boizart1

So I see posts here and there about how smooth you should be when racing on a track or whatnot and try to imitate this when I do some spirited driving, but can't seem to shift smoothly in high RPM's (I have my front end dipping down every shift, specially 1st gear and smoother and I go up on gears obviously). Also what are the perfect RPM shifts to keep our cars in the main powerband?? My main concern is that I fear holding down the clutch to make shifting smoother is burning the clutch and at the same time losing power, just wondering whats the proper way to do it.

SouthFL

It's difficult to bang through the gears on this tranny.
You bought the wrong car if you don't like grannyshifting.

Power tapers off sharply at 8.5K rpm. No need in shifting higher.

cjkim

exactly why you'd want to shift pretty much as late as possible.

SouthFL

http://www.dragtimes.com/images_dyno...-RX-8-Dyno.jpg


See dyno curve. Mind registers 8.5K peak, body ends up shifting at 9K (basically the technique used with a shiftlight- to build in some reaction time for your body to register and execute the shift- something I used to account for during my drag racing days).
My point is that you don't want to linger up there too long.

fizzer

Are you dipping the front at the beginning of the shift or the end?

If its at the beginning, you are probably coming off the gas before pressing the clutch so you're getting some engine braking. If this is the case, its probably a timing issue with your shifts at lower RPMs too, but you don't notice because of the very little engine braking at low RPM. Try to start your shift by pressing the clutch THEN starting to come off the gas at the same time. Lots of people come off the gas first then start to press the clutch which results in a rough shift at high rpm.

If you're jolting forward after you've made the shift, it means you're not shifting fast enough and the revs are falling below the speed needed to match rpm with road speed for the next gear.

Either way the key to being smooth and quick is to practice and try not to think too much about it. Identify the issue, and think about the solution, but when practicing, it should become an automatic sub-conscious motion. You shouldn't have to slip the clutch to make smooth shifts, its all about the timing of your use of the clutch and gas pedals.

Hope that helps, let us know if you have other questions.

TeamRX8

iTrader: (25)

I see a new trans in your not too distant future ....

boizart1

hmm me too I think I abused it too much as unexperienced as I am with manual cars. I took into account everything you guys and got a bit smoother at it.

kjchristopher

iTrader: (1)

How refreshing it is to find someone who asks for advice, learns from said advice and adapts behavior based on what was learned.

Life is so much easier when you're not

kersh4w

iTrader: (3)

you just gave me the best christmas present i've received this year. i read this when you posted it, and for the last 2 days my driving has been so much better.

when i started out driving, i know i did this. but for the last year, as my shifts got quicker and quicker, while they were quicker, they really jerked at upper rpms. it was really a problem (esp. with that 2nd gear...) while drag racing as i was looking for the smoothest quickest shifts possible. and while i had a perfect run when i was stock, my driving has changed since then and now while im faster, i know my runs are still 9/10ths. and my regular street driving is so much smoother now too.

you know, something like this is common sense. let off the gas, you'll get engine braking. during racing, bogging down like that is bad. but man.. us newbs just dont see stuff like that. i love the experience i get just from talking to you guys.

and southfl, im going to try a pass this spring shifting at 8.5k. but for some reason i see 15s in my future? do you really think shifting before the power tapers down will result in faster ETs? i brought this up once before and it wasnt answered. tia.


<3 all you guys. merry christmas. i've learned so much from all of you.

SouthFL

No, no. My point is....

.... if I had a shiftlight in this car, I would set it for a couple hundred revs past the general crest (not the apex) of the HP peak. If 8.5K is the peak, I'd set the light for 8.75K. By the time my eye registers the light coming on, it takes another couple hundred revs to execute the shift (therefore the actual shift takes place at 9000rpm). I hope this clarifies things.

kersh4w

iTrader: (3)

ah, yeah. thats understandable.

but i know exactly how long the shift beep takes when it starts to when im shifting.

BEEEEEEEEEEEEEEEEEEEEESHORIFTO!

the only time i messed up and overrevved is when i was so excited to hit a 2.0x 60' again that i stared at the board and the time and kept my foot planted. haha. and that still resulted in 14 second pass. 14.7 though.

this was after i put in the midpipe. since the midpipe (turboxs, catless, 3") its been pretty easy to hit 2.0x 60 foots.

also, i shift between 9200-9400 rpm.

SouthFL

I wouldn't doubt it if the hp peak has moved slightly higher in the rev range as a result of your mods.

kersh4w

iTrader: (3)

its possible. i wouldnt really know. haha. i need to get the car dyno'd. and properly tuned.

EricMeyer

I've only got 12 months of experience on these crazy 1.3L machines I've grown to love (and sometimes hate). 3 cars worth of experience here. All road racing. All with a 5.12 rear gear (mandated per Koni Challenge rules). The 5.12 spins like a rascal and decreases the amount of time needed between shifts---in orderwords, you shift it more often.

We have 5 transmissions for our 2 race cars and have a pretty routine preventative maintenance routine with every transmission.

Here is what OUR TEAM has learned. You may be different so post your own threads. I'm sharing what our team (and my wallet) have learned. In no particular order:

-The 3/4 synchro wears first
-New drivers ALWAYS toast a transmission. You can toast them in under 3 hours
-The 3/4 shift fork is VERY prone to bending which leads to the synchro wear and ultimately you can't shift the car anymore
-A heavy duty clutch and pressure plate exacerbate the problem (we use stock and they work just fine for our 210 rwhp engines). I have a bunch of new ACT clutches and pressure plates for sale--new, in a box. Cut you a deal.
-The short shifters tend to bend the shift forks more than the stock shifter---we now use a stock shifter
-Shifting points on the RX8 when road racing (in my opinion) have more to do with 2 things: 1. Avoiding high rpm engine operation, 2. Keeping the car in it's powerband. One thing you'll want to do (and I didn't see it in this thread) the next time you go to a dyno is measure your shift points. You can easily do this on the dyno and have your guy print it out----how much rpm drop at a certain shift point? Power goes from where to where? Measure it. Try a few different shift points (and gears) and see what she tells you.
-We are currently rebuilding our transmissions with about $300 of Mazda OEM parts after each 3 day event and they run perfectly.
-The BIGGEST SUGGESTION THAT SOME PEOPLE NEVER EVER GET EVEN THOUGH ITS OFFERED ON THIS FORUM A MILLION TIMES----...............shift very gently. very gently.

Happy rotoring

I8U

iTrader: (1)

Eric makes some good points. These transmissions are fairly fragile. We've had some that were junk straight out of the box and some that have lasted far longer than expected. We are getting somewhere around 9-12 race hrs out of stock transmission. We swap out for a new tranny every Grand-Am race mind you. Probably why we have 22 transmissions on the shelf. We've noticed the 3/4 synchro issue as well, our drivers new and extremely experienced have torn up trannys in less time than it takes to remove and replace one! HAHA
We run ACT clutch kits, our drivers prefer the feel of the the clutch combo over stock. Never had a problem with our AFE short shifters, most damage occurred tends to be driver error for the most part.

swoope

iTrader: (5)

wow,

eric.

great info.. and to all over shifting is bad.. i mean pulling the shifter to far past the point of engagement for to long..

beers

Brettus

iTrader: (2)

great info . Guess common sense wins again - 'if it dont fit , dont force it ' .

kersh4w

iTrader: (3)

you have 22 trannies? want to sell me a decent one? lolol.

definitely by the end of next summer, my transmissions going to be in need of a replacement with the drag racing i do. the clutch-first-then-gas helps the shifting immensely, but shifting at full WOT.. i guess im just not experienced enough to see how it could be anything but gentle.

swoope

iTrader: (5)

and keep your hand off it.. less is more..

your new sig pisses me off...

***!

beers

Brettus

iTrader: (2)

/\ you are the first one to notice it - numbers are made up BTW Just trying to get a rise out of MYSQL .
Sad what amuses me .....

kersh4w

iTrader: (3)

have you had your car dyno'd? do you know what you are really at? or "thereabouts?

EricMeyer

The reason for the premature trans failure is most often the 3/4 synchro. We do an indepth analysis on each trans we pull and have taken a few over to a race shop here in Indy that rebuilds transmissions for IndyCar. They not only rebuild them they improve upon them. NDP and magnaflux procedures that have all pointed to the weak *** shift fork of the 3/4. It bends and then engages the 3/4 on a bit of an angle which prevents a smooth engagement. We believe this is due to the amount of pressure applied to the shifter which is why (we beleive) new drivers are more prone to toasting the trans more so than yours truly (who has to pay for these things). I think our record is 17 hours and on the other end less than 3 hours (driver is no longer with us obviously). Shift slooow and gently and you'll get more hours out of these things. Also, tell your mechanic (or send your trans to me) to closely inspect the shift fork for 3/4. You can replace the 3/4 synchros and it will FEEL better but the root cause is the shift fork. Again, you have to pull them apart to see this and have someone inspect AND MEASURE to validate this info.

Happy Rotoring

EricMeyer

To be clear----measure and look at THE SHIFT FORK. The synchros are the obvious issue which you have to also look at closely.

tibyABv6

NO, you should shift at 9k so you would land higher in power band in next gear ... look at the dyno, compare power you make in rpms that you land next gear to power at 9k

at 9k rpms you make 170whp, shifting to second you land in 6k rpms and only making 140whp... if you shift at 8.5k you land lower.

kersh4w

iTrader: (3)

that isnt what he meant at all. if you read his response to when i originally asked, you'd see.

btw, quite a few of us are making quite a bit more than 170whp at 8-9k rpm.