Styk33

If someone is reading this many pages into the thread, I think technical is what they are looking for

Howard Coleman

iTrader: (6)

"If someone is reading this many pages into the thread, I think technical is what they are looking for"

i will drag out my dyno sheets and see what might fit into this chassis setup thread. i do not want to get into too much shock tech here as i have a number of other important subjects to cover (tires--- brakes---swaybars from an upcoming ontrack session after the snow melts.)

perhaps a separate shocktech thread.

expect some dyno sheets within a week. probably OEM, R1, Tein HAs/Tein Flex/SS. we will do low, medium and high speed plots.

hc

Uncle Hungry

iTrader: (2)

I have to say, everytime I look on the main page and Howard has posted a reply, I read it. I've only been here about six months any most likely know more about fd's than 80% of the membership.You are without a doubt one of the saving graces of the "evil forum".

sevensix

iTrader: (1)

good stuff learned a lot thanks howard

M104-AMG

iTrader: (8)

Howard, the RP's are solid, since this is a dual-purpose setup (street & track) would it better to go with the MazdaSpeed diff bushings or a SuperPro which is supposedly softer ?

Thanks,
:-) neil

dradon03

iTrader: (2)

Neil,

Having installed the Superpro diff bushings last week I can tell you just from the installation they are much tighter, but I think they are far from being where harder compounds would be.

gracer7-rx7

iTrader: (16)

The SuperPro is a solid bushing also. By "solid", Rotary Performance means that they are not liquid filled like the OEM diff bushings.

Pettit Racing also offers solid diff bushings made of poly urethane. They actually offer 2 stiffness/durometer ratings of 80 or 95 depending on intended use.

There are a fair amount of satisfied users of each of those company's diff bushings.

GoodfellaFD3S

iTrader: (213)

I run the RP diff bushings along with RE toe link/trail arms, Banzai diff brace, and superpro control arm bushings. Quite an amalgamation (that's a word right ?) of parts. My FD is fine on the street, with no harsh vibrations that I can feel over the vibrations of my 4 inch exhaust

Howard Coleman

iTrader: (6)

that's great to know we have another source of diff bushings which should be on any modded FD.

so... Pettit and Rotary Performance and SuperPro for diff bushings. anyone else?

don't be afraid of the (non-event) NVH increase on the diff bushings. of course Rich's opinion as to his FD being fine on the street doesn't count as he is running a 4 inch exhaust. he probably has lost his hearing.

not listed in Rich's mods is an Engine Torque Brace (EBT). don't tell me there's something that exists that on his FD.

i just finished my Speedway Engineering front sway bar. i did it myself for a total of $260. the key is finding someone to bend the trailing arms. they are 6061 aluminum 3/4 inch thick by 2 inches. many shops will take a pass on the job. i made a wood model of the trailing arm so as to determine the correct offset.

since we now have the offset is known it might be possible to talk w "Frank" at Speedway Engineering and have him bend the arms.

i will post the pics/details.

of course, until i get out and about judgements will be reserved. the snow is melting. finally.

hc

PDViper77

iTrader: (9)

Howard, would your alignment specs in the first post be good for a drag car too? I just put my Ford 8.8" rearend swap in and changed my bushings, so the front and rear needs an alignment. I also have adjustable trailing arms, and toe links. LEt me know.
Thanks,
Phil

Styk33

Please do share your knowledge. There is only a handful of people that have grand knowledge of the FDs and are willing to share it. That is why most people are here.

Uncle Hungry

iTrader: (2)

I was commenting on the "grand knowledge" of most of the general membership, not my own. Sorry if you didn't follow that.

Howard Coleman

iTrader: (6)

finally finished w the front bar.



on w the nose tomorrow.


i am picking up a Tanabe rear bar to balance out the Speedway front...

hc

Howard Coleman

iTrader: (6)

drag race specs...

first off, i appreciate the question but you are asking the wrong person. you should ask Ernie T or JD or....

any answer i give would have to be conceptual as i don't drag race except when someone pulls up to the light and.

anyway, just a couple of comments.

front... very close to zero toe for minimal scrub. camber 1.2 neg is fine. lots of front air pressure for min drag.

rear... zero toe w solid bushings on lower link and diff a must. camber zero, maybe a degree positive. as the car squats on launch the wheels go negative which for traction/drag racing is a huge negative. camber will be an important setup issue as will shock settings and springs in the rear.

hc

DigDug

Swaybar looks great Howard.

.188 bar? What length? And the lever arm length?

Weren't you going to use the Widefoot bronze bushing blocks?

WidefootRacing

iTrader: (3)

Hi DigDug,
Howard was already working on his own setup, which looks similar
(like the curved spacer/washers on the cut-down bronze bushing
brackets) to something I did before going "all out", and making
billet mounting blocks for the bushings. His setup will work very
well.

Howard, nice job on the swaybar. The arms look hefty enough
that you shouldn't have any issue with them, but if anyone else
tries something like this, make sure to get as smooth a transition
in the bend areas as possible, as 6061 doesn't like to be stressed
in sharp transition zones. Large radius's are good, "pressed-in"
creases from edges of blocks digging in during bending are bad.

If Speedway will supply pre-bent arms, you're set.

[edit] Oh, yeah, try not to use heat for bending 6061-T6 parts
if you can avoid it. Heating the aluminum too much will destroy
the temper of the metal, leaving you with ~1/2 or less the tensile
strength. Aluminum is much less tolerant of heating that steel.

Also watch for signs of "crazing" or networks of small cracks on
the outside of aluminum bends, it's another sign that you've
over-stressed the metal, and a likely failure initiation point.

David Breslau
Widefoot Racing Co

dradon03

iTrader: (2)

I just wanted to note that from Fulcrum they recommended, the Tein Superstreet as a coilover kit to go with the Superpro coilover kit so it says something to further reinforce what Howard has recommended.

Howard thank you for your recommendations some Tein SS 10/8 and Tanabe swaybars are on their way to me.

David B. you have a PM.

Howard Coleman

iTrader: (6)

David is exactly correct. you really need to know what you are doing bending the arms. 6061 is a unique material. i jobbed it out and eventually found the right guy.

the proper offset is 2.5 inches. had i known that i would have asked Frank at Speedway to bend the arms for me.// .188 wall-35 inches length.

the only thing i am unhappy about is that i should have used David's bar-bushing-bracket but i forgot about them and got into the process of adapting the Speedway setup. i am going to watch it carefully to see if it remains solid and if not i will be calling David.

dradon03.... i will be quite interested in how you like your setup. it should be super. keep us updated.

hc

rob20rx7

iTrader: (1)

Great Thread! Lots of Info.

I have an FD Track Car that we built over the last 2 years

https://www.rx7club.com/race-car-tech-103/94-rx-7-track-car-project-begins-506890/

We are now in the stages of setting up the suspension. I use the racing beat front and rear HD sway bar set up now along with a Set of Tein Flex Suspension. we had problems getting the car as low as we needed it because it would rub in the wheel wells. at the track we had to raise the car to stop it from doing so. our soluion idea was to send the suspension back to tein and have them re-valved and purchased 14kg springs for the front and 12kg springs for the rear. we dont have another race now until April, but i cant wait to see how the car performs now.

)EIB(

iTrader: (4)

Howard,

What range of front & rear sway bar rate would you consider appropriate for 12kg/12kg spring rate with 29psi/26psi tire pressure?

gracer7-rx7

iTrader: (16)

Rob,

Keep in mind that race car ride height is often different from a compromised street/track car setup. If you go too low, some shocks won't have enough room to do its job. 'John Magnuson' ran into that problem on his race car FD.

Howard Coleman

iTrader: (6)

rob20RX7:

congrats again for building a really nice trackcar. you will notice a nice pickup from being able to get your ride height down. low is fast. real low is real fast.


given your lighter weight and lots of other advantages your car (track only) will pull lots more lateral Gs and need more roll stiffness so more spring rate isn't a surprise. i am surprised re having to revalve your shocks. i have dynoed them and they have a huge range of adjustment.

there is clearly a point where roll control should be obtained by more swaybar rate rather than springs. should you have any further excessive roll issues i recommend the Speedway Engineering front swaybar as it will enhance tire/track compliance.

good luck in April and pls say "Hi" to Carlos.

EIB
what is the usage for your car? unless it is drifting the first thing to do is go down on the rear spring rate to 10 KG. once you do that your rear will stick, especially w the 29 front 26 tire rear tire pressures.

as to spring/bar rates... in the front, of the total spring and swaybar rate between 40 to 50% should be bar.

hc

)EIB(

iTrader: (4)

Howard,

Thanks for the reply. The car is primarily for street/track use. Based on your suggestion, I will need to go with something much stiffer than the Tanabe sway bars in both front and rear with the 12kg/10kg spring rates, correct?

Howard Coleman

iTrader: (6)

"street-track"

that's what this thread is all about.... dual purpose. your spring rate 12/10 or 680/566 is a tad over the dual purpose and more track.

if you choose to keep the spring rate it would be a mistake to add more rate by upping your bar rate so it comprises 40 to 50% of the total. the total would be too high.

you will end up w too much tire chatter or non-compliance w the pavement and your car will not give you enough advance feedback to drive at the limit.


ideally, you should go to 8/6 or 10/8 and run either the Tanabe/RacingBeat setup or the TriPoint/Speedway combo.

dual purpose is finding the BALANCE POINT.


one of the easy traps to fall into while building a dual purpose FD is not knowing when to say NO. No to too much spring. No to too many bushings where you don't need them. No to $2500 coil overs. No to 80 pound per minute turbos.

the FD is a MAGNIFICENT thoroughbred chassis. w just a bit of tweaking and the right alignment it can handle 95% of what's out there ontrack.

AND

it can still be pleasant, repeat pleasant as a daily driver. i will bet that most w 12 KG springs and another car will lean toward the other car when they have to go to the "store."

i think your FD should be your daily driver. it's too much fun to sit in the garage.

find the right balance, leave 5% on the table, and you really can have it all.

that's what this thread is about.

hc

ptrhahn

iTrader: (9)

^^^^

Howard is correct, a street/track car leaves something on the table, no question about it. I put in alot of quality tracking with my car with Koni Yellow/GC's w/ 500/400 rates.

However, the car is a system. when I lost the A/C and some interior trim etc. to shave 100 lbs, ran 12 psi instead of 10, added a roll bar and Sparco seat, aggressive brake pads and 285 hoosiers, all of a sudden the weak link is shocks/springs. It doesn't feel as good under braking because that braking is occuring at 155 not 140 anymore, cornering speeds are way up, etc.

I'm not sure the car wasn't just as much fun on track, and more livable on the street before (try driving 5-6 hours back from the track in a Sparco EVO, in 95 degree heat with no A/C), but it is faster. Howard's right, if you want to retain balance, you've gotta know when to say when.