reasons why the truck grind and jerks when trying to shift gears

Sounds like multiple things. A transmission will grin if you are attempting to shift too early or too late. The truck jerking and rocking can be caused by being in the wrong gear, or letting off the clutch too fast

 

sounds like u need to better match rpms to speed. the rockin and jerkin could be caused from when u get it in gear ur to heavy on the go petal. roll into the power dont mated the petal just my .01

 

I am better starting out than finishing.

Early in the day everything is smooth as silk, but later at night it might start grinding.
And if the engine is on a regen cycle, forget it.

It's all about matching gear speed with road speed, and it takes a certain feel for it.
Seems more intuitive than scientific.

 

could be a common problem if you are in teh lowest gears.

if i hit mine just right. it jerks. becuase of the jakes being on. but only in the 2 lowest gears.

as for the grinding as others have suggest. your probably not hitting the rpms right yet.

how many miles are on the transmission. could be old age like mine with 1.2 million. it's a flat out booger to shift sometimes.

 

Sounds like your hand is not coordinating with your foot at the correct RPM's

 

I don't know what level you are at so I'll just start at the beginning.

Imagine two different size gears sitting side by side spinning at different speeds. Those two gears won't mesh if they are spinning different speeds. If they are spinning the same speed they will mesh. If they are almost the same speed you can get them to mesh with some grinding and forcing.

What you are doing is trying to mesh them when they are close to the same speed but not exact.

Now your engine controls how fast one gear spins and your tires and drive shaft controls how fast the other gear spins. But your tires/driveshaft has multiple sized gears to pick from for the increasing road speed. The faster you go the smaller the gear on the driveshaft side.

When I was taught which is a little different rpms once you gain experience but it helps getcha going.

Under throttle first clutch in at 1600, come out of gear and clutch out, when the rpms hit 1000 clutch in and go into the next higher gear. Now let the clutch out and simultaneously only a light throttle and then you can increase it. This is about a 2-3 second sequence broken down.

This is just the basics. As you gain experience you'll do progressive shifts and even float the gears. For now try to take notice what gear you are in for what speed... 5mph? 10mph? 15mph? 30 mph? 45mph? Take notice what gear you go around corners in. Then if you get lost you'll have an idea what gear to shoot for.

You have to learn to upshift before you can downshift. But downshifting is just the opposite. Out at a 1000, bump the engine lightly to 1600 and go into next gear.

Doubleshifts you can do at 700 and 1600 for now.

Practice makes perfect. Someone like you takes about 2 weeks to get the picture and then you slowly get better.

Once you have experience it's like driving your car and you don't even have to think much about it. You'll be floating gears and doing it a lot by sound than staring at the tach.

 

without being there to see it's hard to say. but here is my advice on shifting.

1. turn your engine brake off

2. when empty watch your tachometer and try taking it up to 1200 or so. pull or push slightly on the shifter then give the throttle a little tap and release. (with slight pressure on the shifter it should pop right out) as the rpms fall slide it right into the next gear at about 850 rpms.

3. when loaded heavy use higher rpms. try running up to 1500 or even 1600 rpms, and find your next gear at 1100 or so.

if you use high rpms when empty it is torquey and jerky. smoother and easier at low rpms. depending on transmission the release point of one gear and entry point to next gear will vary, but usually with 9-13 speeds it is about 400 or 500 rpm dropping from one gear to the next. after awhile it is more a matter of timing it than watching the tach, but I still use my tach to know when to shift. if you do it the same every time it gets easier.

 

A smiling transmission...sorry, had to do it.

 

I'm only responding to this because I just spent a ton of hours in a truck with all students so watching them and myself and knowing what us new guys had to do to smooth things out on these worn out trucks and empty trailers not because I'm an expert because I'm no where even close. You experience guys might not remember but us new guys get in and mash the clutch threw the floor LOL and because were overwhelmed we'll be at 2200 before we realize its time shift LMAO What worked for me and the guys was progressive shifting and not putting the clutch threw the floor. We had to start out in 2nd gear always so I would shift at 11 then bring 3rd to 12 and so on. Being smooth on the clutch coming up and not going down far was the hardest to workout. Pretty much every time I thought I knew how far to push the clutch in I just cut that in half. The getting worse later on in the day thing I seen that a lot to and think its fatigue. Were not use to this and driving for us wears us out very fast because were concentrating so hard on every little thing and we get tired fast.