Vibration

[Bob Chadwick]

I have a vibration in the car that I am trying to track down. It seems to happen at two points but I'm not even sure they are related.

If you get on it from a standing start you can feel a slight vibration when you first hit it. It lasts a split second and then goes away You don't feel it if you hit the gas with the car moving.

The car also seems to have a vibration when at speed. The car is a fairly rough ride at speed and you feel all of the road vibration but this seems to be above and beyond the road vibration. When you put the car in neutral, the road vibration seems to lessen. If you rev the engine, there is no added vibration but if you put it back in gear and give it the gas, there seems to be some added vibration.

Anybody have any ideas? Do you think the two are related? Am I imagining things?

I'm going to have the wheels balanced and rotated next weekend. This vibration does not feel like out of balance wheels to me.

It has new u joints in all three shafts. It has a new front diff bushing. It has a new rear trans bushing. I'm looking at the motor mounts as a possibility.

 

[bill81vette]

Is your tranny an auto or a manual???

bill

 

[Bob Chadwick]

Auto.

 

[Ripp 73]

Is it like a pulsing vibration. Like going over rumble strips before a construction site? Or is it more a constant vibration? Also, if the vibration goes away with the car in neutral but still going at speed then I would not suspect the tires either.

 

[Bob Chadwick]

More of a constant. And not a buzzing type of vibration. More of a low rumble.

 

[Ripp 73]

From what you have told us it sounds like it has to be coming from the drive shaft. If you can put the car in neutral and rev the engine and not feel the vibration it isn't the engine, also, while in neutral the vibration goes away that means that the wheels and wheel bearings are ruled out. Have you given your drive shaft or half shafts a good shake lately to see how tight they feel? Any play in them?

 

[bill81vette]

I'm thinking it might be a u-joint going bad.

might be worth a look!!

 

[Bob Chadwick]

I suspect you guys are right. I've got the front up looking at the motor mounts. I guess I'll need to raise the rear and take a look tomorrow.

Trying to get it ready for CruiseFest but it's fighting me. Did the drive shaft a year ago, the half shafts last Fall.

Thanks for the feedback.

 

[wishuwerehere82]

Bob,

Do yourself a favor and find a shop that has the Hunter GSP 9700. It just cured all my vibration problems. Log onto the website and find the shop near you.
http://www.gsp9700.com/

 

[Bob Chadwick]

There are several in the area Pete. I'll check it out.

 

[Bob Chadwick]

Replaced the front diff and trans bushing. A little better but still there.

Took it into the shop today. Tentative diagnosis is half shaft bushings and a loose bearing on one side. Going into the shop tomorrow to go over it with the guy.

Probably going to have them do it. I just don't have the time with All-Star Baseball coming up followed two weeks later with 3 1/2 months of football. Not to mention it looks like I'll be out of town on business for a couple weeks this Summer.

Pete it will be taken to one of the shops in the are with "The Machine" for balance after the work is done.

 

[wishuwerehere82]

You know Bob, halfshafts and rear bearings are two things that I would be happy to pay someone else to do. It ain't cheap, but it's more work than I want to do myself.
If they have the machines they have enough knowledge to know the difference between good and excellent. It will be money well spent.

 

[Bob Chadwick]

Pete. I mispoke. Trailing arm bushings and bearings.

 

[wishuwerehere82]

Ask Dave (74 Bigblock) how much fun that is.

 

[lucky76]

Keep it simple first

Pete. I mispoke. Trailing arm bushings and bearings.

I hate to tell you this little story but today I was at my barber shop and talking to a barber about his old 73 Vett. He said he spent $3000 trying to fix a vibration in the rear of his and all that was wrong was he needed to put some additive in the positrac. Duh! Keep it simple first.

 

[Bob Chadwick]

Ask Dave (74 Bigblock) how much fun that is.

That adventure has been part of my decision.

I hate to tell you this little story but today I was at my barber shop and talking to a barber about his old 73 Vett. He said he spent $3000 trying to fix a vibration in the rear of his and all that was wrong was he needed to put some additive in the positrac. Duh! Keep it simple first.

Been there, done that. The whole rear end has pretty much had new bushings, u-joints, lubricants, etc with the exception of the trailing arms and bearings.

 

[vmrod]

...sounds like you know what you need to do now! Well, in the end, you can say that it is all TOTALLY rebuilt!

 

[Bob Chadwick]

...sounds like you know what you need to do now! Well, in the end, you can say that it is all TOTALLY rebuilt!

And at the same time my wallet will be totally empty.

 

[Bob Chadwick]

Went by the shop today. The T-arms are out with new poly bushings, Timken bearings and stainless steel parking brakes. Looks very nice.

 

[Bob Chadwick]

Pickked it up yesterday. He showed me the bushing from the one trailing arm. It was competely gone on one side, about 1/8th of the circumfrence.

The car always used to seem like it wanted to oversteer. Probably because of twisting of the t-arms where the bushings had worn. This is gone. The rear end feels much more stable.

I need to get it out for a freeway run but the vibration seems to be gone as well.

Pete, they used the Hunter GSP 9700 on the car.