When to shift

[hatukazi]

^^^my brother is an OTR trucker, he uses this method to save his clutch (and leg)from wear and tear, in your car most of the time you end up in traffic and can save the clutch for the races.

 

[caboose]

Truck transmissions can't be compared to car transmissions. Trucks don't have syncros, so there isn't any damage done when you don't use the clutch. also trucks have a lot more torque to tear up there clutch with, so it's a benefit to them no to use a clutch.

 

[K2e2vin]

Anytime you use the clutch you're theoretically wearing it out.

Clutchless shifting doesn't harm your synchros/transmission at all unless you're jamming it into gear. If you do it right, the car doesn't jerk at all and is very smooth. I've used it a couple of times when my clutch master cylinder was going out and driving my cousin's HB which has a rediculously strong clutch for his setup(using the clutch made regular driving difficult).

 

[AHHVTEC]

big rig trucks are way different there designed to do that cars are not, now please lock this thread

 

[YBLEGAL]

Waste Of Bandwidth.

Yeah caboose. Google Dog-tooth transmission or a dogbox.

 

[INJEN78]

when you shift without the clutch in hondas it doesnt ruin anything.unless you grind it or whatever..
you ruin the synchros more by actually using the clutch

 

[budda]

i'm surprised it didn't lock earlier when we were all joking

 

[caboose]

you wear your sycros, because they will be trying to align the gears when you shift, but they can't since your clutch isn't disengauged. Just becasue there is no grinding doesn't mean everything is ok.

 

[newb]

Wrong. Syncros work 100% of the time. In a constant mesh tranny, the syncro turns the next gear at the appropriate speed to shift without grinding, rather the clutch is engadged or not.

 

[caboose]

Sorry, what I meant was that you syncros will be working to align the "dog teeth" which lock the gears to the shaft, although constant mesh doesn't mean constant synchronized.

Constant mesh means all the teeth of the gears are always engaged, but only one is locked onto the shaft at any given time. If you change gears, the input and output shafts have to be synchronized with each other, hence the need for syncros.

Synchromesh

If the teeth, the so-called dog teeth, make contact with the gear, but the two parts are spinning at different speeds, the teeth will fail to engage and a loud grinding sound will be heard as they clatter together. For this reason, a modern dog clutch in an automobile has a synchronizer mechanism or synchromesh, where before the teeth can engage, a cone clutch is engaged which brings the selector and gear to the same speed. Moreover, until synchronization occurs, the teeth are prevented from making contact, because further motion of the selector is prevented by a blocker (or "baulk") ring. When synchronization occurs, friction on the blocker ring is relieved and it twists slightly, bringing into alignment certain grooves and notches that allow further passage of the selector which brings the teeth together. Of course, the exact design of the synchronizer varies from manufacturer to manufacturer.
The synchronizer[1] has to change the momentum of the entire input shaft and clutch disk. Additionally, it can be abused by exposure to the momentum and power of the engine itself, which is what happens when attempts are made to select a gear without fully disengaging the clutch. This causes extra wear on the rings and sleeves, reducing their service life. When an experimenting driver tries to "match the revs" on a synchronized transmission and force it into gear without using the clutch, the synchronizer will make up for any discrepancy in RPM. The success in engaging the gear without clutching can deceive the driver into thinking that the RPM of the layshaft and transmission were actually exactly matched. Nevertheless, approximate "rev-matching" with clutching can decrease the general delta between layshaft and transmission and decrease synchro wear.

 

[newb]

Your still missing the fact that when you shift without the clutch, you let off the gas. This in turn slows the input shaft without using the syncro, meaning less wear. To a point anyways.

 

[caboose]

Sure the engine slow it down, but the syncro is still going to try and match the speed EXACTLY. But the problem is now the syncro is fighting the engine and flywheel and input shaft, as apposed to just the inertia of the input shaft. Therefore you are going to have more wear.

Additionally, it can be abused by exposure to the momentum and power of the engine itself, which is what happens when attempts are made to select a gear without fully disengaging the clutch. This causes extra wear on the rings and sleeves, reducing their service life.

 

[K2e2vin]

Key word, "can".

 

[caboose]

Key word, "can".

Alright wise guy, go ahead and clutchless shift your tranny all you want. I'm on my third tranny thanks to some dipshit who though that his second gear syncro was indestructable.

Sure you can get away with doing it a few times, and who knows, maybe you will never have a problem, but I've seen WAY WAY to many transmissions with gear and syncro problems (hondas included). Have you ever price out replacing a syncro? Not cheap (BTW, I believe syncro price goes up as gears go down).

Honda designed the syncro to only be used to syncronize the input shaft with the output shaft, not the input shaft + engine+flywheel. If you use them correctly, then they probably last forever, becasue knowing Honda, they have done rediculous testing on them. But they were never intended to take that kind of abuse for extended periods of time.

So if you feel like replacing your sycros or swaping out you trans at some point, be my guest.

PS! Notice that raceing gear boxes and truck gear boxes are designed differently to be used for clutchless shifting. Think about it.

 

[K2e2vin]

Do you know how many transmission I've taken apart? Of all the transmissions I've taken apart, only one of them had a worn synchro, and it honestly wasn't that bad nor was it caused by clutchless shifting(the teeth were slightly worn on the 4th gear synchro on my Accord...car was stock/never raced).

Even dog-box transmission can be used with the clutch. The only way you'd damage a synchronized transmission is if you gas it or jam it into gear(actually forcing the synchronizers to "synchronize"). When you do it right, the synchro's never grind or anything...it just "pops" into gear. If you knew how to rev match the synchros would NOT work against the engine/flywheel/inertia. This is why you rev match in the first place.

 

[newb]

If you knew how to rev match the synchros would NOT work against the engine/flywheel/inertia. This is why you rev match in the first place.

Exactly what I was tryin to say.

 

[caboose]

Exactly what I was tryin to say.

Yes, theoretically if the rpm of both were exactly the same, then you would be ok, but they are hardly ever EXACTLY the same. They may be close, which will make it go in smoothly, but there is wear.

Plus, when you clutchless shift, don't you apply pressure agianst the next gear until it pops in? What are you loading up agianst until it pops into the next gear?

And if you can rev match like that, then why not use the clutch anyways, because then there would be no wear on that if you engage it at the EXACT same time the flywheel and trans are spinning at the same speed.

But to each his own. I'll just never buy a trans or car from either of you.

 

[newb]

Is this not how a constant mesh tranny works? All gear constantly turning to minimize wear when switching gears?

P.S. I couldnt give less of a fuck if you ever buy a car from me.

 

[K2e2vin]

I'm assuming you've never even tried it?

That's how a synchro works; the RPM does not have to be exactly the same; but once one ring catches it'll "match" the assembly allowing it to engage easily. The rev matching comes from the revs falling. As newb stated, all the gears are already turning. It's not like you're having to accelerate the shafts to match and what not.

You apply light pressure; you're not actually pushing it in. Once the revs match, it'll fall into place by itself. If you ever open the transmission, you'd see that doing that would just push the selector on the collar. Not enough to force it in but rather has the synchro pretty much sliding "at the edge of engagement"..the blocker ring will prevent it from actually engaging until it's synchronized.

The point of this was not using the clutch, but if clutchless shifting harms your transmission. If had to clutchless shift a couple of times due to clutch issues(either no clutch due to hydrualic issue, or simply too stiff of a clutch/harsh engagement).

You don't have to buy a transmission from me, shipping would be killer anyways Plus, I wouldn't sell my transmission...consists of a few hard to find parts.

 

[caboose]

All gear constantly turning to minimize wear when switching gears?

Yes, all gears are turning.

I don't think you know the difference between Syncromeshed and Constantmesh. You can have a Constantmesh transmission that isn't synchronized.