Coilovers

Intro: When I first bought my Rx-7 from one of the 4 or 5 previous owners he told me that one of the other previous owners installed a set of used R1 shocks courtesy of PFS. The R1 shocks are very respectable and I really didn't see any cause to mess with such a perfectly balanced car.  However with 130K reading on my odometer I figured chances were my shocks were on their way out and figured I might as well upgrade. At first I decided I wanted what Mazdaspeed had to offer, which had a dual rate spring and was developed specifically for this car. I shelled out around $1700 through Corksport. As it turned out I ended up waiting a few months for a product that was discontinued. Honestly though I knew very little about coilovers and was basically banking on my idea that Mazdaspeed did my research for me. Mazdaspeed replaced their version with a newer version with an external cylinder for dampening but the price was higher and I became unimpressed with the design. So the long process of becoming educated began. I focused on two guiding principles. First was the theory behind building a shock, for example what difference does piston size make and what spring rates should I desire. Second was reputation but not just in the US market but in Japan as well. I went to great lengths to research the Japanese market including buying several Japanese magazines that compared shocks and talking to people from Japan. With these two research points along with price it became a process of elimination.

Features: One of the advantages of upgrading the shocks is the ability to get adjustable dampening. Normally you get a dial at the top of the shock that adjusts compression and rebound together but a few shocks are double adjustable meaning compression and rebound can be adjusted independently. I'm not the kind of guy that buys stuff just to say I have it but instead actually use what I buy to the full extent. So if adjustability is something I buy I need to know how to use it, which is a semi daunting task. I decided that adjustability was something I wanted but not double adjustability. I just didn't think I would ever be knowledgeable enough to take advantage of double adjustable shocks. I also wanted something with clicks instead of an infinitely adjustable dial where I could unbalance the car left to right. Also fewer the better, maybe 5 through 10. Next I decided I wanted a complete kit. This is contrary to what many of my fellow Mazda enthusiasts do, which is to buy a Ground Control kit (your choice of spring with threaded shell, perches and associated hardware) and their choice of shocks, normally Koni. This has proven to be economical at less than $1200 and very respectable on the track. I however considered that the shocks were not being valved specifically for the springs. This can be done but the price jumps considerably. I decided a kit with shocks valved specifically for the springs was a better option. Next is ride height adjustability independent of stroke. Many coilovers claim to be height adjustable but in doing so you raise/lower the spring perch, which in turn changes the stroke of the shock (lowering) or the spring pre-load (raising). Think about an extreme example, you lower your car 8 inches using the spring perch. The stroke would suffer so badly you'd be sitting on the bump stop. This means that the bottom of the shock has to be threaded with an adjustable base. I decided that since most kits assume the owner desires to lower their ride I would need an independently height adjustable shock so I could raise my car back to the near perfect height I currently have. I read on one Japanese site that the recommended lowering is 25mm front and 45mm rear. I plan on lowering my rear about 20 or 30mm and my front as little as possible.

Competition: I did my best to research every brand except for those that couldn't easily be obtained. Below is a chart with the brands I considered. Note that spring rates are in kg/mm. 1 kg/mm = 55.88 lb/in

Eliminating Brands:

• Cusco was an interesting brand and everything was in place as far as features but I had a very difficult time researching them. Nobody seemed to own a set and finding opinions was really hard. Based on the price and the lack of support in the US I opted against Cusco.

• HKS is a very reputable brand both here and abroad however that is as a whole. Reviews of the suspension was lukewarm both here and in Japan. I was able to find an awesome deal on them but even the specs were turning me off. Equal spring rates, too many points of shock adjustment and they weren't height adjustable.

• Mazdaspeed was a case of price vs. reputation and not really Mazda's reputation. I learned these shocks were outsourced to KYB, which is a fine company but doesn't jump at you as a racing brand.

• Apexi looked like a really high quality unit and had a decent reputation among the few people that owned them however even these people admitted that the coilovers were best used only for the track. At 11/11 the spring rates are not only equal where they should be offset but also far too stiff.

• Tanabe really didn't fit the bill in either features or reputation. They are basically in a lower class however they are upgrading a lot of their products currently and just released a race only system that looks very nice.

• DMS offers an Rx-7 specific kit through M2. It's a great kit but is actually a bit too high-end for me.

• JIC has been enjoying a great reputation in the US and has all of the features I was looking for at a reasonable price. However I read of hood denting problems from the shock poking up too high, which led me to believe they weren't built with a great deal of car specific testing. Their reputation in Japan is also not nearly as good as it is here and could even be considered poor.

• Tein is probably the biggest in the states but has only an average reputation. I read reports of corrosion problems and blown shocks. I'm sure these were isolated incidents that many of the other brands could suffer from if they sold as many units but I still got the feeling they were of lower quality. Even their website was lacking in technical content especially considering they are focused on suspension.

• Endless wasn't perfect but it came the closest. They had all the features I was looking for however unlike all of the other brands they didn't offer a pillow ball upper mount as standard. ($300 option) I almost eliminated them because of this in favor of JIC but when I contacted Endless USA they were very helpful and responsive to my questions. Have you ever sent an e-mail asking around 5 questions and received answers to maybe 2? Well Endless USA answered all of my questions including why pillow mounts weren't standard. They said it's because they can be noisy/incompliant and are only suitable for the track. I figured that since the stock system didn't use pillow mounts I would be fine without them. I also got the impression each kit is thoroughly tested on each vehicle. When I asked why the spring rates were not as off-set as much as the stock system is they said because the front end tends to lift at high speed if the rear is too soft. They are also slow to release kits for new vehicles and have a limited number of current applications suggesting to me they take their time with each vehicle. Although Endless doesn't have a strong presence in the US their reputation in Japan is very strong. They are very active in GT racing and have a reputation that seems to be exceeded only by Aragosta and Ohlins. They also have several different shock options to choose from including versions without dampening adjustability, height adjustability or both. You can also get different spring rates of which I went with the street version. In looking at their site everything indicates quality and experience. The price was however a bit hard to swallow but when I found them on sale at Evasive Motorsports for 15% off I went for it! To top it all off ya got the ever popular Endless girls, which can't be missed in Japan!

Installation: I thought this was going to be more difficult than it actually was although there are a few pitfall to be aware of. First is to measure the height of your car before you begin so that you have a better idea of what is going on once you get the kit installed. Next are the sway bars, disconnect them first from both sides so that you don't have to worry about one side preventing the other from being disconnected when the suspension is at a different level due to the new coilover. Next is that an extra set of hands comes in handy particularly when doing the fronts. Personally I was unable to disconnect the ABS sensor so had to be very careful when everything was disconnected that too much tension wasn't applied to the wire. This was much easier when one person dealt with the shock and the other the suspension. Lastly is what to do with the front brake lines. I decided to zip-tie them to the coilover but may create a bracket of some sort later.

Alignment: Naturally you will need a full alignment after you get whichever kit you choose installed. Getting your car aligned to the stock settings should be fine however you may wish to pick your own settings or use ones recommended by companies like Pettit. Let's review what each setting does to the car's handling.

• Front Toe: Toe is the angle of the wheels relative to each other, out being further apart at the front of the tires, in being closer together. Toe out improves turn in while toe in improves straight line stability.

• Rear Toe: Same as above although rear toe out is dangerous in that it promotes oversteer particularly when power is applied.

• Camber: Camber is the angle of the wheel relative to vertical, negative is leaning in towards center. Negative camber is desired for a better contact patch during cornering, which reduces understeer. Too much however will cause uneven tire wear particularly in a street driven car.

• Caster: Caster is the steering axis angle relative to the contact patch, positive being were the axis intersects the ground ahead of the contact patch. Positive caster increases negative camber as the tires are turned. It also increases straight line stability.

Well it doesn't get much more dumbed down than that. You can find suggested alignment specs on Pettit's site. My chosen alignment specs are as follows, which take in to account the fact that I run both 16" and 17" wheels, depending on my mood.

Height Adjustments: Due to my larger wheels and tires I didn't want to go much lower in the front but I did figure I could go a bit lower in the rear. So in the front I set the adjustability at max height with about 2 turns of pre load on the springs. The rear was much more flexable and I found I could raise or lower the car to my content. From fender lip to the ground these were my measurement. Overall I dropped the car about an inch.

Corner Balancing: Wow was this ever a disaster! So I go to this performance shop per a friend's recommendation where an actual racer works and regularly balances cars to have my car corner balanced. Instead of telling the story let me just list the things this monkey did wrong.

• Initially tried to raise/lower corners using spring perch instead of height adjustment feature even after I explained how to correctly do it.

• Against my wishes attempted to lowered the front more that 1/2 more inch.

• Lowered the front driver's side so much that the tire was resting on the fender liner.

• Neglected to disconnect the sway bars and was dumbfounded as to why the car wasn't balancing.

• After working on the car for 6 hours (it is a 1.5 hour job) the car was back to square one.

• After semi completing the job I asked if the coilover lock collars were secured. He said yes but when I got home (after racing that night) they were not.

• The sway bar end link nuts were left at the end of the bolts just waiting to fall off.

So what is my suggestion with corner balancing? Well unless you have a sway bar with adjustable length end links I feel that the uneven height side to side pre-loads the bar and has an adverse effect on a car. I consider my money wasted even though my front bar does have this feature. I could feel no difference in how the car handled after messing with this.

Overall suspension Setup: Currently I'm struggling with this. At first I had bad understeer because I had only a front bar. I bought the RB rear bar to even things up but had to set it to the stiffest setting due to the fact that the bar sticks out toward the thicker coilovers. The stock end links are too wide and would not connect to the outer position. This caused oversteer. I plan on buying some rod ends so I can use the outer setting but right now I have created a decent setup by adjusting the front bar to a stiffer setting. As for dampening it is more of a fine tuning tool. When I was over/understeering no amount of adjusting the dampening helped. Generally though I run it softer on the side I want to have more traction. Since I'm currently oversteering a bit I run the fronts at 6 and the rears at 3 or 4. (On the street I run the fronts at 3 and the rears at 1.) Thanks to Kent over at Endless USA I received some tuning advice from the guys in Japan that help develop and race these coilovers. Kent's comments with a few edits by me are below.
 
Hello. Of course, settings will depend on the driver's preference as one becomes more experienced, but I will do my best to give you as much information as possible, as explained to me by my technician here and sources in Japan.
 
This basic advice, is obviously from ZEAL which tunes its settings with the goal of receiving the "fastest times" in mind. Also, that for FR vehicles, it is usually recommended for the front to be stiffer than the rear.
 
The drifters really like to soften up the rear so they can push the rear end out easier. (I believe softening the rear decreases the ability to kick out the rear.)
 
We never recommend the front to be too soft and the rear too hard, since this can cause spin outs and dangerous situations. But this is also the case if the front is too hard and the rear is too soft.  Pretty much similar adverse affects. (For FF vehicles, all this is ruled out, it seems here in the states. In Japan, they seem to keep this similar frame of mind, but that's probably due to the fact that the straightaways here are much longer, quicker, and the FF drivers have their own idea of what's the quickest method of completing a turn).
 
Obviously the FD3S, being a front midship tends to oversteer, but at the same time it has a great balanced weight ratio of nearly 50/50.
 
Since you are using the STREET rate setup, it is recommended that the settings are at 5 or 6 (6 is recommended) in front and 4, 5, or 6 (5 or 6 is recommended) in rear. The other necessary settings would obviously be preload, vehicle height, as well as camber and toe.
 
A spring preload of 1 ~ 2 (2 recommended) is recommended in the front and rear.
This meaning, when the suspension is out of the vehicle, hand-tightening the spring seat lock so that the spring is snug is the "0" preload. 1 full turn is "1" preload and 2 full turns is "2" preload. No more than 2 full turns is recommended. This will help the inner portions of the tire grip better.
 
Regarding height, the front should be a tad lower than the rear with roughly about a 30mm drop maximum in the front and rear (from stock height). 
 
A 2 degree camber is suggested all the way around as well as slight "Toe-In" in the rear.
 
Obviously, it's about a total balance, so it's difficult to explain what happens when the front dampening is increased and the rear is not, or vice versa, or when the front and rear or increased or decreased without adding in all the other factors such as vehicle height, preload, tire type, etc.
 
I'm sure you know most of this, but I hope this helps somewhat. They tell me that it's harder to control when the rear becomes really stiff.
 
Anyhow, please contact me regarding any other questions. I'll be sure to try and get back to you quicker.

After Purchase Brands: These are the brands I didn't find or hear about until after I bought the Zeal coilovers.

• Silk Road looks like a nice kit but I wasn't able to find much info on them. I might have looked at these closer if I knew about them because they match my requirements very nicely.

• Buddy Club also looks nice but again, not much info. Then again, I didn't try that hard because my research is over. The spring rates are a bit strange though. Chuck over at Rotary Extreme started to offer this line at good prices with a group buy at $1246.

Overall impressions: So far I am very happy with these coilovers. The support has been great from Endless USA and they are functioning as I had hoped. They are easy to adjust and come with clear instructions as to the limits of adjustability. Endless has apparently become strict with their warranty claims in regards to non-certified people installing these coilovers and charges a fee that is sent to your shop of choice to insure that the service is completed. I told them that from my experience having such a shop install the coilovers will not decrease the possibility of a incorrect install that causes damage. They have also become very strict with offering service to used coilovers in an attempt to dissuade gray market sales. So be careful if you are thinking of buying a used set because they are so strict it is very possible you won't get any service from them if they need rebuilt. The price has also jumped considerably since I bought my kit. In all I think these policy changes will hurt sales but even so I would highly recommend Endless/Zeal and noticed that they now have several new models available along with different spring type options. I hope that my B6 coilovers offer many years of enjoyment before needing rebuilt but when they do I am sure it will be an easy process through Endless USA. For a discussion on the new policies visit this link to the forum.

			My friends brought a helping hand and their tools.

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