Comfort with Improved Handling
 

Hey guys, so I'm out here building what I want my turbo Miata to be:

I want my Miata to be the equivalent of a 2009 Porsche Cayman S in terms of comfort and performance. The MK turbo kit boosts power a good bit, so that's good to go there. Time to tackle suspension and brakes.

A) I don't want to go with the harsher ride of coilovers, but I also don't want the wallowy softness of stock suspension. Some of the roads around Florida are marginally better than that of a third world country, and half the highway is under construction at any given time, so I want something that will absorb the bumps when I go over them.

B) However, when I take it to the track, I want to be able to drive up and with minimal adjustments go out there and crush it. I think stiffer suspensions really aren't necessary for good track handling anyway, you still want some degree of body roll and weight transfer. These aren't Formula 1 cars.

I will not be lowering the car beyond 1 inch. I don't want to scrape on leaves.


So realistically I am probably looking at some spring/shock combo. Maybe H&R and Bilstein? Tein and Tokico?

Xida GS.
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550/350 spring rates are probably going to be extremely stiff and harsh, there's no way they'll be livable on the poorly maintained dirt road known as I-95 or State Road 826.

$1700+ is also wildly out of budget. I should have stated that, perhaps no more than $1k for all components.

Assembled a spreadsheet of different springs and dampers

So I'm kinda looking at the Tein S-Tech springs, rates of 224/168, which are slightly higher than that of MSM springs at 215/158. Combo this with Bilstein B8 dampers and I think this could be good and comfortable. What do you guys think?

I was considering FM springs, but at 318/233, I've read that they tend to be on the harsher side.

Racing Beat springs are 195/145, so that might be a bit too soft, even softer than MSM.

Realistically a custom bilstein setup is going to be the closest thing for what you want that is also within budget.

The Xida GS is the perfect solution for what you want though, I have the 550/350 springs and it rides better than stock. (Rural Canadian backroads that get layered in salt for half the year.)
They're also very nice on track.

If you say so, I'd love to try them out for myself. There's no way 550/350 can be more comfortable than 162/118. If it wasn't for my blown shocks, my Miata would probably glide over bumps in the road.

I used to own a 240SX with BC coils, harsh ride. I then had another 240SX with Fortune Auto coils, better but still pretty stiff.

I'm not yet an old man, I just want to find the best compromise between handling and comfort without going broke.

Not an apples to apples comparison, but I'm running (IIRC) 550/350 on my NA, on Pro-Tech shocks with custom valving to match the springs - so a similar-ish setup to the Xidas.

The ride was a massive improvement compared to stock (on NA bilsteins) - sure if you hit a big pothole you can feel it, but the car remains composed. UK roads are pretty much as bad as US ones, and it's certainly not too bad to daily drive, and has worked well enough on the track when I've taken it there.

We also have a 987 Boxster-S in the family, in terms of suspension only - with the suspension on normal mode (not sport) it's not that much different in terms of firmness (although the rest of the car is much more refined).

I suppose what I'm trying to say is spring rates are only half of the story - how the shock is valved is the other half, if they are setup to work together then you are going to get good results. From everything I've read about the Xida range, they are properly thought out in terms of rates and valving so I don't think they are going to be as harsh as you think.

When I removed my old suspension they only had 45,000 miles on them, so it's not like it went from blown shocks to properly functioning shocks.

When a spring is too soft it rides lower in the stroke and creates a harsher ride as it blows through the available travel and begins to get into the stiff part of the spring or even the bump stop. Keeping the suspension higher in its range of motion means it works as it should.

On track with stock suspension the car would be locked onto the bump stops with the inside front wheel in the air, no bump absorption at that point.

Hmm yeah that's right. Conversely, having a spring that's a bit softer means that at rest it's compressed a bit, and when you go into a dip then the softer spring can extend to fill the gap between the tire and the dip. Your scenario covers comfort with compression, this scenario covers comfort with rebound.

I've actually experienced situations with my 240s where riding over a dip in the highway would actually cause the car to "fall" into the dip because there wasn't enough suspension travel to cover the distance. It jiggles all your internal organs and you feel awful when you get out of the car. Not fun.

Judging from the responses in this thread, I'd actually really love to try out the Xida coils, y'all are raving about them. Unfortunately they're vastly (bigly?) out of budget for me, so I can't consider them for this build. The GS coils would cost almost as much as I paid for the entire car.

I get what you are saying however you are on a turbo miata forum, most of us have spent much more on mods than the initial cost of the car. You can't really use how much you paid for the car as a metric for what you should pay for mods. I am using Koni/GC for the time being. With 350/250lb spring rates I find them to be acceptable and we have awful roads.

The stock Miata rates are designed to allow contact with the tall stock bump stops as soon as you start cornering. Settling with age causes this contact to occur more easily.

The car needs enough spring rate and travel to keep it off the stops in steady state cornering with your chosen tire. Stickier tires require more spring or more travel to achieve this. Stock rates were designed to get firmly on the stops with skinny all-seasons in a corner.

A 200 lb per inch spring will support 200lbs of weight with 1 inch of available travel but will carry 400lbs with 2 inches of available travel. 400lb per inch springs can carry 400lbs off the stops with 1 inch of travel. Lower cars need more spring and/or travel to not crash into the stops.

Proper digressive valving is important for ride quality, moreso than spring rate. Some "performance" shocks have way too much high speed damping, causing a rough, jittery ride over damaged or uneven pavement. Some shocks have too little low speed damping, making the ride floaty and uncontrolled. The proper digressive damping curve should inspire confidence and stability on smooth surfaces at speed but relax that control when irregularities are encountered so the tire can maintain surface contact and not unsettle the car or lose cornering adhesion. Xidas were optimized for the best of both with modern sticky R-compounds which is why they were recommended.

For a budget setup with a plush, controlled ride and wider than stock street tires, and lower than stock ride height (5.25-5.75ish pinch weld), I would reccomend the Bilsteins with 400/300 rates, cut down or replaced bump stops, and rear extended tophats. I had a similar setup and was amazed how much more comfortable than stock it rode. I was also concerned about the higher spring rates and didn't believe it could possibly ride anything but worse. I was wrong. It was much, much better.

TL;DR- Shock valving and travel contributes more to ride quality than spring rates, within reason.

FWIW, spring rates on Xidas don't actually feel as high as they may seem. My Xida Race 700/400 setup is way more comfortable and compliant than my previous FM stage 1 with 318/233 springs.

You're not going to get Porsche quality with Teins

Sixshooter and others have nailed it; I went thru the same debate with my Lotus Elise: horrible street ride with stock, lower rate(Bilstien coilovers) springs, almost as if it had wooden tires. Reading about the P-Zero coilovers the UK guy's were running made them sound great, but the spring rates were up quite a bit over stock Bilstien's, but I went with them and could not believe how it transformed the car; MUCH more comfortable ride, much better, controlled in a track situation. Probably the best $$ I'v spent on the car.

What you interpret as a rough ride on sub-200 rates is actually contact with the stops.

Hmm yeah, I've only been looking at spring rates without looking at damping as well. I wonder what exists within my budget of say, $700-800 that accomplishes what I want.

I know I shouldn't look at the price of the item relative to what I paid for the car to judge its value, but I also don't have $1700 to blow all at once. I don't even have the $800 to spend right now, this is a purchase I'm planning for the future.

So I take it that this setup might not be ideal for my purpose? It is within budget, so that's nice.
https://cimg1.ibsrv.net/gimg/www.mia...e659002ad5.jpg

I didn’t see anywhere what model/year your car is or really what your end goal is other then some nebulous comparison to a 2009 Porsche. If you’ll never see a track or an auto-x event just go out and buy the FM V-MAXX with the sway bars as a package. Install and drive... you could do worse.

2002 Miata, and yes I will be tracking the car on occasion

You could build yourself a set of Bilstein based 2.5" coilovers for close to the low end of your budget depending on how you source and shop for parts. Then just buy the Supermiata sway bar kit and install at the same time. You'll be just over a grand.

The thread has gotten a bit off topic at times but still usable: The Better Bilstein Ebay Coilover Thread