Hah, I see that and raise one better: If I think the light’s going to be more than twenty seconds I turn off my engine altogether. Putting it in neutral at any stop is just par for the course with a manual transmission though.
Can some confirm/deny something about automatic cars for me? When I accelerate occasionally the engine will “growl” - much like a manual does when you need to change gear - a driving instructor told me that’s basically what the car is doing… my Da on the other hand says I’m burning out the engine [again*] and yells at me
*I have never damaged the engine of his precious car
Lobelia,
From your description, it sounds like your car is making the sound associated with reaching higher RPM.
The car in my driveway has an engine with an operating range of 650 to 6000 RPM.
If I accelerate steadily to speed, it will go from one gear to another at between 1500 and 2100 RPM.
If I use substantial throttle, the computer realizes I need more horsepower than I can get from low RPM, and it proceeds to let the engine achieve higher RPM to gain access to more power. That could mean upshifts would happen at 3000 to 4000 RPM.
Finally, if I floor the throttle, the engine and computer will attempt to give me as much power as possible. That means my upshifts happen around 5500 RPM.
At 2000 RPM my car doesn’t sound very “revvy”. Somewhere after 3000 it does sound like it’s turning substantial RPM, and by 5000 RPM it is screaming.
If your car has been running for more than a few minutes and you’re pushing it for more power, you’ll be fine unless you’re actually flooring the gas all the time.
If the guys who made your car thought that 4000 RPM would break it, YOU WOULDN’T BE ABLE to get to 4000 RPM.
If you are really interested in this let me know, I can dig up some good reading for you on this topic.
I think this is generally true of smaller (or Japanese cars) but not big honking american cars. I’ve put probably 50K-70K miles on big americans with pedal to the floorboard and they’re all purring along just nicely but the Honda, Toyota and the tiny Saturn all lasted about 10K-15K after I started driving them.
Hmm…I am almost always in neutral if I’m at a full stop, long light or not–Ive’ just been taught to never ride the clutch (or whatever the equivalent expression would be in this case). I was taught that even clutch fully-in at a stop, you’re causing wear to your transmission. Is this not the case?
sigh
Glad I read this thread. I will shamefully admit to following the practice of backing out of my driveway, throwing it into neutral for a bit while the car slows down, and then throwing it into drive while the car is still moving (albeit slowly) backwards. I actually do the same thing with our manual. I’m not sure when or why I developed the habit, but I think this thread will put an end to it.
:smack:
I don’t know, I think time causes wear to your transmission. If the clutch is fully in I do not believe anything in your transmission is moving, while if you are in neutral with the clutch out (I don’t know why you would be) parts of your tranmission are moving. Right?
Transmission will experience no wear if you sit with your foot on the clutch at a stoplight.
Inside the clutch itself there is a bearing that does not rotate when your foot is off the clutch but turns at engine speed when your foot is on the clutch called the throwout bearing.
Back in the day British cars used a carbon block that wore against the clutch pressure plate. If left your foot on the clutch too much you could wear out the throwout bearing before the clutch itself was bad. This then required the removal of the engine or transmission to replace. The same labor as replacing he entire clutch assembly. So usually at this point the entire clutch was replaced.
Cars now a days use a ball bearing, or a roller bearing. I cannot recall the last time I heard of a throwout bearing going out before the rest of the clutch.
But if it makes you feel all warm and fuzzy, hey knock yourself out, you aren’t hurting anything.
Thanks for sharing this.
A few questions!
What was the failure mode when these cars lasted 10-15K miles?
Tranny went out? Cooling failure? Etc?
Your big American cars… V8? V6?
The Honda and Toyota vehicles, were you running the base model 4-cylinders or the V6 models?
There is something to be said for a lower specific outfit.
I saw a formula for engine life that went something along the lines of:
Avg Operating Horsepower / Cubic Inches Engine Displacement * X = Engine Lifespan in Hours
Funny enough, I learned to drive manual from a British guy, so maybe that’s where he picked it up from. Good to know that I sit on my clutch without any worries.
Engine blowouts. The Toyota kept blowing gaskets and warping different heads. After two resurfaced heads and four blown gaskets I gave up and junked it. The Honda blew a head gasket and was not worth fixing. The Saturn (american, I know, but small, four cylinder and uses similar design methodology) broke a piston rod at 90Mph and wrecked the engine at a mere 108K Miles on the odometer.
These weren’t 10-15K from the factory. These were 10-15K from the time I started driving them. All of the cars were fairly aged but roughly the same age(~60-90K miles).
A Jeep I6 and a Chrysler V6.
4-cylinders
A total WAG but I would go with
(Engine Age x Average Operating RPM x # of Cylinders)/ (Displacement) = Probability of Engine Failure
With each of those variables multiplied by some unknown constant.
Shifting an automatic manually will wear it out more quickly. Perhaps not all of them, but at least some. I’m not sure of the details, but if I remember correctly, shifting manually causes more hydraulic pressure than normal resulting in a rough shift. It has been said time and again by the experts in my car club that if you want to shift manually, you need to either get a manual valvebody (which is designed for manual shifts, I have one in one of my cars) or a manual transmission (I have one in the other car). An exception to this is disabling overdrive in a vehicle with an electronic transmission. That tells the computer, rather than the transmission, to downshift, so it actually happens just like it would if it downshifted automatically. It can cause wear on the engine and rest of the drivetrain if done at high speed though, so don’t get crazy with it.
That said, it’s not like it’s going to grenade your transmission the third or fourth time you shift manually. If you need to do it, then do it. Just don’t do it all the time. The manufacturers wouldn’t have put that shifter there if you couldn’t use it. But if you just want to use it for fun on a frequent basis, get a manual valvebody.
I may have spoken too generally. Here’s an article by one of the engineers that designed the Ford AOD-E and 4R70W transmissions. It answers this question (for these specific transmissions) in chapter 6.
My car is a 1994, so I learned not to shift manually. I guess it depends on how well the transmission was designed.
I am afraid I am going to need a much better cite than what you heard from the “experts” in your car club before I will believe that.
In a strictly hydraulic transmission, shifts are governed by throttle pressure, and governor pressure. When governor pressure overcomes throttle pressure the trans shifts up, when the reverse happens it shifts down. The shift itself is controlled by the transmission line pressure. If you manually select a gear, and then move the shifter, you are taking the governor pressure / throttle pressure out of the equation. The shift is still controlled by transmission line pressure with is constant.
In an electronically controlled transmission the computer controls all the shifts. No governor or throttle pressure. So on an electronically controlled trans it is the TCM / PCM controlling the shift solenoids. Line pressure in an electronically controlled trans can vary via a pressure control solenoid, and the computer determines the correct pressure under various conditions.
The only exception I can think of to this is the GM trubo 400 behind a Jag V-12. If you left it in first gear and floored it when the engine passed red line the transmission would shift into 2nd gear and burn the tires.
Probably not healthy for the trans, but very impressive to have the rear tires burn at 70MPH. 
groman If you kept blowing 4 cylinder Toyota head gaskets, either you had defective machine work being done, or a incompetent mechanic. There is no reason that that engine should have kept blowing head gaskets.
Hmmmmm.
Very interesting info on those failures. Thank you!
As an aside, the 4.0 Liter Jeep I6 is bigger than some small V8 engines and has a reputation as an UNSINKABLE piece of machinery.
The Chrysler V6 engines I don’t really know too much about by reputation.
If I didn’t know better, I’d say you killed your small vehicles by simply exceeding the limits of their cooling systems, what with the blown gaskets and all.
On your formula I should point out that we answered two different questions… I spoke to engine lifespan, you spoke to likelihood of failure.
Incidentally, I suspect that you could save much time by representing horsepower with gallons of fuel burned, as so:
Gallons Per Hour Consumed / Cubic Inches Engine Displacement * X = Engine Lifespan in Hours
If you won’t trust someone who designs transmissions, I don’t know what better cite I could provide.
snailboy you last post wasn’t there when I started writing.
I will run this by some of the Ford tech specialists that I know and get their look on this.
Yeah, I thought about that after I made my post.
As you wish. The article was written by Jerry Wroblewski. I’m sure you can confirm with them that he is one of the designers of the AOD-E and 4R70W transmissions. Again, I’m not saying all transmissions have these problems, just some, including the earlier models of the above transmissions. They were trash. I know. I have one.