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Old 10-22-2021, 08:59 PM   #1 (permalink)
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Transmission wear from P&G (pulse and glide)?

Hello all, I'm wondering if anyone has experience with prematurely wearing out a manual transmission from constantly shifting in and out of gear.

I used to only shift to neutral on decently long/steep hills (perhaps 10 or less times per day on my daily commute) and got 42-43 MPG average. However, last tank I experimented with shifting to neutral while going down every hill and I averaged 49 MPG over the tank for the first time. Very nice! My previous best was 45.4 MPG over the tank and that was under better traffic conditions, so the new strategy seems like a massive success.

My only concern is that shifting to neutral on every hill is a LOT of shifting, there is no flat ground where I live. There's constant small hills and I drive ~50 miles per day, mostly on country backroads.

I sort of worry that I could eventually wear out 5th gear from shifting in and out of it constantly. For what it's worth, I always blip the throttle before shifting back into gear to speed up the transmission's input shaft to as close to the required RPM as possible as an attempt to minimize synchronizer wear and, to a lesser extent, clutch wear. I'm not too worried about the clutch or its hydraulics since that's not a big deal for me to replace, but I don't want to excessively wear the transmission's internals.

Anyways, I would like to continue to experiment with different coasting and P&G strategies, but only if doing so won't excessively wear my transmission. How concerned do I need to be about this? Have any of you had premature transmission failures as a result of frequent shifting? Thanks very much in advance as always!


Last edited by MetroMPG; 11-10-2021 at 12:42 PM.. Reason: (added info to title)
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Old 10-22-2021, 09:10 PM   #2 (permalink)
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I haven't heard of, or experienced transmission problems from P&G. The only excessive wear I noticed on my Civic Wagon was the ignition switch. And it was old enough to have issues from normal use anyway.
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Old 10-22-2021, 09:17 PM   #3 (permalink)
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Quote:
Originally Posted by Gasoline Fumes View Post
I haven't heard of, or experienced transmission problems from P&G. The only excessive wear I noticed on my Civic Wagon was the ignition switch. And it was old enough to have issues from normal use anyway.
Thanks. My ignition switch isn't a concern since I don't shut the engine off to coast, I just shift to neutral and let it idle until I need it again.
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Old 10-22-2021, 09:39 PM   #4 (permalink)
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I always clutch it, and people tell me I’ll wear it out. By my estimation, clutching had to occur anyhow to get into neutral. Might as well keep it pushed in and avoid the synchro wear.
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Old 10-22-2021, 09:53 PM   #5 (permalink)
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Quote:
Originally Posted by redpoint5 View Post
I always clutch it, and people tell me I’ll wear it out. By my estimation, clutching had to occur anyhow to get into neutral. Might as well keep it pushed in and avoid the synchro wear.
I assume you mean you hold the clutch down to coast instead of shifting to neutral? Never thought of that. My process has always been shift to neutral as I release the throttle without using the clutch (very easy and smooth if done properly). Then to go back into gear I blip the throttle, push clutch, shift into gear, and release clutch.

I can think of 2 downsides to coasting by holding the clutch instead of shifting to neutral. Obviously there's the leg fatigue and potential clutch/release bearing/thrust bearing wear. I think there would also be somewhat more drag than in neutral since the entire transmission/input shaft assembly is spinning rather than just the output side, but how significant this drag is I'm not sure.
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Old 10-22-2021, 09:54 PM   #6 (permalink)
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Keeping the clutch pushed in (with the engine running) causes more wear to the clutch release bearing and the crankshaft thrust bearing. I don't want to be the one to find out if it's a significant amount of wear!
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Old 10-22-2021, 09:56 PM   #7 (permalink)
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Quote:
Originally Posted by EcoCivic View Post
I always blip the throttle before shifting back into gear to speed up the transmission's input shaft to as close to the required RPM as possible...
Do you mean you blip it, push in the clutch, then shift, then re-engage the clutch?

If you blip it after you push the clutch in it won't spin the input shaft unless you have some clutch drag.
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Old 10-22-2021, 10:01 PM   #8 (permalink)
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Quote:
Originally Posted by EcoCivic View Post
My process has always been shift to neutral as I release the throttle without using the clutch (very easy and smooth if done properly). Then to go back into gear I blip the throttle, push clutch, shift into gear, and release clutch.
That process should keep the transmission in great shape.
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Old 10-22-2021, 10:03 PM   #9 (permalink)
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Quote:
Originally Posted by M_a_t_t View Post
Do you mean you blip it, push in the clutch, then shift, then re-engage the clutch?

If you blip it after you push the clutch in it won't spin the input shaft unless you have some clutch drag.
Yes, I blip the throttle before pushing the clutch to shift. That way I manually speed up the input shaft to approximately the RPM it needs to be at instead of forcing the synchros to. It goes back into gear noticeably smoother this way.
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Old 10-22-2021, 10:12 PM   #10 (permalink)
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My recollection was that in Oregon, one can coast downhill in neutral in cars, or clutch in only in trucks,but...

Stack Exchange says
Quote:
[Oregon Revised Statutes, Chapter 811, Section 811.495]

Unlawful coasting on downgrade.

(1) A person commits the offense of unlawful coasting on a downgrade if the person is the driver of a vehicle on a downgrade and the person coasts with the gears or transmission of the motor vehicle in neutral or with the clutch disengaged.

(2) This section does not apply to the driver of a motorized bicycle.

(3) The offense described in this section, unlawful coasting on a downgrade, is a Class D traffic violation.
skeptics.stackexchange.com/questions/14159/is-it-illegal-in-any-u-s-jurisdiction-to-be-in-neutral-at-a-red-light

Not a primary source, that would be the DMV, but the article lists a number of other States as well.

When I worked at a feed & seed company in high school. I knew a driver that could shift the International truck up and down through the gears without the clutch.

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