one Senna story

[Spencifer_Murphy]

Yeh apparently it is possible mep, although I've never done it, mainly because I'm worried that I'll get it wrong and leave myself with a rather expensive mistake to clean up afterwards lol!

Although I know a lot of cars nowadays have a sort of locking system on them which prevents you from pulling into certain gears (often reverse for example) unless the clutch is depressed. (At least my old 1993 Ford Fiesta did! lol) so I think it might not be possible to do such things anymore.

Like I said though, I've never tried so I'm not 100% sure.

[freedom_honda]

just wondering..
how exactly do you match the rpm?

[RH1300S]

just wondering..
how exactly do you match the rpm?

It's surprisingly easy - try it one day.

Harder to do with a "normal" car synchro gearbox with fairly wide gear spacing and heavy gears to slow down. But very possible. Down-changes are easier than up changes.

I have never used a racing gearbox myself (so could be talking rubbish) - but reading a Hewland published operation manual a while back, they suggest that on up-changes at high revs, the faster you can make the clutchless change - the better for the gearbox. So I have to assume that these things are intended to be used clutchless.

[joseff]

Upshift: lift off, shove the shifter to next gear, slam on the gas.
Downshift: feather the throttle a bit, take shifter out of gear, blip throttle, shove shifter to lower gear.

Quite easy really. My friend, who drives slushboxes all the time, even put a (manual) car into reverse without the clutch by accident. The car didn't stall, and we reversed neatly. I have no idea how he did it.

I did it with a rental car. You should too

[Belatti]

I had to did that once!
When my old Fiat Uno´s clutch steel cable broke, I was in the middle of nowhere. Had to start the engine with 1st gear in and then changed to 2nd, 3rd and 4th down the road, without using the clutch.
While reaching to the town had to downshift and stay in 2nd gear to try to synchronize speed with green traffic lights in order to avoid stoping.

Then I reach home without hearing the gearbox complaining and bought a new cable!

you will find joseff´s "tutorial" is very helpful!

[WhiteBlue]

back in the seventies when I was driving military trucks you always had to blip the throttle to downshift because the box wasn't syncronized. the clutch wasn't assisted either. so when I got back into my old trusted Renault 4 after the first week of driver training I thought the clutch was broken. of course it wasn't. I just wasn't used to a civilized pedal force any more.

[mep]

What exactly is the difference in a syncronized and a not syncronized gearbox?
I mean how are they constructed and how do you have to drive them?

[WhiteBlue]

What exactly is the difference in a syncronized and a not syncronized gearbox?
I mean how are they constructed and how do you have to drive them?

http://link.brightcove.com/services/lin ... 1342161566

you see the syncro rings explained. unsynchronized boxes don't have such rings. you have to bring the engine and the diff to a matching speed to change gears. that means you have to uncouple and blip the throttle and couple in the new gear more or less by feel and acoustically matching the speeds.

[mep]

Thanks WhiteBlue
But I still think there is something left.
Thats what I already know:

You have two shafts with gears on it,
the shaft wich is driven by the engine and the output shaft.
The gears are every time in contact with there oposite one.
They are turning all the time.
But on the second shaft none of them is conected with the shaft. They run free.
Now with this ring you can conect one specifig gear with the second shaft and
the movement is transported to the wheels.
Thats also explained in the video.

But now where is the sincro called part in this?
For example when I drive in first gear and I whant so shift into second on
than there is one problem.
The cog wheel of the second gear is rotating with a different speed than the cog wheel of the first gear.
But the ring has to disconect the first one with the shaft and conect the second one in very fast time.
How does the sprung in revs happen.
Is there a hard metal to metal punch?
And how is this managed in a not sincroned gearbox?

[Carlos]

Syncromesh
http://everything2.com/index.pl?node=synchromesh
http://www.tpub.com/content/engine/1403 ... 37_120.htm
http://www.tpub.com/content/engine/1403 ... 37_121.htm