Coilover setup

[mitch_f1]

So I have purchased a set of Tein Flex's which I have not yet installed, and am now debating whether I need them or not. To aid this debate I have a few questions from those in the know. Before we start a few things about me/my car: Regularly tracked, and looking at doing some competition racing in the near future, car itself is a relatively (intake/exhaust) stock NA6, I am not after stance or lowest ride height possible, just something functional.

-I have heard that you should, under no circumstance, adjust the compression/rebound adjustment at the top of the coilover to the full soft or full hard position. Is there a logical reason for this? It seems to be like having a built in self-destruct button right next to your engine start button.

-I have been reading the manual for the Flex, and from what I can gather you undo the lock rings at the base of the threaded section of the coilover, and turn the body of the coilover to increase/decrease ride height, is this right?

-If the above is true, then what am I adjusting when I screw the bottom lock ring under the spring up to the top (compressing the spring), or to the bottom (uncompressing the spring)? Is that all I am doing; adjusting the level of compression in the spring?

-When I am installing the coilover I want to adjust the ride height so that it best suits my car with no rubbing or anything of the sort. Assuming that the car is supported by jackstands, is it logical and safe to put a jack under the lower control arm (is there a strongest point to put it?) and jack it up to see where the tyre sits under full compression? Using this method do I keep jacking until it starts to lift the car, or what?

-My last question, which probably should have been my first question, is are coilovers really necessary? I track my car a lot; probably 3/4 of the milage of my car has either been on the track or to/from the track. Maybe it would be worth my while (and possibly save my money) to get my koni's rebuilt and experiment with different spring rates? Thoughts?

So just want to reaffirm that I haven't installed anything yet, and that I am just trying to get these things straight in my head before I tackle any of it.

[Locutus]

i've had a set of flex's in my NB for about a year now.

- never heard that before, but there is no stop in the adjuster preventing you from going beyond "full soft" (16 clicks from full hard). going beyond full soft can damage the shock. for this reason it is advisable that you adjust to full hard first, when making any adjustments.

- correct. you loosen the single lower locking ring.

- you are still adjusting ride height, but in doing so, changing the amount of shock travel. the lower the spring perch (aka upper locking ring), the less travel before hitting the bump stop.

- your method will work, however the springs will sag in the first few week or so of use so your measurements won't be accurate. i recommend you dial in tein's specs, drive it for a week, and then adjust as required. the place you need to jack will become obvious once you have the car up on stands.

- this is subjective. i would say not necessary, but in reality you aren't saving much between a set of flex's and a full shock rebuild & a good set of springs.

[Charlie Brown]

Page 4 of the tein instructions shows you the setup figures.
Use these figures to set the preload of the springs.
Page 5 shows you the height the car will finish. Check your current height and compare to this tein height. If you're happy, leave dimension A as per the instructions. If not, loosen the bottom lock ring and rotate the shock clockwise to lower the car, anti clockwise to raise it. One turn equals about 2mm.
This is with the wheel off, jack under the normal spot.

[Charlie Brown]

For those without an instruction manual, here's the link for the NA & NB. Sadly there's no English version for the NC.

http://www.tein.com/tech_info/inst/6m40u.pdf

My post late last night was a bit short from my iPad but I hope it made some sense.

Basically the adjustments work like this:

You have three locking / adjusting rings on the threaded body of the shock.
The top ring adjusts the preload on the spring. By this I mean that if the ring is wound up to just touch or trap the bottom of the spring, the spring has no preload. Keep winding up and you induce preload. You can add preload to reduce the amount the car settles on the spring when the car is lowered from the jack back onto the ground so the height of the car is effected by preload however there’s a ‘BUT’ here and it has to do with the Flex's bottom locking ring as described below and droop. More preload = less droop. Droop being the amount the wheel can travel down from the static position. Ideally you want a long stroke length, preloading reduces stroke length as the distance between the bumpstop and top of the shock reduces. The middle ring just locks the top ring in place.

The Flex allows you to set your preload (be it zero if you’re a track car or some preload if on the road) and then adjust the height independently of the preload. Some other coilovers, Superstreet for example, the height is changed by varying the preload. They have no lower adjustment for body length.

To adjust the height of the car (with it jacked up) you just release the bottom locking ring, grab the top part of the shock body (spring and all) and rotate it so it screws down or up in the lower section of the shock body. Screw it into the lower body lowers the car.

So it is extremely easy to raise or lower your car to suit your requirements. Crank it down for track days and when you take the track wheels off; crank it up for daily driving. I brush the threaded body down and give it a squirt of bottled compressed air to clear grit before adjusting. I also use WD40 on the thread and on the top of the spring to make it easy to turn.

The 16 stage click adjustment on the top of the shock should be wound fully down (clockwise) to full hard and the clicked back to your desired softness setting every time you make an adjustment. The instructions warn about not exceeding the 16 clicks, otherwise damage will occur.

So set the shock up as per the manufactures instructions and then vary the height using the bottom ring.

Hope that helps.

[mitch_f1]

So to adjust height I do not have to remove the bottom bolt, the entire body of the shock rotates (when the top hat is bolted in, and when the lower bolt is bolted in)???

Also, I should have mentioned that the Flex's are not new, they are used, so would have settled in by now.

Also, preload, what handling characteristic does this adjust/change?

[Locutus]

yes - you don't need to unbolt anything to adjust the height after installing. just loosen the correct locking ring and rotate either the spring (spring perch height adjustment) or entire shock assembly (shock body length adjustment).

my teins weren't new either, but the springs still needed time to settle. i was surprised to find that when i first dropped the car, the front was slightly higher than stock!

other than suspension travel, i don't know how preload changes handling characteristics TBH.




CB, how does preload change suspension droop if the spring rates are linear?

[mitch_f1]

"be it zero if you’re a track car or some preload if on the road"

Also, Charlie Brown can you please explain this comment here

[Charlie Brown]

"be it zero if you’re a track car or some preload if on the road"

Also, Charlie Brown can you please explain this comment here

Very Important. You should first set it up as per the Tein instructions. They are the experts not us amateurs.

In my case the NC instructions were in Japanese and not as clear as the English version for the NA & NB.

I spoke with a well know NB racer about what preload I should apply and was told to just tighten it enough to capture the spring, which I did. The problem was that I was hitting the bumpstops regularly which made the ride uncomfortable. So while I had the important parts of the Japanese instructions translated into English, I put in a call to the Aussie dealer to find out about how much preload I should have.

The manual said 5mm, the dealer 10mm, so I set it at the manual’s 5mm and I put a cable tie around the shock shaft to see if the shock body still hit the bumpstop. It did, so I increased the fronts to 15mm, left the rears on 5mm and cut the bumpstops down. It still hits the bumpstop but not as bad as before.

I’m a little short of time at the moment to crank in more and hesitant about putting too much preload on as I don’t want ‘spring bind’ to occur.

So to answer your question I’ve cut & pasted this quote from another forum:

“What good is preloading the spring then?

It can provide you with more suspension travel in certain situations. In the ideal world, having the spring at 0 preload would place the piston inside the shock exactly halfway through it's stroke (middle of shock) once the car's weight is resting on the spring. This is almost never the case. By preloading the spring, you can adjust the amount of rebound, or compression travel you have in the shock. If you preload like 200lbs, this will give you more compression travel, and will help keep your car from bottoming out when cornering. You have to be careful though, because you don't want to sacrifice too much rebound travel, or you could cause all sorts of other problems.”

Track cars strive for maximum stroke so they don’t overload the tyres under compression or loose grip under suspension extension. On the road we look for more ride comfort. In the NB that may well be with no preload on the Tein springs, it isn’t on the NC.

So as I said in the first line, set it up as per the Tein instructions.

[mitch_f1]

Charlie Brown, you are my hero. Thankyou so much, the information you have provided is invaluable!

[mitch_f1]

Okay, so I am in the process of setting them up as per Tein instructions, but I first have two questions:
-The adjustments, do I do them A B C D, or is there another order. Because changing one is going to change the other?
-How close are they supposed to be to the instructions (there is an accepted variation given for some but not others), and compared to either side of the car (like if one side is 2mm off of the other side)

[Okibi]

Excellent post(s) Charlie Brown, very informative.

When I installed my flex many moons ago I figured i'd start with the tein recommended settings and go from there, I haven't touched them since.

[mitch_f1]

If anyone was interested, I just found this thread over on m.net and it is everything I could have ever dreamed of, and more, in terms of setting up coilovers. http://forum.miata.net/vb/showthread.php?t=266038