Progress Technology Springs
 

R&D has completed and the AutoX springs are soon to be available.


AutoX Springs: MSRP $350

GB going on now: https://www.rx8club.com/series-i-wheels-tires-brakes-suspension-55/exclusive-progress-autox-springs-group-buy-183663/

Front: 425 Lbs./In
Rear: 280 Lbs./In

Front Drop: -1.2 inches
Rear Drop: -0.8 inches

These are finalized numbers.

Thanks for organizing this!

Would I be correct in assuming these springs would work with any stock style shock? e.g. konis. I think someone like TeamRX8 could give great feedback on this subject.

Personally, I'd like to see a 1" drop front & rear with a front spring rate around 420-450lbs/in, and a rear spring rate around 275-300lbs/in.

I'm sure more will chime in...

I like 1"drop ront, 1/2" drop on rear, 400lb front, 275lb back

I'd like to see some direct replacement springs with spring rates similar to what is found on the popular coilover kits (450-400 lbs/in Front, 300-250 lbs/in rear) with a very small drop, 0.75-1.0" or so.

Revalved Konis + stiff springs should work well for STX.

In the mean time I'm figuring out how to mount Bilstein ASN shocks, inverted, at all 4 corners.
http://tbn0.google.com/images?q=tbn:...w.gwracing.com

450/275. 1" drop F & R.

Glad to see you chime in Doug. You were the other person that I was interested in hearing input from.

Thanks guys Keep it coming.

I agree with the above sentiments. No current aftermarket spring, near as I can tell, would be a good choice for STX. The rates above are the current consensus, and they seem reasonable. As for the drop, about 1" is good, and give a front/rear drop bias that will achieve roughly neutral handling for the spring rates choosen. I don't care about looks.

Also, please let us know what bump stops were used in the development of the spring (i.e., stock, untrimmed, or trimmed, etc), as this can influence handling balance as well.

Very good point!

I will be very interested, currently running mazdaspeed springs and dspecs for STX/Track. Would love to go stiffer, 450/275 1" drop sounds great to me!

ding, ding.

nice to see you around george!

beers :beer:

I'm interested in seeing how this works out, looking at STX for 2010.

I'd prefer a little less than 1" drop. With the 1/2+- from the Koni's a full inch would be a little more than needed. IMO. The rates sound about right. If anything I would like to err on the side of stiffening up the rears. I'd like the option to remove the rear sway bar and balance with a stiffer front bar to improve traction.

Thanks swoope.

I was about to suggest that they set the springs up to work well with both the OEM and Progress sway bars (if that were possible) but StrokerAce brings up a good point. I know this approach (no rear sway) is common in the Miata community.

Anybody else have comments on that?

Agreed on the drop. I'd like to be at a 1" total drop when on koni yellows (which seem to be the most common/popular performance shock in the RX-8 community).

With regards to rear stiffness, one other option is for Progress to make multiple spring rates available for the fronts & rears. e.g.

Front: 450, 425, 400
Rear: 300, 275, 250

If this were the case, serious autocrossers would probably want to purchase multiple sets of front and rear springs as they figure out the right spring rate balance for asphalt & concrete.

And on that note there are now going to be 2 Springs being offered and Manufactured and designed by Progress at our Request.

There will be a Track Spring 450/260 Maybe 270, but the rear is reaching the limits of coils on the spring, If I remember correctly from our conversation today.

Then there will be a Street Spring with lower rates in the 230/180 Range.

The Track spring will be exclusively available through Fluid Motorsports and will hopefully have 2 prototypes to get some field testing *cough* need a volunteer. *Cough* Not Just yet of course ;)

The Challenge in Front of me is 40-50 spring sets will be needed to make the project remotely affordable, if the demand is there for the majority of that I have no issues pushing this through.

Thank you to everyone for their input and please continue to watch this, please feel free to post up to express interest.

The more interest I see, the more this project will see production.

^Any idea on what the targeted ride height drop will be for the Track Springs?

We are going higher initially and once we get Field testing feedback we will go from there.

Range is 1.2-0.8

Sounds good. Thanks!

I favor the 0.8 better..

Why is that?

the RX-8 has a fairly low roll center already. Going too low changes the angles of the control arms and drops the roll center too far, giving it greater leverage on the springs. You have to increase the spring rate to compensate for the increase in leverage. Keeping the car just above a 1" drop, like .8" places it within it's sweet spot. Look at the championship-winning Speedsource cars. They avoided dropping their cars very far at all. What does Speedsource know about the RX-8 chassis? Think they've extensively modeled the motion of the control arms to see what happens?

Boy you must really an an "in" with Jeff at Progress Technology because I asked them two years ago to do RX-8 springs! All I heard was "blah, blah, blah... not enough of a market..." :D

Yes, I'm familiar with all this.

I'm just wondering if somebody has something specific as to why .8" would be better than 1."

Looking at the Speedsource cars, I'll agree they don't look slammed, but I sure can't tell if they have lowered the cars .8, 1" 1.2" etc. by looking at the pictures. Besides, wouldn't they use custom control arms & links to correct the geometry?

Not trying to be a PIA, just wondering if somebody has something specific.

Jeff is a great guy and they were looking to expand the market. Not sure if they really had to many distributors that carried the RX-8 line then.


0.8 is best becasue going to low you start getting negative camber, among others issues.

Swift went with that number as well, he favored 1.2 and .8 the most Front to rear.

Talking to him today, he is extremely intelligent and has been doing this for a long time I am confident in his decisions and hope to see this project through.

Sounds good, I look foraward to seeing these on the market!