Real Fiero Tech

http://www.zeroshift.com/animation.html

be sure to click on demonstrations too for some onboard video.

What do you guys think? A good alternative for the outdated syncro systems. Seems like a possible upgrade worth investigating..

LMK

I saw that site a long time ago. At the time, there was one sentence buried deep in the site that said that it would need to work in concert with engine management and active control of the clutch to reduce torque spikes.

Ever seen a chassis dyno graph of an automatic transmission car? Torque spikes on the shifts. That's what happens when you have to change the rotating speed or anything: torque is involved. In the case of zeroshift, if the transmission shifts instantly, then engine rotating speed has to drop from redline to the corresponding speed in the next gear (or vice versa) *instantly*. That energy goes out the driveline as a torque spike. The faster the shift and the greater the RPM drop, the more severe the torque spike. They're right, there's never an *interruption* of torque, but withot SOME type of system to mitigate those torque spikes, you may bark the tires on anything more than a casual gearshift, significantly reduce the lives of driveline components and outright break parts in a WOT redline shift.

Lenco transmissions act similarly, but are built incredibly strong and are connected to engines with low rotating mass and compliant tires.

Hydraulic damper + spring. Done. Next question.

why not a cvt.

CVT's right now can't take much in the way of torque.

whipped wrote:Hydraulic damper + spring. Done. Next question.

But where on the website does it say that?
They tout the benefits of lack of power interruption during a shift, and even go to lengths to exaggerate the problems associated with lack of power during a shift. They never address the very obvious drawback of their technology. Not only to they not address how to mitigate the torque spike, the very nature of the device applies the torque spike to relatively small interfaces on relatively small parts. With that sort of impact loading, I can't see those dogs lasting very long without some way to mitigate the torque spike.
Also, a driver can not shift that transmission in a relaxed fashion. Just like the Magnus dogbox for DSM's, you can drive it on the street, but you ALWAYS have to drive it hard. Trying to shift that mechanism slowly will chatter the dogs and wear them out even faster. Obviously you can't rely on Joe Average to always shift fast and hard, so the only practical application for the technology is in dedicated automanual gearbox designs, where the MFG has control of the shift action.

For example, at 6500 RPM in 1st with a 282, the output shaft (and thus 1st gear output) is turning about 1850 RPM. The 2nd output is turning 3170 RPM. The difference is ~1300 RPM. There are three dogs 120 degrees apart. This leaves probably 100 degrees of rotation open. 100 degrees of rotation at 1300 RPM is just less than 13 ms. Can anyone here move that shift fork in 13 ms? I don't think I can.

Also, when the shift is made, engine RPM will drop from 6500 to 3800 as close to instantly as real materials allow. The loads would be enormous.

The Dark Side of Will wrote:CVT's right now can't take much in the way of torque.

SOOO....


You dont have shock loading like in a 1-2 shift that tears apart an izusu. unless you put it behind a sbc, they should be fine.