A833 Vibration Issue

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pa karp said:
I have been chasing two vibrations in my 340 1969 'Cuda. I got the drive shaft issue taken care of, new drive shaft from a supplier that knew what they were doing.

There is a 2nd issue. I have a vibration at 3000 rpm, aproximately 65 mph. When I kick in the clutch, let the engine go to idle, or shut the engine off, and shift the trans into neutral the vibration goes away. No vibration what so ever, clutch in or out.

I have checked the flywheel and dampner, both are neutral balance because of the forged crank. The engine has been balanced by my reputable engine builder.

Where this gets really interesting, with the engine at idle or shut off, when i depress the clutch and shift the trans into 4th the vibration returns! I do not engage the clutch. When I shift the trans into neutral, the vibration stays, whether the engine is at idle or shut off. I repeat the process, vibration disappears as soon as I shift into neutral. But if I shift back into 4th, clutch depressed, the vibration is back.

What should I be looking for here? Is this a possible bushing issue in the trans tail shaft?

Thanks

Curt Rees
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pa karp said:
Vibration is gone! After more money, oh well.

I was able get to a drag strip, KRP in NE since Oahe had closed for the season. I made 4 passes in the 14's, the best at 14:74. Since KRP is at 2100 feet, with the factor that would be a 14:50.

That was my goal all year. 14:50's is what it ran in 1969.:burnout:

Curt Rees
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Did you ever fix you vibration? I have a 73 Duster 4 speed with a vibration and it's driving me nuts. Can you help? Thanks
 
After much searching, spending money, the problem was a bent water pump pulley. The vibration disappeared once that was replaced. Live and learn!

Pa karp
 
I've never had a 4 speed vibration till this car. Car is really nice, but vibration really pisses me off. I'd spend whatever and I am about ready to start throwing money at it. I guess the first thing to do is pull the belts?What do you think? Could you see the pulley wobble when it was running? I gotta get this handled....
Thanks
Robb
 
A few thought, can you duplicate the vibration in neutral? if so then yes could be pulleys, get the car rolling shift into neutral and coast is the vibration still there? Basically eliminate things and situations. The four speed could have bad bearings is the vibration in all gears etc. Pu the rear up on a lift or stands run through the gears with the rear hanging,is it a bent wheel etc. its alot of work but if you systematically run through a process of eliminaition, you should get down to if the trans has to come out and apart or not. Keep in mind everythin tgthat rotates needs to be balanced, then there are worn universals,and bearings and bushings etc.
 
Dartswinger70 said:
A few thought, can you duplicate the vibration in neutral? if so then yes could be pulleys, get the car rolling shift into neutral and coast is the vibration still there? Basically eliminate things and situations. The four speed could have bad bearings is the vibration in all gears etc. Pu the rear up on a lift or stands run through the gears with the rear hanging,is it a bent wheel etc. its alot of work but if you systematically run through a process of eliminaition, you should get down to if the trans has to come out and apart or not. Keep in mind everythin tgthat rotates needs to be balanced, then there are worn universals,and bearings and bushings etc.
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My first senetence should read "can you replicate the vibration sitting still in neutral? then yes it could be pulleys..." :)
 
Does it do it sitting still revving the engine in neutral? And the detailing looks really good! Just to add my experience, and it may be here earlier in the thread, I had a vibration in neutral and while driving, it ended up being a bad/out of balance pressure plate. Yes it was clutch related. it took alot of trial and error, and i got real good at pulling the four speed out in under an hour. I had an automotive lift and air tools :)
 
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TX9 73 said:
The vibration is in the rotating assembly and not the driveline. I'm going to remove the belts next. The I guess I'm down to harmonic balancer, flywheel, clutch assembly, or engine itself. The engine was out of car when I bought it. The guy thought he was going to build a 360, but never got that far. It is a 29,000 mile 340 that is still factory built but I did head work, camshaft, etc. I feel like it's flywheel/clutch related. Just a real pissed to get it all done and now this! Everything is detailed, so gotta be careful taking stuff apart. Just stinks!View attachment 1715575313
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Is that a cast crank 340? Do you know what year it is?
 
Good point,if there is mix and match parts internal vs external balance etc. Speaking of is there nay parts list with part numbers for the external internal balance engines?
 
Not that I know of, As far as I know, vibration damper and torque convertor or flywheel. I personally balance everything to keep from being in this situation. Also one of the reasons I dislike 360 engines.
 
Dartswinger70 said:
Does it do it sitting still revving the engine in neutral? And the detailing looks really good! Just to add my experience, and it may be here earlier in the thread, I had a vibration in neutral and while driving, it ended up being a bad/out of balance pressure plate. Yes it was clutch related. it took alot of trial and error, and i got real good at pulling the four speed out in under an hour. I had an automotive lift and air tools :)
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It does it in neutral. It's in the rotating assembly. I'll find it. Just time and money.
 
TX9 73 said:
1973
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Then it should be a cast crank and special cast crank vibration damper and torque convertor or flywheel. Check those items first. If there are no weights on the torque convertor, B&M used to make a flexplate to use a internally balanced torque convertor. You can also have a machine shop balance a flywheel for a cast crank 340.
 
66fs said:
Then it should be a cast crank and special cast crank vibration damper and torque convertor or flywheel. Check those items first. If there are no weights on the torque convertor, B&M used to make a flexplate to use a internally balanced torque convertor. You can also have a machine shop balance a flywheel for a cast crank 340.
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It's a 4 speed as previously stated
 
if it is the correct balancer and flywheel, look into the pressure plate. They sometimes throw weights if they are balanced or are just not properly balanced. Mine would shudder the whole car and rattle the dash revving in neutral. I wonder if there is a listing of part numbers for the year and engine. etc. for the crank balancer and flywheel. I am not 100% sure but if it is an external vs internal balance, I would think thepressure plate wouldnt bolt up from one to the other, maybe someone can clarify. ususally the bolt holes are offset,so you could have the correct pressure plate but it is defective as in missing a counterweight etc.

On another note, this is why I keep a 318 lying around as a spare engine,it is same balance as my 340, and save for the motor mount brackets (ears) it is a direct swap. If going 340 to 360 yo need the different balancers/flywheel /Torque converter etc.
 
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