TeamRX8

iTrader: (25)

10" long @ 475#???

unless you're building a rock climber you may want to double check your calculations and dimensions again

Nathan Atkins

whoops, that's what i had planned to use in the front actually, not the rear.

rear was 8" @ 475#

springs are available in 4,6,7,8,10,12...

so i figured (for the rear) that stock rear springs at 113#/in get collapsed by the weight of the car to a length of 7.45 inches, then a if i want to go roughly an inch lower give or take then an 8 inch spring @475#/in would collapse to a length of 6.44inches under the same load

according to my numbers
10@475 should lower the car a half inch in front
8@475 should lower the car an inch in the rear
that seems to get me in the ball park of what i had wanted, then i can even things out from there with ride height adjustment.

I'm using:
F/R motion ratios of 0.82/0.84
F/R corner (unsprung) weights of 676/622

Please let me know if im way off base with this, I seem to be over simplifying in a couple critical ways as you guys mentioned before and this may be no different. I certainly welcome the constructive advice and comments

Kennetht638

iTrader: (2)

I wouldn't say you're way off base, but you seem to be assuming that your spring perches will be in the same places as stock which definitely will not be true if you're running 2.5" race springs. I don't know what dampers you intend to run, but either way, the upper perches will end up at least an inch lower than stock because the race springs won't fit over the huge rings for the stock springs. I know that with my old converted Koni Yellow setup, the perches ended up much closer together than stock and even with a 7" spring, I couldn't lower the car to where I wanted it. I ended up machining off the stock perches to lower my coilover sleeves to compensate.

Edit: It seems I had mentioned a bunch of this before (with some pictures) on page 124

Nathan Atkins

right, i was going to use the good win racing delrin adapters in the rear and i think they rob you of about 5/16" of space. In the front i was going to use the bilstein 2.5" top hat which i thought i could make adapters for the top using the stock top ends as a template. I understand there will be some basic fab work here.

Dampers are take apart converted Bilstein B8 HD, like the standard Bilstein B6 HD but with a shorter shock body, lower perches are on a 5" threaded sleeve made to fit over the 46mm diameter bilstein body.

If I must. What was your rear rate? I guess i had assumed that being in the ballpark I'd have the ability to adjust out the discrepancies with the threaded sleeve lower perches but from the sounds of it, they might reach the bottom without getting the ride height im after

I saw your pic and I appreciate that, did you consider helper springs to keep them seated on droop?

TeamRX8

iTrader: (25)

I can't see using 10" in the front either, 8" is typically more than enough.

Nathan Atkins

yeah youre probably right, i need to see how much the perch to perch distance is with the new shocks...im going to order in pieces so that i can measure as i go.

OR:

TeamRX8

iTrader: (25)

back in the STX aero allowance day I had a 2.25/400# front rate and only used an 8" length with 2" long zero helper spring. The helper was mostly collapsed at full suspension extension. I ran 375# in the rear then too, so almost square, but when I had to take the rear wing off the car went way loose. This was with a stout 1.25" OD x 1/4"wall speedway front bar and the OE rear bar. The OE rear bar is so soft that removing it doesn't do much more that cut the roll/pitch couple loose between the L and R rear suspension. This cause more issues than it solves IMO, but maybe I just never figured out the right combo to run without a rear bar.

Nathan Atkins

Hmmm....it had occurred to me that i typically run 35 psi rear and 32 psi front to try to loosen the car up a bit, maybe loose will suit my style.

I hadn't considered any other side effects of unhooking the sway bars, so that's more food for thought. I think for my next autocross that has a morning and afternoon session on the same course I'm going to straight up disconnect the bars in the afternoon just to get a feel for the difference on the same course. There is a whole camp that claim that sways compromise grip in the pursuit of stability, so it'll be interesting to feel what the effects are.

Edison found something like 4000 ways not to make a light bulb before he was successful, It will at least satisfy my curiosity to put some of these theories to the test, even if they dont work and i end up with a more traditional setup.

Kennetht638

iTrader: (2)

My rear rate is 350 lb/in both on the old coilovers and on my Koni 2812's. Both sets also have 7" springs. I have the upper perches on my 28's just shy of rubbing the shock mount to get to my desired ride height. I did have helpers at one point, but again, they compromised my ride height so I took them out, and it hasn't been an issue for me at all as the springs should never unload in normal driving.

That Edison analogy is cited a lot as a reason to fail at things, but in this case it doesn't totally apply because a lot of this has been figured out already. Cars are not magic, and a 50% front roll couple will be looser than the 68% that I run. In fact, at an event just this last weekend, a change from 65% to 68% took the car from undriveably drifty to nicely neutral. Even the almost-square spring setup that Team mentioned has a very heavy front bias due to that crazy stiff front bar and no rear bar.

As I've already said, I don't want to discourage you from experimenting, I am just providing my opinion in order to help you out as I wouldn't want to see you waste time/money. If this does turn out well, I will be both surprised and happy for you!

ABQautoxer

I realize it's less fun and probably cheaper in the long run, but it was such an easy button to put the KW's on my car. Sure the initial cost was more but with an FSB, catback, and KWs the car was plenty fast in TX, faster than I could drive it.

BRODA

iTrader: (7)

This is the best discussion I've seen on the RX8 club in a long time. I'll be testing a square spring setup this weekend, but I'll have more front roll couple than Ken with the bar(s). Should be interesting.

Nathan Atkins

Haha, this body roll makes a pretty good case for moving from CS to STX, these suspension bits cant arrive soon enough :-P

TeamRX8

iTrader: (25)

what's that hanging down by the LF corner?

Nathan Atkins

Cone rash resulted in the death of the plastic panel between the wheel and the oil cooler, the dangling thing is the connector for the fog lights i dont have :-) I need to zip tie that thing back up there

Nathan Atkins

So I decided to go with the Tein tapered 70mm-90mm springs like the FCM coilovers use.

also the square setup has fallen by the wayside, rates are 10kg/mm out front and 7kg/mm in the rear (560/392) they're 175mm (6.8inches) long and I'm using hypercoil tenders,

dampers are still the bilstein b8s, I'll be valving them to suit the springs and weight.

Parts are trickling in both for the suspension and my DIY shock dyno, so everything is going to come together toward the end of the summer, I have to wait for the springs to be made and shipped and the lead time is 60-90 days (!)

In the meantime i picked up a $100 set of RB lowering springs to throw on the bilsteins so i can re-immerse myself into the local STX environs.

I'll keep you guys posted as things come together, then hopefully I just start posting screenshots of me at the pointy end of the timesheets, surrounded by pit babes and paparazzi and stuff.

Nathan Atkins

so as it turns out there is a 60-90 day wait period on the Tein springs because they dont stock them, in the meantime i picked up some Racing Beat lowering springs for a song to throw on the bilsteins for the time being. The Bilsteins will be a bit overdamped out of the box but until the dyno is assembled im just going to use them as is. I know it's not going to be the most competitive setup but it should be more fun than stock. I'm already only about 1.5 seconds of the top STX step typically and with a completely stock car, so even this modest bump from the RB/bilstein combo should be something. I'm pretty stoked about eventually getting the stiffer springs in and getting the dampers dialed in :-)

I have all my parts for the shock dyno but my load cell isnt reading right so im investigating that, it might need to be returned. I think I'm going to experiment with revalving the bilsteins to match the setup with the RB springs for the meantime once i have a dependable load cell.

Tofu*Monster

Thought I would join the fun in here. Lots of good info floating around that is for sure. I am sure some of you have seen my build thread as well. I finally got to take the car out to my local San Diego region for some testing in STX with all my new suspension upgrades. Car felt outstanding and I am very happy with where I ended up with results. 2nd/10 in STX .1 off 1st. Also PAXed 14th/ 166 entries. I am still very in the process of my build and was curious what some of you would feel would be the next best mod for STX.
Car Currently: AEM intake, CAT back, Bilstein PSS9, hotkis front adjust able sway, Agency power adjustable rear bar, 245 Kumho XS on Kosei K4r 17x8.

Been looking into getting an access port, just not sure if that will really help all that much. Are light pulleys much help on a 13b? I am used to not running them on tradition engines due to harmonic balance issues, but Rotary is new to me. Not sure the same issue applies. Brakes are still stock, but haven't had an issues with that yet. I have been looking into autox aero as well. That is more for fun as I haven't played with aero much in the past.

Any insights would be great.

MikeTyson8MyKids

iTrader: (1)

Honestly, a set of the latest generation of Autox tires would be the best thing for you.

Tofu*Monster

Agreed, I bought them purely for testing as I know they don't really heat cycle out as quick as RS3, R1r and a like. My Kumhos are practically corded so I am sure there is about a half second gain at least with better fresh tires. I was more looking at other weaknesses the 8 may have I could improve on.

Nathan Atkins

I'll be trying out new 17x9's and R-S3 Ver 2's tomorrow, I'll post any comments i have about it in the afternoon.

WDCR SOLO Event #2 @ FedEx Field
Log In

dezau

iTrader: (3)

dis is so beautiful imma cry






Video of that particular cone

Nathan Atkins

I tried out the Hankook R-S3 v2 this weekend in 255/40/17 on 17x9 +45 Enkei PF01's

result:

Grip levels were quite a bit higher, it took some getting used to :-)

TeamRX8

iTrader: (25)

looks more like the grip level at your limit is narrower

BRODA

iTrader: (7)

Anyone have an open seat for an STX co-drive at Nationals?

Nathan Atkins

It was just unfamiliar, the finish here particularly because it's on that darker sealant and it's slippery there.

I'm just going back to using rivals on the stockers tomorrow.