ProjectRxSeven

Forgive me father, its been a bloody long time since my last post. This is a long post but please read it.

Firstly, I'm kinda concerned about the fact that there has been a rash of rx7 owners selling their cars. Everything's gone E-bay. Rx-7's seem to be parted out and written off or sent to early graves. Maybe the economy is to blame, people need to sell their rides to pay bills. That's tragic. Thats life, but tragic. I'm not loaded either. My FD is happiness. Without it, i'd just be another driver. Even if the value of my FD ever depreciates in a book, it still be worth every penny. She doesn't own me. We just have a very nice relationship. Kind of like having a beautiful, loving, expensive, smart, sexy and fun girlfriend. Someone you won't be pissed about if some other guy said she had a nice ***. But I definately suggest having a real gf as well. Ultimately its just a car. But who says you can't tax it till you lose it. JK, sorta.

People seem to be into the RX-8 now, but I won't be selling my FD for a normally aspirated RX-8. I hear mazda lied about the performance numbers. (hp and so on) I'm sure it's a great car but it's not an FD. Maybe I'm being biased. Oh well. Did I read Ford oversaw its development? and now owns 1/3 of mazda? I'm not knocking on anyone, just asking.

I looked on mazdatrix today, the site has changed and it seems a lot of everything leads to something RX-8 first.. so do many other RX sites. It's alright as long as they don't stop carrying the parts.

PLANS :

I have been looking for a suspension package lately.

I need new shocks and springs. If i was loaded right now i'd go for streetable TEIN coilovers. There are many TEIN coilovers but i'll be getting the most streetable.

I will probably wait to get them if possible. I want ride comfort but something very performance oriented. I don't want to ride on rails.

If I don't get the TEIN coilovers, I will probably get BILSTEINS HD's. Gas pressure shocks. NON adjustable.

How often does anyone adjust adjustable shocks?

If anyone has the BILSTEINS, please let me know what you think of them and what springs you're using or recommend for performance and comfort on stock 16 inch wheels. I don't want to lower the car.

TOKICO 5 way ajustables seem to be very popular and the ILLUMINA'S seem to be on very many RX aftermarket part sites. Pettit racing sells them and I remember reading a review on either pettit or another major RX performance shop site which said that they thought they were the best shocks tested or something.

However, several months ago I spoke to an RX-7 specialist in which I have some serious confidence in. He said he wasn't impressed with the Tokico's. I remember him laugh actually. He suggested TEIN. I trust this guy..so .. yeah. He's a specialist with cred.

plus you get what you pay for.

Koni - I have read a few things about Koni's. These seem pretty hard for shocks. I've driven other cars with Koni shocks and everything seems to rattle over bumps. I guess Koni's would be good for track use.

So, any feedback would be great. I think lots of people buy coilvers and shocks that sound badass or race oriented or that are to the x adjustable. But all that **** just makes you feel like you're skating uncontrollably down a cobblestone street. Plus add 18 inch wheels and low profiles and you'll be trying to dodge everything instead of driving/racing in a straight line. Even a blow out over a small pothole in a VW is painful and costly. A nightmare if they've discontinued the wheel. Plus, I don't want to add a shower of sparks light show to my street presence everytime i hit a bump from being too low.

Not to deter anyone from all the above. It just depends on how you want to drive your car.

I have read a lot of posts on suspension on this forum, everyones always asking about setups as I am, but experiences and set-ups vary widely and it would be cool to get a poll set up to really compare and contrast options and experiences so people have a better idea what to get or buy. I'll be willing to set up a poll or pool of info, if people are willing to post their set ups and a basic rating or general experience overview.

Also, If you guys would like to list what tires you're using, what you like and dislike, all season or High performance and cost. Maybe I could put together a little rating/experience set up for this too in one or two posts on this site. For Rotaries. No offence but Honda (and so on) experiences don't mean too much to me when im looking for parts. Especially on sites like tire-rack.

Ofcourse, I'm looking for tires too. So we can help eachother out. It be cooler to just get the info in one easy to find place like this site. Rather than wasting money on stuff you don't have to through trial and error.

peace,

Mo

alberto_mg

You need to spend some time in the Suspension Forum. Scroll down a bit beyond 1st Gen... Don't be afraid to search either howard coleman has tons of useful suspension posts as does damonb

If you are looking for ride comfort, stay away from coil over setups. Spring rates on most coil overs are about 500lbs/in up front which is a lot stiffer than your run of the mill Eibach and H&R springs. I forget the rear spring rates. Another thing that affects ride comfort with coil overs is that most require using a heim jointed "pillow ball" upper strut mount instead of the factory rubber pieces. Those pillowballs contribute to a stiffer ride that can't absorb bumps as well as rubber.

I love my Konis with PFS springs. I adjust my shocks pretty often actually. I like playing with them and I often twist them to full soft when I know I'm going somewhere with rough roads. Then I stiffen them up a bit when I want to play.

As for tires - search through the suspension forums. I recently had a good thread going asking about "best rim/tire size for neutral balance" and there is lots of good info there as far as rim sizes and a few suggestions from guys about tires they liked as well.

As for your comments about people dumping their 7, I feel you. I've considered selling mine (getting married soon) but am disgusted by the prices and the dumb *** ricer low ballers.

macdaddy

Mo:

About the only way to be objective about suspension setups is with a very consistent driver, plenty of track time and data acquisition. Everything else is very subjective, and "one man's meat is another man's poison." The FD's stock suspension is so superior to most street cars that it's hard to improve upon for the street (other than replacing worn-out shocks, bushings, etc.).

That said, it's really a matter of whether you want bragging rights (my car's lower than yours, my car corners flatter than yours, etc.) or whether you are trying to tune your car for a particular purpose. An autocross setup is different from a road racing setup is different from a drag racing setup. Oh, and if you want to keep the car "steetable" it's extremely subjective as to how far towards optimal for the cones, track or strip you care to go as far as tolerating NVH. If you want to go all the way towards a specific goal, pick the brains of the national champs. If you want a compromise, I know no alternative to driving/riding in someone's car who has a setup similar to what you want and seeing how it feels to you.

Sermon over. Following comments do not apply to drag racing, about which I plead almost total ignorance.

Unless you're trying to stay in the Stock classes for autocross, coilovers are the way to go - I like Ground Control, but there are lots of options. These allow you to use any number of different standard 2.5" race springs and adjust ride height (and to corner weight the car). Once you're talking about standard 2.5" race springs - I like Eibach - you can go a little stiffer than stock or a lot stiffer than stock, and change as needed/wanted - i.e. start with spring rates close to stock, and go stiffer as you get more addicted to the track. The main difference between autox and track is that most autocrossers set the rear of their car up stiffer than most track folks do, to help encourage rotation at the slower speeds of autox. Use matched sway bars - Racing Beat has lots of experience with street and race FD's, though I'm using the Suspension Technologies bars on mine. One of the nice things about Ground Control is that if you talk with their tech guys about how you intend to use the car, what shocks and sway bars you have, etc., they can usually point you in the right direction as far as spring rates. As far as shocks, I've always liked Koni Sports (the single-adjustable yellow ones). At full soft, they are a little stiffer than stock, as full stiff, they are very stiff. Without data logging, a full race crew, etc., double adjustable shocks are just too complicated for me. However, I am comfortable playing with my tire pressures, rear sway bar setting and single shock setting to get my car the way I want it on the track. Then I just soften the shocks for ride comfort when I'm on the street. I'm not even going into the discussion about whether to stiffen one end of the car primarily with the swaybar or primarily with the springs - now you're way over my head into true automotive engineering.

Good luck.

DamonB

All these products and topics have been discussed over in the suspension forum. Won't you come be our guest there and do a search of posts? Lots of info from people who have tried these things.

ProjectRxSeven

wow you know, I really think i'll spend more time in the suspension section. I've been there but It's just really difficult to seem to organize all that info at once, because someone's view is constantly tipping you one way or another.

Like mac said its really subjective. Honestly I don't know much about spring rates but I'll read up on it and try to figure it out. It would be easier to experience it or get shop or actual experience than trying to understand what digits feel like or translate to the actual feel of the suspension. But that won't happen over night. I guess I have to start somewhere. I pretty much have focused on everything but the suspension.

https://www.rx7club.com/showthread.p...hreadid=286201

was pretty helpful in general. It linked me to

http://www.scuderiaciriani.com/rx7/upgrades.html

and your posts

this guy has a lot of specific info. Once again a lot of technical info which i'll have to think out.

In my perfect world. I want to have great traction. I want stability, tons of control. Ride comfort. I guess i won't be doing auto cross and mainly want to be able to uhm.. race in a street like environment. (not the actual street)

I'm definately going to read into what you guys said and do some research on the springs and shocks and get back to posting.

koni's + pfs

ground control

koni yellow's.

wow, two postives about koni's.

Thanks a lot

Kento

This is a common misconception with springs, and their relationship to overall "ride comfort", and the car's ability to handle bumps.

Unless you're running some ungodly stiff spring rate like some of the TEIN setups I've seen that have 800-something pound/in springs in the front, your spring rate actually doesn't have much effect on the suspension's ability to absorb a bump-- that is the shock absorber's job, or more precisely, the shock's damping rates. The spring rate mostly controls the dynamic ride height of the car-- not the suspension's ability to absorb bumps, and hence, its ride quality. A stiffer spring rate does not necessarily translate to a "stiffer" ride, unless you are close to bottoming out.

When I installed my Koni Sport coilovers, my spring rates were naturally quite a bit stiffer than stock, to minimize weight transfer, etc. But the overall ride was smoother than stock, because the Koni's damping rates are adjustable (and actually, more consistent), so I was able to maintain decent wheel and chassis control without the monster rebound damping rates that the stock shocks use in their effort to "control" the chassis. Manufacturers usually use heavy damping rates as a compromise to maintain chassis control, because they need to establish a safety margin for when you carry passengers and extra loads (due to the non-adjustability of average suspension).

The factory rubber upper shock mounts are mostly there for road noise insulation. The reason people think that pillow ball mounts contribute to a stiffer ride is because they've got their car "slammed" to the ground, so their suspension is close to bottoming out anyway; in that case, sure, any bump that bottoms out the suspension (which doesn't take much) will be fed right into the chassis.

Going to a coilover setup does not necessarily equate to a stiffer ride.

ProjectRxSeven

consequently. I got to ask. but what is a low baller? I have a general idea, but if you'd clear it up that be cool.

thanks for the feedback too kento

4CN Air

iTrader: (7)

it's a term too often used by sellers when selling there goods. A low baller is someone who offers a rediculously low amount for an item. (i.e. "I'll give you my yellow V6 convertible mustang for your 94 Pearly White FD, straight up")

the problem is sellers too often don't understand that their parts/cars are worth much less used then what they bought them for. If a seller doesn't liek a price he/she shouldn't respond, the term "low ball" shows a misunderstanding of economics,

Econ 101:
the buyer goes low, the seller goes high, price fluctuates until both agree or no sale

ProjectRxSeven

so the car has to go. someone's got a low offer on the table, the buyer wants a high amount. they work up from the low amount.. and the car gets sold for not much because, the seller should have walked away instead of negotiating with the low baller.. got a higher bidder, but stayed realistic.

jimlab

Just a little clarification...

The main job of the springs is to resist the weight of the car and keep it from causing the suspension to bottom out. I believe this is what you meant by "controlling dynamic ride height". Spring rates must be high enough to prevent this from happening without being so stiff that they remove all of the compliance from the suspension.

However, when you increase the spring rate, you are decreasing the amount of compression that will occur when the weight of the car is unsettled by hitting an irregularity in the road surface or during cornering or acceleration. Reducing the amount of "give" that the suspension has will unarguably affect ride quality to some degree.

The job of the shocks is to control the rate of movement of the springs once the suspension is in motion and eliminate bouncing by damping (hence the term "damping rates") the motion of the spring both on compression and rebound. Adjustable shocks set on higher settings can increase resistance to movement in either direction which will also directly impact ride quality by removing more compliance from the suspension.

Bottom line, the springs and shocks work in conjunction to control suspension movement and either or both can affect ride quality negatively if mismatched.

Less damping was required to control rebound because there was less compression (and therefore less rebound) to control due to the higher spring rates. The combination of the two apparently resulted in a smoother ride overall, despite the increase in spring rate. This is indicative of a well-matched combination.

Yep.

Not necessarily. You don't need an aggressive ride height to have a ride that will loosen your fillings, but a lower ride height almost always means stiffer springs and shocks because the range of suspension travel is reduced and therefore spring rates and damping rates must be higher to prevent it from bottoming out. Still, you could put together a package that would shake your teeth out of your skull at stock ride height if you really wanted to.

True. Good post.

DamonB

..okay...


Wha? A higher spring rate will always require higher amounts of damping. A "stronger" spring requires "more" (firmer) damping.

Kento

Not necessarily, especially with coilover setups. At a given spring preload setting, a higher rate spring actually is softer in the initial portion of its travel; it's when it gets towards the halfway point in its compression that the energy is higher, thus requiring more/firmer/stiffer damping to dissipate that energy.

jimlab

I'm not sure where you got that idea.

When a spring is compressed, it creates a stored force that wants to extend the spring back to its equilibrium state, or in other words, return to the installed (or ride) height. With a linear spring rate, that force is equal to the amount of force required to compress the spring to that state.

If a spring with a rate of 500 lbs. per inch is compressed 2 inches by movement of the suspension, the force required was 1,000 lbs, and 1,000 lbs. of force will be released when the spring rebounds and must be controlled by the damper (shock). A spring with a rate of 650 lbs. per inch, on the other hand, would only be compressed about 1.54" by the same 1,000 lbs. of force. It will also release the same 1,000 lbs. of force on rebound, and therefore require the same amount of damping.

So how does a stiffer spring always require higher amounts of damping?

DamonB

By definition a higher spring rate is a higher spring rate. Spring rate is measured in pounds required to deflect the spring a given amount. When a spring with a higher rate is compared to a spring of a lower rate the higher rate spring will always be stiffer at any given displacement and will always have more energy stored in it at any displacement and will always require more damping force to compensate for this.

If you preload any given spring you have also just increased the initial amount of force it takes to displace the spring. Preloading any spring will make its initial travel stiffer than it would be if you left the spring at its free length.

Rate is a direct meausurement of the spring's stiffness. There is no time that a higher rate spring is softer than a lower rate spring.

jimlab

Assuming a progressive spring rate, as opposed to a linear rate. That's a completely different discussion.

jimlab

True, but you're assuming that the suspension will compress the same distance with the stiffer spring, which is not the case unless you've added a considerable amount of weight to the vehicle. See my example above.

DamonB

Because the motion ratios (wheel displacement vs. spring displacement) of most every car on the planet are not 1:1.

Your comparison makes sense if the springs/dampers could be held in your hand and squeezed between your thumb and finger, but not when installed on the car.

Spring rate is the measurement of the amount of force it takes to give a particular displacement of the spring. Once installed on the car however wheel rate is what counts. Wheel rate takes into account the mounting geometry of the installation and in most every car a 1" displacement of the wheel gives much less than a 1" displacement of the spring.

Since the wheel rate is not 1:1 you cannot say that going from 200 pound spring to a 400 pound spring will give half the suspension displacement for a given bump.

Good worksheet from Eibach

jimlab

It doesn't matter if they're installed in a Thigh Master.

Assuming linear spring rates, if you install a spring with twice the rate of the original, it will still compress half as much as the original with the same input force, and require the same amount of damping to return to the installed height.

spurvo

Weird question: shouldn't there also be a time coefficient in a spring rate. A spring deflects a certain amount given a certain force at a certain speed? Has to do with the harmonics of the spring, but I would also think it would effect the ride characteristics of the spring. A spring that can deflect 1 inch for 500 lbs applied in one second versus one that deflects the same amount over 2 seconds would be more compliant. no? I guess I mean this: drop 500 lbs on the spring, measure the time it takes to deflect 1 inch. "stiffer" spring would take longer to deflect, no?

The stiffer spring by this criteria would be more prone to upsetting the suspension over small bumps in a corner, as the suspension could not move fast enough to go over the bump, so the whole car is bumped. I see it as articulating over the bump, and the stiffer spring can't do this as well.

Anyway, just my silly musings...

DamonB

True.

Only when measured outside the car, once on the car that is not true because the spring reacts due to wheel rate. The spring when installed on the car no longer has a 1:1 ratio with the movement of the wheel. Since this ratio is no longer 1:1 you do not get half the suspension displacement for a spring with twice the spring rate.

You would only get half the displacement if your WHEEL RATE doubled. Doubling the spring rate does NOT double the wheel rate unless your spring is mounted perfectly vertical directly above the wheel like the landing gear on most aircraft for instance.

When installed on a car the forces are fed into the spring through movement of the control arm. The control arm is in effect a lever with its fulcrum at one end, the tire at the other and the spring mounted somewhere in between at some angle. The wheel has more mechanical advantage against the spring and the spring is also mounted at some angle in the majority of cases. You can see right away that a 2x displacement at the wheel does not equal a 2x displacement at the spring because the spring is not perpendicular to the control arm. For a given car it would take more than a 2x increase in spring rate in order to give a 2x increase in wheel rate and therefore provide half the suspension movement for a given bump.

Here's a pic:


You can see that since the spring is mounted further inboard on the arm than the wheel and the spring is leaned over in relation to the wheel that a 1" displacement at the wheel is going to be less than a 1" displacement at the spring. Since this ratio is not 1:1 and the spring has less displacement than the wheel it in fact takes more than double the spring rate in order to accomplish double the wheel rate and therefore provide half the suspension displacement for a given bump.

When speaking of suspension displacement what counts is wheel rate. The wheel rate is a purely mechanical function of the spring mounting and if you don't know the wheel rate you have no idea how much firmer a given spring will "feel" in the car.

DamonB

No. Springs don't care about time as they are merely displacement sensitive: The farther you move them the more force they exert, speed doesn't matter.

On the other hand dampers (shocks) are velocity sensitive: The faster you move them the more force they exert, displacement doesn't matter.

Time really doesn't come into effect until you start talking harmonics and that really only counts for something that sees very high speeds; valve springs for instance. Keep in mind that harmonics don't technically effect the rate of the spring, they are just reflecting forces through the system that can become disruptive. You can overlook this when talking suspension because the speeds are much slower and at the same time a suspension spring is damped while a valve spring is not.

jimlab

Damon, I think you're missing the forest for the trees.

It doesn't matter if the ratio is not 1:1. The ratio of movement is the same regardless of the spring ratio, unless suspension geometry changes. The leverage imparted to the spring is therefore the same, and the rate of the spring takes over from there.

In other words, moving the wheel a given distance (let's say 2 inches) puts force F on the spring in its installed location. Agreed? Therefore 2F would be required to compress a spring with twice the rate the same distance (2 inches of wheel movement). This is true unless suspension geometry changes, or unless the spring is progressive rate, or unless the the ratio is not fixed.

DamonB

jim's right; I confused my figures in thinking how wheel rate changes due to spring inclination as the suspension compresses.

Wheel rate= Spring Rate*Motion Ratio squared.

Since motion ratio is constant on a given car a doubling of spring rate results in a doubling of wheel rate.

Score one for jim, but I will no longer come to his aid when people bash v8 powered FD's

ProjectRxSeven

A lot of great information. I have to read it a few times. But, those are great explainations and the diagram helped and its a great technical discussion. Thats a lot of great information and great questions. If it wasn't I wouldn't be bothered by the fact this sounds dangerously like *** kissing. It's not.

DamonB

jim, I prepared this long post about how righteous, wise and wonderful you are but the server puked on it. Apparently the rx7club disagrees