Transmission wear from P&G (pulse and glide)?

[SDMCF]

Originally Posted by freebeard

AKA, double clutching.

Yes, that's it. "When I were a lad" it was quite common as lots of cars had poor or no synchro, but it is not so common now. We always called it double de-clutching for some reason - maybe fashion or maybe just a British English v American English difference.

[freebeard]

When I was a mere sprout, I rode with a truck driver that could shift up and down through the gears without using the clutch at all. Not all the time, just to show off.

[EcoCivic]

The results are in for engine off coasting. I filled up on my way home today and ended up with 48 MPG over 240 miles, which is pretty much in line with what the Scangauge says and what I predicted- not much benefit to killing the engine while coasting and certainly not enough of a gain to offset the additional wear, potential dangers, or inconvenience over the long run.

I averaged 47 MPG (1 MPG less) over my previous tank driving the same route the same way except leaving the engine running at all times, but the weather was quite a bit colder last week so I can't even definitively say that the 1 MPG gain was from engine off coasting.

I wonder if only engine off coasting once the engine is fully warmed up may produce better results? The engine takes several more miles to fully warm up when it's shut off while coasting compared to when it's left idling, so that probably negates some of the gains.

[Isaac Zachary]

Good question.

There is also the question of whether the transmission oil has warmed up and thinned out enough.

[EcoCivic]

I think I figured out why 5th gear was sometimes acting up. The aftermarket passengers side CV axle popped out and dumped the oil out of the trans, so it was running low on oil for who knows how long. I popped it back in and the same thing happened again 3 days later. Bit the bullet and bought a new OEM Honda axle, which was about 1/8 of an inch longer than the aftermarket axle. I guess that's why it was popping out because it was too short. Anyways, a month later the trans is still full of oil and I haven't felt anything weird with any of the forward gears since so I guess it survived.

[EcoCivic]

I think I accidentally discovered a trick to minimizing synchronizer wear when bump starting- hold the clutch in for a few seconds while in neutral before putting the trans back in gear. It seems to go back into gear with less resistance that way.

I think what's happening is having the clutch disk disengaged lets it and the input shaft spin up a bit so the synchro of your chosen gear has less work to do to bring it back up to engine speed. Even in neutral, the input and output sides of the transmission will still have a slight connection through the bearings and oil, which is why many cars will spin the wheels when running in neutral while jacked up.

[Piotrsko]

Not sure it is a trick but possibly obscure data. You do have a handle on the process however

[EcoCivic]

Originally Posted by Piotrsko

Not sure it is a trick but possibly obscure data. You do have a handle on the process however

Could be, I'm now curious how much the input shaft/clutch disc actually spins up when coasting in neutral with the clutch disengaged. I bet it spins up at least somewhat, but I can't think of a way to test that at the moment.

[Piotrsko]

Well it should spin up as fast as a similair disk sitting on a shaft but my experience says about a second to accelerate/ decel to trans shaft speed. More if you were at redline, but a crash box fixed that with ramped gear teeth or sometimes skip tooth

[Silent Blood]

Originally Posted by M_a_t_t

If you blip it after you push the clutch in it won't spin the input shaft unless you have some clutch drag.

Exactly! This is why automatically rev matching devices in some newer cars didn´t reduce the wear of the synchronizer rings.