[pggto]

Originally Posted by Blued and Painted

you did not montion the drive shaft.

Yes I've tried those as well, currently has a new one, with joints.

[HWYSTR455]

Does it go away when you put it in N and coast?

.

[pggto]

Originally Posted by HWYSTR455

Does it go away when you put it in N and coast?

.

I haven't tried that, but I will.Thanks

[HWYSTR455]

Originally Posted by pggto

I haven't tried that, but I will.Thanks

If you put it in N and it doesn't vibrate, it's before the trans. If it does, it's after the trans or chassis related.

Another thing to check is to rev it to the 2600-2800 RPM while parked, see if it vibrates. That will also tell you if it's engine or chassis related.

Usually, if it's RPM related, it's engine related, if it's speed related, it's a chassis issue.

I've seen people have pulleys and fans out of balance that they kept swapping for config to config, car to car, and it followed them.

.

[pggto]

Originally Posted by HWYSTR455

If you put it in N and it doesn't vibrate, it's before the trans. If it does, it's after the trans or chassis related.

Another thing to check is to rev it to the 2600-2800 RPM while parked, see if it vibrates. That will also tell you if it's engine or chassis related.

Usually, if it's RPM related, it's engine related, if it's speed related, it's a chassis issue.

I've seen people have pulleys and fans out of balance that they kept swapping for config to config, car to car, and it followed them.

.

New engine has new balancer, water pump, ps pump, and alt. I was just playing with the timing up to 3000 rpm and it runs smooth while setting the timing. But i did transfer over the pulleys, they were bead blasted and repainted, and look to run true on the engine, but I give them a closer look while running. Thanks

[HWYSTR455]

I had a vibration issue with the LeMans once, and it ended up being the yoke on the rear, the 'nubs' that center the u-joint caps were worn, and the u-joint would shift making it 'wobble'. It took a very close visual inspection to catch that.

Keith - What's the source of that diagnosis chart, etc? I'd like to have a copy on hand...

.

[Keith Seymore]

Originally Posted by HWYSTR455

Keith - What's the source of that diagnosis chart, etc? I'd like to have a copy on hand...

.

Looks like some things got packed away during my last office move; I believe it is from a Chevy S/T truck service manual.

I also have a (very interesting) Pontiac Vibration manual from the mid 60's but am hesitant to post that in case there are copyright issues.

K

[Keith Seymore]

pggto -

Did you do this yet?

Originally Posted by HWYSTR455

If you put it in N and it doesn't vibrate, it's before the trans. If it does, it's after the trans or chassis related.

Another thing to check is to rev it to the 2600-2800 RPM while parked, see if it vibrates. That will also tell you if it's engine or chassis related.

Usually, if it's RPM related, it's engine related, if it's speed related, it's a chassis issue.

You've really got to "split the dictionary" to know where to start.

This first step will eliminate half the car, so you know you don't have to worry about that part of it and can begin homing in on where you need to focus.

K

[goatwgn]

Is the tranny crossmember bent in any way? Another thing to check is how close your engine sits to the engine crossmember. (Does the fan come real close to hitting the bottom of the shroud?) Sometimes (especially on cars that have been drove hard or have a lot of miles) the engine crossmember tends to "spread out" ever so slightly, letting the engine sag and throwing off the pinion angles. Just something else to check. Still comes back to the basic pinion angle deal.

[Nicks67GTO]

Heres a question for you vibration guys since we are on the topic. Could it be a slightly bent pulley? I have a bad vibration that comes in after 2500 RPM and gets much worse with vehicle speed but its never present before 2500rpm in any gear and it only shows up strong in 3rd 4th and 5th.....I think I have a crank pulley that has a small bend in the outer portion of the ring from when I put in in a tire to haul it. Its not messing with the fan belt but the bend is obvious. Im going to tap it back in place tomorrow and report back. I guess im thinking out loud since we are on the topic.

[Bobalong]

Originally Posted by goatwgn

Is the tranny crossmember bent in any way? Another thing to check is how close your engine sits to the engine crossmember. (Does the fan come real close to hitting the bottom of the shroud?) Sometimes (especially on cars that have been drove hard or have a lot of miles) the engine crossmember tends to "spread out" ever so slightly, letting the engine sag and throwing off the pinion angles. Just something else to check. Still comes back to the basic pinion angle deal.

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Really ? I had to shim my engine mounts up slightly to get the fan to quit rubbing the bottom of the shroud. I tried everything trying to determine why after all these years it started rubbing. Shimming fixed the problem, but I never knew the cause.

[Bobalong]

Originally Posted by pggto

Yes I've tried those as well, currently has a new one, with joints.

Without a doubt you have given this a lot of thought and $$. Hopefully someone here will help. Bet it doesn't vibrate in neutral at the given RPM, that's too easy. If the mirror / steering wheel are shaking but not so much in your butt it's an indication of front wheel- tire- rotor balance. Can you find an old school tire balance machine that uses spinner and strobe light. The wheel-tire stays on, and is spun on the car ? You can individually check each wheel.
Put it on a dyno ? Where you can tour around the car as it revs the desired RPM.

[pggto]

Originally Posted by Bobalong

Without a doubt you have given this a lot of thought and $$. Hopefully someone here will help. Bet it doesn't vibrate in neutral at the given RPM, that's too easy. If the mirror / steering wheel are shaking but not so much in your butt it's an indication of front wheel- tire- rotor balance. Can you find an old school tire balance machine that uses spinner and strobe light. The wheel-tire stays on, and is spun on the car ? You can individually check each wheel.
Put it on a dyno ? Where you can tour around the car as it revs the desired RPM.

I haven't seen one of those style balancers in decades, I used to work at a Goodyear dealer and we had one in the 80's. I've had the tires balanced, and I've put different wheels on the car, same problem. I've replaced the rotors and wheel bearings. I don't feel it in the steering wheel, it's in the chassis. The dyno is a good idea, there's a place not to far from me that does that, I think I will check into that, Thanks