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Old 08-14-2021, 12:28 PM   #1
al's28/33
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Default help with vibrating mirror !

My rear view mirror vibrates too much when driving at any speed. The bracket is mounted directly on the metal header over the front windshield, so would a felt pad work better or is a rubber gasket good enough to keep that darned mirror steady?
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1928 "A" Phaeton (mid year with many early features)
1933 "V8" Closed-Cab Pickup Truck
(originally a Model B, 4 Cylinder dating to May, 1933)
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Old 08-14-2021, 01:10 PM   #2
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Default Re: help with vibrating mirror !

In your phaeton? Cork does a nice job for quieting down vibrations, if you don't squeeze it to much.
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Old 08-14-2021, 02:08 PM   #3
al's28/33
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Default Re: help with vibrating mirror !

not the phaeton, my 33 pickup in which I am using a modified bracket and mirror so I can see right thru the rear window. I could never locate the correct one and other mirror angles did not align up with the rear window.
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1933 "V8" Closed-Cab Pickup Truck
(originally a Model B, 4 Cylinder dating to May, 1933)
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Old 08-14-2021, 02:09 PM   #4
al's28/33
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Default Re: help with vibrating mirror !

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1928 "A" Phaeton (mid year with many early features)
1933 "V8" Closed-Cab Pickup Truck
(originally a Model B, 4 Cylinder dating to May, 1933)
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Old 08-14-2021, 03:06 PM   #5
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Default Re: help with vibrating mirror !

rubber grommets............
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Old 08-14-2021, 11:06 PM   #6
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Default Re: help with vibrating mirror !

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The 33 Pick-Up originally did not have an inside rear view mirror, only an outside mirror on the left side. You may try making the mirror bracket very stiff. Any springiness in the bracket will accentuate the vibration.

My opinion,

Chris W.
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Old 08-15-2021, 05:57 AM   #7
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Default Re: help with vibrating mirror !

Does anyone else remember this: Many years ago there was an article about how to analyse the reflection in the vibrating rear view mirror to determine engine problems. If it was jumping up and down it was a rod bearing or side to side a main. I am pretty sure it was a spoof, more humor than fact.
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Old 08-15-2021, 06:12 AM   #8
Patrick L.
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Default Re: help with vibrating mirror !

Quote:
Originally Posted by nkaminar View Post
does anyone else remember this: Many years ago there was an article about how to analyse the reflection in the vibrating rear view mirror to determine engine problems. If it was jumping up and down it was a rod bearing or side to side a main. I am pretty sure it was a spoof, more humor than fact.



lol !
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Old 08-15-2021, 09:39 AM   #9
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Default Re: help with vibrating mirror !

If the header is vibrating….the mirror will do the same. Maybe worse as it is extended and gets more leverage/wiggle room
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Old 08-15-2021, 11:21 AM   #10
KenBolton
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Default Re: help with vibrating mirror !

Aren’t they suppose to vibrate????????
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Old 08-15-2021, 11:54 AM   #11
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Default Re: help with vibrating mirror !

Vibrating tells you that the motor is still running!
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Old 08-15-2021, 11:54 AM   #12
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Default Re: help with vibrating mirror !

The mirror vibration problem also often occurs on modern cars when you replace a broken side mirror glass with a cheapo non-factory piece. WHY??-

Every object has what's called a 'period of motion'. That's basically the frequency at which it will swing/vibrate when given one impulse of inertial movement. Mounted automobile mirrors are like clock pendulums. Change either the distribution of mass or the length of the arm and the period of motion changes. When the vibration of the vehicle approaches any mathematical relation to that period of motion the mirror will go into a harmonic and vibrate strongly.

Modern cars that suffer after a non-factory cheapo mirror replacement have less mass and incorrect mass distribution. The fix there is to epoxy some weights to the back side edges of the glass.

To fix the mirror on a Model A, in addition to isolation mounting as suggested above, you need to increase the mass which will lower the frequency of motion. I have tamed several add-on exterior mirrors by opening or drilling the external SS case and filling the void with #7 lead shot.
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Old 08-15-2021, 11:59 AM   #13
J Franklin
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Default Re: help with vibrating mirror !

Counterbalances on the crank and a full balance of the reciprocating parts will help. Maybe a harmonic balancer up front would be a good touch. Back in the day there was no problem with a dancing mirror because the model A was so far ahead of all the other cars on the road!
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Old 08-15-2021, 01:56 PM   #14
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Default Re: help with vibrating mirror !

Counterbalances on the crank and a full balance of the reciprocating parts will help. Maybe a harmonic balancer up front would be a good touch. Back in the day there was no problem with a dancing mirror because the model A was so far ahead of all the other cars on the road!



except the 6 cylinder chevys!!!!!!!!!!!!!!!!!
Chevy outsold them by a ton.
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Old 08-15-2021, 01:57 PM   #15
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Default Re: help with vibrating mirror !

Might try a rubber faucet washer.
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