AirGrabber

Is there a way to get the engine to decellerate faster. Although its not to bad when shifting at high rpm, Im losing to much momentum (with or without clutch) or slowing the engine down with the clutch. All manual trans common rails that ive driven have been like this. I've been considering a exhaust brake not only for slowing down but hoping it would help with this as well.

bulabula

Not sure I understand the question, nor can I recall anyone bringing this up.

What problem is the "slow deceleration" causing?

What are you towing that you lose that much momentum? Or are you racing it? Operator error? What are your shift points. One of the 6 shooters big advantage over the 5 speed was reducing the rpm drop between gears to minimize loss of momentum.

Since all the CR trucks you've driven are like this, maybe you've got some unrealistic expectations? I dunno.

But to give you a direct answer to your question, reduce the rotational mass of your flywheel. That'll enable the engine to both accelerate and decelerate quicker; but I don't think thats the right solution.

Another thought is to toss the handshaker and drive an auto; that'd easily solve any momentum losses between gears.

Strjock81

What he is trying to say I think is that the engine does not decellerate fast enough when he pushes in the clutch--effectively delaying his ability to shift to the next gear at a near idle engine speed--thus resulting in a loss of momentum for the truck and whatever load he is hauling/towing. If the engine immediately fell from say, 2300 to 750 RPMs, it would speed up his shift process a lot more than if it very slowly falls from 2300 to 750 rpms. Either that or grind the ^#*$ out of the synchros trying to shift from 2nd to 3rd at 2100 RPMS!

bulabula

huh? Still sounds like operator error to me; maybe an automatic tranny should be in his future.

There's nothing wrong shifting at 2100 rpm. When driving one of our trucks, and if someone lifts at 2700 rpm in one gear and engages the next higher gear at 750 rpm, that'd be one horrific ride - and he'd never be allowed to drive my truck.

If you know how to shift, you often don't need synchro's.

AirGrabber

bulabula, this has been discussed before, rpms have a delayed drop of about 1/2 sec after You let off the throttle and push in clutch. exists in autos as well, but not as noticeable. It has to do with rail pressure, I believe. Every 3rd gen I have driven has been like this. Some worse than others. When I asked the dealer about this, he said they replaced a few TPS (throttle position sensors) on other trucks, but never made a difference. As far as the 6spd goes, I love it, and would'nt choose another way to go from gear to gear, and if someone were to take my truck up 2700 and engage next gear at 750 I woulnt only throw them out of the truck but I would hit them with a big hammer while they were in the air

G1625S

I think AirGrabber is trying to duplicate what some big rigs do when going up throught the gears--they often leave the engine brake on so the motor doesn't 'hover' when they let off to shift. Letting all the way off the accelerator with the engine brake on and no load pushing the truck creates rapid motor deceleration, apparently aiding the selection of the next gear. This is how I understand it, though others with more experience can chime in any time! I would think an exhaust brake would theoretically produce similar results, though I'm not sure how quickly they react in comparison to an engine brake. If the flapper in the exhaust brake closed and opened in the blink of an eye, then I would say it would produce a similar effect.......ok, that got too long winded, sorry, but I hope it helps!
greg

MikeyB

AirGrabber, Here's what I do and it seems to help. As I start to disengage the clutch I move the shifter to the neutral position, and the when the clutch is to the floor I move to the next gear. Speeds up the process just a little. Also helps if you feather the throttle a little when releasing the clutch, takes some of the driveline shock out.
On big rigs I never took my foot off the throttle when shifting, but we don't use the clutch either, just RPM match to allow the shifter to fall into the next gear.

MikeyB

bulabula

AirGrabber, ok - gotcha; mine used to do that too. Either it doesn't do it anymore or I just don't notice it.

Mine only did (does?) it at while at low speeds, so I figured it was the low speed gov trying to keep it from bogging.

My 5.0 Mustang has always done that too, so its never bothered me - plus I always liked that little "rev" when pushing in the 'stang's clutch.

As far as our trucks go, I think its the nature of the Beast.