Hypermiling techniques that are invalid (potential mechanical wear/cost)

[chipsndukes]

Originally Posted by PaleMelanesian

'zactly. I can do bump-starts that my passengers don't even notice.

Most of the time I can do this, but sometimes when I roll up to a stop and try and bump, the engine jerks back and forth before catching.

I am usually almost at a stop and use 3rd gear. If I go any lower, the rear tires chirp.

One thing that seems to help is having the A/C on, automatic idle boost to 1500rpm...

[Christ]

If you're having trouble with 3rd gear causing bad feelings, try using 2nd gear. It'll give you more revs at the engine, so it should start up without shaking so much.

If your rear tires are chirping, you're doing it wrong, or you need better tires. I've pop started my Coma in 1st gear @ 20 MPH and the tires didn't chirp.

[PaleMelanesian]

Here's the problem with a bump-start at speed. The purple collar is spinning with the gold shaft at driving speed. The clutch is to the left, between the green shaft and the engine. When you engage the collar into either of the blue gears, it's spinning while the blue/red/green parts are not. That's what makes the grinding. The faster the vehicle is moving, the more likely that is. Synchronizers make the process smoother.

I have still not had any problems with this on my car, but you can see how it's possible.

[cfg83]

roflwaffle -

Originally Posted by roflwaffle

Exactly! Just let the clutch and flywheel kiss to get the engine spinning. Shouldn't be any harder/rougher than any other shift if done properly.

Yup. I don't know if my terminology is accurate, but I call it "tapping the flywheel". I also use 5th gear 98% of the time.

CarloSW2

[tasdrouille]

Originally Posted by chipsndukes

I am usually almost at a stop and use 3rd gear. If I go any lower, the rear tires chirp.

Use an higher gear! Bump start earlier if need be. When I do it, I use 5th gear around 20 mph and my passengers always wonder how I restarted without turning the key on.

[chipsndukes]

Originally Posted by tasdrouille

Use an higher gear! Bump start earlier if need be.

Thanks tasdrouille, I think I need to start the bump farther back, I am nearly at a stop and it makes the engine shake.

I don't want to use 2nd gear, like christ says, because regardless of the condition of my tires (or my light rear end), I find that moving into 2nd gear at 20 mph causes the synchros to "whizz", better not...

I'll try starting the bump farther back...I can do it smoothly usually, but every so often it gets out of hand...

Chipsndukes

[99metro]

Gee, I won't even mention changing gears with a manual without using the clutch...I've never seen anyone ever do it right except my ex-stepdad (prof truck driver) and me.

Don't try this at home folks - this is something that has to be taught one on one, not "trial by error".

[robchalmers]

yeah now that i think about it, it kind of is a black art - practice on someone else's car first!!!

[Christ]

Originally Posted by 99metro

Gee, I won't even mention changing gears with a manual without using the clutch...I've never seen anyone ever do it right except my ex-stepdad (prof truck driver) and me.

Don't try this at home folks - this is something that has to be taught one on one, not "trial by error".

There are some (not so good) videos that I made when I was towing my wife's new Saturn home on a Ute' trailer with my dad's 4 cylinder S-10, where I was shifting w/o the clutch, demonstrating rev-matching.

So now you know someone else that does it.

[Snax]

Originally Posted by MazdaMatt

ditta on alignment... inner edge wear is NOT a normal thing.

I wasn't going to go back to this, but since three of you piped up on my inner shoulder wear, I'm just going to say that the wear patterns of some vehicles simply defy normal. It is all a dynamic of how alignment changes when the suspension moves, thus an alignment that is optimal for straight level travel can turn into shoulder scrubbing in a turn. I won't go into the details of what and how, but a google search of "Mazda5 tire wear" will return a plethora of results on this. It's also worth noting that 24k miles out of the set of 50 profile Z-rated tires that are standard issue is not out of the ordinary for a vehicle setup to handle the way our minivan is.

Lets just say that I understand the tradeoffs there for what actually is normal for our vehicle and leave it at that.

As for bump starts, I always use the highest gear possible to get the job done, which is usually top gear and rarely at anything over 45 mph. This assures the least rpm difference between the shafts and the least wear and tear on synchros and motor mounts.