1957 Century - Slight vibration troubleshooting...

[Yohdda]

Hello, 

 

I have a 57 Century with a 401 transplant in it and a Dynaflow.  Over the winter I changed the tires and did a oil change.  Now I have a slight vibration that I can feel in the steering wheel when driving around 30mph and around 60mph.  If I go 70mph the vibration lessens.  

 

The tires are BG Goodrich Silvertowns from Coker, and I have had them rebalanced twice at different shops.  I have also rotated the tires, and eliminated one tire at a time by swapping in my spare tire.

 

I also had a little to much engine oil in the block, about 1/4inch above full, so I drained it and it is now right on the full line.

 

I have checked my bushings and they look good, except for my sway bar bushings, they are 100% shot, but I will replace them tomorrow when the parts store opens, but i don't think that is the issue.

 

I have checked the steering linkage and it looks/feels solid.

 

I have a feeling it has to do with the engine balance or something like that.

 

I was thinking it could be a U  Joint, but with a torque tube, I don't know where/how to check that out...

 

Any suggestions on what I can check to diagnose this problem?  Any tips are greatly appreciated!

 

Jason

[Caballero2]

One thing that is overlooked is the grease fitting for the universal joint just in front of the differential.  There should be a access  hole in the torque tube housing allowing access to the fitting through the housing.  With good lighting, and the wheels off the ground, one can rotate the driveshaft to an acceptable position.

Edited July 2, 2023 by Caballero2 (see edit history)

[Yohdda]

30 minutes ago, Caballero2 said:

One thing that is overlooked is the grease fitting for the universal joint just in front of the differential.  There should be a access  hole in the torque tube housing allowing access to the fitting through the housing.  With good lighting, and the wheels off the ground, one can rotate the driveshaft to an acceptable position.

Thanks for the reply.  I checked around the torque tube and couldn't find a hole for servicing.  I also read up on the front U-Joint in the Maintenance Manual and it states "The universal joint, torque ball, and speedometer drive gears are automatically lubricated from the transmission."  and something similar for the rear U-Joint about packed grease from the surrounding bearings.

 

Is the access hole on top of the torque tube?

[Yohdda]

Upon further troubleshooting, when I am parked and rev up the engine about 1/4 throttle, (if I had to guess 1500rpm) the car produces a similar vibration.

 

I removed the balance plate cover and did a visual check of the teeth and plate, and rotated it a few times to check it out and there are no visible cracks or damage.

[avgwarhawk]

The 401 has a crank balancer?  Did it slip it's ring? 

[old-tank]

2 hours ago, Yohdda said:

The tires are BG Goodrich Silvertowns from Coker,

Radials or bias?

Date code?

[Yohdda]

33 minutes ago, old-tank said:

Radials or bias?

Date code?

Radials, new this spring with a date code of 33rd week of 22.

[Yohdda]

36 minutes ago, avgwarhawk said:

The 401 has a crank balancer?  Did it slip it's ring? 

Hey there, I am not to sure as this is out of my scope of knowledge.

 

Is there something that I couldn't check to know that it would be out?

 

I went out and check the front harmonic balancer and the bolts seem okay and visually it looks okay.

[avgwarhawk]

5 minutes ago, Yohdda said:

Hey there, I am not to sure as this is out of my scope of knowledge.

 

Is there something that I couldn't check to know that it would be out?

 

I went out and check the front harmonic balancer and the bolts seem okay and visually it looks okay.

The harmonic balancer. I believe there is a rubber insulator between the outer ring and inner ring.  Some times the outer ring will move when the rubber insulator can no longer hold it in place. 

[Yohdda]

6 minutes ago, avgwarhawk said:

The harmonic balancer. I believe there is a rubber insulator between the outer ring and inner ring.  Some times the outer ring will move when the rubber insulator can no longer hold it in place. 

I read on another site that the distance from the timing mark to where the weight start (going counter clockwise) should be 5in on a 401.  Tomorrow I'll try to located it and measure it out.... never done this before.  Ah, the adventures 😊

[Frank Falconeri]

Call Matt Martin 530-272-1564 at Centerville Auto, he is the Nailhead guru and will most likely know where the problem is, all Nailheads are externally balanced but they are all not the same, different years have different balancing weights, I highly recommend calling him. Hope this helps 

Edited July 3, 2023 by Frank Falconeri (see edit history)

[EmTee]

What flexplate and transmission was used?  Were the engine and transmission swapped as a unit, or was the 401 bolted to the 1957 Dynaflow?  If the latter, was the 401's original flexplate used and is it properly indexed to the crankshaft (not sure if it can be installed in the wrong orientation)?

[Yohdda]

2 hours ago, EmTee said:

What flexplate and transmission was used?  Were the engine and transmission swapped as a unit, or was the 401 bolted to the 1957 Dynaflow?  If the latter, was the 401's original flexplate used and is it properly indexed to the crankshaft (not sure if it can be installed in the wrong orientation)?

Honestly, I do not know the exact flexplate.  I believe the 401 came out of a 62-63 and mated to the original 57 Dynaflow.  This vibration is a recent issue, it has been running fine for the last 35 years.

[old-tank]

Engine and transmission mounts if defective will transmit  and enhance  minor vibration.

If the carburetor leans out at a certain RPM there will be perceived vibration.

[Yohdda]

3 hours ago, Frank Falconeri said:

Call Matt Martin 530-272-1564 at Centerville Auto, he is the Nailhead guru and will most likely know where the problem is, all Nailheads are externally balanced but they are all not the same, different years have different balancing weights, I highly recommend calling him. Hope this helps 

I'll reach out after I try a couple of things and fail, thanks

[Yohdda]

2 minutes ago, old-tank said:

Engine and transmission mounts if defective will transmit  and enhance  minor vibration.

If the carburetor leans out at a certain RPM there will be perceived vibration.

I checked the three mounts and they look good.

 

I'll try adjusting the carb and see if that changes the vibration at certain RPM's

[carbking]

Externally adjusting the carburetor will have no effect on a vibration above maybe 900 RPM.

 

Jon

[Yohdda]

Ok, so I measured the weight on the balancer.  From what I read, find the center mark and then measure counter-clockwise until you get to the weight, that measurement is 7.25".  That is the distance for a 364...  I was told that I had a 401 because my water pump is the long one.  I measure the distance between the two intake bolts and it is 9" which is an indicator that it is a 401 as well.  So maybe my weight spun to the exact distance of a 364?  or this Buick has had the wrong balancer for the last 35 years and ran smooth until last month.

 

I am getting my information from - https://www.nailheadbuick.com/post/balancer-info

 

Here is an image of the cast numbers at the front, starts with letter C

 

 

I've attached a photo of the number on the upper block by the firewall.

Edited July 3, 2023 by Yohdda (see edit history)

[Yohdda]

Ok everyone, with help from Matt from Centerville Auto, this is what I have determined.

 

After some digging I believe it is a 59 or 61 - 401 with 364 Heads.

 

So here are some numbers 

Block Cast - 1196546 - (61 - 401)

Intake Manifold - 1185976 - (63 - 401)
Head Cast - 1172889 - (57-61 - 364)

 

And the balancer is for a 364, which it had on it for the last 35 years without an issue.  Now I am debating on whether or not to switch it to a 401 balancer, even though it did run smooth with this 364 one.

 

I am planning on going to the BCA show in Spokane, WA and was planning on leaving this Saturday.

 

[Yohdda]

Just an update,

 

I adjusted the carb to run richer than it was, and opened up the idle screws  1/2 turn.  Took it out for a run and it is smoother than what it was before.  Tomorrow I am going to pick up a new fuel filter and swap that out.

[avgwarhawk]

25 minutes ago, Yohdda said:

Just an update,

 

I adjusted the carb to run richer than it was, and opened up the idle screws  1/2 turn.  Took it out for a run and it is smoother than what it was before.  Tomorrow I am going to pick up a new fuel filter and swap that out.

Don't let a small adjustment throw you off. I have been chasing a vibration on my 54 264 for 13 years.  It occurs at 50 mph. Still scratching my head. 

[Yohdda]

10 minutes ago, avgwarhawk said:

Don't let a small adjustment throw you off. I have been chasing a vibration on my 54 264 for 13 years.  It occurs at 50 mph. Still scratching my head. 

I am going to put some miles on it this week and see what happens.  I also used some carb cleaner to clean up the sinuses of this old girl.  I also need a new rad cap.  If it's not one thing it's another...

 

From my most recent test drive I think it will be ok for the drive from Alberta to Washington state.  We are going to take the scenic route through Montana starting Sunday and spend a few days there before we end up in Spokane on Wednesday.

[avgwarhawk]

26 minutes ago, Yohdda said:

I am going to put some miles on it this week and see what happens.  I also used some carb cleaner to clean up the sinuses of this old girl.  I also need a new rad cap.  If it's not one thing it's another...

 

From my most recent test drive I think it will be ok for the drive from Alberta to Washington state.  We are going to take the scenic route through Montana starting Sunday and spend a few days there before we end up in Spokane on Wednesday.

Running it like you stole it often helps clear up soot and other accumulation of junk.  Ask Willie @old-tank. Hell ask me. Happy motoring! 

[lancemb]

On 7/2/2023 at 7:06 PM, Yohdda said:

Thanks for the reply.  I checked around the torque tube and couldn't find a hole for servicing.  I also read up on the front U-Joint in the Maintenance Manual and it states "The universal joint, torque ball, and speedometer drive gears are automatically lubricated from the transmission."  and something similar for the rear U-Joint about packed grease from the surrounding bearings.

 

Is the access hole on top of the torque tube?

The access hole that these are often equipped with is actually for a grease fitting for the rear splined shaft, but not all cars had the fitting and access hole.   It was on later production builds and was added to earlier builds if a problem developed; this is covered in a service bulletin.

 

The rear U-joint will eventually fail and will require taking the torque tube apart to replace it.  Only the front one is lubricated by trans fluid.  When I did mine I added an access hole to grease it; the original didn't even have a grease fitting.

[60FlatTop]

Sometimes grease will take the path of least resistance.

 

When you have checked everything thoroughly you just have to go deeper.

This could have been worse that a little squeak at low speeds.

 

Good timing. I have just started outlining a presentation for facilities managers on addressing non-binary failures.

 

Edited July 5, 2023 by 60FlatTop (see edit history)

[60FlatTop]

11 hours ago, lancemb said:

The rear U-joint will eventually fail

Two types of failure, latent and binary.

[lancemb]

3 hours ago, 60FlatTop said:

Two types of failure, latent and binary.

Okay?

[Yohdda]

I'll take a look for an access port on the rear end.

 

My vibration is happening while not moving at around 1380rpm.  It is not as severe the last couple of days once I changed the fuel filters, re-tensioned the belts, and adjust the choke and idler screws. 

 

I am traveling for 3 hours down to Calgary, and picking someone up, then continuing on.  If the situation gets worse I'll bail on the Buick and drive down in a Honda 😳.

[NailheadBob]

There is a service bulletin for engine vibration for 1958 and has a procedure for adding weight to the torque converter, it is a tedious process and a lot of trial and error when adding and removing weights, but when solved has great satisfaction, I did this on my '58.

 

part # 1178110 (.120") thickness

 

#1178109 (.060")

 

#1178108 ( .0345")

 

Bob