put the power down coming off of tight corners compared to the same chassis bias without one. This effect is dramatic with an open diff, and subtle with a limited slip.

More subtleties: having the same stiffness bias in your ARBs as you do in your springs (all after motion ratios) will help make your car more predictable as traction conditions change.

I am trying to make the point that there are a lot of decent ways to setup a car, but don't make the mistake of taking good advice in a vacuum. What works for one person, almost certainly works because of some other stuff in their setup that makes it work for them. I've seen many people take advice like "a stiff rear bar is good" and "you can increase front tire pressure to get rid of some oversteer" and so on and make a car with potential handle ok, but be slow. The most important part of each piece of the setup is WHY, not what.

As an example, everyone here talks about how you need a stiff front bar. I set fastest time of the day (beating out even the karts) with no anti-roll bars. Does that mean, in the absence of the rest of my setup, you'll be fast just removing your bars? No!

In addition to the comments above, NB mounts have separate load paths for the spring and shock, whereas NA topmounts have both the spring and shock loads going through a rubber isolator.

The sway advice you received is completely dependent upon the relative ratio of front to rear spring rates and, as stated above, is different for every different combination of front and rear spring rates, vehicle weights and balances, and alignments. With the rates you are getting, I would use the FM sways with full stiff on the front and full soft on the rear, then see how it FEELS TO YOU. Adjust from there if necessary.