Charles R. Hill

iTrader: (7)

Take my word and that of others who have been on this forum long enough; the Aisin tranny is grossly mismatched for use in the RX-8. It is the same tranny as used in the S2000 but it is not strong enough for anything above "spirited" street driving and, even then, it still falls short. I will have plenty of modified/strengthened trannys available next spring when you discover this for yourself.

Don't believe me? Ask Team RX-8.

chetrickerman

for how much?

Rotary Rasp

iTrader: (2)

how much HP is our diff good for?

Charles R. Hill

iTrader: (7)

Since I don't have the serious levels of h.p./torque that others do, I can only base my opinions regarding this matter on the conversations I have had with those who have REAL power, like 800-900 h.p. I also recognize that discussing such matters using "h.p." as a reference isn't exactly scientific. Torque would be more accurate.

IIRC, the RX-8 transmission loses its input shaft(and sometimes countershaft and synchros) around 400 h.p., the rear axles around 420, the PPF about 450, and the rear links start to bend near 600. The diff, itself, I haven't been able to ascertain but I will try and find out.

One thing I DO know from firsthand experience with my own car is that the Torsen diff in the rear is able to sustain 7,000 rpm, nitrous-boosted, wheel-hop havin', launches. I have actually TRIED to break my rear to see what it would take but it still holds up.

chetrickerman

what would you price your tranny's at?

Charles R. Hill

iTrader: (7)

Not sure yet. I need to cost out the parts and take a look at other stuff, too.

MrCairo

So where are you (or where will you be) in the Phoenix area?

Charles R. Hill

iTrader: (7)

I should change that in my location. I'll actually be in Casa Grande in a brand-new house I am having built. I will start Paradox from my own garage and then quickly grow into a shop with a dyno and all that. I am starting to take on work out there and make special trips for the serious stuff.

tajabaho1

yay! I actually helped with the sales

pls pls pls install Nos for me lol

Charles R. Hill

iTrader: (7)

Taj, you're the only one holding you back on the install. With as much time as you've spent posting your usual nonsense you coulda been studying my nitrous threads and been learning to do it all by yourself. Scott from Mazsport was concerned that I was giving away my secrets with those threads but I reassured him that idiocy abounds and most people don't realize the value of them. Thanks for making my point, Knucklehead!

TrochoidMagic

crh, i didn't mean to get into depth as is its indestructable or its flaws. and i think the question should stay on hand from what the original poster was asking. i only assume his concern was if its normal(factory wise) and if at all, mild tuning. not anywhere doubling the horsepower etc.

its nice to take advise on someone like yourself if building a custom performance trans as we can see what you tried and what are good and areas to focus on weakness. thats what i really mean. and i believe the minor noises are normal and tolerable. i don't want to get scared in thinking something is actually really really wrong.

and if it really is junk, from your view, than we might as well go ahead and assume the our 8's motor are junk as well compared to the ones in a 7. this is in areas concerning boost and what h.p.'s it can take stock form.

of course we are aware of this car's weakness, but also its strength. BUT, we are accepting of it. its a great car. but the real question i believe is that is the noise maybe he's unused to-normal?

i think so, and if i go back to the dealer and drive every other stick 8's, i doubt there'll be one the doesn't do the same. and if its an REAL driveability issue, lets all hope to get some free recall repairs. thats all i'm saying so don't take offense.

as far as you studies in building high torque handling tranny. good tips! its nice to know the rear end is built like an monster... but thats completely HOT-RODDING territory, and the main concern(i'm also now concerned) is would that be just normal, or an actual problem, or can it just be one of those build-in flaws that you gotta live with...... maybe being that having a light CF driveshaft that may have some torsional flex contribute to these unusual behavior??? thoughts?

on those areas, can you first clarify the first concerns first. and also pls keep update your knowledge on the drivetrains strong and weak points.

TrochoidMagic

shelby, i tried a few things on this subject. do you think it is less noisy when you let out the brakes before getting on the clutch and put it in 1st? i just tried this and its considerably less noisy than being on the brakes engaging into gears. any gears, in fact.

do you agree on that? try it out and tell me what you think.

CRH: what type clutch are we equipped with? is it by any chance a PUSH in type diaphragm spring clutch? i am just very curious as i'm sure you had the tranny out and probably know. and all my other manual cars have been of the normal pull type clutch, where it never makes noise like those and disengage easier from powertrain-drivetrain. this would also make some difference, right?

Charles R. Hill

iTrader: (7)

Sorry about the redirect/hijack, Troich. Taj and I have had a little fun harrassing each other lately.

The factory clutch is an Exedy unit(diaphragm-type) and is thought to be able to handle roughly 325 h.p.(although h.p. is not the way this stuff is assessed) based on 2 things; 1)Reverse extrapolation of numbers provided by ACT and, 2) the fact that there are several of us who are still using the factory clutch with various types of power-adders.

Lemme rephrase my sentiments on this matter; the Aisin transmission in the RX-8 is a huge disappointment as it seems to be underrated for the application it has been placed in. The reason you hear less noise when you let off the brakes and place the shifter in first gear is because that is the synchro lining up easier with no pretension on it.

Lest any of you think I am hyper-critical of the RX-8 and making blanket statements, my history on this forum shows otherwise. The strength of the engine has never been in question in my mind, however, Mazda DID screw up with low OMP volumes and, thus, many of us with '04-'05 models have needed new engines far earlier than what would be reasonably expected.

289shelby

Thanks for the responses. Following are answers to a number of questions asked:

Well is it a "clunk", or more of a "cachoonk" sound?
>>>yes - cachoonk is probably a better description.

shelby, i tried a few things on this subject. do you think it is less noisy when you let out the brakes before getting on the clutch and put it in 1st? i just tried this and its considerably less noisy than being on the brakes engaging into gears. any gears, in fact. do you agree on that? try it out and tell me what you think.
>>>Will try and let you know.

its very hardly noticeable at all in FWD cars if thats what you're doing the comparison with.
>>>My comparison is from other rear wheel cars (miata, mg’s, triumph TR6, sunbeam tiger)

Mobile

[QUOTE=289shelby;2091131]Thanks for the responses. Following are answers to a number of questions asked:

Well is it a "clunk", or more of a "cachoonk" sound?
>>>yes - cachoonk is probably a better description.[/qoute]

Then it's totally normal. You shouldn't be feeling any resistance in the shift though. All of the newer rear wheel drive car's that I have driven make that noise (including a Z4). I actually kind of like the nice heavy positive "cachoonk" sound.

Like it or not, relax because the sound is normal.

TrochoidMagic

crh: thanks for all the good info and knowledge. i knew what i suspect from feel was correct. and thats the reason why i let off the brakes too not have the gears lock(or "pretension"). and as far as the unit it uses itself...its nice to know whats in there. but yeah, i'm less worried that its capable of handling 325hp as i will never put it to over 300. but thats not enough for you and i'm sure thats what you base it on, and want to address.

289: sorry to make comparison's to fwd. as i had a few hondas myself, and they make pretty damn good shifters imo. i've driven s2k's many times in the dealereship, and even those have some clicking to it...but its a very nice click, and even "notchy"if you will. my '94 miata just feels too loose. i think its very subjective in how you like the shifter feel. but i would say some noises are just purely normal. i would only worry if it gets too notchy and have slight grinds when shifting while ur driving.

either way...some cars are just notchy or make a few noises new. if it bothers you, i can look into brandishing procedures for you which may lessen the noise.
let me know =)

TrochoidMagic

o, and btw CRH, don't worry bout it. i woouldn't think hyper-critical...ok, maybe a lil. but don't have ppl having heart attacks here. in either case, the info and the knowledge u got on things u've already tried are very useful nonetheless. but i think the simple questions should just have simple answers to it. if it was a question like" will my tranny last 200k miles? or handle 400h.p.", then i would like the sufficient answers and info which you have. but, no worries. =)

Charles R. Hill

iTrader: (7)

I have one request, Troich; before you consider yourself settled on the issue do as much of a comprehensive search on transmission problems as you can because I think you'll find far more problems with this transmission and they are not simple complaints about noise. There are way too many weaknesses in this transmission and they are not directly related to the power output of the engine, they are directly related to design and materials used therein.

I don't intend to sound pompous but I have been here for 4 years and read all about this transmission. That's why I have decided to build versions intended for heavy-duty street use and/or racing applications. I won't need to push the marketing, either, as the factory tranny itself will do that for me.

muythaibxr

All three of my rear-wheel-drive vehicles do this...

A 1985 Corolla GTS, a 1986 RX7 GXL, and a brand-new '07 RX8.

When you push the clutch after sitting in neutral, the input shaft on the transmission is still spinning. Throw it in gear and it suddenly stops, but not without briefly moving the gears, output shaft, drive shaft and the gears in the differential. That's where the thunk comes from.

Ken

Mobile

CRH:

I think Troich saying that his question had nothing to do with wondering if the tranny will take 400+ hp - an answer that not many of us would be concerned with.

He doesn't have a transmission problem at the moment, and the sound he is hearing is normal; so there is not much point in trying to find fault in the transmission. There is also no point in replaceing a perfectly good transmission with a stronger one if it's not necessary. It's all about choosing the right tool for the job, and it sounds like your power requirements are far beyond the interests of most.

You say you have been reading about people's transmission problems for years on the forums; but you forget that the only people posting are those with problems. You don't constantly see posts from people with no problems saying "everything is ok".

It sounds like you have done a lot of research and application to the RX8; but I am just trying to put a little bit of "real world" perspective on your transmission views.

Charles R. Hill

iTrader: (7)

I'm done discussing it as anything further will run the risk of being misconstrued and start yet another fight on the forum.

Lest any of you think that I am aware of only the problematic vehicles around here, I talk to many people and most of them don't have problems. So, I have been in the "real-world" this entire time. Thanks, anyway.

Mobile

Glad to hear you have been in the real world the entire time.

I only commented because your posts in this thread were giving the impression that the transmission was going to fail due to poor design. Good to see that most people you talk to have not had problems.

Socket7

Sometimes my tranny goes clunk when I'm releasing the clutch in first gear. It only seems to happen at very low speeds, when I'm releasing the clutch slowly because I'm in a tight parking lot or something.

I hit the bite point on the clutch at about 1.2k rpm, the car starts to move forward and at about 3-4 mph, just before I release the clutch completely it goes *cathunk*. I don't feel anything unusual in the motion of the car or anything, so I figure its normal.

My tranny also goes "whoop whoop whoop" when I'm in first gear and put the clutch in. as soon as i pull it out of gear it stops. I think this is my fault though, seeing as i was letting the clutch out too fast for the first week I was learning stick.

mmats69

I'd keep an eye on it but don't obsess over it. I hadn't had the first noise or problem with my tranny and one day driving down the road I could no longer shift into third gear. Happened all of a sudden. Took it to the dealer and a week later a new transmission was in my car.

imrtommy

Hey charles would the broken clutch bracket assembly be the problem for me not being able to shift quick from 1st to 2nd above 9k?(around 8k I can shift as fast as I want from 1st to 2nd) =\