idle changes when pressing clutch

[viridionplague]

this is in my 1g.

at idle the car has a little shake in it. originally i thought it was the lack of balance shafts, 272 cam, and poly motor mounts. but when i push in the clutch the shaking goes away and the car idles almost perfectly smooth. as soon as i let off the clutch the car is back to shaking.

its a lot like engauging the mower blades on a riding lawn mower when you get that bark and it runs rougher.

im guessing this is either something wrong with the clutch or my first signs of crankwalk.

 

[Albrecht09]

Normally thats a sign of crank walk, even though I think you should have a 6 bolt motor...definitely check out the crankshaft endplay regardless.

 

[reddragon1]

Normally thats a sign of crank walk, even though I think you should have a 6 bolt motor...definitely check out the crankshaft endplay regardless.

Since when? It sounds to like the added pressure is just taking up more vibrations.

 

[Albrecht09]

Since when? It sounds to like the added pressure is just taking up more vibrations.

I remember reading somewhere on here that if the idle changes when pressing the clutch in, that it's an early sign of crank walk.

 

[reddragon1]

I remember reading somewhere on here that if the idle changes when pressing the clutch in, that it's an early sign of crank walk.

You are adding a load to the engine when pressing the clutch down something is going to change.

 

[WES_393]

A healthy engine/trans will actually raise in idle when pressing in the clutch. With the clutch disengaged, the engine no longer has to spin the trans which sits in pretty thick gear oil. Crankwalk typically does lower the idle with the clutch disengaged.

The fact that the engine idles smooth with the clutch disengaged is puzzling. I would definitely check end play by having a friend push in the clutch (engine running) while you carefully watch the crank pulley. But it seems to me your problem might be in the clutch or trans. Possibly a damaged clutch disk that is off balance? Does the trans shift smooth? Are there any noises while driving?

 

[H@xtGSX]

Is it rough with the clutch out and in neutral and smoother when you push the clutch in, if I am understanding the post right? If it is sitting still in nuetral, with your foot off the clutch, and it is vibrating, it is likely to be exactly what you thought thought initially. Poly mounts, no balance shafts, and a engine spinning free at lower rpm is going to vibrate and shake the car more. Mine does this also. When he clutch is pushed in, your applying a load to the motor, so it will speed up a little, and faster rpm means faster vibration at lower amplitude so you won't feel it shaking nearly as much. That vibration is picked up by the drive train and the now loaded mounts because the motor is now pushing itself constantly in one direction against them.

 

[Talon IV]

Is it rough with the clutch out and in neutral and smoother when you push the clutch in, if I am understanding the post right? If it is sitting still in nuetral, with your foot off the clutch, and it is vibrating, it is likely to be exactly what you thought thought initially. Poly mounts, no balance shafts, and a engine spinning free at lower rpm is going to vibrate and shake the car more. Mine does this also. When he clutch is pushed in, your applying a load to the motor, so it will speed up a little, and faster rpm means faster vibration at lower amplitude so you won't feel it shaking nearly as much. That vibration is picked up by the drive train and the now loaded mounts because the motor is now pushing itself constantly in one direction against them.

I am going to 2nd this motion. If I recall right, with the poly mounts, no balance shafts and 272's you should feel a vibration. everything is stiffer and moving more free plus the duration of your cams at idle... As far as crankwalk, A. you should have a 6 bolt. B. Have you ever had your bottom end rebuilt? If so was the thrust bearing preloaded properly? C. even though crankwalk is more promenant in 7 bolts, it's a pretty rare thing. But to be on the safe side, double check your crank puley like said above. And verify you get no abnormal drivetrain noise while driving.

 

[viridionplague]

neutral with foot off the clutch leads to shaking.

tranny shifts pretty well.

also wanna add in that free revving while in neutral with the foot off the clutch is also kind of hampered.

it just feels like there is some kind of drag on the engine when my foot is off the clutch in neutral.

 

[viridionplague]

also going to add in that if i press in the clutch, idle is fine and smooth

if i slowly let the clutch out idle changes slightly.

if i let out the clutch quickly it causes a lot of shaking at idle