DPE

iTrader: (1)

Okay, finally getting around to making this post! Tom and I were able to get out on track in two very similar RX-8s, drive each other's cars on track, and get a few impressions about how the shocks (and tires, and brakes) work. Note: This is just a couple of average guys in a couple of street-driven RX-8s; we don't claim to be the gospel on any of this stuff. It's merely our unbiased observations, and DPE makes equal money on Tokicos vs. Konis so it's not meant to be an endorsement of a particular product, either . The background:

Tom's car is a 2004 Sport with about 50k on it. Engine mods are a Greddy exhaust and K&N filter. Suspension mods include Koni shocks and Tein H-tech springs, Whiteline adjustable sways, and new Bridgestone RE050A Pole Positions in 245/40 on OEM wheels. Brake mods consist of Carbotech AX6 (Panther Plus) pads up front, Carbotech Bobcat pads in the rear, and Goodridge SS lines. And Motul RBF600 fluid.

My car is a 2004 GT with about 43k on it. Engine mods are the MS Sport exhaust, AEM intake, and Magnecor plug wires. Suspension mods include Tokico D-spec shocks and Tein H-tech springs, Whiteline adjustable sways, MS front strut tower brace with MC stopper, and new BFG KDW2s in 245/40 on OEM wheels. Brake mods are Carbotech XP8 pads all around and Agency Power SS lines, along with PBR BF600 fluid and the aforementioned MC stopper on the MS STB.

The track was the Heartland Park 2.5 mile course, the largest configuration of the track and what is used for the SCCA Runoffs. We often run the 2.1 mile version, but the 2.5 mile adds in a very interesting (and fast) banked carousel that can generate some amazing g's if you trust your car to handle it. Which does take some time for a slow learner like myself.

Anyway, in the interest of not taking all night to write this, I'll get down to the points of comparision. We each got in roughly 120 track miles, and probably did 20miles or so in each other's car after running all morning in our own vehicles.

Shocks: (Konis set at ~50% front, ~25% rear; Tokicos at ~90% front, ~70% rear)In the realm of Koni vs. Tokico, I continue to think the Koni is a better shock. But the difference between the two has grown smaller for me over time. Tom's car is simply smoother. The way it bends into corners, the way it handles undulating pavement, and the way it responds to inputs mid-corner just felt more progressive yet more responsive to me. In a word, well-damped. In contrast, my car also felt very good as most modded RX-8s do, but seemed a bit more abrupt in chassis motions. Not a night and day difference, but one that was notable. As an example, if you turn in quickly it felt like my car took a split second and a bit more body motion to take a set. Tom's car seemed to bend into the corner with a seamless transition. Tom noticed less of a difference between the two shocks, but that stems from a difference in driving style that I'll get to later. Point being, for RX-8 shocks, not much has changed. For the best replacement shock for performance and feel, I still think Koni is the way to go. However, with Tokico you are not giving up very much (if any) in real performance, though the feel of the shocks is a notch down. But you gain simple rear adjustability, which is nice to have. And now one can get Bilstein too, which I need to try out.

Tires: Very interesting comparison here. We both agreed my BFGs are superior in steering feel and response over the Bridgestones. However, the BFGs also go away in 3-4 laps, while the Bridgestones maintain consistent grip levels for several laps before they overheat. Overall grip seemed quite similar for the first 3-4 laps. The Bridgestones also wore MUCH better, showing some wear at the end of the day but nothing out of the ordinary. In contrast, my right side BFGs, particularly the right front, were chunking severely along the center rib and a bit on the outer rib as well. Really never seen anything like it. I suspect the banked carousel had something to do with it; it's a long, sweeping, fast turn where you can generate some serious gs; enough that it takes a few tries at it to recalibrate your internal g-meter to just how fast you can go through it. That puts enormous stresses on the outside tires, and since they were near full-depth with too much tread to squirm around it really beat the crap out of them. Live and learn.

Brakes: The XP8s all around win the day here. The AX6 and Bobcat combo held up great and Tom's car could brake quite well with no fade, but my car will brake downright violently lap after lap. It is a very notable difference. And probably didn't help in keeping my front tires cool . Feel was similar, but it seemed like my pedal was a bit more solid when you were really on them, most likely attributable to the MC stopper on the MS STB. Nice touch by Mazdaspeed, I think.

Driving style: Here's where I suck, and Tom is good. Tom consistently ran about 2 seconds faster than I did, be it an average or a fast lap. Interestingly, I ran my fastest lap of the day in HIS car, but my fastest lap in my car was only a tenth slower and given how much we were experimenting with lines and how often we were being run down by 911 Turbos and the like (It was a Porsche Club track day for advanced students and instructors only, so we weren't QUITE the fastest cars out there), clean laps were pretty hard to come by. Anyway, I still drive my car like I'm driving a Subaru STI, in which you do everything fairly violently and tend toward a later apex. I've come around to an earlier apex somewhat, as that is a better way to go in a momentum car like an RX-8, but I still don't exactly have it down. Tom, on the other hand, seems to have the car figured out. His lines just flow smoothly from one corner to the next, to the point that while following him I couldn't fathom how he was inching away from me yet appeared to be on a casual Sunday drive. Point being, Tom is quite smooth and generally is driving the rear of the car; it always feels like he's right on the edge of spinning, yet he never does. On occasion it does get exciting mind you, and I believe he trimmed some grass at the edge of the track a time or two to save the groundskeeper from having to do it, but overall it's clearly a better way to drive the car. I just need to shake off all of the old habits, and perhaps one day I'll be able to keep up!

Overall, a very fun way to spend a Friday, and it was nice to be able to compare parts as well as driving style in a fantastic track car like the RX-8. I'll see if I can get Tom to post too, to see if he has anything to add. Questions, comments, criticism and outright insults are all welcome!

olddragger

iTrader: (3)

interesting. I run in agroup that has many different set ups and realistically speaking
the suspension set up seems to be a personal preference over actual performance based facts. I just like the konis and H tech springs yall advised me on. I cannot find fault with it. i would wonder how the tokico's would handle the harder braking of the xp 8's.
speaking of which---i am ordering my 2nd set of them today---they are great track day pads---they have lasted me for approx 8-9 track w/e's(over 200 miles per w/e)---i have converted more than one 8 owner from the hawks. Again thanks for all the guildance yall have given me guys --yall rock!
olddragger

swoope

iTrader: (5)

phil,

great post.. your job sucks as much as mine..

beers

swoope

iTrader: (5)

https://www.rx8club.com/showthread.p...42#post1980942

phil.

hope you dont mind.. did not want you time missed..

beers

SouthFL

Good stuff.

RX8Maine

Thanks for the comparo. I think I will eventually be doing shocks only, on stock springs and sways. I am 99% certain it will be the D-specs, for the sake of adjustability. I am very interested in hearing about the Bilsteins, especially if they will have similar adjustability.

Paul_in_DC

For me, the Tokico's rear adjustability is an absolute necessity. Tracks are different, and conditions change. (I didn't use the same setting while driving in the rain as I had the day before on dry pavement.) Plus if I add other things like a rear tower brace, I'll need to experiment with softer settings in the rear. And I set them much softer for day-to-day driving.

GeorgeH

iTrader: (2)

Hi Phil, thanks for continuing your comparison of these shocks.

Just an FYI, if you look at the dyno graphs of the two shocks in page 4 of this thread:

https://www.rx8club.com/showthread.p...light=bilstein

You'll see that for the rears anyway, that the Tokicos at 70% have more damping than the Konis at 25%. This might explain why the your car felt more abrubt - it was more heavily damped, and thus wont' let the suspension react as fluidly. I don't have dyno curves for the front of the D-Specs, but I'm pretty sure that the Tokicos at 90% are stiffer than the Konis at 50%.

Not trying to second guess your conclusions, just wondering if backing off on the D-Specs a little might have changed your impressions.

Anyway, it's nice that we have dyno curves now comparing the two. As you have noted in earlier posts, the Tokicos can go much softer, but it appears that at full stiff, they are very similar, although the Koni dyno graphs only go to 2.5 turns - that last 1/4 turn probably means the Konis go a little higher.

George

DPE

iTrader: (1)

Wow, a little late back to the party on this one. Sorry!

Swoope, feel free to pass it around wherever!

Olddragger, thanks for the comments, as always! Glad your setup is treating you well, and those XP8s are on the way to you today .

GeorgeH, the dyno results are very interesting. I'm not familiar enough with them to know how shock dyno results translate into real world performance, but I'm certain my behind isn't as well tuned as a shock dyno .

As it happens, I had a chance to do a good deal more experimentation last Friday up at MAM in Iowa. The track is a very flat 2.2 mile road course, that is generally smooth but is starting to get a lot of undulations in the pavement. Not 'bumps' per se, but more like ripples. Makes the suspension have to work anyway! Unfortunately Tom wasn't there with his car, so no direct comparo with Konis this time.

I started with the shocks at about 60% front and rear; on accident. Drove them up to the track that way and forgot to crank them up. As I've experienced, they're simply too soft at that setting and the car was unsettled and 'soft', for lack of a better term. The dyno doesn't lie, but I know the Koni car does not feel that way even with the front and rear shocks both at 25%. I understand that's inconsistent with the dyno, but subjectively that's what I feel. Perhaps at slower piston speeds the Konis do a better job of damping even though they are theoretically 'softer'? Not sure how that gets represented on a shock dyno.

Anyway, I cranked them up to 93% front and rear, and the car was back to driving properly but pushing a bit much. Dropped the fronts to 80% and left the rears at 93% for the rest of the day, and the car worked very well.

At MAM, there is a lot of pavement and literally almost nothing to hit if you go offroading. Therefore, I was more comfortable hanging the rear end out. And there are a lot of long, sweeping turns at MAM that exacerbate understeer, which the shocks helped dial out a bit at those settings. I still feel the car pushed too much, but I'll work on that. Certainly was plenty eager to rotate at will, so it wasn't a pig or anything. For that, Craig brought his Mazdaspeed 6 along, which taught us all about terminal understeer though it lapped close to the RX-8 for a couple laps before the intercooler and front tires fell off the pace due to heat. Really a sweet car driving up to about 80%, and it feels nicely balanced on the road, but push it to the limit and it's still a 3600lb sedan with most of the weight up front. At least the brakes worked vastly better than Craig's Z with only XP8s up front and ATE Blue fluid .

Anyway, I'll reiterate that the car is quite wonderful on track whether you have Konis or Tokicos. And I too appreciate the rear adjustability; enough that I'll leave Tokicos on my car for awhile. Need to try those Bilsteins, but that's a few notches down on the project list.

I'll also reiterate that if you are going to track your car regularly, the BFG KDW2 is NOT the tire for the job. Mine really look awful now, with significant chunking at all four corners, and they have just a bit over 300 track miles on them. Yeah, I know, I shouldn't be using a street tire on track, but my Avon M500s never looked like this and wore just fine down to the wear bars. I've tracked a LOT of tires on a lot of different cars, most of them harder on tires than an RX-8, and I've never seen anything like this.

And the last thing I'll say is that this car continues to amaze me. I've not had great luck with it day to day, as it had the front seal oil leak and a couple exhaust leaks at the manifold and such (this motor only has 15k miles on it; my first as I bought the car used, but the car's third). I wasn't even sure if they fixed the exhaust leaks right, and wasn't sure what to expect at the track this time. Instead of having to worry, I simply drove 140 track miles in one afternoon without the car missing a beat. The consistency is just amazing. Braking, responses, engine, etc.; it all just keeps right on working. Heck, it even consistently gets to right about 70 track miles before fuel cut becomes a factor with 3.5 to 4 gallons left in the tank. And 70 track miles = one quart of oil too; like a 2-stroke, just add oil when you fill the tank and you're set .

swoope

iTrader: (5)

phil,

where are your sways set???

beers

DPE

iTrader: (1)

Front on soft and the rear on stiff. I had been running with the front on stiff and it didn't seem to push quite as much, but too many things have changed since I last touched the bars to make that determination. Never mind my comfort level with the car, which has increased a great deal. The tires are chunking along the center rib as well as the outside, so I don't think the car is pushing worse because there's not enough roll stiffness in front, but I guess I'll have to put the front bar back on stiff and go to the track AGAIN to figure it out, darnit.

I would have changed the front bar settings at the track, but you know, we were just having too much fun lapping .

I think some of the push might be coming directly from the tires, which after a couple violent heat cycles are not feeling like the direct, responsive tires that they did before. And keep in mind it's all relative; the car pushes a bit, but as I said it'll rotate just fine under trail braking and on lift-throttle in mid-corner, so it's not far off of just right. MAM just instills a bit more confidence than HPT, so what works balance-wise for HPT to keep me from hitting walls might be a touch too conservative for MAM.

swoope

iTrader: (5)

hey,

i ask the tough ?s... so back to the track you go... get to work..

and as to the sways. i would think ft hard and rear soft would solve the problem with stable tires..

wondering what tires do you think will cover your needs????

beers

takahashi

suspension you have it firmer front and the sway is softer front... do I read it right? So if you adjust them - will it make more different and how? Love to share logics. Me still finding a way around my settings, although I don't have luxury to the sway adjustments.

I think you should consider not driving like you were in an STi too. That is very different, just realise how much so after driven an EVO hard.

DPE

iTrader: (1)

Yeah, suspension is a black art of sorts. GENERALLY speaking, you go stiffer in any facet at one end of the car and that end will break away first. So you stiffen the front swaybar, and it'll understeer more all else equal, right? Maybe. Thing is, if you stiffen a front bar more and by doing so reduce dynamic camber change, then it MAY result in more ultimate grip. This was definitely true in the Subaru world.

And speaking of that, I'm weaning myself off of my STI ways, and certainly understand that's the wrong way to drive this car. It's just difficult when you have a couple thousand track miles in Imprezas and switch to something totally different. Let's just say old habits are hard to break. But I'm coming around, and this last trip to MAM definitely improved quite a bit. Still work to do, and there will always be, but I'm not quite the embarassment to myself that I once was.

For tires, what I would like is Toyo RA-1s or perhaps that Nitto NT-01. What I can afford, however, does not match up with those two. Despite what I do for a living, discounts on tires are miniscule at the wholesale level. I'm considering Falkens, but am a bit hesitant as Craig wasn't particularly impressed with them on his Z. However, the Z actively conspired against us by rebelling against every mod we did to it, so perhaps that was true of the tires as well? At any rate, I might give those a try, and worst case will just go back to Avons as they are cheap and pretty effective on track. The Bridgestone RE050 PP seemed to do quite well on track (but is expensive, relatively), and the Kumho MX holds up well but I never cared for the numb feel of them.

Michael

I can totally attest to the chunking of the KDW2's - front right tire, center of tire, and along the outside. If it weren't so late I'd go take pics, as I just rotated them.

I'm going to have to dismount and switch them over to the left side eventually, as they'll chunk themselves to death before I wear them out tread-wise.

As far as no wholesale discounts, I got 4 275/35-18's for $836 total from tireshack.net, and that was a whole lot cheaper than anywhere else.

Thanks for the writeup - I'll be purchasing a Koni/S-Tech combo from you in the near future, as this thread reaffirms everything that I was feeling already!

Spin9k

An opinion from one who's been there with two of the three [235/40/18 and 275/35/18 RT-615s; 245/40/17 Nittos]. Falkens are a fine street/track tire, can't go wrong.... However, if you want better grip without fuss, more stable handling and improved confidence in the car on track go NT-01s. A whole 'nuther animal that moves the bar up for your driving enjoyment.

Here's a little pic to inspect what could be...

Paul_in_DC

Do you have the stock front tower brace? Before gettting my Mazdaspeed one, I was worried it might make the front too stiff, and I'd have to adjust the shocks to compensate. But instead, the front is much more "planted" than it was before, and holds much better in a turn. I assume that since the front end doesn't twist as much, it allows the suspension to work better.

takahashi

Spin9K. Your tyre is so much like the pattern of BridgeStone RE55S, without those 2 circum grooves.

olddragger

iTrader: (3)

before you do final adjustments on suspension --decide on the other 4 springs.
This car does well with 17's and a 235/245/40-17 lightweight combo. you also can get used(but almost new) 2nd hand r compunds for less than $100 bucks apiece. If interested I will pm you my supplier Phil.
Dont forget the old trick in loading up the opposite rear tire when going over the "rough"-so need enough stiffness's for that!
olddragger

PhotoMunkey

The entire point behind Bilstein's design is that they don't NEED to be adjusted. The velocity-sensitive valving on both compression and rebound means that the shock self-tunes to every bump, to every motion. For hard, quick bumps it responds instantly with virtually no resistance. For slow transitions, like left-to-right sweeper turns on the track, the shock remains firm, complimenting sport springs very well. That is the genius behind Bilstein, and also why they do tend to win lots of championships. A self-adjusting, velocity-sensitive shock is imminently more qualified to adjust itself than we are, unless we happen to have a degree in race car chassis engineering.

DPE

iTrader: (1)

Michael, we've got three sets of Konis in stock as of today, and a ton of S-techs, so if you're ready in the near future we should have them. Sorry to hear you also got into the chunky tires; I really like BFG, and it's a good tire for 'normal' use, just exceptionally bad for a track tire even by street tire standards.

Spin9k, I do like those tires! It's 'what could be' if I actually had any money though . Only thing, I'm not seing a 245/40/17 in the NT-01? I may be going blind in my old age. I do see a 245/45 which would work, but I wouldn't mind 5% shorter gearing and lighter weight of the 40-series either.

Paul, I've got the MS STB. Mostly got it for the brake MC stopper, which does a nice job of improving an already outstanding OEM braking system. I can't honestly say I noticed a lot of difference in chassis stiffness with it, but I think I changed tires about the same time that went on and was paying more attention to what they were doing.

olddragger, I'll be hitting you up for a source on lightly used R-compounds; even better, can someone find me some cheap, light 17x8" wheels for this thing?

Munkey, Bilstein makes great stuff and has indeed won a number of championships, but it's still nice to have damping adjustability. There's a reason, for example, why Bilstein's top mainstream coilovers are 9-way damping adjustable . If nothing else, it allows you to tune a bit of chassis balance with the shocks, which is a nice thing to be able to do and certainly doesn't require a suspension engineer to figure out. Their HD for the RX-8 is by all accounts a great shock, and is no doubt vastly better than OEM; espeically if you pair them with aftermarket springs. And the price is right. But they aren't going to be as versatile as an adjustable shock no matter how good the internal valving is. Certainly might be better in some ways and for some applications, but adjustability is a good thing when it comes do dampers and playing around with RX-8s on race tracks or autox courses.

Spin9k

Opps! Mind cramp...they are 245/45/17s $174 not too expensive I thought. Interesting read of customer comments here -->http://www.discounttiredirect.com/di...l.do&tc=NITHZ7

I used these HotWheels 17"x9" 45 offset 20lbs here --> http://www.discounttiredirect.com/di...14.3&tc=HOTSIX as I figured with the higher aspect ratio & sidewall of 17s - supporting it with wide 9" wheels would add stability over say an 8".

Got a great deal mounted balanced shipped plus an add'l ~$100 off for no good reason. Couldn't believe it but 'What ta hey!" - Great place to deasl with. The wheels ARE hot, i really like them, esp. the machines lip. Total weight of wheel/tire is 2 lbs more than my 275/35/18 RT-615s and Enkei 18x9.5' RPF-1s (46lbs) so I'm feeling good about keeping the unsprung weight down to reasonable amounts.

With 3 days of track so far I'm a happy camper. They fit in the back seat no problem!

costello

Can you elaborate more on this? I haven't seen closeup pictures of the Mazdaspeed strut tower bar, but how does it help with the braking system?

Paul_in_DC

The strut tower bar has an extension at the back that angles toward the brake master cylinder. Through that, there's a bolt that presses against the brake master cylinder. The bolt steadies it and limits its flex, so it makes the brakes feel firmer. See the pics.

rogerdodger

I just installed the Bilsteins HD on my 06 with 4k miles. The difference with stock is very noticeable. The car now has that unmistakable Bilstein feel to it, very firm but supple at the same time, if you know what I mean, almost like a MB coupe. With the stock springs, though, it is now obvious that the car is sprung too soft. So I just ordered the H-Tech from DPE and plan to put them on this weekend. My set up now will be that with stock wheels and tires (yuk!) ms front and rear sways, ms front and rear stb, power slot rotors with s/s lines and ms pads. The handling is very "pleasant" for street with lots of controlled travel from the Bilsteins , very neutral to easy on oversteer, but it still leans too much on the turns and with the breaking just being simply unbelievable, the nose dive is annoying.

I will give an update next week but no track day till Sept.

Question for DPE: do the pu bushing on the ms sway bars make a lot of difference?