ganseg

iTrader: (5)

Do you have a way to know how the camber is changing up front? I have read not to lower it more than an inch, which is what i did. I'd like to get more camber too but -2 is all I got with the 1"drop and a track alignment (he pryed them out further than just turning the camber bolt to the max position). I would love to know if I can drop the front more without screwing up the geometry,

Chris_Bangle

iTrader: (2)

Dave -

You may want to take a look at - RX8 Racing Lower Control Arm Bushings made by MazdaSpeed from MazdaTrix:

http://www.mazdatrix.com/8susp1.htm

Listed in the middle of the page. While I am not an expert they may help with the front alignment settings.

Keep us posted on the event.

NYC Drift King

iTrader: (5)

Welcome Dave,

I look foward to following your thread. Good luck bro....

Modified Dave

Chris, spherical bearings aren't STX legal so I can't run those lower control arm bushings. I could run their Delrin front upper replacement bushings though, I think.

Anyway, here's a few pics and some data from the track test last night. I was pretty happy to get the car down into the 1:25's after starting out in the 1:29's. The upgraded wheel and tire package made a world of difference. As you can see, we were working the outsides of the front tires pretty hard (understeer) but using more of the middle and inside of the rear tire (sliding the car a bit on corner exit to get rid of some of the understeer). FYI, TMP is a clockwise track that puts an especially hard beating on the left side tires, especially the left front. We didn't touch the alignment at all, just tried to get the tires working as best we could with the stock alignment for this test. Once I put the coilovers on we'll really try to dial in the alignment settings for optimum tire temps across each contact patch.

Oh, and before you guys rag on me about the lack of a helmet, I always, Always, ALWAYS wear a helmet at the track (and usually wear my full safety gear including nomex head sock, suit, gloves, socks and shoes) but like a rotard without the ro part I left my duffle bag full of race gear on the garage floor. My driftbox was in there too, so we just made do with what Will had handy, meaning a Longacre pyrometer and Hot Lap timer and a tire pressure gauge. We were kickin' it like it was 1999! Anyway, please don't be a dumbass like me. Always wear a helmet at the track!







No video this time, but will definitely take video next time.

ganseg

iTrader: (5)

I had another racer (in this case autocross) tell me today not to drop the front lower than 1". he also said that an RX-8 doesn't need as much camber as like my E36 M3. I ran -3.4 degrees on that at the track. He's thinking -2.5 would be good on an RX-8 (I know -2 is still too little for track). Thanks for the dialog - this is fun!

Modified Dave

I assume this recommendation comes from concerns over bump steer? It's easy to measure bump steer if you have the right tools (my friends at Auto Analyser Racing have a jig that mounts to the hub and you then stroke the suspension through its full range of travel and dial gauges show you how much toe change is occurring. You then shim the tie rods to greatly reduce toe change and therefore eliminate bump steer, since bump steer is simply toe change that occurs while travelling over a bump).

However, I'm not sure if bump steer correction is permitted in STX. I see in Section 14.8 A of the 2010 rulebook that roll center adjusters aren't permitted, where the rule reads "This does not allow the use of spacers that alter suspension geometry, such as those between the hub carrier and lower suspension arm." I also see in 14.8 F that shimming the steering rack isn't permitted, but I wouldn't be shimming the rack, I'd be shimming the tie rod end. But maybe the tie rod end is considered part of the steering rack? Does anyone know the SCCA's position on bump steer correction by shimming the tie rod ends? Is it STX legal?

Anyway, I will do a bump steer analysis of the 8 using AAR's jig so that I can at least see how bad the bump steer gets as we reduce the car's ride height.

ganseg

iTrader: (5)

Whoo hoo!

Kennetht638

iTrader: (2)

Dave, I'm pretty sure that because there is no rule that specifically says something like "tie rod ends may be relocated to alleviate bump steer," you can't do it. The bit about prohibiting shimming of the steering rack is just to clarify the steering rack bushing allowance.

I'd still love to see your bump steer curves though! Front and rear would be awesome.

Also, great thread!

Modified Dave

Yeah, I think you're probably right Kenneth, but maybe I should shoot the SCCA an e-mail just to be sure. Woud be sweet if I could shim the bump steer out of the front at least.

Either way, I'll do a bump steer analysis of the front and rear so we can all see what we're working with. It'll make a good tech story for the mag.

Question for you all: are transmission problems common with the 8? During track testing I was having a hard time shifting quickly into 4th gear at first. Was getting a nasty grind, so I had to slow the shift down and apply very light pressure with the lever for it to slide in smoothly. By the end of the night I wasn't losing much time shifting this way, but I was kinda bummed out to find 4th gear being so uncooperative at first.

I also noticed some high-pitched whining, presumably from the gearbox, during the drive home. I'm going to put some high quality gear oil in the box to see if that cures it, but strangely the whine was quite noticeable in 4th and 6th gear but completely gone when cruising in 5th gear. Weird!

I'll also admit that I spent some time looking for the DSC kill switch only to eventually realize that my '05 Sport version doesn't seem to have DSC. LOL. She drifts quite nicely on the track -- definitely a more stable platform than a S2000, though I was surprised by how much body roll the 8 has compared to a S2k.

Brettus

iTrader: (2)

The new oil may help . I tried Redline75w140ns (recommended by Teamrx8) and IIRC it did help with this .





Have always had that myself as well - I don't worry about it these days . It is just the way the shift lever transfers noise from the g/box . Some 8s do it most dont .
Try putting very slight pressure on the lever with your hand and notice how the noise dissappears .

Modified Dave

Thanks Brettus, appreciate the feedback. I've had really good results using Redline MT-90 (1.5q) and a bit of Heavy Duty Shockproof (0.5q) in my Honda K20 transmissions on the race car, so I may try this recipe in the 8 too. I assume the 75w140 TeamRX8 recommends is the Light Duty Shockproof? Seems like my MT-90 + a bit of HD Shockproof is likely a similar overall blend to a full fill of LD Shockproof. Hrm. I guess I'll stick with what I know and try my MT-90 + HD and see how it works. I'll let you know how it goes!

What do you guys recommend for diff oil? Redline as well?

Speaking of diffs, has anyone here upgraded to a clutch-type LSD? Overkill given the low torque of the Renesis? Thoughts on me going with a OS Giken clutch-type an testing it against the OE helical-type? I saved 1-second a lap by going from the viscous LSD to a clutch-type LSD on my G35, so was hoping to find a similar savings with a diff upgrade on the 8.

EDIT: my car definitely has bad engine mounts, so it just occurred to me that this could have been contributing to the 4th gear shifting problem. I've also just read about a clutch pedal flex problem, so will look into that further too. Man, lots of little fixes to do to get my '05 in tip top shape!

Brettus

iTrader: (2)

It's just Redline 75w140ns (non slip) but yeah the MT90 is favoured around here as well and what I currently use .

Modified Dave

Brettus, you also using MT90 in the diff?

Here's a few sexy-time pictures I shot last night in preparation for the RX-8 project car intro story...

Alrib

Hi Dave,

Check out this thread on the Canada forum:

https://www.rx8club.com/canada-forum-35/mazdamaniac-dyno-tuning-gta-spring-summer-2010-a-195294/

Jeff aka MazdaManiac is flying up to Toronto to do a tuning day with the COBB!

Modified Dave

Thanks Alrib. Not sure if I'll have all the planned power adders installed by July 17, but once I figure that out I'll see about attending. Most likely I'll end up doing a custom tune with Sasha at SG-Motorsport or Dan from U2NDyno.com. These guys do the ECU tuning for many of the top race teams in the country including some rotary-powered cars.

wankelbolt

iTrader: (21)

I think more transmissions have been killed by "slam-shifting" than by horsepower by a huge margin. I doubt you are slam-shifting, but it does sound like you may be rushing. I think it was John Muir (VW repairman) who said something like "all people and gears need is a little grease and a little space". I'd say it like "All transmissions need is a little grease, a little space, and a little time." You found like I did that give the synchros a little time to do their job and the gear engages easily. Eric Myer backs me up on this (and recommends stock shifter and clutch). That thread is worth a read.

The RX-8 trans is good, but not all that strong. Somebody said (Eric, IIRC) they think it's because the PPF is on the wrong side, illustrating by saying the one Mazda transmission thought of as completely bulletproof is the one Miata transmission that has the PPF on the other side. (Can't find the thread.)

I had some trouble with the 3-4 shift when I got the car (15k miles on the clock), so after 5k miles put in Red Line MT-90. That smoothed things out nicely, but the 3-4 shift would still get stiff when running hot and hard on the track. So I just switched to SWEPCO 201 for this season. Now first is really stiff and cold the car tries to pull forward in neutral! But now the 3-4 shift is like butter on the track. That SWEPCO is some really weird sticky blue stuff. Here's the analysis results of the original fill at 20k miles and the Red Line MT-90 after 16k miles. I'll do the same for the SWEPCO after a similar number of miles. I'm still keeping my eyes open for an improved 2009-10 trans cheap.

I think that's pretty common. I get the same thing, though I do have a short-shifter installed (not really that fond of the SS anyway).

HA! Be happy you don't have it! One less system to fail or hassle with. Eric had his ABS fail leading to an agricultural excursion, which tempts me to disable mine on the track so I don't rely on it and have it fail at a bad place. If yours is the "stripper" car like mine, you also don't have the silly HIDs and associated leveling system, fogs, leather seats, or Bose system. All that stuff just adds weight. My buddy who was the original owner of my car swears Mazda made these no-sunroof strippers just so the racers could have a lighter, low-option car to start with. Dealers didn't seem to stock many.

Interesting comments about S2K vs. RX-8. A friend of mine is big into the S2K world and has a very, very quick yellow one (#141). I'll have to let him drive my 8 and see what he thinks. After my latest spring and alignment job, I think my car is perfectly balanced. At the limit it is just unflappable, but I can still induce under- or over-steer with just the right input. I just can't get over how good the RX-8 is. Zoom-Zoom!

Modified Dave

Thanks wankelbolt, I appreciate the feedback. Once I got more patient and smooth with the 3-4 shift it did seem to go into gear quite happily. I had to use less forward pressure on the shift lever than I'm accustomed to, but only on the 3-4 shift. Anyway, seems like some driver tuning and some better trans fluid will take care of it. I'll definitely watch for your SWEPCO fluid analysis. Never heard of the stuff. I'm going to try some Redline in the meantime.

So here's a new riddle with my "box of chocolates" RX-8 (which is indeed the base GS model with cloth interior, no sunroof, no HIDs, no DSC/TCS or any of that weight adding garbaggio). Just did a couple quick pulls on the U2Ndyno.com Dynapack, which is quite pessimistic compared to any other dyno I've ever tried including the local Mustang dyno which is notoriously pessimistic. Knowing that the dyno is pessimistic, I wasn't too disappointed with a peak value of 162 hp and 119 tq, but I'm a bit concerned to see hp peak so early. From what I gather taking a quick look at the main dyno thread hp should peak around 8k rpm, not 7k like it does on mine. Any thoughts on why hp is peaking a little early? CAI effect? Bad coils? The engine does have fresh oil in it and fresh leading spark plugs (but I haven't installed the fresh trailing plugs yet), but I have not inspected the coils or wires yet. Anyway, any thoughts on this are appreciated!

Brettus

iTrader: (2)

/\ classic case of stuffed coils

Modified Dave

Really? Thanks Brettus, I'll order me some fresh coils tomorrow! I'll redyno as soon as I install the coils so we can confirm. Do you recommend changing the wires (about 40k miles on them, assuming they're original) while I'm at it?

Brettus

iTrader: (2)

absolutely yes .
Get some high quality leads with good connections - made a big diff for me . (autoexe)

OR get the BHR coils if you are allowed to use aftermarket coils .....

Modified Dave

Thanks Brettus. You live in NZ? I spent a month there a few years ago and loved the country and was impressed by the car culture. Tons of nicely tuned Subarus and Nissans (plus some of those Aussie V8s), though I can't say I saw any RX-8s while I was there.

dieselsdad

I know of a few who have had luck with stock coils but I know of no one who has had BAD luck with the BHR coils. I highly recommend them if the rules allow.

chiketkd

iTrader: (5)

Actually, aftermarket ignition systems are allowed in stock class. So yes, they're legal for STX.

Brettus

iTrader: (2)

8"s are becoming popular here as they get within reach of the boy racers . Almost all of them are imported from Japan . Very few people have any idea of the potential of the car as a track weapon though as it has never featured in any kind of racing here . There is no racing class that suits it.

ganseg

iTrader: (5)

Just a minor detail you may not have come across yet. The tach reads high (you may have noticed it goes to 9,500 before the power gets cut. Well that is really 9,000 rpm. I think my current car is 300 to 400 rpm high at 8,300. People including Eric Meyer say there is no reason to run up to redline - no power there and potential extra wear. I have set my personal redline at 8,500 indicated (where the tone goes off) so the engine lasts good and long.