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RPM for shifting

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22K views 24 replies 16 participants last post by  cdstl  
#1 ·
This is a new truck to me. At what RPM do would you guys recommend shifting while unloaded? I have been shifting between 1500 and 1900. Also, what are your opinions on shifting without using the clutch? I know that may require running the RPM up to 2500ish.

Thanks
 
#2 ·
Power shifting it is hard on the synchros, but if you know how to do it without grinding, or excessively forcing the gear, go ahead......

As for shift speed, just listen to the truck, it will tell you when it wants to shift....

Mine seems to perfer i shift no later then 2200 rpm unloaded, and cruise at approx 16-1900
 
#6 ·
Entirely based on feel and load conditions. And by load conditions I don't entirely mean having a load in the bed or towing something. Load can be based on throttle input and uphill situations. If you are gentle on the throttle you can shift lower and not risk burning the clutch up or breaking something. If you are on a hill you want the RPM's higher before shifting. I'm half deaf, so I'm not going to say to run it by ear, but run it by feel. And shifting without the clutch is NEVER a good idea with a synchronized transmission. Even if it appears to shift smooth the synchronizers are still taking up the slight differences and causing wear.
 
#9 ·
I would rephrase that to say probably not a good idea unless you know the transmission. I have been around heavy duty trucks for a while and I can tell you for a fact that most of the people I know who haul (mostly gravel and water) use the clutch in first and maybe second but then float the rest.

My advice on this one is don't do it unless you know what you are doing and you know the gear box. I do it with my truck when I'm lazy and I'm working on 215k and never had an issue. Original 5600 nothing but a dual disk. Just be careful and make clean shifts and you shouldn't have much to worry about.

Shifting is on you. When to shift is based off of what you want from the truck. Generally I stay around 2k and hold 4th and 5th just a bit longer because of the gap.
 
#7 ·
Ok, good advise by all. I have always shifted by ear and try not to be hard on equipment. I have a friend that has driven a semi occasionally and he is wanting to power shift. I will put the kabosh on that and tell him when he uses the the truck to use the clutch.

The truck seems to like to shift closer to 2000. I was reading another thread about getting better MPG and a guy was doing better by shifting lower.

thanks
 
#8 ·
According to my ScangaugeII, cruising at 30-35mph in 3rd gear (5 speed, 3.55's) yields better mpg than in 4th gear. Same with 55-60 mph in 4th gear as opposed to 5th. Essentially, the higher rpms for cruising are better with low throttle input as the engine has zero "lugging" to it. I get my best mileage at 58-62 mph in 4th gear (still talking about the 2000 2500) and that's at 2200 rpm or so. When I changed my shifting habits to wait until 2400-2500 rpms, I noticed my avg mpg for the tank went up as well. I'm not talking about hammering the skinny either, I'm talking very little throttle input all the way through the gear. Again, I only say this because I have paid close attention to it thanks to the scangaugeii. If your results aren't the same, Im not responsible. In fact, I would advise you to buy a scangaugeii before even attempting it, but I am confident you will see what I am seeing. I never use 5th gear unless planning to go 70mph or more (quite rare).
 
#21 ·
According to my ScangaugeII, cruising at 30-35mph in 3rd gear (5 speed, 3.55's) yields better mpg than in 4th gear. Same with 55-60 mph in 4th gear as opposed to 5th. Essentially, the higher rpms for cruising are better with low throttle input as the engine has zero "lugging" to it. I get my best mileage at 58-62 mph in 4th gear (still talking about the 2000 2500) and that's at 2200 rpm or so. When I changed my shifting habits to wait until 2400-2500 rpms, I noticed my avg mpg for the tank went up as well. I'm not talking about hammering the skinny either, I'm talking very little throttle input all the way through the gear. Again, I only say this because I have paid close attention to it thanks to the scangaugeii.
+1 100%. Since getting my ScanGaugeII I've been shifting later and not lugging the engine and my MPG has gone from 17 to 18-19 average with no mods besides driving habits. Still feels really weird cruising in town at 1800-2000RPM when my instinct is to shift up, but the numbers don't lie.

Also, for easy upshifts I don't think I use the clutch very often. I don't think about it, but when I drive something else I find myself grinding 3rd or 4th and realizing I didn't put the clutch in. If the shifter falls into gear you're not hurting anything.
 
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#11 ·
I float the gears up but not down haven't mastered that one yet lol. As far as rpm shifting normally I do around 1,700 or a little more if going uphill
 
#12 ·
Don't lug your truck ....
There really is no point to speed shift, or clutchless shift.
Don't know what your occupation is .... but, shift like you would if driving a Peterbilt or Kenworth. Easy, deliberate, and smooth. Your transmission will thank you for it ....
 
#14 ·
Don't lug your truck ....
There really is no point to speed shift, or clutchless shift.
Don't know what your occupation is .... but, shift like you would if driving a Peterbilt or Kenworth. Easy, deliberate, and smooth. Your transmission will thank you for it ....
Just don't float the gears like you would if you were driving a Kenworth or Peterbilt... :stirpot:
 
#13 ·
i shift every gear around 1500-2000.
I take off in 2nd gear usually and shift that at around 2400..
 
#17 ·
Truck was designed to us the clutch. It is not a 60's Peterbuilt. OD is fine at 50 and above, no or light load.
 
#22 ·
The sweet spot for shifting is kinda personal preference and what your driving conditions are. Its more about being "in tune" with the engine and the load more than it is about always shifting at "X" rpm.

But in regards to shifting without using the clutch..... Not to bash anyone who chooses to do so as its your vehicle, but just in case anyone doesn't fully understand whats happening inside your manual tranny, here is a fantastic video where he's not only explaining how syncros work but also the different kind of syncros and how they function. He even goes into a small explanation towards the end of how the "synchromesh" components work and why specific oil is necessary for their function.

After watching this video, you may change your perception on shifting without the clutch. https://www.youtube.com/watch?v=MXsRfbOiBhE :thumbup:
 
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#23 ·
these engines are most efficient at 1800-2200 rpm's. 1600-2400 is still in the useable rpm range. 1500rpm and below, your are borderline lugging the engine. With that in mind, shift accordingly. Try to time your rpm shifts so that once the shift is completed, you are above 1500rpms. With a 5spd, your engine will drop around 800-1000rpm when shifting...so example....when shifting from 3rd to 4th.... 3rd gear rpm's should be 2200-2400, so that when you shift into 4th, your engine is now turning 1600rpms.....The end goal is to cruise 1800-2000 rpms.
 
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#24 ·
I shift low, long as you aren't lugging lower RPMs provide better mpg, I usually try to shift 15-1700, but as mentioned shift when it sounds right.

Both my trucks have a sweet spot 1700-2000 they get the best MPG anything over 2000 mpg down the tube idk why but that's how she is