downshifting

Forget the road speed.

Your engine is like a step ladder in RPM. If you downshift at 1100, you will kick your engine to around 1600 or so maybe 1700 and the next heartbeat will have you into the next gear down and adding power.

If you are in a gear say 9th at highway speed at 1500 Cruising. Downshifting is not a option. Do you have a 10th gear, then upshift.

Now if you were cruising in 9th and hit a hill and rpms dropped towards 1100, you will downshift to 8th with using one heartbeat to clutch in, next beat out of gear and at the same time slap the hammer to get engine up to 1600 to accept the next gear down when you slide it in more or less.

There is nothing more complicated than that. You come up the gears one way in RPM's and you climb back down the gears the other way using RPM's to tell you when.

road speed has nothing to do with it.

As far as jacobs braking etc. There are a couple other thoughts related to that but I'll leave it out to avoid confusing you. Generally you are on a downgrade against your Jacobs at or near the top RPM range for max braking without having to up-shift or use your brakes to keep it from taking off on you.

 

the problem is that you guys are using a truck that has a gas motor. gas engines rev up to like 5-6 k. thats no good for pulling heavy loads for extended periods of time. tell your boss to switch to diesel engines. great for pulling for long times

 

Forget the clutch. Use it for starting/stopping! Learn how to float the gears, or to ''feel'' them synchronize. You can shift up and down by this method. Also, learn to brake with your left foot and then right foot on the throttle and you can manipulated everything to mesh in one beautiful motion. No clutch. That's a big waste of your much needed energy! A guy I tested with in the 70's saw me floating the gears and said ''son, use that clutch or you won't work here for me!'' ''Yessir!'' I replied! What do you think I did as soon as he was out of the truck and I got the job?

 

It goes without saying most everything is diesel nowadays.

It has been a very long time since I had a heavy gasoline truck. Something like a 460 v8 that gulped fuel like crazy. In them days fuel was cheap.

Those old gas push rods were awesome for what they were. But when loaded as much as we put on them poor things... there is only so much it will take.

 

I doubt the truck was actually a gas truck I think he was thinking I'll like a 4 wheeler and should have said fuel pedal instead of gas lol.

I have been driving for a year and I still use the clutch but I touch it only enough to separate engine and transmission. Most of the time I get it to slide right into gear not even feel it in the shifter knob.

I usually bring it down to 1,100 when downshifting on a hill otherwise I do it about 1300 or so. I'm shifting an 18 speed but don't usually split gears downshifting, so you handle it like an 8 speed.

The rpms of your downshifting is going to directly depend upon your circumstances. Going up hill your downshifting at a higher rpm to keep it in the power band say 1,500; otherwise you will quickly have to go down another gear and loose more momentum. Going downhill your going to do it at a much lower rpm so when the shift is complete your not over revving the truck. Level ground is going to be somewhere in the middle.

Shifting is something you just learn the more you do it the better you will get. I hope this helps.

 

I'm not sure I follow your question. Are you asking how he dropped from 10th to 7th without braking? As in skipping gears on the downshift? If you lug a gear down (say 900-1000) and race the next gear (1600-1700) you can skip the gear without changing your road speed. You'll see some long time drivers downshift that way, by lugging down to 900-1000 with the jake/brakes and then gear out to rev up to 1500 and catch an extra gear down. Is that what you are asking about?

Edit: And ThomasTrueTrucker is correct. If you brake with your left foot and float gears you can keep braking and dropping through the gears without having your feet constantly moving from brake to throttle and back again.

 

They way they teach you to drive in school is a lot different than how you'll drive on your own. When down shifting I'll apply pressure to the shifter and bump the accelerator to pop out out of gear and gently push it into the lower gear as I'm gradually raising the rpms. Once the rpms get to the sweet spot it will just pop into gear. I really only use the clutch when stopping or taking off. Sometimes when you're going downhill and/or the rpms are really high just bump the clutch to pop i out of gear. That double clutching BS will kill your knee real quick. Up shifting is almost the same process but just use a little bump of the accelerator to bump it out of gear and let the rpms drop will you gently push it into the higher gear.

 

To rationalize what he did....
He had to be dropping tenth to well below 1100 rpm's.
Then he had to rev 7th above 1600.
Also doing this without a load. Don't think one would do that with a load.

If you're driving a truck that is governed at 1600. You can't do it.
I don't have that much experience. I do know, my Volvo with engine brake on, can kick to a low enough gear to rev the engine to 2000. That's it's using the engine brake strongly.

 

Stop thinking about it. Stop putting numbers behind it.

I don't know why they teach it this way, it's dumb. It over-complicates the process.

Use the brakes to slow down to when the motor almost lugs, push on the stick and tap the throttle (don't call it "gas", you are driving a diesel-powered truck), it'll pop out, then as you are going to find the next gear down, rev the motor up until it falls in.

It's really easy when someone shows you how it's done properly, and doesn't try to get you to move more than one gear at a time. If you plan your stop accordingly, you should be able to downshift through every gear from top to 1st.