Grinding Gears

Now you are way over reeving.

 

Grind em til you find em.

 

Bumped that throttle up above 1,550 if you are shifting out at 1,100. Take it down to 1,000 rpm to downshift when going down a hill to make it easier. Only press the clutch a half inch for shifts, cause you might start the clutch break if you push too far. I never looked at the tach during training, even though they assumed everyone learned that way, it only made me overcomplicate the process and lose concentration on the truck sounds.

 

One of the things I noticed as I was trying to downshift for stopping was I'd start to downshift when I hit the desired speed. By the time I got the rest of the sequence done, I had decelerated past the speed I needed the rpm's to match.

For instance, if you're going from 7 to 5 (in my rig, I want to be right around 15 mph for 5th to take.) so when I started the downshift originally I'd begin when I got to 15 mph. With the second and a half or less that passed, my rig may have dipped down to 12 or even 10 mph. That would throw it out of sync.

Newton's laws of motion still apply, so remember as you're shifting, it's better sometimes to start a half-second earlier. (So in my case, I might start to downshift at 17 or 16 mph)

..I hope someone can explain that better. I feel like it's nothing but confusing.

 

As a student myself in my 4th week of an 8 week course I have no useful experience beyond, "make it simple stupid". In other words for us our trucks may have an operating range of say 1300 to 1800 with a 400 rev on the down shift. I actually shoot for 1100 and rev to 1500 which gives me a big ole "15" to shoot for on the tach..On skip, get speed in line first, like 10 on a 90, get to about 12-11, put her in neutral, rev to your 90 rpm's then get to your gear..Now, mind you this is easy as heck to type but harder to execute. Keep plugging away..

 

We don't downshift much at my school unless we are coming on a red light (where we start slowing down and maybe downshift once just so we don't have to stop all the way).

If we have to make a complete stop we just slow down, stop, then put the shifter in the correct slot for starting up again.


But don't listen to me! I only have a week in the truck!

Do what the veteran guys on here tell you to do!

 

Now you're going to be watching the tach trying to match these rpm's. Just relax a minute and know when you're down shifting you've got to bump the throttle a LITTLE to get into the gear you want. It should be a fast bump and not way up against the peg. After awhile you'll know what gear to be in for the speed the truck is moving. Most new drivers want to shift too soon and grind a lot. With today's engines if you can accelerate you're not lugging the engine. For cruising you want to select the gear that will run 200-300 below rated rpm's. So relax and know it will come to you.

 

good advice posted here. Also, try to note what speed (mph) you are at when upshifting; ie: my 6th gear(my 'go to gear') is about 15-22 mph (10 speed trans). It's a starting point; when turning I can brake the truck down to below 15 and drop it into 5th. 10th to 9th, usually around 55mph (rev way high if 10th to 9th over 55); brake down to 35 or so for 8th gear etc..
I got put into different trucks when I went to driving school also. Usually they are well beat on and they all have their own temperament so to speak. I was shifting this old International beautifully, then when I went to test with the state there was another truck sitting there for me to use ( Inter. was broke); I freaked out and couldn't shift worth a crap and flunked.

 

Well yeah that will happen if the trucks have different transmissions or different engines.

For example a C15 Cat has a much longer stroke than an M11 therefore when you blip the pedal on the M11 the engine/tach spins up real fast but the C15 will be slower.

Next is the trans. A 10 speed will have bigger steps between the ratios than a 13. A 10 will be approx 300 rpm and a 13 will be more like 200 rpm on the low side and even less when you get into high range and start splitting. Those numbers might not be exact but I'm too tired to look up the steps from the Eaton book I'm sure you get the idea.

 

Dropping a gear without grinding them is all about feel and coordination. I think most have trouble because they over rev the engine when the stick hits neutral and then wait to long to select the gear. When everything is in coordination the stick should go into the gear like butter.