Bad vibrations

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bf15

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I just picked up a nova, and saw a note in the previous owners papers that replacement body bushings were recommended.

Would these cause bad vibrations in the car? what other symptoms could bad body bushings cause?

how hard are they to replace?
 
Body Bushings by themselves, don't cause or eliminate vibrations.
Their intention is to suppress sound, but do to some extent moderately limit vibrations. I can see if one was totally squashed/deteriorated, that there may be a rattle if the body was touching the frame

If you have a vibration, you need to start looking for another cause...
Wheel Balance, Bent Rim, Driveshaft bent, misfiring Cylinder(s)...

Tell us more about when/how the vibration happens.
 
It seems like the vibrations happen mostly in the 30-50 mph range when i let off of the gas.

It has almost a pulsing feel to it until it slows down to around 30 mph.

The car does have a built 383 engine with a 350 transmission. Most of the suggestions ive heard offline were to check the transmission mount and the u joints; however i have not took it to a professional mechanic.
 
Do you know how many rpm the engine is running at when you feel the vibration? If so do you get the vibration if you are standing still and raise the rpm to that level? If you are doing 30 to 50 mph let off the gas and place the transmission in neutral so the engine drops to idle speed does the vibration go away?
 
Im at work for a few more hours and will drive it again and test it out, if it does stop vibrating when dropped into neutral what would that mean
 
If it does stop the vibration source is something related to the engine or flywheel/ring gear. You would check the harmonic damper to see if it has shifted or the fan has excessive play or the water pump is starting to go, etc. You also should check if the timing is correctly set.
 
could an exhaust leak at the headers cause it? it has a knock that sounds very much like an exhaust leak knock

It has an electric fan and should have a new harmonic balancer thats less than 6 months old but it could still be bad.

i dropped it off at the tire/wheel shop and they are going over the front end and suspension now and balancing the tires but its only a block up the street so i wasent able to actually test it out at highway speeds.
 
got it back from the tire shop, it was not the balance of the tires or the alignment. Alignment was perfect and only 2 tires were off balance, and all the tires are pretty much perfectly round.
 
If you have a blown header gasket it should be pretty obvious when the engine is idling. I take it you didnt have a chance to try the drop it into neutral test while going 30 to 50?
 
it seemed my account had been deleted earlier so I created a new post, but now all my post are showing back up? anyways

I had the tires balanced and an alignment done, but its still having a pulsing vibration at cruising speeds 55-60 in drive and it also does it around 30 mph while in drive and not pushing the gas

I tried shifting into neutral and it stopped but it also slowed down pretty quick.

If I downshift into second when going 30mph it seems to go away.

Things I do know are that the previous owner had several recommendations from shops to replace the body bushings.

I have bought new U joints to put on tomorrow unless the ones on it seem to be in good shape.

any recommendations as to what could likely be the problem?

Below are the specs of the car from when previous owner had the engine built and various other stuff done in January of 2011

doug seawell built 383 stroker with arp bolts, 10.0-1 comp
high pressure oil pump
heavy duty drive shaft (pump)
cloyes true roller time chane set
street oil pan with pick up
stainless valves
edelbrock intake
MSD high energy hei dist and plug set
new balancer
new flexplate
mini starter
new cam for street built
600 edelbrock carb
engine mounts welded to correct degree angle
Eaton Postration unit HD/3:42 Gear set
headman headers
 
I noticed something earlier when looking under the car.

It has these things in the bottom of the front coils that look like large socket wrench extensions wedged between the spring and base of the coil.

Is this normal?
 
This is odd it looks like several of the post in this thread are gone now?
 
at anyrate, i looked at the ignition system some more, it has a msd blaster 3 coil, and it also has a msd pro billet distributer. I was looking for a timing control I figured with all of this it would have one but i did not see it.

I did however notice something that looked odd on the carb.

there is a rod coming from the firewall that looks like it would clip below the throttle cable. onto the carb. It is missing a clip on it. any idea what this would be?
 
Sounds like it may be a kick down cable for the automatic transmission. I previously gave you an answer about the coil spring spacers but will repeat it just in case it was deleted. They are simply spacers that lazy people twist into the springs in order to raise the car a little bit and MAYBE stiffen the sagging springs some. Not worth the money, nor time and effort it takes to put them in. Best thing to do is replace the springs with new ones.
 
Chuzz said:
Sounds like it may be a kick down cable for the automatic transmission. I previously gave you an answer about the coil spring spacers but will repeat it just in case it was deleted. They are simply spacers that lazy people twist into the springs in order to raise the car a little bit and MAYBE stiffen the sagging springs some. Not worth the money, nor time and effort it takes to put them in. Best thing to do is replace the springs with new ones.
Click to expand...

it does look like a kick down cable from the pictures ive seen online. Does this need to be connected?
 
Yes, it does if you're driving an automatic. It's what's connected to your valve body to down shift the transmission when you push on the accelerator to pass someone. I'm not much on the GM setups, so someone else will have to advise you on the way to do it.
 
zora said:
OK, if it's a th350 there definitely has to be a second cable connected to the carburetor for the kickdown mechanism to work. Watch this video and look at the th350 hookup

http://www.youtube.com/watch?v=HWurb3N3ZCU
Click to expand...

ok took care of that, and can definitally notice a difference while driving I did not drive much but I have not drove it enough to tell if it makes adifference when letting off the throttle.

I have not got a timing light yet, the ones msd recommended seemed to all be 150 plus and I might be able to take it to a shop for that price.
 
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