How a manual transmission works... a question

Trying to understand more about manual's, and came across this
excellent article:

http://auto.howstuffworks.com/transmission5.htm

However, here's the part I don't get: What is preventing the driver
from shifting into reverse while going 60 miles an hour?

>From the colored diagram.... Please correct me if I have this wrong:
The purple collars are always spinning when the car is moving. The
blue, red, and green STOP spinning when the clutch is in neutral and
the clutch is pushed in, or at least, spinning slowly from the friction
of the output shaft (yellow) rubbing on the bearings that the blue
gears ride on.

TIA!

In article . com>,
wrote:

> Trying to understand more about manual's, and came across this
> excellent article:
>
> http://auto.howstuffworks.com/transmission5.htm
>
> However, here's the part I don't get: What is preventing the driver
> from shifting into reverse while going 60 miles an hour?

Nothing whatsoever, beyond the difficulty likely to be encountred in
trying to get the involved gears to mesh at those speeds. (never mind
the fact that the tranny is likely to actively fight you due to the fact
that the reverse gear is being driven "the wrong way" by the
forward-turning wheels/driveline)

Muscle it hard enough, and/or play with the throttle right, and you
could indeed do it - Although you'll almost certainly wish you'd failed
within a second or so of your "achievement". A grenaded clutch disk
(spun apart by way too many RPMs) would be the most likely outcome, I
would think, with other parts possibly "going south" on you as well -
Perhaps with great noise and violence...

--
Don Bruder - - New Email policy in effect as of Feb. 21, 2004.
Short form: I'm trashing EVERY E-mail that doesn't contain a password in the
subject unless it comes from a "whitelisted" (pre-approved by me) address.
See <http://www.sonic.net/~dakidd/main/contact.html> for full details.

Don Bruder wrote:
> In article . com>,
> wrote:
>
> > Trying to understand more about manual's, and came across this
> > excellent article:
> >
> > http://auto.howstuffworks.com/transmission5.htm
> >
> > However, here's the part I don't get: What is preventing the driver
> > from shifting into reverse while going 60 miles an hour?
>
> Nothing whatsoever, beyond the difficulty likely to be encountred in
> trying to get the involved gears to mesh at those speeds. (never mind
> the fact that the tranny is likely to actively fight you due to the fact
> that the reverse gear is being driven "the wrong way" by the
> forward-turning wheels/driveline)

I understand that if the clutch is engaged, but why would it be turning
if the clutch is pressed in?

If you look at the 2nd diagram on that page above, but input shaft
(green), layshaft (red) and blue gears should NOT be turning when the
clutch is pressed in and the tranny in neutral, right? If I'm
incorrect in this, please explain why.

wrote:
> Don Bruder wrote:
> > In article . com>,
> > wrote:
> >
> > > Trying to understand more about manual's, and came across this
> > > excellent article:
> > >
> > > http://auto.howstuffworks.com/transmission5.htm
> > >
> > > However, here's the part I don't get: What is preventing the driver
> > > from shifting into reverse while going 60 miles an hour?
> >
> > Nothing whatsoever, beyond the difficulty likely to be encountred in
> > trying to get the involved gears to mesh at those speeds. (never mind
> > the fact that the tranny is likely to actively fight you due to the fact
> > that the reverse gear is being driven "the wrong way" by the
> > forward-turning wheels/driveline)
>
> I understand that if the clutch is engaged, but why would it be turning
> if the clutch is pressed in?
>
> If you look at the 2nd diagram on that page above, but input shaft
> (green), layshaft (red) and blue gears should NOT be turning when the
> clutch is pressed in and the tranny in neutral, right? If I'm
> incorrect in this, please explain why.

The reverse gear is still being driven "backwards" by the rear wheels
so even if the input shaft and layshaft have completely spun down,
you'll have quite a bit of speed mismatch. Now some modern vehicles
have synchros on reverse so you theoretically *could* engage reverse at
speed if you wanted to; not that that wouldn't be a spectacularly bad
idea...

nate

N8N wrote:
> wrote:
> > Don Bruder wrote:
> > > In article . com>,
> > > wrote:
> > >
> > > > Trying to understand more about manual's, and came across this
> > > > excellent article:
> > > >
> > > > http://auto.howstuffworks.com/transmission5.htm
> > > >
> > > > However, here's the part I don't get: What is preventing the driver
> > > > from shifting into reverse while going 60 miles an hour?
> > >
> > > Nothing whatsoever, beyond the difficulty likely to be encountred in
> > > trying to get the involved gears to mesh at those speeds. (never mind
> > > the fact that the tranny is likely to actively fight you due to the fact
> > > that the reverse gear is being driven "the wrong way" by the
> > > forward-turning wheels/driveline)
> >
> > I understand that if the clutch is engaged, but why would it be turning
> > if the clutch is pressed in?
> >
> > If you look at the 2nd diagram on that page above, but input shaft
> > (green), layshaft (red) and blue gears should NOT be turning when the
> > clutch is pressed in and the tranny in neutral, right? If I'm
> > incorrect in this, please explain why.
>
> The reverse gear is still being driven "backwards" by the rear wheels
> so even if the input shaft and layshaft have completely spun down,
> you'll have quite a bit of speed mismatch.

How is it driven backwards if the tranny is in neutral? The reverse
gear isn't engaged, is it? IOW, on that diagram, the blue gears are
riding on bearings, are they not? They'not not connected to the
differential, only the purple dogs are, right?

wrote:
> N8N wrote:
> > wrote:
> > > Don Bruder wrote:
> > > > In article . com>,
> > > > wrote:
> > > >
> > > > > Trying to understand more about manual's, and came across this
> > > > > excellent article:
> > > > >
> > > > > http://auto.howstuffworks.com/transmission5.htm
> > > > >
> > > > > However, here's the part I don't get: What is preventing the driver
> > > > > from shifting into reverse while going 60 miles an hour?
> > > >
> > > > Nothing whatsoever, beyond the difficulty likely to be encountred in
> > > > trying to get the involved gears to mesh at those speeds. (never mind
> > > > the fact that the tranny is likely to actively fight you due to the fact
> > > > that the reverse gear is being driven "the wrong way" by the
> > > > forward-turning wheels/driveline)
> > >
> > > I understand that if the clutch is engaged, but why would it be turning
> > > if the clutch is pressed in?
> > >
> > > If you look at the 2nd diagram on that page above, but input shaft
> > > (green), layshaft (red) and blue gears should NOT be turning when the
> > > clutch is pressed in and the tranny in neutral, right? If I'm
> > > incorrect in this, please explain why.
> >
> > The reverse gear is still being driven "backwards" by the rear wheels
> > so even if the input shaft and layshaft have completely spun down,
> > you'll have quite a bit of speed mismatch.
>
> How is it driven backwards if the tranny is in neutral? The reverse
> gear isn't engaged, is it? IOW, on that diagram, the blue gears are
> riding on bearings, are they not? They'not not connected to the
> differential, only the purple dogs are, right?

Sorry, I mis-spoke. The reverse *dog* is being driven by the wheels,
and the reverse *gear* will be driven by the input shaft/layshaft.
There's going to be a speed differential between the two at any speed.
Even if the clutch is held disengaged long enough for the clutch/input
shaft/layshaft/reverse gear assembly to spin down to 0 RPM the reverse
dog will still be spinning with the output shaft at whatever RPM the
driveshaft is turning. Thus if there is no synchronizer at any speed
above a couple MPH you will get a lot of metal on metal noises and
nothing much will happen when attempting to shift into reverse. If
there *is* a synchronizer, when you try to engage the dog the synchro
will spin up the gear/layshaft/input shaft/clutch etc. *in the opposite
of normal direction* which will allow engagement of reverse but
probably wouldn't yield very desirable results should you release the
clutch after doing so.

nate

wrote:
>
> Trying to understand more about manual's, and came across this
> excellent article:
>
> http://auto.howstuffworks.com/transmission5.htm
>
> However, here's the part I don't get: What is preventing the driver
> from shifting into reverse while going 60 miles an hour?
>

Absolutely nothing, I have done it. I hit reverse in a car once and
only locked the rear wheels into a chirp when I realized it. Nothing
blew up.... I was lucky....

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's

In article >,
Mike Romain > wrote:

> wrote:
> >
> > Trying to understand more about manual's, and came across this
> > excellent article:
> >
> > http://auto.howstuffworks.com/transmission5.htm
> >
> > However, here's the part I don't get: What is preventing the driver
> > from shifting into reverse while going 60 miles an hour?
> >
>
> Absolutely nothing, I have done it. I hit reverse in a car once and
> only locked the rear wheels into a chirp when I realized it. Nothing
> blew up.... I was lucky....

Yep, that would make two of us - Although I accomplished mine in a car
with an automatic. Had this "hit the lights all green" strategy that
seemed to do *WAY* better than 75% - Come off the the north/south
freeway onto the east/west freeway leading into town, and mash the
throttle for all it could give me/all traffic allowed in the space
between the end of the off-ramp and the "Freeway ends 1 mile" sign.
Usually that meant I'd be hitting somewhere between 70 and 80 as I blew
past the sign. Bump the shifter into neutral, and coast in to the first
light, which would (more often than not) change green just as I rolled
up at about 40-ish. If I caught the first one, bumping it back into gear
and holding at 40 would put me through the entire ten light sequence
with every one of them green my way.

One day I did this for probably the 100th time, if not more, only my
"bump" was a bit too energetic, and I went through neutral and into
reverse... <SHREEEEEIIIIIIIIK!> Smoking rubber, ass-end juddering around
like it was about to go into bucking bronco mode, and me grabbing wildly
at the gearshift with one hand while trying to keep the car pointed
straight with the other, and the engine stalling out. It was a rather
"interesting" ride that I don't have any wish to go on again!

Didn't do any damage (that was evident right then, anyway... Strongly
suspect that it WAS the death-stroke for the tranny, though, since it
was only a couple months later that the thing went completely
tango-uniform) but by all rights, that transmission should have gone off
like a bomb... Manual or automatic, they just aren't made for being
punched into reverse at 70+!

--
Don Bruder - - New Email policy in effect as of Feb. 21, 2004.
Short form: I'm trashing EVERY E-mail that doesn't contain a password in the
subject unless it comes from a "whitelisted" (pre-approved by me) address.
See <http://www.sonic.net/~dakidd/main/contact.html> for full details.

Shifted into reverse once while driving a automatic Ford Crown
Victoria. It was a rental car I had just picked up at the airport and I
hadn't taken the time to "adjust" everything before I left the lot.

Decided to adjust the height of the steering wheel while hitting about
60 mph. Only the "steering wheel adjustment lever" I grabbed was
actually the gear shifter.

Car came to a complete dead stop with as mentioned a horrrific
screeching of tires. Started right up however and I drove it some 25
hours with no problem before returning it to Hertz. Don't know what
happened to it a month down the line, however.....

On Tue, 24 May 2005 20:19:04 GMT, Don Bruder > wrote:

>In article >,
> Mike Romain > wrote:
>
>> wrote:
>> >
>> > Trying to understand more about manual's, and came across this
>> > excellent article:
>> >
>> > http://auto.howstuffworks.com/transmission5.htm
>> >
>> > However, here's the part I don't get: What is preventing the driver
>> > from shifting into reverse while going 60 miles an hour?
>> >
>>
>> Absolutely nothing, I have done it. I hit reverse in a car once and
>> only locked the rear wheels into a chirp when I realized it. Nothing
>> blew up.... I was lucky....
>
>Yep, that would make two of us - Although I accomplished mine in a car
>with an automatic. Had this "hit the lights all green" strategy that
>seemed to do *WAY* better than 75% - Come off the the north/south
>freeway onto the east/west freeway leading into town, and mash the
>throttle for all it could give me/all traffic allowed in the space
>between the end of the off-ramp and the "Freeway ends 1 mile" sign.
>Usually that meant I'd be hitting somewhere between 70 and 80 as I blew
>past the sign. Bump the shifter into neutral, and coast in to the first
>light, which would (more often than not) change green just as I rolled
>up at about 40-ish. If I caught the first one, bumping it back into gear
>and holding at 40 would put me through the entire ten light sequence
>with every one of them green my way.
>
>One day I did this for probably the 100th time, if not more, only my
>"bump" was a bit too energetic, and I went through neutral and into
>reverse... <SHREEEEEIIIIIIIIK!> Smoking rubber, ass-end juddering around
>like it was about to go into bucking bronco mode, and me grabbing wildly
>at the gearshift with one hand while trying to keep the car pointed
>straight with the other, and the engine stalling out. It was a rather
>"interesting" ride that I don't have any wish to go on again!
>
>Didn't do any damage (that was evident right then, anyway... Strongly
>suspect that it WAS the death-stroke for the tranny, though, since it
>was only a couple months later that the thing went completely
>tango-uniform) but by all rights, that transmission should have gone off
>like a bomb... Manual or automatic, they just aren't made for being
>punched into reverse at 70+!

Yea, other than burning the CRAP out of the reverse/high clutch pack
(reverse/low if GMC, don't know Mopar trans too well, ) and the band,
there's probably not too much else you could screw up. Of course, all
that clutch material that's suddenly been given a permanent vacation
from the disks (and the band!) would probably have contributed to the
death of that trans...

but, **** happens.

-LMB