VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1929-1932 down shifting

My 1930 chevrolet coach won't downshift while moving It shifts and drives good but in order to downshift I have to completely stop. Is this normal? If not what would cause this to happen?

Thanks

The 1930 doesn't doesn't have a synchromesh transmission, to downshift you need to double clutch. It takes a little practice.

You need to double-clutch to up-shift as well.

In my short history with pre ww2 chevy,double clutching seems to work for up shifting ok, but in my 31---downshifting is nearly impossible unless you get engine/tranny speed right,and double or triple clutch,even then the gears grind a bit---really seems to be an artform!!! This is my first non-syncro vehicle so I need lots of practice

remember when down shifting to and enough gas to equal the correct rpm for the gear you are trying for while double clutching.Good luck, Al

Ok, I guess I am not old enough to know exactly what double clutching is. Is it explainable how to do this, or does it just take the right feel?

JunkYard,

It seems to upshift fine, shifting normally. Is it bad for the transmission not to "double clutch"? I am going to have to figure out how to do that.

Kevin,

Double-clutching is easy enough. For example let's say you want to shift from first to second. You depress the clutch and move the shift lever from first to neutral. Now (this is the double clutching part) let the clutch out in neutral, and then depress it again. Now with the clutch depressed move the shift lever from neutral to second. Repeat for the second to high (third) gear shift.

If I remember my mechanics correctly, the action of letting the clutch out in neutral causes the input shaft speed to drop (because your are reconnecting the engine which has spun down since you have taken your foot off the throttle), which puts it at a speed that is closer to the speed of the gear you are shifting into because the output shaft of the transmission is spinning slower than the input shaft in first and second, giving the engine mechanical advantage.

Since the oil in the 1930 transmission is fairly thick (I drive a 1931 myself...), I would figure that its viscosity helps to slow down the shaft speed, which allows you to shift without double clutching. These transmissions are fairly stout, however double clutching will help prevent damage to the dog-teeth / gear teeth that are being engaged when shifting from one gear to another.

For downshifting, I have found that it is a pretty tricky maneuver (especially when turning a corner... too many things to focus on...), however when I have been successful, I have found that I needed to blip the throttle with the clutch out in neutral to spin up the input shaft to match speeds of the gears inside the transmission. Your best bet is to find a long parking lot / empty road (one that lets you get up to third gear) and practice the third gear to second gear downshift. I wouldn't recommend doing second to first, because the difference in ratios in the transmission are so great that it makes it tricky to accomplish with little benefit.

One thing to consider also, when there is a mismatch between the transmission input shaft speed and the engine speed (such as when you are downshifting from second to third) something has to slip until the speeds match. This something is your clutch. Clutches are designed to wear and handle a certain level of abuse, but there are limits. One of things to keep in mind is that it is easier to change brake-pads than having to have the clutch relined, and the flywheel and pressure plate resurfaced because they have been warped from abuse.

Just my two cents (thoughts and rambling words are cheap aren't they... )

Happy motoring,

Respectfully submitted,

Rusty Berg

Thanks Rusty,

So double clutching is like an art almost by the sound of it. I have to let my clutch completely out before it seems to catch, should I adjust it before attempting to learn this? Or should I just stop before down shifting to avoid tearing up my car?

When you eventually get the art of double clutching perfected, you'll find that you can actually do it without the clutch and just use 'blips' of the throttle to get the RPMs right whilst gently easing the gear lever into the slot at the right moment.

Handy for getting home when you've broken a key clutch component.

WOW,THAT IS A SCARY ONE--WE WILL NOT BE TRYING TO SHIFT MY 31 WITHOUT THE CLUTCH---HAVE DONE THAT IN 50'S CARS AND MY MOTORCYCLES,ALL HAVE SYNCRONIZED TRANNYS THOUGH......SOUNDS TO MUCH LIKE TEETH FRAGMENTS LAYING ON THE BOTTOM OF THE CASE FOR THIS GUY-----BBBBBEEEEE CAREFULLLLLL !!!

Jay, Not so hard to shift without using the Clutch at all. An experienced "Crash Box" driver can do it without any thought. A good Ear and trained feel on the stick make it easy. I don't recommend it but it can be successfully done on a regular basis. Al W. (Please stop Yelling.).

One thing I think, is that it is much easier to learn when you are a peach fuzzey kid with quick reactions and lot of hours behind the wheel, and you are unaware of, or don't care, how many pieces can fall into the bottom of the gearcase of a 28 three speed.
I learned the shifting without the clutch method in a Mack B-73 twin screw with a mechanical clutch peddle and a 5th over and a 3 speed brownie behind a Cummins 250 HP non-turbo aspired six back in 1959. Later,when I went into the military and the artillery motor pool as a 2.5 ton driver, I about ran my NCO "Driver Trainer" nuts, by not using the clutch...."and we called them the good old days"?

TURN YOUR VOLUME DOWN,I'M NOT SCREAMING---JUST TYPING DUDE,LOW VOLUME,PEACEFUL,QUITE !! I DO NOT CARE IF ALL THE CRITICS DO NOT LIKE UPPER CASE--THEY WILL KNOW WHEN I HAVE SOMETHING TO YELL ABOUT---JUST BE HAPPY---I AM !!!!!!!!

YOU HIT ER ON THE HEAD,MR.MACK---WHEN IT AIN'T YOURS--OR YOU BEEN DOING IT EVERYDAY FOR YEARS YE-HAAA--BUT WHEN ITS 80 YRS OLD,WEAKENED OR BRITTLE METAL AND SOMEWHAT DIFFICULT TO GET PARTS FOR---I WILL ALWAYS ERR ON THE SIDE OF CAUTION,AND I AIN'T YELLING ....

LOUDER!!!! al W.

I CAN'T HEAR YOU......

All the Best, Chip

CHIP, YOU KILL ME!!!! AL W.

Finally someone is talking in a normal voice instead of YELLING!

Thank you!

An old truck driver who has several early cars in Horseless Carriage of America circa 1908 to 1913 told me the easiest way to remember. He said that when up shifting (ie from 1st to 2nd, 2nd to 3rd) you want your Rs (rpms) DOWN. And when downshifting (3rd to 2nd, 2nd to 1st) you want your Rs UP. After awhile you can easily catch 15 to 20mph from 3rd to 2nd. For instance if you were going up a hill and it started to lug down. Like one of the other fellows said all it takes is a little practice.

I think your attitude will carry you a long way in our Forum. It appears you have not been on this Forum very long and have already generated a negative attitude.

Put it in reverse and back out an then come join us again with a toned down attitude and you will be much better received.

Anyways back to the downshifting thread I started. I practiced the double clutching a little today since I drove it to work and back today. My technique is still far from perfect but I did have a few succesful downshifts. I still need alot of practice

Thanks for all the advice guys

Jay please don't act a fool, some people are seriously looking for help here and there seems to be a lot of guys with a wealth of disappearing knowledge which I greatly appreciate

MrMack, you and me both mate. I learnt my double clutching skills as a newbie 17 year old driver in a sixties vintage non-syncro Army International ACCO. 5 speed six wheel drive with air assisted splitter. I had huge probelms getting my foot onto the clutch pedal as I'm 6'5" and the engine cowl was too close to the steering wheel to get my knee out around the wheel... the only answer was to learn to drive without the clutch.

I learnt to do this at 17 and I'm now 50 and I can hit every gear up and down the box without so much as a clink. Just one of those things I learnt early and it has stayed with me.