Vehicle vibration
 

Hi all, im new to the thread and also new to owning a 1929 Model A Tudor. I have gotten the vehicle running and on the road. I am curious though about how much vibration from the engine is considered “normal”. At a idle the vehicle sits smooth and the motor sounds good. Once off of a idle is when things start to vibrate. Driving down the road it has a droning vibration that does seem to come and go depending on vehicle speed and load on the motor. The vibration/drone is loud enough To have to speak louder than normal while driving down the road. I do have the timing advanced about halfway down while driving. Is this vibration considered normal or should i start thinking about diving into the motor? The car was restored in 1995 and has had very little use (couple hundred miles) since then. Not sure how much of the motor was rebuilt. I know the car is 91 years old, just not sure what is considered normal.

Re: Vehicle vibration
 

Motor noise and transmission whine is normal, but how much is normal? It's hard to describe verbally, perhaps watch a few youtube videos to get a feel for it. Vibration from the engine though isn't normal, you could do a few tests to help diagnose it:

Is it the same with the clutch in or out?
When you accelerate in 2nd gear and then shift, does the vibration stay the same, or decrease in frequency?
Or try on a downhilll section, shifting to neutral. Any vibration now?

Re: Vehicle vibration
 

The vibration seems to be the directly linked to motor rpm. I have noticed it during downhill coasting and during acceleration but it seems to be the worst when driving on flat road with little engine load. Seems to be the worse at 25-30mph and 40-45mph. I will have to check to see what it does with the clutch pushed in.

Re: Vehicle vibration
 

Many things contribute to engine vibration. I recently found that something as simple as reassembling an engine with the flywheel 180 degrees made quite a difference. Another issue could be a crank that is out of alignment by more than a few thousandths of an inch. It doesn't take much. Some Model A's I've driven feel like they are going to shake apart over 45mph. Mine has its share of vibes too. One way to get a feel for it is to go for a ride with others who have Model A's or see if they will let you drive theirs. I find that I feel the vibes more in the steering wheel than being a passenger. Most Model A's that have not had many $$ on engine refinements vibrate, and all vibrate more than any modern car.

A very common thing is that vibration is generally related to RPM. I find my car has more vibration at 45 and over. I get used to it.

Also common is to have less vibration when the engine is under load either going up a hill or accelerating. More vibration when going down hill against engine compression.

Re: Vehicle vibration
 

I had a bad vibration on my coupe when I first bought it. A friend suggested inspecting the front motor mount to be sure all the pieces were there, and if so, tightening the center bolt as needed. Also said to check the fan blade to make sure it isn’t cracked or bent. I did those things, and the fan blade was good, but the front motor mount was missing the brass bushing. I replaced that and put in a new center spring and snugged it up to where the cotter key would fit, and the vibration was gone.

Re: Vehicle vibration
 

Great points! I forgot that last year when I put my engine back in after working on the transmission, I must have forgotten the cotter key in the front engine mount. After a week that bugger was vibrating like crazy. The nut had worked loose and it, the spring and the brass bushing were all gone. I replaced those and viola!

Re: Vehicle vibration
 

As mentioned, many things contribute to vibrations, and driveline components are also an area that creates just as many issues. Most restorers do not check the driveshaft to be straight. Also, the driveshaft bearing and/or race in the torque tube is one area that is often overlooked and allows the universal joint to run at a double misalignment.

As for the engine, it can be the flywheel, the crankshaft, connecting rods or pistons, ...or a combination of any of those. Many aftermarket piston sets can be between 10 and 50 grams difference in weight. Connecting rods that have a heavier big end (-due to thicker cast bearings) will likely be out of balance weight, ...and even crankshafts that were ground improperly will exacerbate the harmonics issue. Buying a rebuilt engine strictly on a low price point generally has these details overlooked.

So as for remedying the vibration issue, ...it boils down to what is your plans with the vehicle? Vibrations will cause premature wear or damage, so at some point you (-or someone) will get to repair the damage. As far as what is normal, for those of us who have been around low-mileage original Model-As will tell you that you can see a clear image out of the rear view mirror at all speeds. If your Model-A rear view mirror shakes where the vehicle behind you look like a blur, then it is not normal.

Re: Vehicle vibration
 

Re: Vehicle vibration
 

Bratton's says, "The brass washer was used from Nov. '28 thru Jan. '29 then it was replaced with a steel flat washer. It is believed the brass shouldered washer restricted the yoke stud from moving side-to-side when one wheel went into a pothole, thus putting too much stress on the stud."

700rpm - Maybe that is why yours was "missing"?

I installed one on my '30 Town Sedan not knowing it was not supposed to be there?. Have not experienced any issues. I wonder what others do or think?

Re: Vehicle vibration
 

Sounds like i have some tinkering to do... i get the vibration even at a high idle while in neutral. I will try pushing in the clutch to see if it goes away and then start looking at the other possibilities mentioned. I did notice this morning that the water pump shaft has some play in it at the end the fan is mounted. I’ll remove the fan belt and run it quick to check that as a source. Another thing i failed to mention in the first is that the head gasket is starting to fail. I have a leak just above the serial number on the motor. I tried torquing the head again by loosening a 1/8 turn and tightening again with no luck. New gasket is on its way.

Re: Vehicle vibration
 

My suggestion was going to be to try and isolate the vibration, to see if it was the engine or driveline. So, you're on the right track with what you're now doing.
If it turns out to be the engine, is the engine mis-firing ?

Re: Vehicle vibration
 

it does seem to have a miss that isn’t necessarily consistent but certainly enough to be noticed at a idle. I havent been able to pickup on it when i bring it off idle but i mainly hear it in the exhaust. So maybe its got enough going on that i wouldnt hear it in the exhaust off of idle... i also have carb gaskets coming so i can get that cleaned also. Also to reply to brent, my intentions with the car is to do as much fair weather driving as i can find time for. So i would really like a smooth running A

Re: Vehicle vibration
 

The harmonic balancer pulley is a simple way to eliminate most vibrations that occur over the rev range. It is relatively simple to fit and reasonably inexpensive.

"These dampers are made by Murray Horn in Levin N.Z. His Company is Engine Restorations Ltd. His email is [email protected]
Murray says this is the best way to contact him.
The dampers are a straight fit to replace the standard Model A pulley. An added benefit is a shallow reverse scroll in the rope seal area to help contain oil."

Re: Vehicle vibration
 

Do you have engine side pans?

I once had one come loose, vibration and sounds really only happened when I took my foot of the gas.

Just a thought.

Enjoy.

Re: Vehicle vibration
 

I do have engine side pans. The vibration im experiencing is vibrating the entire car. Its almost like driving on rumble strips in a new car at about 45 mph

Re: Vehicle vibration
 

When you order, specify whether you have the rope seal or the modern style seal. Balancers for motors with modern seals do not have the spiral.

Re: Vehicle vibration
 

Just got done running the engine with the fan belt removed and the clutch pushed in. Vibration is the same. If the flywheel isnt “flush” to the motor or out of balance, would i feel it in the clutch pedal? Clutch is smooth when engaging and disengagement

Re: Vehicle vibration
 

Probably not!

Re: Vehicle vibration
 

Just be aware, on that Murray balancer you can not change the belt once on. The engine must be lifted to get the belt on.

I was told this by Murray directly.