Larz

I have never done work on the suspension, so I have some questions.
How low can I go without having problems and affecting streetability? Can I use these springs with no adverse effects on stock wheels?
http://www.rx7store.net/product.asp?0=219&1=280&3=486
What will be a bolt on swap that will work with other stock components? I don't have the cash to change everything out at once. General information will be much appreciated.

EVLFD

try posting in suspension

racer1

About streetability it depends on how hard the springs are, nobody can tell you that, it took me 4-5 hours to adjust mine.

Mahjik

iTrader: (1)

You can use those Racing Beat springs with the stock struts. The ride should only be slightly different as the spring rates are fairly close to the stock spring (but you'll have the car lowered).

Larz

Sorry about posting it in third gen. I forgot there was a suspension section. So what suspension upgrades can I do without making it unbearable to ride on the street? I was suprised the first time I drove my FD. It had a tighter suspension than anything I've ever owned. And I felt the road a lot more. But I can stand a little more bumpyness for better handling.

Mahjik

iTrader: (1)

Lowering springs are a good start. I would only suggest that if you go for some of the higher spring rated linear springs, change your struts at the same time.

However, the Racing Beat ones you are looking at would be just fine on the stock struts. I doubt you'll notice too much extra harshness in the ride, but you'll like the lowered look and better handling.

the_saint

RB springs are give a VERY HARSH ride.

Great for autocross, lower the car nicely, haven't sagged.

I like them, the passengers think the car is too harsh.

Cheers

Howard Coleman

iTrader: (6)

hi larz,

stock 93-95 rx7 springs are approx 245 pounds per inch in front and 181 pounds in the rear. generally, fd owners who spend alot of time on road courses run springs around 450-500 in the front and 400-450 in the rear. according to the link re the racing beat springs they are 260 front and 212 rear.
i have SCCA road raced for 22 seasons and suspensions have been my strong suit. i own a shock dyno and a high tech spring rate tester and have compeletely plotted the fd suspension.
i have dynoed lots of fd shocks and spring setups.
i have never actually checked a set of the Racing Beat springs but if the rate is as advertised i would not run them. they are too close to strock.
i do have an enthusiastic recommendation for you, the Eibach Pro Track springs. their rate is 350 front and 255 rear and they are linear. they set the car at the very close to the optimum ride height. (you will need to reset your camber after installation.) you will love these springs... they transform the car and are comfortable on the street. run about 29-30 psi air pressure front and 27-28 rear cold. 1.2 degrees neg camber front and rear.
btw, i have no commercial relationship w Eibach....

howard coleman

7racer

Howard,

can I pick your brain about setups? I read a bit on your recommendations in another thread.

I was just wondering, when you mentioned "optimum ride height" how is that based and determined?

Thanks.

Howard Coleman

iTrader: (6)

the dynamic positive effect of lowering a car cannot be overstated and is generally misunderstood.

low is fast as far as cornering.

in a corner, weight is transferred from the inside to the outside tires. weight transfer is bad... equal weight on each tire is the goal.

the only 2 factors that effect the amount of weight transfer are center of gravity and track width. all other things like sway bars (roll bars) effect the speed at which weight is transferred not the amount.

the center of gravity of a stock fd is 17 inches above the track. by lowering the car, say 1.5 inches you reduce weight transfer by 9%.

in addition, body roll, which doesn't change weight transfer, negatively effects tire alignment with the track. (the fd has a racecar suspension and therefore compensates for body roll with negative cambergain on bump but body roll is still unsettling)
it is here that the benefit of lowering the fd is underappreciated.

body roll happens when lateral forces act on the vehicle at the center of gravity. the moment arm (leverage) of these forces is effected by the distance between the roll center and the center of gravity. think of it just like a ratchet wrench. if you need to put 100 ft pounds of torque on a bolt would you pick up your 3/8ths drive ratchet w a 6 inch handle or your torque wrench with a 24 inch handle?

lowering the car lowers the center of gravity closer to the roll center decreasing the moment arm and therefore force... less body roll! for instance, if the stock fd w it's 17 inch center of gravity has a roll center at 10 inches a 1.5 inch reduction of that distance decreases body roll by 15%.

you can also decrease body roll w heavier swaybars, springs and shock settings but all decrease the feel and therefore control of the car. (increased roll stiffness is necessary for short course turn-in such as solo events etc)

as to "optimum" ride height... i run Tein HA coil overs and my rideheight both on the street and track is 25 inches measured at the top of my wheel wells. you can't run much less since as you lower the car the negative camber increases to the point where you have too much and can't dial it out and back to minus 1.2 degrees.

the Eibach Trak Pro springs set ride height within 1/2 inch of the 25 inch optimal setting.

BTW, another point i forgot to mention is the stock non R1 fd shocks work great with the Eibach springs. i would absolutely install the springs and drive the car before buying aftermarket shocks.

howard coleman

SleepR1

Wow, the RBs are only 6% stiffer than stock up front, but are 17% stiffer than stock in back? No wonder I spun out alot with the RBs. The handling balance was biased more toward oversteer with the RB springs. If you're using the stiffest rear sway bar setting, with these RB springs, you probably should use wider wheels/tires in back to offset the extra oversteer.

Howard do you know what the spring rates are for the H&R Sport Springs? They're progressive rate.

Howard Coleman

iTrader: (6)

stock rx7 springs are 263 fr and 195 rear.
according to Jason's site Racing Beat springs are 260 front and 212 rear. so the front are about the same as stock and the rear are up 8.7%. as i said, they are too close to stock to make any difference if the site's numbers are accurate.
high powered front engine rear drive cars oversteer on road courses. when all the proper engineering is done the challenge is always getting rear bite. so it isn't unusual that your car was oversteering. if you want your car to go faster i suggest you readjust your rear sway bar to the softest setting and make absolutely sure you are running 3 pounds less tire pressure in the rear. run minimum 1.2 degrees neg camber front and rear w a touch less than 1/8th toe.
i have not rated H&R springs on my machine but i do not like (alot) progressive springs. they change rate in the middle of a corner making them very hard to drive very fast. if you run the Eibach Pro Kit/ named Track Pro at Pettit you won't need the softer rate for the street as 350 fr and 255 rear are very friendly streetwise.
howard coleman

SleepR1

Good info, thanks howard!

Larz

So what we're saying is, "Larz, don't buy the racing beat springs, they suck. Go with the Eibach. And after you're done reset the camber angle. And these springs are alright for street use. "
Right?

Larz

And if you don't mind me asking, Howard, what would be a good setup for my 93 touring so it would handle good on the track, yet still be good for street use. I was planning on adding rb sway bars, strut tower bar, and the springs. Maybe replace the bushings with something harder, also.

Howard Coleman

iTrader: (6)

there undoubtedly a number of ways to go but here is what i KNOW works:

eibach Pro Kit springs
engine compartment strut tower bar
replace front bushing in (rear) lower longitudinal link w nylon available from: http://www.suspensioncontrol.com/
set camber 1.2 degrees neg front and rear
set toe-in a touch less than an 1/8 inch
run 29-30 front and 27-28 rear cold air pressure
rear sway bar full soft
stock shocks are fine.
carefully check front swaybar mounting bracket for cracks
i also recommend you switch the differential mounting assembly bushings for nylon.
you will totally love this setup on the street or track.

the springs run around $250 from the rx7 store or Pettit.

if you want to spend a bit more buy the Tein HA coil-overs (spring and shock combo w infinite ride height adj) about $950. a bit more spring rate but still o k on the street. magnificent. set ride height at 25 inches at the top of your wheel wells.

i don't run aftermarket swaybars. swaybars do not change the amount of lateral weight transfer, only the speed at which it transfers and the give up is feel. i like the feedback and slower weight transfer of the softer bar. if i were autocrossing i would run huge bars for immediate turn in. but not for the track or street.

it is my suggestion that anyone buying the Eibach springs initially run them w stock shocks. you should be very happy w the setup.

one final note... pls check my post entitled "fd brakes" to complete your running gear.

howard coleman

Larz

What's a rear sway bar full soft? And can you go more in depth about weight transfer and the sway bars? Can you give the number to the place that you got the brakes from?

SleepR1

Yeah, I'm confused. I always read that larger diameter sway bars resist lateral weight transfer to the outside tires during steady state cornering? Maybe I've had it wrong?

Howard Coleman

iTrader: (6)

sway bars resist body roll.

sway bars do not effect the amount of lateral weight transfer.

only the center of gravity, 17 inches on a stock ride height fd, and track width determine lateral weight transfer.

there is nothing wrong w swaybars of course but they present trade-offs... less roll w more bar but quicker transfer of weight and harder to drive at the limit.

w a non-aero car such as... NASCAR, you want some roll so you can drive it closer to the EDGE. Nascar geometry is designed to create negative camber gain on bump just like our double A-arm FDs... so roll doesn't hurt our geometry like it would a BMW or Porsche w it's inferior Macphereson strut front suspension.

note on NASCAR restarts how free the cars are (how much they roll) as the drivers weave back and forth warming their tires.... lots of roll.

OTOH, F1, IRL cars don't move rollwise. that's because they must run HUGE springs in the cars to counter the 2 to 3 G's of downforce when they are running top speed.

roll stiffness effects turn-in and you want lots of both if you are autocrossing.

howard coleman

Larz

So for high speed turns a little roll helps you get around. Right? So sway bars aren't needed? Should I stay stock where that is concerned?

Howard Coleman

iTrader: (6)

yes, roll helps you control.

sway bars are needed... i am just saying that the stock bars work better than most think and it is easy to go too stiff w too much spring rate, too much bar or too much shock stiffness. too much stiff is as bad as too much soft. generally w too much stiff you end up in the fence however.

howard coleman

DamonB

From the Suspension and Handling Links:

Everything about Sway Bars by Grassroots Motorsports The second must read!

Don't you guys read this stuff?

...I've got a '93 with the stiffer rear bar and this car LOVES lots of front bar on the front when it's on race rubber. More front roll stiffness will move towards understeer all else equal so it's plenty safe to run. What it does is let the car turn in without keeling over (turns in quicker) and then it makes the inside rear do more work under throttle on exit. If I were a real newb I wouldn't do it though; the body roll helps most people key in on what the car is doing and since the car reacts quicker it can be overdriven more easily.

As howard says weight transfer amount is determined by cg location, wheelbase and track width. The rate of weight transfer however can be increased with stiffer bars, springs and/or shocks. You feel the springs and bars under steady state cornering and you feel the shocks at transition (entry/exit). Be certain you're tuning the correct one for your goals.

If I could run stiffer springs I wouldn't need as much bar...

Larz

So will the cheap racing beat bars be alright? OR are they too stiff?

Howard Coleman

iTrader: (6)

you initially stated you didn't have the cash to do everything at once... that will work well for you as some mods should be done in stages.

if you install the Eibach Pro Kit springs on your car w the stock shocks you will be quite surprised how much better it drives.

you might be happy with it suspensionwise... (that's assuming your run correct air pressure and settings... see my previous posts)

shocks just control the springs from bouncing. the stock shocks, which are excellent, control the Eibachs very well. sure you can bolt on aftermarket shocks and make the car ride like a truck but you will be overcontrolling the springs which is counterproductive.

increased spring rate (Eibachs plus 33%) resists body roll so as you increase spring rate your need for additional sway bar rate decreases

so my point is, buy and install a set of Eibachs and drive the car. then, if you wish to take it up a few clicks you will be in a better position to make the call.

do not misunderstand my comments as to mods... there is nothing wrong w aftermarket shocks, bars etc but it is really easy to end up w an autocross suspension on the street and not everyone will be happy with the tradeoff as to harshness.

howard coleman

Larz

This has got to be the best thread I've ever started. Thanks for the advice. Well maybe not THE best. My chicks with moustaches one in the lounge was a riot.