Very interesting, thanks for that. I had seem an allusion to this earlier in the thread but never looked into it after finding some other threads prodding at the data a little.

Looks like using 600f/325r gives me a 58.4% FRC assuming consistent calculations on rear sway stiffness. I'll have to do some measuring and see how much stiffer the rear bar is when it's on full soft and do a % based calculation. There was a miata at the local pull-a-part but I missed the rear sway on it.

With the "option b" running 500/275 yields a 58% frc, but that gets into the territory where i'm afraid that the spring rates will be too low. I'lll measure this rear bar, but feels like I should just track down an OEM sway

 

If the spring balance ends up being off further than the adjustments can compensate for, buy the next softer/firmer springs and re-sell the old ones.

I'm on 550/350 with a 1in front full firm and 5/8in rear bar full soft, but the bars have different arm lengths between 1.6 and 1.8 cars, I believe. Mine is a full weight '96 with A/C. It's reasonably well balanced on the track but I'm not 10/10ths like the real racers.

 

I finally read through the whole thread and then put together a spreadsheet of my build.
https://docs.google.com/spreadsheets...it?usp=sharing
However, I need you guys help me improve the list before I order everything. Please let me know where to get better quality parts and for cheaper.

I want to go with Hyperco springs on all 4, but eshock doesn't have the 300 lbs rate that I want for the rear. Should I just buy the available Eibach springs instead? I'm not sure which brand is more reliable.
About the bump stops, which set from FCM is ideal for my set up?
And are those Torrington thrust bearing really necessary and worth the money ~$55?

I have a base "99 Miata with stock suspension, beside the Eibach pro spring set. The car is my daily and I do take it to the canyon very often, so it's a dual-purpose car.

Thanks in advance!

 

If you're serious about brand vs function you could look on Summit for no brand 7" springs. Bump stops are also available there for less than FCM and cut to length. Re the thrust bearings, no you don't need them but will need to put something on the collar to keep the spring from chewing it up. Use another isolater.

 

^All of what he said.

 

Thanks for the reply. I want to save money but I don't want to go for the cheap quality parts either. I think I will just buy the Hypercoil and have a peace of mind. Anyway am I missing anything from the shopping list?

 

For those that would be interested I've found a potential source for revalved Bilsteins. The Inertia Laboratory guys are located here in the DFW Metroplex. Their head engineer worked with AST around the same time they were supplying Emilio with shocks for the Xidas while John is an active member of our local Miata Facebook page. I will probably look into them to see if I can get a good revalve on my Bilsteins this summer.

 

Inertia Labs is also who services Xidas, and I believe the people who worked with 949 and Tractive to make the current gen Xidas.

 

.

 

What's your ride height? I'm running a similar setup on MSM Billys (7", 550/350) and with the sleeves adjusted all the way down, I'm still over 5" at the pinch rail. Seems high to me...is this normal?

 

Are you running drilled out NA tophats or something? A higher C-clip slot? A thick rubber piece between the spring and tophat? Do the sleeves sit right on the C-clip or do you have a perch in between? Are your sleeves threaded all the way to the bottom or do they have a non-threaded lip at the bottom? Is the adjustable perch thicker (taller) top to bottom than mine?

Please take pictures of the sleeve's position on the C-clip, the adjuster itself, and the underside of the tophat where the spring meets it.

 

NB tophats, stock c-clip location. I am running a rubber spring isolator between the spring and top hat (blue, pictured above).

 

From the pic he has ebay sleeves which sit ON the clip + 2 adjuster nuts. I think this thread got away from the ebay stuff pages ago in favor of the QA or Allstar/Advanced Autpsports sleeves.

Mine are just like yours and with the nut pretty much at the bottom + 7" springs you just can get to the 4.25-4.5 height.

 

Here, I measured a rear shock off a set I have on my workbench. You can see or calculate the difference in the height of the spring seat.

With the Advanced Autosport Spec Miata sleeve the top of the nut is .233" above the circlip (assuming the circlip is .062 it may be slightly more/less).

I don't have a set of ebay sleeves to measure the collar thickness but; 1. you sit ON the clip + 2. you have approx .125" to the bottom of the first collar + 3. the thickness of 2 collars.

I don't know, maybe 1.125" from the top of the clip to the top of the collar so that gives you a difference of .892" +/- which explains why you can't get lower. Change the sleeves.

 

Brilliant. I was eyeing those rusty *** circlips, I wanted a sleeve that captures them. This gives me a good excuse

 

Your shock bodies are going to rot through soon enough if you don't do something to stop them from rusting more. Maybe wire brush + POR15 before re-sleeving.

 

You can also get lower by losing the blue spacer on top of the spring as mentioned in posts #41-50 of this thread. And by using a sleeve that goes over the c-clip (as mentioned above) and by using a sleeve collar that locks with some mechanism other than the two rings (because two can take more space than just one). See pics below of mine from post #40.

Also know that lowering the shock height by one inch yields more than one inch at the wheel because the wheel is further out on the arm. I cannot recall what the ratio is off the top of my head.

 

My shocks are garbage and I need new sleeves. Whelp, time to buy Xidas.

 

This probably isn't the place for this but...


What's the current going rate for a set of low mileage, good condition MSM bilsteins? Just the dampers?

 

I've seen them as low as 200$ and as high as 350$, new HD's are in the 450 to 500$ range.