looking for suggestions on vibration issue

[jeryst]

I have a 73 Challenger. Originally a 340 4-speed car. Original motor blew up and was replaced in 74 with a factory 360 replacement motor. The motor is stamped a 74, and has no serial numbers, so this seems to support the story. I did not buy the car from the original owner, so I am not certain, but I am assuming that since it was a factory replacement motor, the replacement was done by a Chrysler facility under warranty circumstances.

Anyways, I have had the car for a few years, and really dont get to drive it much. I have always noticed that when I start to get on it, it has a vibration that shouldnt be there. It's a very high frequency vibration that makes the console and shifter buzz. Gets worse the faster you go, but I am positive its not a wheel/tire thing. I am pretty sure it is a drive train issue.

I decided that this year, I am going to look into it, so I am looking for suggestions. Does anyone know what happened in a warranty motor replacement situation back then? Did they replace the whole motor, or just the short block? Could they have used parts from the original 340, like the damper, flex plate, etc, that may be causing the vibration? I know that some 340 parts are not compatible with the 360, and that a 360 was externally balanced while a 340 was internally balanced. It's possible that a weight came off of the drive shaft, or something like that as well, but I'm not leaning in that direction.

Any suggestions on what to look for would be really appreciated.

 

[R/T4speedconv]

How many miles on it? Have you checked the tail shaft bushing play?

 

[71droptop]

Whats it do in neutral when you hold rpm-s up w e-brake on (basically in park). if its not noticible then you have other issues. a simple quick check. If you have trim rings-pull em off the wheels. Next- road test.Had that problem once. After that put car on GOOD jack stands. put in gear go low and slow-wait for vibes.Good luck.........

 

[ramenth]

Just a thought, but when's the last time you adjusted the clutch? The high pitched whine you're talking about makes me think the throw out bearing might be scrubbing...

 

[jeryst]

Just a thought, but when's the last time you adjusted the clutch? The high pitched whine you're talking about makes me think the throw out bearing might be scrubbing...

It's not a high pitched whine. There is no noise associated with it at all other than the vibration of the console, shifter, dash, etc. It's a very smooth, very fast vibration, which is why I described it as high freuency. Its not like when you have a wheel or tire going bad, that causes a wobble or shake. Its a very smooth but very noticeable vibration when the engine revs, that increases as the RPMs go up, which is why I'm considering an incorrect flex plate or damper. I do believe that it does it when you just rev the engine in neutral, but its not quite as noticeable. I was also wondering if anything else in the clutch assembly could be causing it.

 

[BIGSHCLUNK]

I had a wierd vibe issue... it was a cracked trans mount.... It was hard to tell untill I pulled it off.

 

[rumrunner70]

I had the same thing happen to me..... and it ended up to be the drive shaft not balance and u joints.

 

[hpjunke]

same thing drive shaft on my 73 challenger was installed upside down so i flipped it over and it fixed it for some odd reason

 

[70ChallengerConv]

I remember reading the 360 has an internal or zero balance with a forged crank and most of the automatic 340 engines had a cast crank externally balanced. That should not be an issue if the original was a 340 in a four speed car. I have the same problem in my big block but have traced it to a bent axle and the drivers side. My vibration also shakes the shifter and console and is the worst at about 1500 rpm and smooths out until around 2500 rpm. The Dodge service department drove and suggested flipping the drive shaft 180 degrees but it did not help. I even put a new drive shaft but no change.
Best of luck,

I have a 73 Challenger. Originally a 340 4-speed car. Original motor blew up and was replaced in 74 with a factory 360 replacement motor. The motor is stamped a 74, and has no serial numbers, so this seems to support the story. I did not buy the car from the original owner, so I am not certain, but I am assuming that since it was a factory replacement motor, the replacement was done by a Chrysler facility under warranty circumstances.

Anyways, I have had the car for a few years, and really dont get to drive it much. I have always noticed that when I start to get on it, it has a vibration that shouldnt be there. It's a very high frequency vibration that makes the console and shifter buzz. Gets worse the faster you go, but I am positive its not a wheel/tire thing. I am pretty sure it is a drive train issue.

I decided that this year, I am going to look into it, so I am looking for suggestions. Does anyone know what happened in a warranty motor replacement situation back then? Did they replace the whole motor, or just the short block? Could they have used parts from the original 340, like the damper, flex plate, etc, that may be causing the vibration? I know that some 340 parts are not compatible with the 360, and that a 360 was externally balanced while a 340 was internally balanced. It's possible that a weight came off of the drive shaft, or something like that as well, but I'm not leaning in that direction.

Any suggestions on what to look for would be really appreciated.

 

[Brads70]

I had a vibration in my old family sled 93 caprice only at hwy speeds, turned out to be a weight on the brake drum had fallen off. I put it on jack stands, revved it up to hwy speeds with wheels off, then drums off before I found it. ( don't touch the brakes just turn it off to stop it) I left both doors open to see the vibration sort of acted like a visual gauge .

 

[mofart]

solve your problem yet?

I have a 73 Challenger. Originally a 340 4-speed car. Original motor blew up and was replaced in 74 with a factory 360 replacement motor. The motor is stamped a 74, and has no serial numbers, so this seems to support the story. I did not buy the car from the original owner, so I am not certain, but I am assuming that since it was a factory replacement motor, the replacement was done by a Chrysler facility under warranty circumstances.

Anyways, I have had the car for a few years, and really dont get to drive it much. I have always noticed that when I start to get on it, it has a vibration that shouldnt be there. It's a very high frequency vibration that makes the console and shifter buzz. Gets worse the faster you go, but I am positive its not a wheel/tire thing. I am pretty sure it is a drive train issue.

I decided that this year, I am going to look into it, so I am looking for suggestions. Does anyone know what happened in a warranty motor replacement situation back then? Did they replace the whole motor, or just the short block? Could they have used parts from the original 340, like the damper, flex plate, etc, that may be causing the vibration? I know that some 340 parts are not compatible with the 360, and that a 360 was externally balanced while a 340 was internally balanced. It's possible that a weight came off of the drive shaft, or something like that as well, but I'm not leaning in that direction.

Any suggestions on what to look for would be really appreciated.

.....

 

[jeryst]

No. I hardly drove the car at all this summer. In the spring, I tried a few tests. It definitely vibrates when the car is standing still and in neutral, so it has nothing to do with wheels, drive shaft, etc.

As a result I didn't want to drive it because I'm afraid it will take out the bearings. Since I haven't been working, I dont have any extra cash to throw at it so unless I can figure out what is wrong with it, I figured it's better just to leave it alone.

I've been contemplating buying a fluid dampner for it. Would that take care of the vibration regardless of what in the engine is causing it?

 

[pagilman]

I have the same problem with my 73, big cam and solid motor mounts shakes my lid on my consil untill almost don't like to drive it more than 15 miles.......I resigned to live with it....

 

[Chryco Psycho]

the balancing would be different between the 340 & 360 , it could just be that they reused the 340 flywheel

 

[73-cudadude]

I had a problem like that and it was the drive shaft out of balance. Other good ides here too. The damper could be off, anything with the clutch or throw out bearing too.