Too high of a gear=shacky car?

[savageskaterkid]

I never really thought of this b4, i always just kinda blew this thought off.

 

You know how when you start the car in 3rd accidently, and the car shakes becuz your in too high of a gear, or you shift at too low of an RPM? Why does this happen? Is it becuz of the torque at that RPM just not enough to turn those higher gears? or is it sumthing else? This seems like sumthing to ask Grumpyvette, he always has this kind of info. Can sumbody give me an explanation or a site that explains this?

[240ZR]

I never really thought of this b4' date=' i always just kinda blew this thought off.

 

You know how when you start the car in 3rd accidently, and the car shakes becuz your in too high of a gear, or you shift at too low of an RPM? Why does this happen? Is it becuz of the torque at that RPM just not enough to turn those higher gears? or is it sumthing else? This seems like sumthing to ask Grumpyvette, he always has this kind of info. Can sumbody give me an explanation or a site that explains this?[/quote']

 

your stalling hte engine but the enigine is still spiing fast enoguh to semi maintain combustiong i belive..... my dad called it umm Lugging the engine? all i know is he said its VERY BAD....

[rudypoochris]

your stalling hte engine but the enigine is still spiing fast enoguh to semi maintain combustiong i belive..... my dad called it umm Lugging the engine? all i know is he said its VERY BAD....

 

I believe you are talking about something else. Not sure though

 

But the shaking I always thought (at launch) was because at a certain rotating speed the grippyness of the clutch is on a certain threshold of slipping or holding so that it grabs then lets go back and forth until a certain speed is met between the two plates in the clutch. Im probably wrong but that makes the most sense to me. I might not be understanding your question correctly though, this often happens to me in first at low speeds (b/c i have a heavy car and often engage at 600-700 rpm)

 

if you mean the low note the engine makes when you pull 35mph in 5th, which can be accompanied by shaking, I believe that is from the engine spinning too slowly for the amount of combustion. So basically the pistons are taking a heavy load, thus shaking the car. Also not positive on this one!

[Pathogen]

rudypoochris: You sure your not experiencing Clutch Chatter?

[Rival5]

I thought because theres backlash between the teeth of the gears in the transmission it was from the car bouncing off of the front and back side of the teeth of the gears in the transmission.

[Pop N Wood]

It is because your engine cannot run at 100 RPM. The engine starts to stall, so you automatically easy up on the clutch causing it to grab and slip, grab and slip.

 

We always called it lugging the engine. A good way to soot up your combustion chambers.

[rudypoochris]

Im probably experiencing what you call clutch chatter then, whats the deal with that? (explaination please im intrested to learn)

 

And ya you might be lugging the engine, Im not really sure what the exact situation is. Do you mean like when the car is bucking because you took the gear to low or when the car is just wigling a bit on launch. If it is this then it is because the pistons are taking an explosion on them but are not able to spin at the correct speed to maintain the rotation correctly/smoothly. This is pad push clutch in and take the correct gear. Plus the back and forth on the driveline might leave you with some broken parts if you do this enough.

[savageskaterkid]

so, i know that in my truck when i drive it-if its anything below 2000 RPM it will shack and lug the motor(i have too heard this expression) and i know that between shifts i loose 1000rpm, so i shift at 3000rpm and i always get a perfect shift, except when shift into fifth, which is only a 500rpm drop, so shift from forth at 2500rpm.

 

My dad likes to shift at 2000-2500rpm, and i always told him it was bad for the clutch, becuz i thought this caused it to slip, but is this actually more worse for the engine then it is the clutch?!?!? He basicly shifts it so that it goes to around 1500rpm and it runs horribly-all the change in the cup-holder shakes when he does it. And mind you, this is a 4cylinder truck, so it has sum low gears to it. He'll put it in 4th at 25 mph, and when i drive it i shift into third at exactly 25-26mph. He always blew it off as "i've been driving manual cars for years and i never shift above 2500 in any of them, and never had any clutch problems other then a normal clutch job every 80,000-100,000 miles." so i say, "yes dad, but this is also the only manual truck you've ever had, it has lower gearing, so it needs to b shifted a bit higher." Was i right? What kind of damage does this do?

[rudypoochris]

so' date=' i know that in my truck when i drive it-if its anything below 2000 RPM it will shack and lug the motor(i have too heard this expression) and i know that between shifts i loose 1000rpm, so i shift at 3000rpm and i always get a perfect shift, except when shift into fifth, which is only a 500rpm drop, so shift from forth at 2500rpm.

 

My dad likes to shift at 2000-2500rpm, and i always told him it was bad for the clutch, becuz i thought this caused it to slip, but is this actually more worse for the engine then it is the clutch?!?!? He basicly shifts it so that it goes to around 1500rpm and it runs horribly-all the change in the cup-holder shakes when he does it. And mind you, this is a 4cylinder truck, so it has sum low gears to it. He'll put it in 4th at 25 mph, and when i drive it i shift into third at exactly 25-26mph. He always blew it off as "i've been driving manual cars for years and i never shift above 2500 in any of them, and never had any clutch problems other then a normal clutch job every 80,000-100,000 miles." so i say, "yes dad, but this is also the only manual truck you've ever had, it has lower gearing, so it needs to b shifted a bit higher." Was i right? What kind of damage does this do?[/quote']

 

Bwhaha lets trade dads. Mine takes the explorer into the garage (7 degree incline) from stop in first gear and tries to do it at 4,000 rpms. He seriously tries to keep it from stalling by getting it to 4k! Unsensitive foot or whatever. He uses the same excuse been driving stick forever (he learned on a fiat 500), but this is a 4300lb behemoth with not so low gearing (first goes to 35) and i can get it in at 600rpm from stop w/o needing to slip the clutch the whole way. Any way after he is in the clutch is burnt almost always. So now i have to launch at 600-1500 always because the 2500-4000 range is burnt.

 

But wow you must have a week powerplant to be lugging below 2000, does the car buck or simply make the throaty noise?

[Gollum]

I feel lucky, my dad just brakes late. Bugs me everytime in traffic.

[JMortensen]

your stalling hte engine but the enigine is still spiing fast enoguh to semi maintain combustiong i belive..... my dad called it umm Lugging the engine? all i know is he said its VERY BAD....

Yes. This is LUGGING the engine. In fact, this is lugging the engine really bad, so that the power strokes don't have the power to accelerate the engine, which basically causes detonation to occur. VERY bad for pistons and rods. You don't have to get that awful shudder for it to be bad for the engine either. Anytime you're stepping on the gas and the car can't accelerate you're straining the engine. It's time to downshift.

[savageskaterkid]

The car bucks....ALOT when its under 2000 btw this a 92 mazda b2600i with 155 on the clock, but its been drivin under-revved for atleast the past 10k, and i can't remember how my grandfather used to drive it.

[rudypoochris]

ahh if it is bucking then yes very bad thats lugging. It gets power in then it is insufficent for the load then it gets it in back and forth just barely staying alive. Ya i would imagine that causes a ton of stress on all the parts pretty much.

 

Can anyone explain to me why clutch chatter is?

[JMortensen]

Clutch chatter is when the flywheel and pressure plate gets warped and when you let the clutch out, the high spot in the flywheel or pressure plates rotate around, and every time they find each other the clutch grabs really hard then lets go. You only feel it when you're just to move in 1st usually, because you let the clutch out too fast in the higher gears to notice it.

 

Chatter also happens when you use puck clutches, just because the material is so aggressive that it won't let any slippage occur. Because it doesn't like to slip, this frequently also leads to grooving of the flywheel and pressure plate which makes the chatter worse and worse.

[Guest grimlynsan]

my car seems to do the same thing but in a different way. At normal operating temperatures, i'll approach an intersection or something and downshift to 2nd gear. As i round the corner i'll accelerate again and the car will 'hesitate' maybe once or twice. This happens most when I push the accelerator more rather than less. If I barely touch it and increase speed very slowly, the problem rarely occurs.

 

Am i damaging my engine? should I be changing into first?

[rudypoochris]

What rpm are you at? If it is low rpm sounds like your just bogging the engine a bit. Do you run EFI or carb?

[Guest grimlynsan]

twin SUs. Its well over 1500 rpm when it happens. Its different to being bogged down. These hesitations are like split second power losses. its hard to explain.

[Guest grimlynsan]

now that i think of it, its similar to when the car is cold and you floor it from a slow speed. That kind of (cars voice: "I dont know man, its too early in the morning. oh all right then") for just a split second.

[rudypoochris]

Iono seems just like with any carb if you get into the gas fast at a lower rpm it heasitates because there is too much gas and not enough air, just my thought.

[savageskaterkid]

now that i think of it, its similar to when the car is cold and you floor it from a slow speed. That kind of (cars voice: "I dont know man, its too early in the morning. oh all right then") for just a split second.

 

I HATED THAT, my 280zx was notorius for that-the cold start valve gummed up and i never cared to fix it-u wanna talk about hesitation, that thing would hesitate, then miss, then miss again, then miss sum more, and finnally take off. I hated driving first thing in the morning.