double clutching

[TDunk]

I look at it like this. The average cost to rebuild a 1/2-1 ton truck tranny is about $1500. I'll use the clutch rather than take the chance on not matching the gears just right and ruining the tranny. It's not worth it to me just to save a little wear and tear on my left leg.

 

[ozzy42]

Guess this post demostrates that all you idiots can't drive:jester:

I would think shifting a snynrco box with out using the clucth isn't a good idea unless the clutch went out and you had to. If the speeds are the same it will work no problem its just finding that speed that wears the syncros.
My scooby is auto and that runs on a big rubber band anyway.
I also think think that D C-ing is really for big trucks and in most cases not needed. my neighbor kid told me he was D C- ing his Jetta.

:agree2:

 

[mic687]

Guess this post demostrates that all you idiots can't drive:jester:

I would think shifting a snynrco box with out using the clucth isn't a good idea unless the clutch went out and you had to. If the speeds are the same it will work no problem its just finding that speed that wears the syncros.
My scooby is auto and that runs on a big rubber band anyway.
I also think think that D C-ing is really for big trucks and in most cases not needed. my neighbor kid told me he was D C- ing his Jetta.

:agree2: You can double clutch anything with a clutch but for most things if you don't need to why would ya right.

 

[Crofter]

:agree2: You can double clutch anything with a clutch but for most things if you don't need to why would ya right.

I think more importantly, if you are not fetching the rpms in the right direction when you are doing it, you are adding to the synchro's work not helping it.

I have a 5 speed standard in my car that is completely synchronized but I double clutch and bring the rpms up close to required rather than listen and feel the whine of the synchros as they have to provide friction to bring the gears to the same speed to mesh. Up shifting merely takes a slight hesitation to accomplish the same thing. It takes no conscious thought (unless you try to explain it) and seems to be satisfying.

 

[turnkey4099]

Guess this post demostrates that all you idiots can't drive:jester:

I would think shifting a snynrco box with out using the clucth isn't a good idea unless the clutch went out and you had to. If the speeds are the same it will work no problem its just finding that speed that wears the syncros.
.

You do NOT make the synchros do any work when clutchless shifting. The gears slide right in as the engine speed/gear speed matches. I don't even pull the shifter to engage the synchro, when I pull, it is in. I suspect all the people "don't clutchless a synchro" are ones who have never done it or learned how to do it. Done right, the synchros never come into play. I do it all the time on my F150 empty or loaded and don't grind gears or make the synchro match speeds. Did get caught one a few years ago way out in the boonies. Hit a stop sign, Bang! and clutch pedal stayed on floor. Clutchless shifting all the way back to town and through some moderate town traffic.

Harry K

 

[DK_stihl]

Why...if the gears are moving the same speed...shouldn't hurt a thing....

I learned how to drive semi last fall...during sugar beet harvest. Super 10...

Thing drove me NUTS....I have driven manuals in EVERY vehicle I've ever owned learned in them etc...and for some reason, that thing would still give me fits! The little thumb swithc would throw me....I would rather have a splitter and go through all 5 and start over.

Have you ever driven an 18 or 13 speed?

 

[TDunk]

You do NOT make the synchros do any work when clutchless shifting. The gears slide right in as the engine speed/gear speed matches. I don't even pull the shifter to engage the synchro, when I pull, it is in. I suspect all the people "don't clutchless a synchro" are ones who have never done it or learned how to do it. Done right, the synchros never come into play. I do it all the time on my F150 empty or loaded and don't grind gears or make the synchro match speeds. Did get caught one a few years ago way out in the boonies. Hit a stop sign, Bang! and clutch pedal stayed on floor. Clutchless shifting all the way back to town and through some moderate town traffic.

Harry K

You don't hear the gears grind because of the synchronizers. The synchros. are spinning along with the gears, and at the same speed as the gears. So when you shift, the sliding gear must first mesh with the synchro. then it will finish engaging to the next gear. Every time you shift, your first going through the synchro. then the gear. Even if your matching the gear speeds almost perfect, the synchro. is still working to get the two gears to mesh.

 

[TreeClimber57]

Hmmm, I disagree, the whole concept of double clutching is to get the gear box spinning at approximately the same RPM's as the engine for the next gear, hence the throttle blip when in neutral, so you sentence should read ....

Double Clutching would be pressing in the clutch, releasing it in neutral, blipping the throttle, then pressing down on the clutch again and then shifting to the next gear.

Try it, you'll see what I mean, get that next gear spinning at the right RPM and then get mesh not mash.

Trottle blipping is true, but only on a downshift.

 

[TreeClimber57]

Have you ever driven an 18 or 13 speed?

Yep 18 speed roadranger.

 

[TreeClimber57]

TMD; back to the original post, I'd say that was skipping a shift, not double clutching.

Agreed.

 

[hokiewheeler]

What the OP was referencing is skip shifting. You can run up through the gears empty much quicker than loaded. When loaded your target is 300 rpm. When empty, you rip through 300 too quickly, so you start off in 3rd, jump to 5th at 600, hit the split and continue through the high range. Procedure would be the same in 13, 15 or 18 speed. 13 is a variation on 9, 15 is a 10 with super low, and 18 is a 13 that lets you split the low range box of the trans. As for synchro trans, if you mesh the gears right, it doesn't hurt it. The problem is, in light duty vehicles, the trans is a lot tighter and the gas engine slows down a lot faster than the diesel in a heavy truck (less rotating mass and the throttle butterfly) so you have to be perfect and quick on the shift. The heavy transmission gears have less preload and the engine responds slower so you have more time. I hate the autos in even the medium duty trucks. We have a new chip box with some weird kind of pushbutton auto similar to EF auto shift. It sucks. I'd much rather have to row the gears. I don't like the IH super 6 or the spicer 6. The 7 isn't bad, but at that point, why not a 9 or 10? You know what the Operators say? Trucking only takes a 9th grade education. (Not to start any crap with the professional drivers, I've done it, it's hard, my hat's off to you, and I can't take it).

 

[DK_stihl]

18 speed

Yep 18 speed roadranger.

I only asked because both the 18 and 13 have thumb switches and a butterfly

 

[Tree Pig]

I drove a while when I was younger, 8 and 9 speed Eaton Fullers. I skip, double clutch, no clutch and ground every gear in there. It all depends on RPMs if you time it right no clutch needed and you blurp only on the way back down to get your RPMs back were you need them. The only time its bad is when you get caught in between gears in a wrong RPM especially down hill with a heavy load .... YUCK, you learn how to get your RPMs right fast.

So why is this thread still going anyways?

 

[mowoodchopper]

Normal shifting would consist of pushing the clutch in, changing gears, then releasing the clutch.

Double Clutching would be pressing in the clutch, releasing it in neutral, then pressing down on the clutch again and then shifting to the next gear.

100% correct, that is double clutching. It does not always include blipping the throttle as eka said!
Double clutching allows the trans and engine to sync back up when you let the clutch out before you go back into a gear, and know you should not have to blip the throttle on a upshift if you do it correctly, while you are double clutching the rpms fall and you catch them on the way down, you just have to get your timing or use the tac and know your split usually 3-8 hundred rpm depending on the trans. You will only have to hit the throttle on a down shift and if you know your split there is no ? what rpm you need!

 

[mowoodchopper]

I only asked because both the 18 and 13 have thumb switches and a butterfly

Fifteen also , super ten also has the splitter switch but no low and high side switch or butterfly as you called it!

 

[mowoodchopper]

You don't hear the gears grind because of the synchronizers. The synchros. are spinning along with the gears, and at the same speed as the gears. So when you shift, the sliding gear must first mesh with the synchro. then it will finish engaging to the next gear. Every time you shift, your first going through the synchro. then the gear. Even if your matching the gear speeds almost perfect, the synchro. is still working to get the two gears to mesh.

You are also correct, just because your not using a clutch does not mean you are not using the synchros, it is not a choice.

 

[mowoodchopper]

That's the whole reason they starting putting synchronizers in tranny's was for people that couldn't shift that good. I'm pretty sure even some of the 10 and 13 speeds are being synchronized.

I'm not argueing here, but my old man and i have torn down alot of tranny's. We torn down a 6 speed spicer with 50K that looked like there could have been sand used instead of oil. The driver was about 400 lbs. plus and was to lazy to use the clutch. We've also torn down the same model tranny with 200k and looked like new. Driver was easy on the truck and used the clutch.

The main reason semi transmissions are not fully synchro is to stop you from destroying the motor and trans. If you put a fully synchro trans in a loaded semi you could be going 60 down the hiway and put it into 4 gear, which would blow the engine all to h*** !! They are built so that you can only go into a gear that you can match the rpms if it needs to be 5000 rpm to run in that gear it simply wont go in! Also people get confused about this and think a semi tranny has no synchros , not true it is just not fully synchronized like a pick up trans!
Nothing wrong with your post T just used it because I wanted to explain the reasoning behind synchro and non synchro!

 

[mowoodchopper]

The main reason semi transmissions are not fully synchro is to stop you from destroying the motor and trans. If you put a fully synchro trans in a loaded semi you could be going 60 down the hiway and put it into 4 gear, which would blow the engine all to h*** !! They are built so that you can only go into a gear that you can match the rpms if it needs to be 5000 rpm to run in that gear it simply wont go in! Also people get confused about this and think a semi tranny has no synchros , not true it is just not fully synchronized like a pick up trans!
Nothing wrong with your post T just used it because I wanted to explain the reasoning behind synchro and non synchro!

One more thing T is correct that even in a semi trans if you tear one down you can tell if the clutch has been used properly! Do I double clutch no I dont use the clutch except to take off , Is this the correct way No, is it the trucker way and the way I was taught to drive yes! Can I double clutch YES!

Sorry guys maybe I should be on the truckin site! LOL

 

[HEAVY FUEL]

Just put both feet on the dash on PULLLL!:jawdrop:

 

[mowoodchopper]

Just put both feet on the dash on PULLLL!:jawdrop:

Where did you find that W9 heavy fuel? Is it your own pic?
I have looked but not many good truck avatars around!