Tips on double clutching..............

[GregS]

Pardon my inexperience, but this is the first vehicle I driven that I had to double clutch when down shifting. I am able to do it fine when going from 3rd gear to 2nd gear, but going from 2nd to 1st gives me fits. Any tips from the veterans?

I have been driving my M38 around like crazy. It is a ball to drive.

Greg

[OKCM38CDN]

Greg, have you rebuilt your transmission? It sounds like the syncros are out or worn... I drive mine regularly and have no prolems like you describe...

Just a thought...

[GregS]

Up shifting is fine and don't need to double clutch on the way up, but don't you have to double clutch on the way down?

[Bob_C]

Up shifting is okay, down shifting from 3rd to second is okay too. However, in the T90 transmission, there are NO syncros inbetween the 1st and second gear. This means you gotta double clutch downshifting from 2nd to first. I think this was done because there can be so much torque on the gears that if there was a syncro between 1st and 2nd, you would snap the syncro.

The first gear isn't completely flat I dont think. I think it has a curve to it to make it easier for them to mesh. (if that makes any sense to you all. Im not sure of the technical way to describe it -- brain constipation).
_________________
Bob Collins
1954 M38A1 MD79056

[GregS]

I am clear on there not being a syncro between 2 and 1, that is why I am double clutching, I just am looking for hints on how to better master the double clutch technique.

I guess it is just something I will have to get a feel for................

[davem201m38]

I've driven 32 to 48tonners (as the laws changed) all over Europe and the Middle East in most types of tractor. I was in the British Army when our trucks were hardly updated from WWII in the late 70s and early 80s. I've had lots of experience but I only consider myself an average driver on a good day (the biggest mistakes you make , you never notice) BUT I find it VERY hard to hit first gear on the roll from 2nd without a crunch no matter how I try.
The crunch is (I believe) normal, don't worry about it. Just enjoy the fact that you have skill that is lost these days
I was stationed near Bitberg in Germany in the early 80s boy could those boys play tunes on those Reo gearboxes, at the time I never understood this till one day I got inside bitberg and asked a guy that explained that most recruites could only drive automatic and the Reo was a bit of a shock till they got used to em. Us poor Limeys knew nothing else as our vehicles weren't powerful enough to have 'proper' auto gearboxes.
I only mention this as my M35 and my M41 also 'crunch in first but are brilliant in all the other gears. An American trait???
All the best,
Dave

[PeteL]

As you know, you must match engine rpm speed to road speed. Going into first at even a walking pace requires a LOT of engine rpm, and the relative speeds change quickly. It is a narrow window.

It's hard to hit first gear just right, even with experience. It will always be tougher than third to second, where things happen at a more moderate pace.

Don't get discouraged! Practice practice practice. Whenever I hit first without a crunch it's still a sweet thrill - after 40 years of jeeping.

"If you can't find 'em, grind 'em!"

Pete

[GregS]

Thanks guys! If anything you have reaffirmed for me that it is hard to do and not that I just don't know what I am doing.............well maybe not totally.

[petesilfven]

When the syncros are a bit worn, double clutching can be a useful technique.

My personal preference when upshifting is to just momentarily pause in neutral and give the gears a chance to slow down. Just think of it as two distinct separate movements: 1st-neutral, neutral-2nd. When downshifting, you will have to shift to neutral, let the clutch out and rev the engine, depress the clutch and shift to lower gear, let the clutch out and accelerate. Done properly, it's very quick.

Big heavy trucks often have what is known as a clutch brake that slows down the clutch disks and input shaft when the pedal is depressed to the floor. This simplifies upshifting by slowing down the massive transmission and clutch parts more quickly.

The best way to learn to double clutch is to get an old time trucker to show you how it's done. Let him drive and watch what he does. A person who has raced sports cars can do it as well.

Anybody in the SE MI area wanting a few pointers on shifting is welcome to get hold of me, and I will have you double clutching in about an hour.