double clutching

[HEAVY FUEL]

Either way most of the bigger, newer engines should be shifted at a lower rpm. 1300 to 1500 is about all ya need to rev to.

 

[smokin_dodge]

ive only had to double clutch in one truck, thank god it wasnt mine. when i worked for groundskeeping at my school they had a 1990 GMC 3500 HD with a dump bed and housing for a chipper (had a 454 in it, it drank the gas). here's the lowdown, its soo good its in a list.

- no parking brake
- no key needed to start
- no speedo after 45ish mps
- fuel gauge was off, so at 1/4 tank you had no gas (great trick to play on the noobs)
- door handles didnt work unless you could pull it just right
- after 15mph, if you touched the brakes the truck would violently dive to the left
- reverse was only shifted into if you could throw the shifter hard enough into the gear, so if your weak, its not going into reverse
-everytime you shut a door, the mirrors would fall to the ground
-when the dump bed was up the hole truck would shake from left to right, we got the left rear off the ground once....
- anything over 55 and you could make a lifter chatter with the fuel pedal
- at 50mph, unloaded got all of 7mpg...if you had a wind behind you

so we would tow an old chipper behind it, decent sized vermeer before they put all the bs safety crap on it, and that plus a full bed load of chips and there was only one way to stop the truck, downshifting. so after the two miles to get it up to speed it would be the halfway point and we would have to slow down, so i would rev the truck to 5K and shove it in a lower gear and just wait for the engine to slow the truck down.

with all my diesels ive only had 1 standard, i had a 2000F250 with a 7.3 and a 6 speed and i could go from L to 2 to 5 and it would just dump smoke. easy way around shifting 6 gears. but i also had a southbend, dunno what it was it came with the truck but took about 100lbs to push the clutch down.

 

[mowoodchopper]

Either way most of the bigger, newer engines should be shifted at a lower rpm. 1300 to 1500 is about all ya need to rev to.

#1 they are not like the old 2cycle detroits! LOL

 

[HEAVY FUEL]

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

I took it in my shop with my cell phone, then sent it to grandpatractor's cell phone, he emailed it to his computer, then I logged on his computer and he put it in my avatar. Then I got a pm from caseyforrest asking if I was grandpatractor and I said "No, are you sawin redneck?" and explained the situation. SIMPLE

Company truck, I ordered it and park it in my shop winter nights.

 

[mowoodchopper]

I took it in my shop with my cell phone, then sent it to grandpatractor's cell phone, he emailed it to his computer, then I logged on his computer and he put it in my avatar. Then I got a pm from caseyforrest asking if I was grandpatractor and I said "No, are you sawin redneck?" and explained the situation. SIMPLE

Company truck, I ordered it and park it in my shop winter nights.

Awesome pic!!!!

 

[turnkey4099]

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.

Noone says you don't use the synchro if you don't match rpms.

By extension you are basically saying that it is impossible to shift a non-synchro without grinding because you can't exactly match input/output rotation.

If you match the rpms, the synchros do not operate as there is nothing for them to do.

Harry K

 

[Crofter]

Noone says you don't use the synchro if you don't match rpms.

By extension you are basically saying that it is impossible to shift a non-synchro without grinding because you can't exactly match input/output rotation.

If you match the rpms, the synchros do not operate as there is nothing for them to do.

Harry K

Just quibbling here Harry, but the "synchros" consist of a number of elements such as blocker rings or slippers and detent springs, as well as the friction rings. It is correct that if the rpm is a perfect match the friction rings will get no wear but the detents still go through the sliding motions.

As mentioned the transmissions and clutches you find on heavy gvw trucks are often not able to be synchronized with enough moxy to mesh a gear if it is too far outside reasonable. You have usually twin clutch discs and a lot of weight to spin up or slow down by those little brass rings in the synchros that only have a few square inches of oil bathed contact area.
A brand new truck will usually have a lot stronger synchro action than one that has half a milllion miles on it. Sometimes you will find one or two of the most frequently used gears will come to have virtually no action.

If you get a clutch that does not release completley it can overpower the synchros and you have to manually (actually ears and feet) synchronize the rpms whether you single clutch or double clutch. A truck that has a notchy throttle cable or linkage complicates that issue. They are all different.

 

[TDunk]

#1 they are not like the old 2cycle detroits! LOL

I still hear those old Detroits coming down the road once in a while. They definitely have there own sound.

Had an old timer ask me one time "Do you know to drive those screamin' demons ?. First thing you nead to do is slam your hand in the door and drive pissed all day. That's the only way to drive those."

 

[TDunk]

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!

I should have clarified that a little more. The first part of the post was pertaining to pick-up trucks and medium duty trucks. I think the only thing synchronized in the semi's is for the high/low range selector (at least in the Mack tranny's they are) But i've heard rumors that there testing some fully synchro'd tranny's for semi's. If you ask me, that COULD have bad news written all over it if in the hands of the wrong driver like you stated above.

 

[randyg]

Bottom line

Both learning how to "double clutch" and learning how to shift without using the clutch at all, should be learned in SOMEONE ELSE'S TRUCK!

 

[mowoodchopper]

Just quibbling here Harry, but the "synchros" consist of a number of elements such as blocker rings or slippers and detent springs, as well as the friction rings. It is correct that if the rpm is a perfect match the friction rings will get no wear but the detents still go through the sliding motions.

As mentioned the transmissions and clutches you find on heavy gvw trucks are often not able to be synchronized with enough moxy to mesh a gear if it is too far outside reasonable. You have usually twin clutch discs and a lot of weight to spin up or slow down by those little brass rings in the synchros that only have a few square inches of oil bathed contact area.
A brand new truck will usually have a lot stronger synchro action than one that has half a milllion miles on it. Sometimes you will find one or two of the most frequently used gears will come to have virtually no action.

If you get a clutch that does not release completley it can overpower the synchros and you have to manually (actually ears and feet) synchronize the rpms whether you single clutch or double clutch. A truck that has a notchy throttle cable or linkage complicates that issue. They are all different.

:agree2: people dont realize how synchros work for the most part and just because you are matching rpms does not mean you are not using the synchros, In fact we just had to tear a transmission apart on a 4020 JD tractor becuase it had a synchronizer out, it would not go into reverse period if you shut the engine clear off or not. It is a common misconception that all a synchro does is make it so you can go into gear with out matching rpms, this is false most transmissions have some type of synchros and if they break or wear out you cant get a gear even if you match rpms or not!

 

[TDunk]

:agree2: people dont realize how synchros work for the most part and just because you are matching rpms does not mean you are not using the synchros, In fact we just had to tear a transmission apart on a 4020 JD tractor becuase it had a synchronizer out, it would not go into reverse period weather you shut the engine clear off or not. It is a common misconception that all a synchro does is make so you can go into gear with out matching rpms, this is false most transmissions have some type of synchros and if they break or wear out you cant get a gear weather you match rpms or not!

:agree2: 1 billion percent with both you and Crofter

 

[mowoodchopper]

:agree2: 1 billion percent with both you and Crofter

At least 3 of us agree! LOL

 

[lmbeachy]

Double Clutch

If you drove an old GMC 06 bus you had better know haw to double clutch. Lmbeachy