downshifting/engine braking?

[Loghead]

I recently swapped a NV4500 into my truck.
Out of habit formed when driving any of the numerous manual transmission vehicles I've owned (all gassers), I downshift when decelerating for a complete stop or to make a sharp turn.
Though I have no exhaust brake, there is a noticeable braking effect - I'm guessing that the truck having 4:10's can be attributed to that.
Whether or not there is a braking effect, are there reasons I should break myself of this downshifting instinct unless/until I add an exhaust brake?

 

[BigPapa]

Nope.

-Scott

 

[Ozymandias]

I learned to downshift on long downhill grades to maintain Speed.

And to not do that for occasional stops like red light or in town traffic.

Clutch linings and synchronizers are way more expensive to replace then brake linings.

So if it anyways dont really helps you slow down, without an engine brake - just use the Service brake and leave the stick alone until the point you know with which gear you'll drive after the slow down.

 

[GAmes]

The noticeable braking affect is engine and driveline friction. A faster spinning diesel has more internal friction, the big selling point of the lockup converter in the early D-Max/Allison combos. You need to downshift for sharp turns to drive through them anyway. I don't see a problem but I don't see much value to downshifting while coming to a stop unless you have an EB. Brake shoes are less expensive and easier to replace than clutch plates.

 

[petersonj]

are there reasons I should break myself of this downshifting instinct unless/until I add an exhaust brake?

If one uses poor downshifting methods, then faster clutch wear and synchro wear will happen, regardless of whether or not you have an exhaust brake.

The key for smooth downshifting is matching engine rpm to road speed for the gear you are downshifting to. The engine speed must be matched by using throttle control while the transmission shifter is passing through neutral and the clutch pedal is not depressed. If you make the perfect match, the gear will slip into place seamlessly even without using the clutch pedal - no synchro or clutch plate wear. Using the clutch pedal to finish the shift will accommodate any minor rpm difference between engine speed and road speed.

If you are coming off a freeway ramp to a stop sign, then a downshift of one or two gears is beneficial (with or without an exhaust brake) - any more downshifts are considered excessive and are usually not productive. I learned this many years ago through a commercial truck driver training school and watching professional truck drivers while riding in the cab.

I replaced my clutch recently - 297,000 miles on the original clutch. The reason for replacement was a failed pilot bearing. The clutch facing was in good condition, but near the end of its life. The transmission synchros are still in excellent condition.

I downshift most of the times for slowing the vehicle. I don't downshift t excessively and I may or may not use the exhaust brake.

- John

 

[Loghead]

Thanks all; it looks like I should not downshift quite so much but not worry too much when I happen to "relapse".

 

[DHayden]

I almost always downshift to third depending on conditions. That is smooth transitions, not high rev jamming.

 

[KATOOM]

I know you dont have an exhaust brake but...just noting that I rarely downshift to 3rd because the EB already has so much braking force in 4th gear. I can let it slow me down to about 25-30 mph and then the service brakes take up the rest. That said, when I'm towing I'll drop down to 3rd and use the EB if I need to slow a little quicker.
Constantly downshifting like a race car driver is only going to wear things out unless you're very good at RPM matching.