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Old 02-24-2010, 11:45 AM   #1
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Default Help break down spring rates

I know this will be beneficial for me, and I'm sure it will help others. Those of you in the know; Would you break down appropriate spring rates for the type of use? i.e.

DD
spirited DD
1-2 DE events a year
3-5 DE events a year
6-12 DE events
dedicated track car

I'm running 342lb front and 228lb in rear. This seems very lite when reading posts on this forum. I'm a 1-2 DE events per year and spirited DD.

Stewart development advised staying with my spring rates when getting his revalved shocks.

How much does spring rate matter when you are going to get custom revalved shocks that match your springs?

Would I gain much going to a higher spring rate with matched revalved shocks.

I get the feeling that a lot of people overkill their suspension when the primary use is DD. I really want to know where the spring rate line is between good DD/occasional DE and dedicated track.

I think this will thread will help people spend their money in the right place if they are honest about how they use their car.
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Old 02-24-2010, 12:26 PM   #2
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I am getting my Bilsteins revalved by Stewart too and we talked about spring rates. I haven't bought springs yet but he said to get 375/250 spring rates. I autocross my car, about 6+ events a year.
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Old 02-24-2010, 12:39 PM   #3
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Personally I wouldn't run anything more than 450/300 on the street, and my favorite setup was 400/250. Very apt handling, and comfortable with NB HDs. I imagine if you're getting a revalve you can street higher rates.

As far as damping effecting spring rates...I've always heard you spring your weight, then damp your springs. This applies to fundamental dynamics and vibrations problems, but the real life "feel" can be improved greatly with proper damping, making what we'd normally consider soft rates feel much more competent than they feel with OTS shocks.

If all springs were critically damped there wouldn't be this skewed anecdotal perception of spring rates, but few of us can afford proper dampers and make up for it with stiffer springs to improve feel and response, while minimzing body roll. In reality a proper shock will do all of this much better when combined with a spring rate suited to the mass and chassis balance of the car, and we instead put up with bouncy, jarring ride quality in the name of performance.



In short, your spring rates sound fine since you are spending your money on custom valved shocks.
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Old 02-24-2010, 12:39 PM   #4
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Subscribed. I've got a set of used GCs with 375/250 springs I want to install with re-valved Bilstein HDs. Judging by the rates some people are running here; 375/250 may be a bit light for spirited DD and a few track events a year.

For what it is worth, Shaik (FCM) says that his Bilstein re-valves are good for plus or minus 100lbs spring rate. Stewart probably has a similar spec if you ask. That provides some latitude to increase spring rate but won't get me to a 550 front rate.
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Old 02-24-2010, 12:51 PM   #5
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Forgot to make that point...

When I talked to Shaikh we wer going to valve mine for right at 450/300, which allowed me to run anywhere from 350/250 (good for street) to 550/350 (great for track) with the acceptable +-100lb/in on the front shocks, and half that in the back.

I think we can all agree you want to have the best possible valving out back, as well as a decent amount of travel.
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Old 02-24-2010, 01:02 PM   #6
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Quote:
Originally Posted by sn95 View Post

For what it is worth, Shaik (FCM) says that his Bilstein re-valves are good for plus or minus 100lbs spring rate. Stewart probably has a similar spec if you ask. That provides some latitude to increase spring rate but won't get me to a 550 front rate.

plus OR minus works in bother directions, have him valve for 450.

450 + 100 = 550

450 - 100 = 350


I'm in the same boat right now, if you read my konis vs bilstein thread. I'm running on 550/300 now, but have a combo of 400/250 that I can/will install to get better ride quality.
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Old 02-24-2010, 01:08 PM   #7
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Quote:
Originally Posted by Braineack View Post
plus OR minus works in bother directions, have him valve for 450.

450 + 100 = 550

450 - 100 = 350


I'm in the same boat right now, if you read my konis vs bilstein thread. I'm running on 550/300 now, but have a combo of 400/250 that I can/will install to get better ride quality.
This is my point about being really honest with what you plan to do with your car. If you never plan on seriously tracking your car, why not just have the shocks valved to something closer to your current/planned setup. I would rather buy new springs to match my shocks perfectly, rather than play in the wiggle room.

Good info developing

How harsh are the 550s brain?
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Old 02-24-2010, 01:33 PM   #8
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Koni says they are valved for 450 lb/in max. They are pretty harsh, read my rant in my other post about my feelings: https://www.miataturbo.net/forum/t44257/

If it was a race car, I wouldn't care.
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Old 02-24-2010, 02:48 PM   #9
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On her car, I've had stock, then switched to the full FM 2.5 kit with KYB AGX.

On my car, I've had GAZ coilovers w/ 350/250, now FCM full kit with short bump rubbers and 550/350.

Stock are stock, FM with AGX was similar to stock ride but better control, pretty good handling with the sways for DE, this is an n/a car.

The GAZ setup was harsher than the AGX on similar rates, the damping was inappropriate and not so good on rebound. Not jacking, but the opposite, lack of rebound control which makes for some discomfort on elevation changes. And, the total grip level was too high for such a light spring.

The FCM setup with 550/350. Unfortunately I didn't get a chance to drive it much before the winter came, but the ride was better than all the others, easily. To the point where I now wish I had gone with bigger spring rates.

Thinking about what gospeed wrote, to spring your weight, it is correct especially when you add in the grip you have. You are going to need more spring to support a really high grip setup, like what I'll get on the 275 A6, you won't need as much spring if you are on 205 Kumho XS. This is what I was running into with the 350/250 setup on my turbo on 225 NT01s, it just wasn't enough spring to not basically collapse the suspension onto the stops in large G steady state situations.

The point is, it matters less how many DEs you are doing per year, but how you are set up when doing them. I would imaging that if you are on 205 XS, doing a little DE/autocross, and wanted a great ride, a 350/250 would be baller, especially matched with the right valving. This could be made to ride like a 7-series, I have no doubt.

If you are on some 225 RS3 or r-comps, doing a little DE or dabbling in autox, 550/350 would be right, again with good valving, again, it will provide a great ride. Mine rides better than anyone would think in the realm of possibility for a Miata, not even exaggerating a little.

If you are very serious about DE, want great times in TT, have huge tires, and/or want a competitive autocrosser, something bigger like a 750+/400-500+ would be more along the lines of what you'd be looking at. If you are at this point, you probably would be testing instead of asking, and IMO there will be a point at which you can no longer control the spring in very bumpy situations. This is why I'm a little hesitant about going with a setup based around a 750# front, we have very bumpy lots, and I may have to give up a little ultimate grip in order to preserve some compliance over the rough stuff.

A bit of feedback I got on a similar question a while ago was from Andy Hollis. He said not to discount both the effect of valving on ride quality, as well as the type of tire effecting ride quality. IE, if you have a big setup, like an STS Miata has 550/350, if it's valved right it can be comfy. If you want it more comfortable riding, you can put some tires on it with taller sidewalls, at least for street driving. The tire also effects the ride.

Looking forward to reading some more responses.
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Old 02-24-2010, 03:01 PM   #10
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Consider your ride height and travel too when picking spring rates. The lower you run the higher your spring rates need to be to keep you off the bump stops. Alternatively if you have alot of bump travel, you can get away with running low with softer rates.

I'm running 750/450 but I do not daily my miata. Only street driving it sees is to and from the track. That said I am comfortable driving 3 hours on them. At 3 hours it's the seat that starts to bug me not the ride. I firmly believe that if you have the valving to support your spring rates, you can have a livable ride.

My 750/540 AFCOs are more comfy than my 7/6 tein basics.
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Old 02-24-2010, 04:54 PM   #11
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Great post webby!

If a cheap set of 550/350 springs come up before I buy shocks, then I might grab them. I plan on running the RS3 because I can get it in 225. Otherwise I think I will stay with what I have. I would question if I'm running even half as hard as some of you at my DE event. I can always have the shocks revalved again if I keep what I have and go stiffer. It's just money, right!
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Old 02-24-2010, 05:03 PM   #12
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chances are i'll be selling my 550/300 7" QA1 springs soon.
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Old 02-24-2010, 05:20 PM   #13
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shoot me a price when you do and I'll make a decision to stay with what I have or go stiffer.
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Old 02-24-2010, 05:29 PM   #14
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It wont be until sometime in March. I'm going to throw my 400/250s on and reevaluate from there.
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Old 02-24-2010, 05:31 PM   #15
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I just sent this email to stewart development. Please chime in if there is interest, so that way if he says yes, we can try to get something going.

How many orders would it take for you to give our forum a group buy price of $600 + shipping for four revalved bilsteins? We would pay, and you wouldn't fulfill orders until you received payment from the minimum number of required buyers within a given time period. All sales final unless you do not get payment from minimum number of people required for group buy. Then we would have the option for refund or continue with full price order.

Dave
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