Does anybody know RX-7 spring rates for base models (Base,SE) and sport models (GTU, Turbo)?

Has anyone ever put stiffer springs from a GTU or Turbo on a base model?

I know most of you will tell me to just buy aftermarket springs, but they are not legal for SCCA Solo2, so I have to stay with stock springs.

If anyone knows the spring rates, that would be great. Yeah.

 

soft suspension specs-

right front spring- 12.0mm wire diameter, 147.0mm coil diameter, 355.5mm free length, 5.83 coils

left front spring- 12.2mm wire dia, 147.2mm coil dia, 366.0mm free length, 6.05 coils

front stabilizer bar- 22.0mm dia

right and left rear spring- 9.9mm wire dia, 84.6mm coil dia, 367mm free length, 10.81 coils

rear atabilizer bar- 13.0mm dia

 

harder suspension specs-

right front spring- 11.8mm wire dia, 146.8mm coil dia, 327.0mm free height, 5.31 coils

left front spring- 12.0mm wire dia, 147.0mm coil dia, 336.5mm free length, 5.51 coils

right and left rear springs- 10.1mm wire dia, 84.4mm coil dia, 355mm free height, 10.79 coils

rear stabilizer bar- 13.0mm

 

Not to sound like a smart-@ss, but are those #'s for real? What is the source? Thanks.

 

FSM

-edit- doh, forgot "harder" suspension front stabilizer bar diameter in the post- 24.0mm dia.

 

hmm, stock is around 130lbs/in for the turbo. the turbo ones are stiffer then N/A by a little. but if you put them on your car it might raise it a bit.

 

That's funny, I wasn't aware you could install TURBO springs on an NA car, and still be Solo2 E-Stock legal..

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If you're going to swap to GTU springs, you've gotta swap *everything* to GTU spec. IOW, you have to run the 4:30 rear gear, you have to run the GTU tranny, etc etc.. Can't create a model by swapping in parts.

All IMHO, I'm not a Solo2 guy

PaulC

 

WOW! When I posted, I didn't think I would get a response like this. This far exceeded my expectations. So, both suspensions have the same diameter rear stabilizer bar as well. Anyone know if they are exactly the same, or if the "harder" bar has shorter arms to make it harder?

 

Nevermind, disregard that question. I just looked in my FSM (don't know why I didn't earlier) and saw that the hard and soft suspension list the exact same rear stabilizer bar.

 

I believe its all the same for the rear stabilizer bar.

Perhaps they were wary of power on oversteer in the more powerful TIIs causing problems for Joe driver?

Perhaps rear roll stiffness affects DTSS operation?

The #s I posted are from '87 FSM, I don't know if they changed springs for the heavier S5 cars, though I am almost certain they did for the convertables.

"Harder" suspension is not just in TIIs, right? Isn't it any 5 lug 86-88? Not sure when they went to all 5 lug in '89.

 

Cool. Thanks, man. I vote for ARCHIVE!

 

Yeah, I checked the spring rates for the S5 cars and they are completely different. They also had a larger 14 mm. anti-roll bar on the S5 hard suspension cars.

The cars that have the hard suspension are GTU, GTUs, and TurboII.

I found a guy selling all 4 shocks and struts from an S5 TurboII for real cheap, but I'm afraid those springs won't work well on my 86 base because it's so much lighter.

 

You're absolutely right Paul. The rules say you can swap parts, but it has to be a complete swap. However, the only differences (to the best of my knowledge) between an 86 Base, and an 86 or 87 Sport are the 5 lug wheels, bigger brakes, and "hard" suspension. The tranny and rear end are exactly the same. I believe the 4.30 rear gear only came in the GTUs, and a 4.10 rear gear came in the GTU. Since the S4 "Sport" cars (Sport, Turbo) all have the same brakes and suspension, I could get parts from any of them to do the conversion. This is only if I decide I want to put that much work/money into it. Right now it is just an idea I have, and I am just trying to find out more information on the possibilities.