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Discussion Starter #1
I think this is my first time posting on this forum but I've been floating around reading it for a bit,
Anyway I see a lot of people here running flex and a few other full coilover setups. What do you guys think of the one in my title?
I am choosing bilstein because they are monotube and can be revalved later for cheap, to match my spring rates and have a better feel.
I want the car just under 13" height so that's why I want the GC.
I drive hard in the mountains, and want to get into some track days and autocrossing for experience.
Anyone running this setup? Opinions? I've heard lot's of votes for koni, but they are more expensive initially, and to revalve.
The FM springs look like they are too tall, but otherwise sound good.

Thanks,
Scott
 

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Discussion Starter #3
A lot of people say the bilstein are too bumpy over rough terrain. Are they being oversensitive or is it a crappy ride? Most aftermarket performance suspension I've been in is bumpy over rough stuff. I have felt bilstein's before, but I can't use it as a comparison because it was on an Audi A4 with neuspeed/bilstein, and it felt NICE.
I know they'll be good after revalve, but what about as is, OTS?
Also thinking of 46mm bumpstops from FCM.

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I'd like to get konis eventually but over all Im very happy
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Sid,
Any reason you would choose koni over bilstein?

Scott
 

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Scott,

Ahh, the black art of suspension.

I'm on KONIs, CG, FCM bumps and FM mounts all around. One nice thing about KONIs is their adjustability. If you change your spring rates, you can adjust the dampers to the new rates. Regular Yellow konis are good to about 450 lbs up front, I'm currently using 500 lbs with good results. But before I was an auto-x junkie, I used the konis with stock springs, then later FM springs (342/228). No revalve required.

Choose your spring rates carefully. If you want your car at 13 inches (which I think is a pretty reasonable height, not too low), you will need reasonably stiff springs to keep you off the bump stops (although the FCM kit is great and will help with travel). The FCM bumps are a necessary part of my setup and my setup would not work without them. I have 500lb springs up front with the FCM bumps AND the FM mounts, and I have my ride height at about 12 3/8 inch. I can probably get away with lowing the car a little more, maybe down to 12 inches, but these New England roads won't tolerate that low of a car. My point is that the lower you go, you are going to need a lot of spring.

What kind of rates were you thinking about?

I think once you figure out what rate you want, then you can look at what dampers are going to work with that rate.

Bruce
 

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Discussion Starter #5
Thanks for the reply Bruce.
I think I'm probably looking to go closer to 12.5" ride height or as low as possible without ruining driveability.
I am now second guessing the standard ground control rates (375F/250R) and I think I may want it more firm than that for my intended use.
I think that I am going to have some shocks custom valved right away istead of dealing with OTS valving and I have been talking to some people about it so Spring choice IS now my big question.
Do you have a suggestion for spring rate on something that would be driven on the track and for fun in the mountains/trips? I would really like to get into track and some autocross and that's why I actually got this car. However, I don't want a dedicated track car yet.
It seems there are a lot of different spring rates being run and would the (375F/250R) GC be a bit softer on track?
How is the 500lb on streets? What do you run on the rear.
Would you go stiffer if your shocks allowed it?
I plan on running an upgraded front sway bar with no rear bar.
 

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(edit 1/14/07) The amount of travel listed below is in error. I checked my notes and the upper control arms contact the chassis at 8.5" in front and 9.5" in back. In front you will likely run into tire rub issues if ride height is set too low and springs not stiff enough. Bottoming out the rear is a possibility if ride height is set too low.

Scott,

I think setting a 12.5" height with 375/250 springs might hurt drivability. I don't think you will have enough reserve travel to soak up bumps mid corner at the limit.

Miatas have fantastic suspensions if setup properly (so good that a properly setup CSP car can lay down times competitive with Super Stock cars on some auto-x courses). The big limitation in miata suspension is lack of total travel, especially M1s. The front bottoms out at about 9 3/4" and the rear at about 10". This is a hard bottom with the upper control arm contacting the chassis. If you set your rear to 12.5", you only have 2.5" of total bump travel which is fine around town and probably even spirited canyon carving, but not good enough for auto-x or track events. For example if you corner hard enough to put a 2 degree roll in the car (which is not that hard), you will eat up almost 1" of travel on the outside wheels. That only leaves you 1.5" before you bottom out. Shock load the suspension with a good sized bump and you can bottom out and slide that end of the car that runs out of travel. If you have high rate springs (and the tires that can accept that rate), it isn't a problem.

I'm currently on 500/300 and this is enough rate for now. I have more rate than my tires can handle (RA-1s), at least for auto-x. I'm hoping to move to dedicated auto-x rubber this year and that may precipitate a change to a higher rate (probably 600/300) and a front shock revalve or replacement (koni race).

The standard GC rates are just a starting point IMHO. I think the next "standard" rate above the 375/250 is the 550/375 combo, which I think would be a very loose, oversteering setup, even with the rear bar removed / disconnected. Might not notice it on the street, but you certainly will at auto-x and I would think it would be rather scary at track speeds. Could you imagine tipping your car into an 85mph sweeper with the rear wanting to come around? Ugh!

If you are set on a 12.5" ride height, I think you will need much more rate, closer to what I'm using, maybe 450 / 250. Take that recommendation lightly, since I don't know if you are driving an M1 or M2, the damper you will end up with or your driving style / experience level or how much of a streetability compromise you are willing to make to find some speed. With these rates, I would set my ride height to 12.75F and 13.25R. That is just my initial humble recommendation.

Your idea about not using a rear bar is valid. The higher you go with spring rates, the less rear bar you will need. I don't run a rear bar, neither do practically all fast CSPers (not that I'm a fast CSPer). I currenlty use an FM front bar (about as stiff as a RB hollow bar, only heavier). I also think that 375/250 is an area where you might be between needing a rear bar or not. That will be very subjective, but I woudn't waste my money on a stiffer rear bar. If you need a rear bar at all, the stock one should be stiff enough.

Each component of your suspension is highly dependent on the other components, so ultimately you need to link all your suspension choices together so that they work well as a system, then spend the rest of your life chasing the perfect setup.

We haven't even talked alignment yet...

Bruce
 

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Discussion Starter #7
Wow, Thank You VERY much for your time and answer Bruce!
This was very helpful; I definately know I have a lot to consider.
Ride height will become less of an issue to me if it can so negatively effect the cars handling capabilities. At least adjustable spring perches can help me dial that in, and hopefully I can find one of these alignment shops that offers lifetime alignment, near me.
My car is an M1 (1995 torsen LSD) and I don't want it to be oversteery with just the springs (without the help of the rear bar).
I will go into detail with the person who is customizing the shocks about the things you have pointed out to me; like ride height/spring rate/travel balance. I was unaware that the control arm bottomed out on the chassis so early.
Thank you very much.
I like the idea of the spring rates somewhere around 450F/250ishR for a good balance of grip, absorbsion, firmness, and stability.
I'll do some more thinking/researching!
Wheels, tires, shocks, bumpstops, springs, sway bars, roll bar, alignment, nut behind the wheel... So many imprortant mods!!

Thanks again,
Scott
 

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Scott,

Great that you have a torsen in your 95. That makes a huge difference in how you can set up the rest of the suspension.

My 95 was open originally and I later added the torsen when I started to have difficulty gettting the power down coming out of corners on course. I felt like I was waiting to really get the throttle down. I had read that the torsen would help comiing out of the corners and that was indeed the case, but I also found that diving into a tight turn on the brakes with the torsen, the rear end was much more stable and confidence inspiring at corner entry.

Cars with torsens, IMHO can be set up a little stiffer in back, and the numbers I shot at you were for a car with a torsen. Without an LSD, I'd back off on rear stiffness a lot, but that is irrelevent for you.

Please note my edit in my last post about hard contact with the front and rear suspension. In front, even though hard contact is at 8.5 inches, you can only really get to about 9.5 - 10 inches of ultimate compression before the front tires start to rub on typical 15" street sizes. So although there is more travel available, you can't use it unless you are on tiny wheels, i.e. 13 inches.

On your comment about an alignment shop. Find a shop that does PRECISION alignments for enthusiasts and understands performance alignments. Some shops have great alignment gear like Hunter LEDs, but only align your car to factory spec, which on a miata means toe spread between left/right can be up to 8mm, and camber angles can be as much as 2 degrees different, left to right! That isn't good enough. Just because the shop has the best rack doesn't mean they know how to use it or understand alignment. A buddy of mine has aligned his Mini with string and has done a more precise, repeatable alignment than a a shop I've tried up here in New England.

I would encourage you to not even think about price for your alignment, but instead find the best alignment man you can and pay whatever he wants. A good alignment man is an artist and hard to find. And not just a guy who can dial in the numbers that you want, but a guy who can come up with a good setup based on what you are trying to accomplish. The guy I used in San Diego, we never really talked numbers. I would tell him what the car was doing that I didn't like and what I would like the car to do. We would have a dialogue as he would verify what I was after, then get to it. With my car on the rack, he would look at the baseline numbers, then keeping my desires in mind, change the suspension to meet that desire. I've been more than satisfied everytime I've used him. Now that I'm up in New England, I've had to spend time coming up with my own numbers which is fine, but I always get that "Are you sure you know what you are doing with these numbers?" Some shops won't even align your car if you want something out of factory specs.

Without a precision alignment, you'll never realize the true potential of a car that goes where you want it to go without even thinking about it. The alignment man is going to put it together for you.

Once you get closer to getting it all done, if you are interested, I'll try my best to give you some alignment numbers that will get you on the way, based on your desires, driving ambition and style. Anything from mild to wild is available in a miata.

Again, I apologize for the incorrect measurements in the earlier post.

Bruce
 

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Discussion Starter #9
Yeah, that is definately true about shops with good machines and bad mechanics! I've brought in a WRX to get aligned, and had inconsistancies on every measure, at every corner! It's pathetic they can get away with something like that for $70. I have heard of people spending $120 for a precision alignment though.
I think there is someone pretty popular out here that does alignments by hand, (without machine) that is supposed to be one of the best. He takes his time and finds out what you want. Definately something for me to consider, thanks.

There are a couple common alignment references that I see;
Lanny Alignment: which is geared more toward aggressive street.
Icehawk Alignment: which is better for auto-x and track, being more aggressive.

I was, most likely going to start out with the Icehawk to get an idea of what I prefer, but when I get my suspension (I was told next month as currently it's being tested) it would be great to hear some more alignment numbers or suggestions from you.

Currently my car has fairly lightweight 15" wheels (konig minuz, 11.8lbs) for the street, but when I'm ready to track I've been thinking of and reading/hearing good things about 13"x8". The 13x8 rota RB sounds like it could work for me, allthough it is a bit heavy, it's not too expensive and has credability. Along with some good tires, I would get some great grip and as you said, some extra travel.

Thanks alot for all of your help Bruce, it's very much appreciated!
I can't wait for everything to come together so I can finaly get some track time! I will post a new topic when I get my suspension parts, and I could PM you then if you are still interested. I can't get enough of talking about this stuff either, so if you have any suggestions or anything I should know, get, or research, feel free to let me know.
Thanks again,
Scott
 

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(
I'd like to get konis eventually but over all Im very happy
)
Sid,
Any reason you would choose koni over bilstein?

Scott
I would pick the koni just because everyone seems to skip bilstein/kyb and go to koni when talking about "serious" shock for "serious" blah blah blah. I have no basis for comparison so it just comes down to what Ive heard said. maybe someone else can chime in on why koni over any other brand but I suspect it might just end up being preference and usage.

basically the adjustment comments are why I picked koni, Im running 450/375 and want to bump up to 500 in the front in the future, and would like the range of the shock to be able to handle it.

I cant answer anything better than what has been posted really great info!
 

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(edit 1/14/07)
The standard GC rates are just a starting point IMHO. I think the next "standard" rate above the 375/250 is the 550/375 combo, which I think would be a very loose, oversteering setup, even with the rear bar removed / disconnected. Might not notice it on the street, but you certainly will at auto-x and I would think it would be rather scary at track speeds. Could you imagine tipping your car into an 85mph sweeper with the rear wanting to come around? Ugh!



Bruce
I agree. I've heard that a 2:1 spring ratio works best.
I had the 550/375 GC Koni on my 95 with 1 1/8" hollow front sway bar and no rear bar. Loose and lots of inside wheelspin. I changed front springs to 700 and it is near perfect.

Whatever rates you choose, get shock valving that can handle it and be sure that you are off the bumpstops and there is no coil bind. Personally, I'm very impressed with my Race Koni/GC setup.

/Mike
 

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Discussion Starter #12
I agree. I've heard that a 2:1 spring ratio works best.
I had the 550/375 GC Koni on my 95 with 1 1/8" hollow front sway bar and no rear bar. Loose and lots of inside wheelspin. I changed front springs to 700 and it is near perfect.
At 700 up front are you able to drive this car on imperfect surfaces or streets well/controlled? Those are stiff springs, and seem like they would hop on bumps, unless the damper match eliminates that somehow.
Sounds like it would be effective on tracks though.

Thanks for the info,
Scott
 

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Daily driver. The Konis do a wonderful job, but bad roads and big bumps are not fun.
Very streetable IMO. I am still impressed with how good this combination rides.
-Mike
 

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(edit 1/14/07)
The standard GC rates are just a starting point IMHO. I think the next "standard" rate above the 375/250 is the 550/375 combo, which I think would be a very loose, oversteering setup, even with the rear bar removed / disconnected. Might not notice it on the street, but you certainly will at auto-x and I would think it would be rather scary at track speeds. Could you imagine tipping your car into an 85mph sweeper with the rear wanting to come around? Ugh!



Bruce
I agree. I've heard that a 2:1 spring ratio works best.
I had the 550/375 GC Koni on my 95 with 1 1/8" hollow front sway bar and no rear bar. Loose and lots of inside wheelspin. I changed front springs to 700 and it is near perfect.

Whatever rates you choose, get shock valving that can handle it and be sure that you are off the bumpstops and there is no coil bind. Personally, I'm very impressed with my Race Koni/GC setup.

/Mike
This is a good discussion and I'm glad folks are getting technical with this stuff. This is also my first post on Clubroadster so of course it would have to do with suspension ;)

First, comments on Koni Sports/RACE. Yes, there is a knob and that makes tuning for different spring rates easy but they are not as high quality a damper as Bilsteins, and revalves for Konis are much more expensive. You're also limited with how far you can take them. Bilsteins are excellent quality shocks and if anyone has followed discussions on the revalves at Miata.net, you'll get an idea of how much potential those shocks have. It's beyond just turning up the rebound for a stiffer spring, more into the realm of how Moton/Penske/etc. works.

I drive my '93LE hard (backroads, autox, etc.) and it has stock springs. I'll probably throw FM springs on there and revalve the Bilsteins to match, but won't go any higher. While it's true you will have the ultimate predictability by staying off the bump stops, this does involve very high rates which are not that street-friendly. I won't go there again. The 375/250 rates are well-chosen and with good damping, enough travel and a reasonable ride height you'll be quite happy. There is also a very nice feel to driving on stock springs and you can make it quite controllable. I was drifting pretty good around some turns at the PR Motorsports Tech Talk a few weeks ago when I took people for rides!

The key to making the suspension work is designing as much predictability as you can. Good dampers are the biggest key, and then handling travel, whether you use a lot of spring and stay away from bump stops, or make use of progressive stops as part of the car's handling dynamic.

My suspension spreadsheet is a great tool to play with you so can see what balance you get with different springs or sway bars. Look at the FRC (%) for various setups and feel free to email me if you have questions about how to use it.

http://fatcatmotorsports.com/FCM_MSDS_v7_1.xls

Miles of smiles,
Shaikh
 

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Shaikh,

Good to have you on the forum. I've used your spreadsheet to help me dial in my CSP setup and still refer to it to try different ideas. It has been an essential tool in setup for me.

Mike mentions that the 2:1 ratio works well and I agree with that for stiff setups. I think for softer setups, you can get away with a smaller ratio. Stock on my ride would be about 1.64:1 (1995). Somewhere between stock and csp stiff, the ratio transitions from 1.64:1 to 2:1. Seeing that 600 / 300 (without rear bar) is a pretty popular csp setup (or at least in that neighborhood!), you could probably draw a line that charts that ratio between stock and csp stiff that balance similarly to the driver. Using the spreadsheet to take it further, one could look at the F/R roll couple ratio for stock vs popular csp numbers and do the same, taking into account sway bar changes also.

Bruce
 

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Shock valving is EVERYTHING. People thought I was crazy shooting for the rates I wanted, but my car feels no stiffer than my buddy's bone-stock STi, which is known for its good dampers. I agree that 450/250 on OTC Koni Sports is a great way to go. If you want to go low, pick up Shaikh's NB upper mounts to increase the travel. The RACE shocks are an inch shorter than stock so I am able to run my car at 12F/12.5R on standard NA upper mounts with no adverse effects.
 
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