RX-7 Rear Suspension Project

[nomadtrash]

My 84 GSL posi-traction measured 42 pounds breakaway. It has two driven plates and two stationary plates on each axle. I added two 0.015 shims and the breakaway went up to 150 pounds.

The GSL-SE that you have uses only 1 driven plate and three stationary plates. It might have similar stock breakaway which should be in the 40-50 pound range. You can get an additional driven plate at the dealer to make it a little more robust and increase the breakaway. I used pinion shims to stiffen it up however thicker driven plates are available which eliminates the need for shims.

If you find that it is a 1 wheel wonder then I suggest increasing the breakaway. I think a Miata torsion differential might fit if you change out side gears. I like the clutch type better but the torsion never wears out and is more forgiving on the street.

[Alvin]

thanks Andy, I spoke to Dan yesterday and he mentioned that it is easy to adjust the breakaway. It is easy to burn both wheels, but I still need to test it on the track/auto-x.

initial impressions from street driving:
It is a night/day difference from the comp leaf spring setup. No more skittering along bumps, it stays planted.
We are using #450 springs, and I think it feels softer, but maybe I just need to get used to it. Still in the tuning stage.
There is enough room now to run 225s or a 205 Hoosier on a zero offset 7" wide rim. Just need to find the right combo now.

[dieter ka24de]

I found that my suspension had to settle...then I did an an alignment and re adjusted the links...
keep it soft for the first bit to let the supension run it's travel and then set it up...You will find that it will be smoother and totatlly different riding car...The harsh bounces will be gone and it will accellerate,brake and corner a lot more smooth.

[nomadtrash]

I run my rear springs at 110 pounds. I like it soft for bite and a 3/4" adjustable swaybar to fine tune the cornering.

[Alvin]

A few more initial impressions and some pictures:

-WOW. I am so stoked. I can't believe it is in the car and how smooth the ride is now. Bumps on the freeway that would send my bottom about 5" off the seat are now soaked up. Much like Dieter said.
We have some actual suspension travel back there!
-When I upshift to 5th gear it feels like I'm still in 4th? The 4.11(had 3.9) makes a noticeable difference!
In-gear acceleration has improved, I found my self short shifting and ending up in 5 quickly!
60mph is almost 3krpm, 80 is just over 4krpm. Not sure if I'll take a mpg hit, will update.
-In corners it just plain sticks, no hops, skips, or drama. Andy we will consider a sway bar later.
-The wallbro in-tank fuel pump is quieter than my external 280zx pump, and (ahem) turbo-ready.
-Brakes...The fronts lock-up before the rears, still need to drive it to figure out proportioning.

Dan and Luke did a fabulous job. I'll drive it for awhile, take it to the auto-x and road course, make more adjustments and hopefully get everything powdercoated. The stainless exhaust with mandrels runs under the axle, it is a work of art, will be v-banded later.
It is just a shame that it is hidden

Specs:
The shock upper and lower bolts are 5/8 through bolts (pass entirely through the steel sleeve)
Forward lower bolt (the one thru the bushing) is 9/16
All heim bolts for links are 5/8
1/2" panhard bolts
All heims are Teflon lined goodness
All grade 8
Double plated frame for the shock upper mount crossbar
The wall thickness of the stock crossbar for the shocks was too thin, before it held the shocks, now it holds up the car!
Equal length link bars
450# springs on a 40 degree from vertical plane (~230# wheel rate)
All tabs, and brackets are 1/4" steel

Pics:
Look Ma, no leaf springs!

QA1 coil-overs:

Lower shock mounts:

The under-axle exhaust:




We tried some 15x7 Konig Rewinds with 205 Hoosiers on...they look mean. Clear with 2" in-board space, won't clear up front.

[dieter ka24de]

Looks really cool.I think the 4.11 gearing is a good match with your engine and trans combination.
Here is a link that you can use to see what speed your car is with any gear and tire combination.

http://www.240edge.com/performance/top-speed-calc.html" onclick="window.open(this.href);return false;

It sounds like you are running very close to a turbo RX7 power combination with about 40lbs more torque...way cool...it must be a hell of a lot fun to run the gears....
Did you change your rims ?....I dont remember them.

[ppeters914]

Very kewl. Care to share the cost of all this kewlness?

[Alvin]

Very kewl. Care to share the cost of all this kewlness?

Kewlness has it's cost...I had to give up my entire porn collection.

[caraddict]

Kewlness has it's cost...I had to give up my entire porn collection.

Wow.. Roadsters are definitely kewl but your ENTIRE porn collection? Did you go cold turkey or do they have a patch for that now?

Jon

[SLOroadster]

Alvin,
If you are looking for an autoX, there is one in Marina tomorrow. NORCAL UFO. I'll be there in the Alfa. I'm limiting the roadster to more local events and track days. I am planning on picking on the Porsche crowd when I get some tires for it however.

Will

[Alvin]

yeah dan mentioned Marina...but it is raining like crazy!

[Alvin]

Kewlness has it's cost...I had to give up my entire porn collection.

Wow.. Roadsters are definitely kewl but your ENTIRE porn collection? Did you go cold turkey or do they have a patch for that now?

Jon

tried the patch, now they got me on some kind of gum.
thank goodness Al Gore invented the internet

[xeddex]

Nice...Very very tricked out! That exhaust plumbing looks sweet. DanG does some nice work for sure.

-Eddie

[Lowdown]

Have you seen this IRS BMW?

http://www.r3vlimited.com/board/showthr ... t=119358

F-ing AWESOME!!!

jEFF

[Alvin]

eh, nothing compared to Bryan Feldman's Jag IRS 510:
http://www.bryanf.com/510/rsusp.htm" onclick="window.open(this.href);return false;