Roger -

Did you notice a reduction in nose dive under braking after you installed the Bilsteins?

 

nose dive is one thing but wiggly rear is another
olddragger

 

phil---i sent PM's --i hear something may be wrong with the site--if you didnt get it let me know ok
olddragger

 

Roger, thanks for the order; I think the springs will improve your dive and body roll situation notably while keeping the ride very reasonable. I run on H-techs and don't have an unusual amount of brake dive, and I've got Carbotech XP8s at all four corners along with AP lines, PBR fluid, and the MS brace. If my car does anything particularly well, it's stopping! I do get a bit of the 'wiggly butt' (technical term) that olddragger mentions under extreme braking on track, but it's quite manageable and I think pretty much unavoidable given the stopping force and a relatively light car.

As for the Whiteline bushings that we sell for the MS swaybar (or OEM swaybar), customers report the nose feeling a bit more direct and the car feeling slightly more solid up front overall, but it's not a huge difference I don't believe. But hey, they're $25 shipped, and for a mod that costs that much to have a tangible benefit is saying something. I personally went directly from OEM bars to Whiteline adjustables (which come with poly bushings of course), as did all of my fellow DPE guys, so I can't speak from experience with that particular mod.

Olddragger, indeed, the site doesn't seem to be working for PMs, but I can read them in my notification emails that I get. I'll just email you directly about it when I have a chance. Thanks for the info .

Spin, those wheels look nice! I didn't ever consider that the '05+ Mustang (what those wheels are intended for, I'm guessing) would share bolt pattern and have a similar offset. I assume they just sent you the correct rings for an RX-8, or are the hubs the same centerbore as well? Nice to have some 17x9 options. I may have to start saving my pennies, but by the same token I'd better do it pretty quickly; just not sure my BFGs can take another track day, sadly.

 

Phil: I think I'll go ahead and order those from you tomorrow. I just finished installing the front springs and I'm pooped.

I don't think the nose dive is any different with the Bilsteins, shocks really don't have much effect under constant deceleration maybe a little when you first apply break and upon release. Stiffer springs is about the only think that reduces that other than changing the geometry. I think I notice the dive more because of the awesome breaking!

Phil: I didn't know about the Whiteline bars until I had already gone with the ms. I'm just scared shirtless to "ruin" my "boulevard" ride by going too extreme, we have some pretty bad roads around here and I live in a rural area. My 03 Miata with the VF s/c and the rb bars, apex coil overs was a go kart on the track but my bad disks in the neck really took a beating. I stopped driving it on the road and finally sold it for the 8.

 

When I ordered I just asked for the cheapest lightest w-i-d-e-s-t wheels for the RX-8 in 17s. I said they'd be track wheels and I wanted no crap stuff failing at 120mph. He immediately said those are the deal, good solid, wide but not overly heavy wheels. Center bore is spot on...exact...so i figured it must be made for RX-8? Seems to be a hidden gem all things considered. They havd them in other finishes, but get extra $ for them. I just needed them to go 'round & 'round

 

spin, did they tell you where they are made or anything? I may follow your lead on those, though they appear to be out of stock at the moment. I like that they're hubcentric with no rings.

I don't know, I found some Flik FTDs at Edge Racing that are 17x8, aren't heavy, look nice and are just obscenely cheap at $79 each. Made in China, but Edge claims to use them for track and autox with no issues. But of course they would claim that, as they sell them. Anyone know anything about them? Seems like a fantastic deal, but it's not as good a deal if they fail on track. Though I have searched and seen no evidence that one has ever failed; some references to finishes not staying pretty, but lots of happy customers and not much talk of easy bending or cracking.

http://www.edgeracing.com/2004/Mazda/RX8/wheel/2005/

 

People in Japan are racing 17x9s and 255 S tyres.

Panspeed switched from A048 to Dunlop. That drives me mad. I just thought a set of Yokohama A048 in 235/40 on my 8.5" +32

 

"Made in China" stamped on the wheel inside, not there is anything (cough) wrong with that. Regardless, they 'appear' high quality, beautiful finish - outside and inside, nice little inlaid emblem on the rim, center caps included. Not a thing to complain about... and they seem to work as advertised lol!

rim stress test (right)...

 

>.......... I do get a bit of the 'wiggly butt' (technical term) that olddragger >mentions under extreme braking on track

That's the one thing I hate about the 8 and it can get very scary at track speed. I have swapped in the complete MSpeed suspension set and it only helps marginally!


>.............. but it's quite manageable and I think pretty much unavoidable given >the stopping force and a relatively light car

Honestly I think it is related to some faults in the suspension design as it doesn't control the weight transfer as well as others. I've ride in some light weight cars before ...E30 M3, Lotus 7 ..... and yet none of them has that wiggly tail symptom under heavy breaking!

 

I noticed it more as my braking evolved (ie, got better). I wonder if it has to do with chassis flex under extreme conditions?

• Member braces?
• Tower braces?
• Sways?

Surely the Speedsource guys don't squiggle around like that?

 

Mazda had difficulties with the rear end stiffness and loss of handling precision during prototyping the car, that's why we have the back of the seat cross brace. My plan early on was to make sure any fixes Mazda put in place like that were made doubly strong for track use.

At a local track NHIS there's a particular short rise as part of a slight right before a huge brake zone (and a 90 deg left)where the car would do the dance and feel...welll... scary so you'd let off on the rise. Well, one of my first mods to my suspension was actually two things....Whiteline Adj sway bars and Autoexe front and rear 4-point strut tower braces.

After that 'no wiggles', no disconcerting feeling at all, whether flying over that rise at full power, or braking full stop before a turn from high speed (like Watkins Glen before the bus stop). I attribute it to the ultra stiffness the braces created. I'm not sure about lesser braces (2-point), but in back the Autoexe brace creates one ultra rigid box made of triangles, plus providing a tower of steel that braces the top-hat of the rear suspension and across the width of the car between towers.

You can see the OEM fitments, nothing really there at all, nothing connecting the floor and top of the tower where it's attached to near the wheel well. The Autoexe massively changes that, even using two additional holes that Mazda stamped into the top area and then didn't use. That I-beam isn't just light sheet metal either, but serious stamped heavy gauge steel. Of course then there's the 'X' cross brace too. If there was tower flexing or chassis flexing back there before...there's little to none now.

Put it all together and this is what I attribute my stable handling car to, compared to other RX-8s at track with me that mention the 'wigglie rear end' syndrome. Of course the SS guys have a full roll cage to accomplish the body stiffness, maybe they use braces too, don't know. One of best mods, handling wise I've put on the car.

 

Thanks, Spin. Good info there.

I noticed a major improvement in the front end when I got the MSpeed front tower brace, so I guess it figures stiffening the rear towers would help too. I was holding off on the rear brace since someone said it had made their rear too stiff, but I don't know what shocks they had. I can probably fine-tune the shocks for that.

What are your thoughts on the adjustability of the Whiteline sways? Have you just "set 'em and left 'em," or do you adjust them for different conditions?

 

When I had stock suspension I just left the sways on full hard, after all... the stock suspension is pretty flabby on track. Everything helped. Now I have the Cusco with eCon and I can change shock settings at will, so I've ended up changing sway bar settings twice this season, seeing what happens and taking note how I end up setting the eCon that day and why. I'm debating a 3rd change before this next DE this weekend, not sure yet.

BL, the sways bar setting changes butt-metter feel in bigger increments than the change in eCon settings. However, the much stiffer Cusco springs provide greatly improved handling feel all by themselves, but also, to some extent, overwhelm the effects of the sway bars & eCon adjustments. I'm also new to figuring out how all these things work out im practice, so what may be second nature to others with experience, I'm just getting to know what works good and why.

BTW, it's not possible to get the rear "too stiff" with bracing. What he may be saying is, when he finally got his chassis stiffened up, his other adjustments (sway bars, springs) were more hardcore than he needed for optimal handling.

I think it safe to say the average joe would try to improve flawed handling by doing everything else BUT stiffen the chassis. So springs, shocks, sway bars, bushing, etc... then MAYBE stiffen up the chassis. It should be done the other way around, otherwise you're modding a 'moving target' literally!

 

I see the benefits of stiffening the chassis, but I'm still not 100% clear of how that will "solve" the fish-tailing under heavy breaking. The fish-tailing is essentially a problem related to weight transfer from rear to front.

Btw, I've actually chatted briefly with the SpeedSource guy years ago when I first realised that problem while doing track events at Watkins Glen. He told me that mostly likely has to do with the rebound setting of the rear shock. Since then I have swapped in the MS suspensions. It seems to improve the situation somewhat but the problem still exists. So I suppose one will need an even better tuned rear suspension setup to really cure that wiggly tail symptom.

 

I can only relate what I know works on track. You're welcome to develop your own solution based on weight transfer if you feel that will help (sorry I don't 'get' the reasoning on that solution myself - all cars transfer weight during braking - most far worse than ours... and they don't all wiggle.).

Here's one theory I could come up with...true or not I know not. The rear under heavy braking goes positive toe and so tries to track out 1st one way then the other in oscillation. Stiffen the rear chassis area, lock the strut tower in place, minimizing suspension flex and therefore toe out. Voila! Much less wigglie tail (WT).

Sounds like SS doesn't experience WT. Perhaps they already "fixed" it perhaps inadvertantly as they couldn't pin an answer down for you, just a 'most likely'. They obviously do a lot stiffening too. Good luck.

 

Searching on the 'net I see several reports of wiggle: bicycle/motorcycle brakes (nak) -- control arm bracing (Mustangs & others). Another solution was to have more aero downforce in the back. One of the better writeups talked about the toe condition under heavy braking, similar to what both of you said...

I can see stiffening the rear with a tower brace to minimize the flex somewhat, and seeing if that will help. My front shocks are already at full stiff (on the track). I'm not yet ready to shell out for lowering springs, though -- maybe next season.

 

Good stuff in here; interesting that the rear bracing made that much difference. The wiggly rear has never been more than an annoyance to me; disconcerting, but controllable. I did notice when running the full-config at Heartland Park that it gets pretty dicey for turn one. Go over a blind rise at full throttle about 105mph, then angle slightly right while braking hard for a 90-degree right turn. You more or less have to either brake early, or brake way late while turning slightly right. Which from that speed was a bit more exciting than anticipated my first couple tries at it. Of course they just repaved turns one and two a few weeks ago to be straighter at the request of the SCCA Runoffs folks, so that problem is no more....

And while my Subarus always felt stable, try a stock 350Z; they do a bit of a dance as well, often with the feeling that entire sub-assemblies are moving independently of the rest of the car. But that makes sense then too. The Z, for all of its structure and girth, seem to have a relatively soft rear end. As evidenced by how well it gets power to the ground (with decent fluild in the rear diff for the LSD to work with anyway) compared to, say, an RX-8 which seems awfully deficient in longitudinal grip for a car with 159ft-lbs of torque (not that it matters much with grippy tires, just saying it'll spin them pretty readily for a car with so little engine. Relatively speaking). But the RX-8 feels inherently stiffer in the rear. So make it even more stiff, and times are good on track. Or at least the wiggles are under control. And I'd strongly guess the additional bracing doesn't cause any issues getting power to the ground, provided you don't have forced induction. But then, having forced induction on an RX-8 on track is an entire barrel of worms that we may not want to open in this thread. . .

As for the toe condition, that makes a lot of sense as well. Lower and stiffer on suspension would be your friend there, given it should reduce overall suspension movement and therefore reduce dynamic alignment changes. Also probably doesn't hurt to run 2-3mm of Toe In in back so that when it does head toward toe out it doesn't get too far out. I know I'm restating what others have said on this particular point, I just add it in for future readers who may have glossed over some of this.

 

I doubt that would help. The problem isn't rear brake lock-up, but rear-end instability when the nose dives and the rear becomes unweighted.

 

but it is a matter of track and personnel preference. ie driving style.
hard braking on a relative light car (mine you I said relative!) after a high speed rise and chassis hasnt settled is a challage.
One thing i do know is --dont lower the rear end a lot---this chassis likes a little rake in it. Go to low and then the rear end gets loose.
WHat I have found to work best for me(and I am NOT a pro) is careful modulation to hard on the brake---have to ease on it more--transferring the weight and letting the chassis recover. You have to feel it. its a seat of the pants thing.
One little quirk I have also noticed is a lift throttle surge the engine has. If I left too slowly the damn car actually goes faster! For only a sec or so but at 130mph 1 sec is a good many feet. So I lift more sudden now!
Phil you may find that with the 17's and lower gearing you may end up a little faster--- approaching that spot! The R's will make your turn in etc and responsivness much better. So managing this turn is going to be a whole new ball game.
Pleae let me know how that is going to work out.
We are at Road Atlanta this coming w/e and a real heat wave is here. I lasered the pavement a few minuets ago and got 137F. At least the car is running cool, the hood vent mod actually helps.
olddragger

 

With all this in my head , I'll closely observe for WT and how the car feels in the real world at Mont Tremblant this WE which has multiple 90-100+ mph brake for corner apexes. My (new) setup this year is mildly (-25mm) lowered w/Cusco 2e, 17" R-Comps, toe 0 r, -1/8 f plus lots of -camber -2 r / -1.6 f. I would like to think (and hope) everything will improve from no coilovers/ no R-comps/ no alignment/ no corner balance last 2 yrs there. As I have lots of Traqmate data sessions from before it'll be easy to see the results. With both sets of data I'll even be able to chase myself around the track in a mock race...

Le Circuit http://www.lecircuit.com/circuitDocu...MT%20areal.jpg (former F1 track)

 

Nice track! Have fun.

 

I thought I was nuts, but if olddragger says there's a lift-throttle surge, it must be true! Not sure if anyone else has noticed that, but yeah, lift of the gas after nearly wrapping out third in my case, and the car briefly surges forward. Very odd feeling! I guess for od it must have been more notable in 4th .

Spin, I suspect you'll have a grand time at that track with all of your new additions. I look forward to hearing about it. I'm pretty certain WT won't show up now if it wasn't a problem before.

I've got my used RA-1s now in 235/40/17, so we'll see how that goes. Another Heartland Park event next week, and Mid America the week after, so I should be able to get a good feel for them. Just have to hope the 97 degrees and humid temps simmer down a bit next week; not that you can't drive in it, but it's not the most enjoyable weather for outdoor activities on pavement. Still, probably beats whatever it's doing in Georgia right now .

 

Swap in one step down in brake compound in the rear and WT should go away.

i.e.
Front: Hawk HT-14
Rear: Hawk HT-10

 

I just had a set of Koni + H-Tech's (50% front, 25% rear) installed yesterday (purchased from DPE- great vendor). The ride is much more comfortable than I had imagined for day to day use. Will have track review from Sebring in a week.