I recently bought and installed a set of used Tein Flex coilovers from a fellow Evom poster (thanks tlim!). So far the ride and handling is far superior to the stock set up. The car is much better planted to the road both at speed during highway cruising as well as in the twisties. There are a few roads nearby where I live that are really tight and twisty. Some are tight radius, off camber corners that travel over the top of small hillcrests. You know, the ones that really get the wife's, girlfriend's or significant other's butterflies churning in their bellies. With the combination of off camber and crests, these types of turns would totally upset the stock Evo suspension but the Tein set up handles them with ease. I love it.

Still, I have to ask myself if I've got everything even remotely dialed in to where it should be. I'm a newbie at suspension set up so I'm open to any constructive criticism or advice. I realize the Teins are not the ultimate coilovers but I think given that 99% of my driving is on the street with about 6 to 10 track weekends per year they're fine.

Setting up the ride height and damping seems straightforward, especially once I figured out that Tein's directions for setting damping force are wrong. On the dampers I have you must turn counterclockwise to increase damping force versus the clockwise direction indicated in the installation manual. Once I got things figured out it was a simple matter to dial it in to remove the bounce from the suspension.

As far as preload goes I barely have any dialed in, perhaps a 1/4" or so at all four corners. Are there any rules of thumb or guidelines for setting preload? It's my understanding that preload will affect cornerweighting, effective spring weight, compression and rebound damping.

Any ideas? Are there any good books that discuss the principles of suspension set up?

Thanks,
Steve

 

Steve the best thing to do is to find a good local road race shop that can actually corner weight and align the car while you sit in it. Anything else is some form of guesswork. Glad you like the improvement allready can't wait to get some coilovers on mine!

 

Ultimately, yes, I'll definately get the car corner weighted and aligned once I find a local shop I'm comfortable with. Until then I'd be happy just getting things to 7/10s or 8/10s of where it should be. I might be there already. Right now the car feels very neutral in comparison to the OEM struts, with little to no understeer and the rear end seems a little less susceptible to lift throttle oversteer now. I guess some more seat time will give me a better handle on the shortcomings.

 

When I first set up my JIC's I had about the same pre-load dialed in as you do. Over the last 9 months I've moved to about 2 turns of preload. I've experimented with as much as 4 turns, but ended up backing off preload off to where the suspension is now.

More preload will make the suspension harsher over fine seams and ripples. It can also remove some of the bounce and/or float when the suspension is lightly loaded. To much preload will limit the effectiveness of your dampers and make your car skip or hop over bumps.

I tuned mine by dialing in preload until I had lost most of the pogo-stick ride my JIC's had aquired after 6 months of hard use. From there I dialed it back out until my car no longer skipped or bounced over the bumps and pot-holes I have to contend with. I also had to do some tuning with my damper settings after each preload change to find the best setting.

If you drive hard, have a race shop cornerweight your car. They should be able to dial your wedge to nearly 50/50. If I remember correctly, my wedge from the left front is 50.05% and my wedge from the right front is 50.03%. Corner weighting will allow you to make sure all of the weight is where it is supposed to be. My baseline before corner weighting had over 100lbs difference beween the weight on my right front and left front wheels. The difference in the back was even worse. And there was over 150lbs difference between my front to rear splits from left to right also. I could feel the car was way off, but all the ride heights were correct. After a proper corner weighting, my ride heights are almost exactly where I started, but the car is dead on - about 7lbs difference side to side in the front and just a bit more in the rear. Have the shop set up your alignment, too. An alignment is always a good idea after major suspension work.

On the track my car is solid. No funny transitions or wierd behavior, and it feels extremely confident at the limit.

 

So the ride quality of the JIC's deteriorated in 6 months?

 

I wouldn't say they went bad, just needed to be revisited. The springs seemed to "settle" a bit and the dampers had some wear. The freeways where I live are like going 75 mph across a lake with a bunch of waves in a very light boat. The car is always moving either up or down; rapidly. Even the stock suspension feels a bit bouncy on these roads.

I had pulled out my JICs and put the stock suspension back in to send my coilovers to RRE for the "John Muller" touch. Before I had sent them off, I ended up buying cams, valve springs, track wheels and tires, and a few other bits. I decided to re-install the JICs and see if I could get them dialed in any better and wait a bit before going the RRE route. My wife was asking how much *more* I planned to spend on the car this spring...

While my coilovers were out of the car I had them apart for cleaning and such, and only had all my measurements to use for reassembly. When I put everything back together and my ride heights set, I could feel that the suspension was "off". I knew the car was going in for cornerweighting before any serious driving, so I just worked out my preloads and damping. I knew that I could still make small tweaks after the cornerweghting and alignment were dialed in.

BTW - A big thanks to Noah at SpeedLab (Minneapolis area) for putting up with me while we kept working the cornerwights. He spent extra time dialing my car in and working both the wedge and ride heights to get them right where I wanted.

 

Thanks guys. This is some good information.

I experimented a bit with the preload last night and I was able to take out nearly all the pogostick bouncing. Ithink I've got a bit more tweaking in the rear. Fortunately it only takes about 10 minutes to pull a wheel and make an adjustment so I'll play some more tonight. So far the results have been very satisfying. Once I get my preload and damping set up where I like them I'll take the car and have it corner weighted.

 

Glad I could help!