Transmissions 101 question

Wait. Isn't it normal to not be able to downshift directly from 4th to

1st if you are, say, traveling at 50mph and step on the clutch?

To clarify: I am not talking about taking my foot off the clutch if I'm going 50mph with the shift lever in 1st -- just asking if the tranny should permit me to move it into 1st position. On my bus, which shift easily, I cannot push the shifter into 1st or 2nd if I am going too fast. But if I keep my foot on the clutch while slowing down, with gentle pressure on the shifter, once I drop below some magic critical roadspeed, the shifter drops right in.

Slow down before shifting - what do you think you are driving anyway, a racing car? You can screw your engine with over revving by slowing down just as you can by speeding up.

wrote:

speeding up.

To clarify: I am not talking about taking my foot off the clutch if I'm going 50mph with the shift lever in 1st -- just asking if the tranny should permit me to move it into 1st position. On my bus, which shifts easily, I cannot push the shifter into 1st or 2nd if I am going too fast. But if I keep my foot on the clutch while slowing down, with gentle pressure on the shifter, once I drop below some magic critical roadspeed, the shifter drops right in.

sounds about right... (thats the way its supposed to work....)

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Whew -- glad we got it cleared up that I have enough sense not to pop the clutch in 1st while going real fast.

So then, back to my original question, a transmission 101 question: by what dark magic does the tranny keep me from moving the shifter into 1st or 2nd when I'm going real fast?

Speedy Jim

Highly exactamente what I was lookin' for. Thanks, Speedo Jim.

Think about the difference in speed between the driving gear/shafts and the driven gear/shafts. There are these mechanical bits in there called synchronizing rings, which match up the differences in speed by friction when the poor little buggers get jammed between the gears.

For the word "friction" above, substitute "wearing out".

What you are asking them to do is match up at speed differences which are far in excess of their design specs - how stupid is that? If you persist, pretty soon they won't be able to do their job at any speed.

The general rule could be "If it seems difficult to do, you probably shouldn't be doing it!"

Even Inge probably knows that, hahahahaha.

wrote:

driven gear/shafts.

match up the differences

in excess of their

able to do their job

shouldn't be doing it!"

Oldbie, I have been driving standard shifts since I was a kid -- I'm 53

-- and I have no desire, no inclination, no reason to want to shift into

1st at 50mph and I know it would damage things. And I've noticed that transmissions won't let you do it. My question was simply a request for technical information about how the brilliant designers of manual transmissions managed to make them smart enough so that an inexperienced driver can't even get the shifter into too low a gear for the speed he's rolling at. Speedy Jim gave me pointers to pages that describe this magic and that's exactly what I was looking for.

Oh - just a youngster, huh ? In future I'll try to be more condescending with my answers.

You better be!