Anybody ever had bad vibration with removed balance shafts???

[90 GSX]

Before I rebuilt my motor and eliminated the balance shafts, there was a short time that my oil pump sprocket was 180* off. I had a horrible vibration above 3800 rpm with the sprocket out of phase. Now, after the new motor and BS removed, I get vibration in the same rpm range although not quite as bad. I have a feeling that the vibes are bad enough to trip my knock sensor because of the noise it makes. Is there any validity to that argument and what can I do about it? Free revving, or driving, vibrations come in at about 3800 rpm and stay there. I also feel a small amount at idle.

 

[xcz504d]

My engine runs just as smooth as it did with the balance shafts... I had some machine work done when I ripped the block apart, but it wasnt balanced and blueprinted... Mostly just porting... I have stock motor mounts though..

 

[90 GSX]

Same here. I had it bored .020" over with 2g pistons/1g rods, BS removed w/ the stub shaft from the 1.6 mirage and everything. Brand new oil pump... I just don't understand why it vibrates...

 

[90 GSX]

Now that I think about it, there has to be some accessory or heat shield making the majority of the noise once the vibration starts at 3800 rpm... That same buzzing noise that occured on my old motor with the oil pump 180* off is almost the exact same tone and frequency as the vibes that my car is making right now. Except, the entire motor/transmission has been replaced, so whatever is making the noise must be outside the motor/tranny core.

 

[brn2race96]

yep, thats whats suppose to happen when you take away the balance shaft.

 

[xcz504d]

I have the 90 rods and 2g pistons... but I dont get any resonance or vibrations...

I have a resonator in my exhaust and high flow cats to keep the resonating down... maybe your exhaust is resonating your interior?

Noises suck... It took me over a month to track down a vibration in my 2001 corvette... Finally today I figured it out, a small plastic piece secured by double sided tape came loose... Good luck tracking down the noise

 

[90 GSX]

I have the 90 rods and 2g pistons... but I dont get any resonance or vibrations...

I have a resonator in my exhaust and high flow cats to keep the resonating down... maybe your exhaust is resonating your interior?

Noises suck... It took me over a month to track down a vibration in my 2001 corvette... Finally today I figured it out, a small plastic piece secured by double sided tape came loose... Good luck tracking down the noise

My Trans-Am rattles so much I just make the exhaust louder and turn the music up higher.

Anyway it's not so much exhaust resonation. It's just vibration which come on at 3800. If you move the throttle body linkage you can hear AND feel the vibes come on.

 

[90 GSX]

I think that the vibration may be a source of phantom knock. How do I test that theory?

 

[xcz504d]

Get a datalogger and see if your ECU is pulling back timing when it starts to shake...

Im protective about my Vette There was a screw making a little bit of noise from the steering wheel once... I couldnt get to it (Chevy likes to make things based off the Rubik cube design) So I made the dealership tighten it 1/8th of a turn... To bad things like that happen with a stiff suspension

Once the Talon pulls 10's then the vette will get it's exhaust and a world full of other goodies... but one project at a time