1952 Dodge with Gyro-Matic

[Marty C]

My 1952 Dodge Coronet with a perfectly working GyroMatic vibrates pretty severely when coming to a stop. Engine runs smooth as silk and quiet too so I know it’s not the engine. 
When I stop and it is vibrating , it will completely stop if I depress the clutch!

There is no vibrating when accelerating , driving or coasting. Only comes in as soon as the car stops. As soon as I start moving , smooths out

Any ideas?

my guess fly wheel or clutch but I’m not too familiar with clutches or flywheels!!

Any help would be appreciated  

[joecoozie]

Transmission and motor mount(s)

[greg g]

IF you shift manually to neutral is there any change? Is it a Hi or lo frequency vibration? What is the state of your drive shaft/u joints? Have you ruled out exhaust banging?  I had a pipe contacting that passenger side under floor heat shield.

?

.

[Marty C]

All motor mounts are new

its a pretty decent vibration

that rattles the windows 

cant be the drive shaft its just when its in “drive” and stopped!!

 

[Roofus]

Quote

its just when its in “drive” and stopped!!

So it's linked to the hydraulic coupler

Edited October 28 by Roofus

[Sniper]

6 hours ago, Marty C said:

All motor mounts are new

 

New made motor mounts are a crap shoot.  Seen them fail fairly quick.

 

I usually end up going with US made polyurethane mounts, if they are available for the application.  If not, there are several companies that will rebuild yours.

 

Might want to see if you can replicate the issue in the garage and inspect.

[Marty C]

I agree with you however the vibration comes in and out with such precise timing , that’s the real confusing thing for me!

if the motor mounts are bad wouldn’t there be other times there would be vibrations?

the vibration starts as soon as the car comes to a stop, and the vibration disappears as soon as it starts moving!!!!

I just don’t understand it! 

[Sniper]

That's because your transmission has a load on it when you're stopped it doesn't have when you're moving. It's kind of like an automatic when you put it in gear it'll twist a little bit. Soon as you step on the clutch you're disconnecting the output of the engine from the input of the transmission and that load goes away and it quit so your transmission is moving

[Marty C]

Sniper that’s exactly the issue 

what do you think it could be?

motor mounts like everyone is saying?

[Roofus]

Could a lack of oil in the coupler cause an imbalance?

[Marty C]

This problem has been an issue since I installed a new engine and topped off fluids in the converter and the transmission 

so I don’t think so …but I just don’t know 

[Marty C]

My personal feels are maybe the clutch tho I feel no chattering in the pedal and there are no problems with the clutch that I know of

Edited November 11 by Marty C
Because I added a few extra words….why do you need a reason for an edit???

[JerseyHarold]

Just a wild-assed guess, but have you checked that the emergency brake is properly installed and adjusted?

[Marty C]

It’s never been out but I inspected shoes when I swapped out a bad drive shaft. The shoes were fine and I adjusted them and they hold the car great!

 

[Roofus]

If you accelerate hard in 3 by preventing the car from advancing by the brake on the foot, vibrations also decrease ?

[Marty C]

I’m guessing you mean try power braking it?

never tried it but I’m guessing the vibration would get less 

the engine needs to be running really slow for it to shift properly , I’ve tried raising idle vibration is less but then it doesn’t shift right