Spring Rates.... 81 IT-7
 

Hey guys- I am working on the suspension of my IT-7 car and I am having great difficulty finding out what springs I should use. MazdaTrix and RacingBeat both want to sell me their suspension package... Which I dont need becuase allot of their stuff is still on the car from when I bought it... I just want to stiffen up the car... The ratings for the springs that are on the car are worn off...so I do not know what I have.... My question is...............

Can someone give me an idea of what spring rates I should use for front and rear...

I was thinking somewhere in the neightborhood of 350 in the front and 250-275 in the rear....

Thoughts... Comments!

a lot of it depends on the track surfaces you run and what kind of shocks you run as well. i personally run on my car run much higher rates. if your running good double adjustable koni's you can run rates in the range of 600 in the front and 325 in the rear, which is what i run. now if your running something like tokicos i wouldnt reccomend more than 350-400 in the front and 250 on the rear at the most. i also run a panhard bar, tri-link, and turn-in spacers as well which will have an effect as well. but thats just my two cents. there is a lot to take into concsideration when it comes to choosing your rate. i would recccomend finding someone with a similar suspension setup as you intend on and see what they use and start there and dial them in once you get on track.

Contact Mike at ISC racing. 863-324-4539. If he suggests something different than what you have, buy a set from him. That helps keep his big trailer full of parts showing up at races in the southeast.

all these racing outfits sell matched packages because they work - they produce a balanced setup.

Mismatched springs and sway bars results in un-balanced chassis. You can't select springs and ignore the swaybars, and vice-versa.

How does your car handle now? Take your springs off your car, and find someone local to measure the spring rate for you. Then, based on how your car handles now, and based on the spring rates used by others, only then can you make an educated decision on what to do next.

http://home.comcast.net/~3.14159/Cro...-Images/32.jpg

Front of the car looks pretty good ... However the rear looks...VERY unhappy!

This was at a hill climb.... relatively fast.... however it is nothing like say turn 12 at Road Atlanta or 1-2 at Savannah....

whats the rest of the setup?
Sway bars?
Shocks/ Struts?
Bushings or bearings in the pivot points?
Panhard? 3rd link? Whose?

Anywhere from 525-350 up front, 250/125 in the rear.


Marcus

Something else I have been curious about...Unrelated...however I figure I should not start another thread......


There was a brake bias in the car when I bought it... I have played with it a couple times to see how the car reacts... however it does not seem to change it...

First off... the two signals on it say More and Less .... I would assume that to be more REAR brake bias correct??

Do you want more front or rear?



Someone asked what the car handles like now.... literally..... :dubs: It is a hand full! Not predictable. Lots of oversteer... Doesn't take much to upset the car...

I bought this car from someone...so what exactly it has on it... I am taking from the previous owner...

The car has racingbeat sway bars front and rear... (appear fairly large)... Is not a speedway bar or anything beefy like that....

Shocks are KYB front and rear.

Bushings

Panhard bar with a Mr. Watts linkages in the back!!! (racingbeat)

A couple points:
More rear brake will add oversteer. With the crappy front brakes these cars have, as much rear as you can get away with is a good thing.

Now, how much do you want to spend?

Marcus

Marcus- Say I had $350 dollars to spend... What would you do... I am racing on a college student budget... so... Its going to be something that comes in steps... ya know!!

start off by removing the rear swaybar, most IT-7 cars do not use them. I don't either. Instantly less rear suspension bind and less oversteer. * * free * *

KYB gas-a-just shocks or cheaper gr-2?

Koni makes much better shocks and can handle the higher spring rates. That's about the budget for now!~!

Watts link or panhard bar? Not enought room back there for both.

http://gforceengineering.net/products.htm

Good luck, Brad

Your photo looks like it was taken at the Crow Mountain Hillclimb Oct1. I set a fast time there last year, and I was there as a worker this year. You cannot make suspension tuning decisions based on how the car feels on that mountain. The pavement is very rough and uneven, which will make the car do very bad things. You cannot set brake bias based on how the car feels on that mountain.

Tells us how the car feels on flat, smooth road racing pavement.

Both a Panhard bar and a Watt's Linkage in the rear? That's crazy :wallbash:
Run the Panhard bar only, and get rid of the Watt's linkage.

And I'll add that be sure its a panhard bar that is attached below the rear end, not one of those short bars that just uses the watts link mounting points.

Looking at the picture its hard to tell because of the terrain but it looks like the front is sprung to soft. The job of the front bar is to keep the rear wheels on the ground. If the front is to soft(springs/bar) it will lift an inside rear. Depending on the courses you are going to run you may want to keep things soft and try to make things work. No matter what, fix the rear end by installing a tri-link and long panhard. Then find out what springs you have front and rear. Have them measured or do the math. When you know what you have then you can probably end up buying only one pair of springs.

The reason I would say stay soft on the springs is those KYB's won't control real stiff springs. So to keep from needing new shocks, stay away from those 450lb fronts etc for now.

I also forgot to add that you should invest in some strut spacers to raise your front roll center. That could be part of the lifting rear wheel problem. GForce Eng. has the best ones because they let you add ackerman at the same time. The increased ackerman will help the car point into a turn quicker.

Haven't seen you at the track, are you planning to race it? Bring it up to RA sometime and I would be happy to do a few laps and give you some feedback.

Your a motorsports whore! :)


BTW SCCAIT7, you should take Russ up on his offer.

-billy

Was at the ARRC last year... At Road Atlanta in June.... Lowes in August... Memphis in June.... Yep... im racing it...!!

Just put a new(er) motor in!

RA and I have issues- however I will be at the ARRC this year!

The reason I bought this car was because someone drove...totaled my last racecar.... Thank you - thank you - thank you - for the offer.... however there are two things I dont share....

1.) My wife
2.) My racecar (anymore) - GOT BURNED BAD.

Please understand Russ- Its nothing against you.


Anyone have rear springs? I am having a hard time finding a place to find individual springs.... Everyone wants to sell me a kit....

Check out the stockcar suppliers like Coleman racing or Speedway Motors. Or call Jim at G-Force Eng. And while you're at it buy his set-up book, its the best money you can spend on an FB for racing.

I'll take you up on that Russ. I'm the Green RX-8 that comes to the NASA events at RoadA and pesters you about your car. :) My RX-7 is almost track ready and I'll be at the next RoadA event. Hope to see you there...

Springs are supposed to be here today!

I totally understand, no worries, swing by at the ARRC and maybe I can help you find a second or two. I'm always parked down on the turn 1 corner of the skidpad.

I'd be happy to drive your car legokcen, I should be at the next NASA RA race too.