RPM Matching when Shifting

[TFaoro]

I shift fast enough that it drops into gear as the rpms drop, then I try to catch them and keep them steady before releasing the clutch. All of this is super fast though haha!

[leathermaneod]

Oh ok gotcha. Yeah I was thinking it must be pretty darn fast if you are catching the rpm you want as it comes down. Idk how fast your rpms drop, but when I press the clutch, i think the rpms are hitting idle by the time I'm hitting the gear I want lol

[KATOOM]

Sometimes its difficult for a guy (especially me) to understand whats going on unless I can visually see whats happening.  Its a known fact that men prefer the lights on.....

 

Anyways, point being is if you want to understand more about how to properly shift a manual or why shifting one way is better than another, there are some pretty good tutorials on Youtube.  Weed out all the worthless junk and look for the ones where a mechanic has something opened up or sitting on a bench illustrating whats going on with the input shaft and counter shaft and clutch.  Lots of moving parts in there and understanding what role they're all playing can better help one to know what things to do in order to keep their truck reliable.

 

Dont overlook the videos helping describe what a synchro is either and how it functions as well.  Thats very important in RPM matching.  There's one video I watched some time ago where a guy actually explained to the viewers what synchro "lock out" was and I thought he did a fantastic job since most people have zero idea what anything like that is.

 

The older I get the more I enjoy learning.....

Edited September 14, 2016 by KATOOM

[dripley]

For me it is more just a feel for the rpm. The shift is just one fluid motion to the next gear. When I feel it is not fluid I blip the throttle. I am never looking at the tach to do this. You get very used to it driving a no syncroed tranny. Try this one day for a down shift. On level ground holding a constant speed just push the clutch DO NOT lift from the throttle. The engine rpm will go up exactly where you need it. It only works while you are maintaining your speed. Wont work if you are under heavy throttle like pulling a hill or such.

 Might have to look into what @KATOOM is talking about. I never heard of synchro lock out before.

[notlimah]

So strictly speaking of driving a manual on everything other then these trucks, I've done this on every other vehicle, from smaller trucks to motorcycles. It really is a feeling thing more then an exact RPM thing. Typically the way I learn to "rev match" while downshifting in an unfamiliar vehicle is to start slowing down way ahead of time by letting off the throttle, depressing clutch, selecting gear, then "blipping" the throttle to the appropriate level for my speed and gear and fairly quickly releasing the clutch. You're not going to be letting the clutch out as slow as you would from a start, it's pretty fast. If this evolution isn't smooth and has some jerks, then you didn't blip enough. The other way around isn't a big a deal, but you won't be slowing down as much. Again, this is all based on smoothness and feel.

 

As for the up shifting, I can't really comment because I've never driven a slower shifting vehicle where the RPMs would drop all the way back to idle before I could have my next gear selected and ready to go. What that sounds like to me is maybe you need to rev it out a little more before shifting, or maybe the trans is just showing some age/wear/tear since it's taking a bit to shift. If anything a quick blip to get the RPMs back up before you release the clutch and then immediately get back on the throttle in this case would probably be your best bet.

 

Anyways, hope this helped, but really all this is doing for me is making me wish my 5speed swap was already happening!

[Nekkedbob]

As a old truck driver that was taught to shift without the clutch, if it is done right it will not hurt one bit. Now that that was said if it is done right you can shift a non synchro box with no gear clash or rattle or a synchro box with effort of 2 fingers. As to RPM matching it depends on my state of mine if I blip the throttle between shifts. From 2nd to 3rd tends to be the slowest shift for me. If you do get the RPM matched your trans will almost fall into the next gear with both a up shift or a down shift. When RPM matching is done correctly I have very seldom found a trans the takes more then two fingers to shift it. I do live and die by the tach and if you pay attention to when you pull it out of gear and what the RPM is in the next gear that will give you a good idea what the percentage of drop to watch for. A good way to practice is to shift early like 1700  and only use 2 fingers. The higher the RPM the more precise that you have to be. 

[Texas CTD]

5 hours ago, TFaoro said:

I shift fast enough that it drops into gear as the rpms drop, then I try to catch them and keep them steady before releasing the clutch. All of this is super fast though haha!

 

Because G56...

 

[dripley]

My 5600 will shift that quickly and did until I shortened to slave rod. Got to put a new on to alleviate the problem.

[TFaoro]

15 hours ago, Texas CTD said:

 

Because G56...

 

Yeah, the 5600 is a jerk when it has a dual disc in it. My brother's is an SOB to speed shift. His speed shifting is my normal shifting