Ok, im getting sick of hearing about how weak the e-shaft is. ill be right in the middle of a good topic when someone comes in and says "oh, that will cause the e-shaft to flex to much..." People always seem to bring up that it flexes to much, or that it can get stressed and so-on. Dident mazda find that our e-shaft was so strong that they basicly used a shaft of the same thickness and geometry in the 20b three rotor engine? And come on, we hear about those engines putting out what? 600hp+?
I want to know how many people broken an e-shaft or bent it or whatever in an over powering situation. I dont want to hear how it failed when you ran out of oil, pushed 125,003rpm or some other circumstantial way for it to break.

 

THANK YOU!

It's hard as hell for rotary mechanic noobs like me to know exactly what the hard truth is, without all this unconfirmed BS flying around.

"Oh, you can't put a turbo on an NA, it'll chew apart the drive shaft."

"Hey, you won't have enough back pressure to run efficiently if you change that exhaust."

Okay, sure, it may have happened to you, but don't exaggerate it so that the new guys don't know what the hell is true.

 

Um, I think E-shaft flex is a real thing (even on 2 rotors) that has to be accounted for when race clearancing an engine.
As far as breaking a 2 rotors e-shaft, yeah right- I agree w/ you.

 

well for u people wanna see what one looks like https://www.rx7club.com/forum/showth...ghlight=eshaft


-Shawn

 

Again, what did he state? I'll break it down. Things that are not due to stupidly pressing your luck with the engine, especially if it's because of oil failiure etc.

 

the only time ive ever heard of E-shaft failure is usualy due to something other than power, like oil starvation or some other non-power situation. im fairly sure that the E-shaft can take lots of power and not even flinch.

 

There is a certain amount of eshaft flex at the rear even if the motor is not abused in any way. Check Mazdamotorsports tech section. It has the clearances listed. flex at high rpms does not always lead to eshaft failure but you will notice in a large number of motors the rear rotor usually goes out rather than the front one.

 

Hehehe, I asked Mazda Motorsports about this since I have a 20B and have also heard the rumors. They said that all their race teams use the regular eccentric shaft, and the strengthened shaft is no longer in production. Since my shaft will see much less abuse than one on a 24-hr endurance racer, I'm not very worried about my engine blowing up.

The rear rotor also fails for reasons besides this, to include detonation and overheating.

 

Eccentrics flex because of extreme over-revving. It is not a common thing, and 99% of people on this forum will never have to worry about it.

 

Define extreme... 10K 12K 15k?

 

Someone was saying that if you install a supercarhger, the belt that drives it would put too much strain on the e-shaft. Yeah right! Let me see something to back that up. i think it can handel a little more then that, just look what the non-pully side of the shaft is connected to!

 

Extreme = a few K past redline. Though it won't hurt the shaft. It may damage rotors and housings.

OC_: While putting a supercharger on the car will not damage the eccentric, you must realise that the shaft sees very little lateral load at the ends. At the tranny end, it is supported by a bearing and the transmission itself. At the front, there is of course a bearing, and very little sideways force on the shaft. The eccentric is very strong.

 

I bet you like this one Aaron.....you swaped the TII drive train yet?

 

I usually ignore stuff like this. Actually, I destroyed a driveshaft when my car was NA. Though no, I have not swapped on a TII drivetrain and have no intention of doing so.

 

just beefen up the N/A drive train?

 

seen a 20b push 1,100 hpr, racing eshaft or not thats still pretty good for a metal bar to have pushing on it...

 

There's nothing really that needs beefing up...save for the front diff mount.

 

I have never heard of an e-shaft breaking. I was under the impression that the e-shaft flexed under high rpms. Without a bearing in the middle, the sheer force created causes the e-shaft to flex and the rotors to run up into the housings, damaging the apex seats and the housings.

You can tell an over-revved motor when you do a rebuild.

 

wait a sec, extreme reving is a few thousand past redline? the stuff i read about rotary engines before i bought my car said that a rotary could spin to 15-20k without causing any damages to itself. if extreme is a few k past redline, then where did the 15-20 thing come from?

 

Exaggeration.

If you take a stocker over about 9500-10,000 RPM, it won't be very happy.

 

People who bullshit.

 

ok the tranny and drivesahft in my car right now came from a car that was pushing enough power to beat a FD

it has been through lots of abuse by me and I'm sure he put his fair share on it............


I had to put it in my car b/c my N/A driveshaft took a **** on me revving up to 6000 rpms and dumping the clutch


ask me the N/A drivetrain isn't as weak as ppl say they are



s/c breaking the e-shaft.... we have a guy locally that runs one on his daily driver still not a problem with his shaft


they might flex but I doubt it is that easy to break on
and as far as extreame being a few 100rpms over the redline.... I shift at 7600 -7800 and I get on the car ALL the time.... 182k miles on the clock and still ticking with 110psi front rotor and 105 rear rotor

 

Wait. Instead of there being E-Shaft flex, I would be more worried about chattering of the rotors on the housings @ high RPMs.

 

rez: that is caused by e-shaft flex. the rotors sit on the e-shaft, after all.

 

I didn't do rotor clearancing because I wasn't comfortable with the amount of information on what exactly was done to them, and didn't have the $$$ to send them out for it at the time.

I was under the impression that e-shaft flex wasn't an issue untill 10K on a stock motor without clearanced rotors.

Typically the redline is based on the combination of mechanical limits of rotating assembly and the volumetric efficiency of the intake plumbing and such. (can the car breath enough fuel and air to make power above X rpms...) So with a ported motor that makes power untill fuel runs out, (from deficient delivery system) I'm wondering if its safe to run this engine to say 9800rpms? I have every intention of correcting the incapacity of the fuel delivery to accomodate the additional flow of the higher revs. I just want to make sure I'm not going to end up back inside the motor from reving it that high.

Anyone been inside a S4 that hit 10K regularly?