Super tard nube question.

metalho

metalho

Well-known member
Ok, this ones obvious and probably not worth asking. My 29 coupe vibrates and rattles inside the cab at certain rpm's. This isn't my first rattle trap, but it is my first A. I'm assuming the only way to solve this is shaving the crank and balancing the motor? Ill inspect all the bolts holding the cab down, but as I said this isn't my first trip to the rodeo and that never seems to solve the problem. Not that I mind, its just the expression you get from unsuspecting passengers, lol...................... Like, "is it gonna blow up or fall apart lol...........:eek:
 
Are you sure you've isolated the rattle to the cab? There are about 1000 places it can rattle (I've fixed several but still have around 990 to go).

Just a thought that you might want to eliminate all the easy fixes before tackling that one. :)
 
;)
dan said:
Are you sure you've isolated the rattle to the cab? There are about 1000 places it can rattle (I've fixed several but still have around 990 to go).

Just a thought that you might want to eliminate all the easy fixes before tackling that one. :)
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Very good point Dan. Actually I'm not thinking about altering the motor. I like the stock low idle, and speed is not an issue. Ill dive into tightening everything up this winter, Ive already started and found a few. I'm just happier than hell to own one now.................;)
 
Metalho,
Is that your coupe under your name? If so, it appears to be in Rose Beige. Nice looking car. Lots of things rattle in my Sport Coupe. But then it is 81 years old. Jim
 
You'll never get rid of all the rattles. I'll give you a $1000 for your coupe to take the trouble off your hands.
 
dan said:
Are you sure you've isolated the rattle to the cab? There are about 1000 places it can rattle (I've fixed several but still have around 990 to go).

Just a thought that you might want to eliminate all the easy fixes before tackling that one. :)
Click to expand...

jimmiej said:
Metalho,
Is that your coupe under your name? If so, it appears to be in Rose Beige. Nice looking car. Lots of things rattle in my Sport Coupe. But then it is 81 years old. Jim
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Why yes Sir it is Rose Beige...................:) I'm lucky that Ive got a half gallon of the original paint and an air brush for touch ups. Ill post some pics on that.
 

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700rpm said:
You'll never get rid of all the rattles. I'll give you a $1000 for your coupe to take the trouble off your hands.
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lol..........................Wow, honest. :rolleyes: I'm thinkin maybe Ill hang on to the old girl and try to fish the loose bolts out of her panties first.:p
 
the first time my adult daughter rode in the coupe the first words out of her mouth was "are we going to make it" LOL
 
Ditto here on rattles, I've got a mean one at about 28-32 mph, seems to be coming from behind dash/dash rail, I've been able to quiet it some. Interesting thing is I kind of use it as an audible speedometer. Having fun and loving it.
Paul in CT
 
I had a mean one in my 1999 E150 van. I swore it was the rear wheel bearing and someone (Who should have known better) said I was the Carrier bearings. Took it out and replaced one axle. Still there! Then I went to the R.F. Wheel bearing. It was bad so I replaced it, hmmm better.. but still not fixed! I balanced the tires on my bubble Balancer, again, some improvement. but still not fixed! Then I did the Ball joints and left wheel bearing. Again some improvement. But still not fixed. I carefully balanced the front wheels again. While I had the wheels off, I spun the discs. One disc always return to the same position. I couldn't beleive it. One of my brake discs was out of balance. I got the little hand grinder out and took some stock off until it was balanced. This diminished the vibration to almost nothing (still a little) Who'd of thunk it? The brake dics are replacements, imported I believe! The wheels were fine up to 62MPH and above 70mph But in that range, life was hell. And this is a 99 ,not 29!
Terry
 
In my S/W sedan, when I hit 45 MPH, the entire cowl area seems to resonate and vibrate, and the steering wheel vibrates a lot. Not like a out-of-balance wheel sort of vibration, but a buzz at engine speed. If I coast at 45 MPH in neutral with the engine idling, things are smooth and quiet.

The motor and motor mounts are stock (with the correct new rubber pads), and the crank and flywheel were balanced when the engine was rebuilt (by a well-regarded rebuilder). And there was zero flywheel runout when I assembled it. Funny thing is, at the critical RPM there does not seem to be a huge amount of vibration on the engine block itself. It's much worse on the cowl panes and steering wheel.

Doe this sound more-or-less normal?

Doug
 
A common rattle source in A's are the top window glass rubber stop strip. Many A's have had it replaced with channel felt, which does not work. When the rubber is hardened or worn out, the glass rumbles. Another common source is the small anti rattle washer in the windshield arms lock nut is often missing. Repro coil brackets buzz the firewall at a certain rpm and sound horrific. Those hood holder brackets that attach to the radiator support rods will make a horrendous buzzing through the firewall. The door stops wear out, the door dovetail rubber wears out. The body bolt rubber hardens and the bolts get loose. The hinge pins wear, especially on the drivers door, and make a knocking rattle at the top of the door as you drive on rough pavement. If the frame has sagged, the choke rod rubs the cowl hole and makes a high pitched squeak. Squeaky front springs sound like they are coming from the floor.Floorboards should have welting along the edges, but often its gone or they are repros that never had it in the first place. Then there are the other 1000 possibilities. I've been A's that were quiet except for a mild door rumble on a really rough road....it can be done. One was an original 30 low mileage cabriolet in remarkable, beautifully preserved condition and the others were recent restorations. Then there was my old unrestored and badly beaten pickup, which rattled so badly that passengers usually burst out laughing.
 
Every object (part) has an inherent resonant frequency. The Model A has parts that cover the full spectrum of engine and driving frequencies. All that fun has been engineered out of most of the parts on modern cars.
All Model A's self-disassemble while driving.

There is a nice article about vibration on wikipedia.
800px-Forced_Vibration_Response.png
 
pat in Santa Cruz said:
A common rattle source in A's are the top window glass rubber stop strip. Many A's have had it replaced with channel felt, which does not work. When the rubber is hardened or worn out, the glass rumbles. Another common source is the small anti rattle washer in the windshield arms lock nut is often missing. Repro coil brackets buzz the firewall at a certain rpm and sound horrific. Those hood holder brackets that attach to the radiator support rods will make a horrendous buzzing through the firewall. The door stops wear out, the door dovetail rubber wears out. The body bolt rubber hardens and the bolts get loose. The hinge pins wear, especially on the drivers door, and make a knocking rattle at the top of the door as you drive on rough pavement. If the frame has sagged, the choke rod rubs the cowl hole and makes a high pitched squeak. Squeaky front springs sound like they are coming from the floor.Floorboards should have welting along the edges, but often its gone or they are repros that never had it in the first place. Then there are the other 1000 possibilities. I've been A's that were quiet except for a mild door rumble on a really rough road....it can be done. One was an original 30 low mileage cabriolet in remarkable, beautifully preserved condition and the others were recent restorations. Then there was my old unrestored and badly beaten pickup, which rattled so badly that passengers usually burst out laughing.
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Great info guys! Im still workin on the soft top this weekend. But winter would be a good time to track down some of the rattles. :D
 
Pat brings up a good point about the repro coil mounting bracket. Notice how they are flat and can vibrate a little against the firewall. This vibration can eventually lead to stress cracks in the firewall.

Original brackets are spot welded to the coil case and have a concave mounting surface, so the 2 screws will tighten the bracket against the firewall in 4 areas, to eliminate the posibility of movement.
 
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