The Final Chapter! by BestCS

8-31-2009

Yup, this was my last foray into the world of MX-5 suspensions. The reason is I acheived what I wanted with the installation of the Racing Beat Springs. The car now has the look and ride that I wanted. I'll discuss each in detail.

First the look and some details first. Before you install any spring, you need some reference numbers to compare your installation to. What I did was measure from the fender lip to the garage floor on all four corners. Forget about measurements from the center of the wheel to the fender lip. They won't be accurate, and they'll be time consuming trying to guess where the center of the wheel is. Also, you aren't comparing the drop on your car to anyone else's but to your own. Also, the very best way to do this is with a full tank of gas. At around 6#s/gallon, this will make a slight difference in you ride height. Incidentally, Racing Beat includes a handy sheet to document your ride height before and after.

Unfortunately, I had measure my stock ride height with a different set of wheels and tires than I'm currently using on the car. The original measurement was done with the stock wheels with 215/45/17 Kumho Ecsta AST tires while the current wheels are aftermarket with the General Exclaims UHPs of the same dimension stretched over an 8" rim. Not only does this reduce the amount of sidewall protection, but there is some slight difference in the diameters between the two. The point is to do all your measurements using the same wheels & tires in each instance.

It's interesting to go to a new car showroom and make this same measurement. Try it with a car sitting on the showroom floor. You may find a surprising difference between corners. It isn't particulary important, since the eye doesn't pick up these small differences. About the only way a car will sit perfectly level is if it has a self leveling air suspension system or carefully adjusted coilovers. Anyway, my best guess of my stock ride height with the current wheels is 26.75". With around 5/8 of a tank of gas, the front is 26" and the rear 26.125" after the installation of the RB springs over the Sport Bilsteins. RB advertise these springs will drop the car 0.5", but this isn't an exact figure. If you properly install them, you should expect the drop to fall in a range of 0.5"->0.75". Anyway, the important thing is if you're satisfied with the look. I certainly am. There are a couple of pics.

What was most surprising was the improvement in the ride. The springs only have a 25% increase in rate, and I'm not sure how to factor in their contribution. The car now has a firmer and very comfortable ride. I drive down a street every day that has a big hump in it. I always go over it fast, and it is best described as the feeling you get on a roller coaster - weeeee! In the past, the rear always had a thump when it settled with the stock suspension, Pro-Kit with stock springs, and Eibach Coilovers. That thump is now gone. Also gone is the floaty feeling going around corners and still using the stock sways! The car corners fairly level, but admittedly not quite as good as the Pro-Kit or Coilovers. However, it's good enough for me.

I also discovered something interesting while reading a post by MXGeorge about his new Japanese Bar (hick!). He had to drop one of the dampers down to get the bar on. He then claimed that the feeling in the steering associated with "bump Steer" disappered! What happended was his bar was designed to be under some tension in a sense forcing the side of the car out, so when I installed the OEM FSTB, I put it on with the front wheels off the ground or the front suspension in full droop. I reasoned that this would draw the side of the car together and put some tension on the bar (it'd be intereresting to see what the WSM says?). Anyway, the steering wheel seems less disturbed by irregularities in the road (probably my imagination!).

How about some great deals on some tools? Autozone has a high quality spring compressor like the one they loan for $35. Also they have some Duralast car stands very similar to my Big Reds (but two tons) for only $25. You can't pass these deals up?

The cost of the Racing Beat Springs were $185 + shipping. This was a great mod which closes the book for me on MX-5 improvements. Just for the record:

1. Greddy Ti-C rear Muffler

2. K&N Panel Filter

3. Racing Beat Springs

4. Synthetic oil in transmission & 3rd member.

Now, I'll happily drive off into the sunset lookin' , feelin' & soundin' good with the sweet resonance of my Greddy!

Happy Trails Pardner!

9-1-2009

If I complicated things like you suggest, I'd still be measuring. I don't want to average anything. I just want to take the yardstick and get a number. I'll know exactly when I put on the original set, my winter tires, but it isn't really all that important.

Note I said ride and that encompasses a variety of conditions Previously, I wasn't hitting the bumpstops all the time; however, I did hit them from time-to-time. I may also hit them again, since I didn't trim them as RB recommended or buy the FCM's which would have been a good idea.

No you're wrong. When I find a decent compromise, I stay with it. I don't want the lip of the fender tight to the tire, and if the handling in this configuration isn't good enough, then I'm going around corners too fast. Also there isn't a whole lot to select from out there for spring choices. If I was a VW guy, I could get drops in quarter inch increments!