Vibration/shaking at Cruising Speed

DJ S

DJ S

Well-known member
After rebuilding the front axle and steering box entirely, I still have a vibration/shaking around 35 mph, just cruising along. I don't have these symptoms on acceleration and higher speeds. What could be causing this?
 
Gosh the list of things to look for are pretty endless.

Are the tires seated pretty uniformly on their rims? (Most tires have a "mould line" just outside the bead area which can be used to check for seating.)

Are the tires round? - check for roundness with the wheel jacked up so you can turn it? Use a stationary block of wood or indicator on the road as a reference.

Are the rims round? Same methodology except use the reference to compare the rim edge.

Are the rims wobbling? Same method except look end-on.

Toe in? I used sticks of wood and c-clamps for a front to back comparison.

Camber-caster. Can be measured somewhat accurately by the Les Andrews method but a honest to goodness tire shop with a lift/instruments will do a better job - and give you a computer print-out. Can be indicative of a front bent axle which can be major to straighten/replace.

Brake drums "round?" Rubbing in one spot? You can remove the front brake shoes and CAREFULLY drive the car and see if the problem is still there. I have heard of those who use a "dummy spindle" to mount the front hub/wheel/brake drum to test for this with a dial indicator. Can be done on the car in your driveway if you remove the backing plate but this makes it a bigger job for a determination.

Phew. Getting tired on this.

Joe K
 
I have new steering arm balls, toe-in is set, I do not have new tires. Wheels aren't bent and are within spec.
 
Which front wishbone radius ball mounting design do you have - the thick, clunky repo cr*p one with a rubber ball inside or the correct authentic style? The answer to which is better is in the question. The rubber ball design WILL create shimmying sooner or later. Dumb design lifted from the '32 V-8 Ford with its different mounting design. 'Doesn't work long on Model A's because leaking oil from the rear main bearing softens the rubber ball and the gyrations begin. If you have this style, replace it with the correct design and your shimmying will go away. If you don't have this rubber ball mounting design, we'll have to look elsewhere for the cause of the shimmy. 15,000,000 Model A's did not leave the factory shimmying, ya' know!
Marshall
 
Hi DJ,

A. Hate to be so blunt; however ...... Think!

B. In your words: "After "rebuilding" the front axle and steering box "entirely" ..... I "still have" a vibration/shaking around 35 mph, just cruising along."

C. Now, just suppose you have a tooth ache and you get a (1) a heart transplant, (2) new hearing aids, (3) new eye glasses, (4) a face uplift, (5) a shave, (6) a haircut and (7) toe nails clipped.

D. Maybe a possible clue would be to consider which problem item in paragraph (C.) above was not altered, replaced, or thoroughly investigated?
 
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Wheel balance, they have not been balanced. The radius rod socket is the original style. I just took it for another drive and I would describe it more as a shuttering, felt througout the car and only kind of felt in the steering wheel leeding me to believe it could be the u-joint? I would think an out of balance tire or out of round wheel would cause problems at any rpm range, any speed and regardless if i was decelerating or accelerating.
 
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Not trying to be funny; however, one (1) simple, one (1) man Model A mystery "shuttering" test could be:

1. Jack up all four (4) Model A wheels & place Model A up on (4) jack stands.

2. Remove (4) Model A wheels and lean them up against a tree outside your garage.

3. Start car, place in gear, pull throttle downwards.

4. Get out of car to look at your (4) wheels against the tree to see if they or the tree are mysteriously "shuttering" with the engine running in gear at different engine rpm's; and if not,

5. Look at your jacked up Model A to see if it is mysteriously "shuttering" with the engine running in gear at different engine rpm's.

6 Investigate further that which may be mysteriously "shuttering" with the engine running in gear at different engine rpm's..

7. Please let us know what you see and think after this observation test to obtain sincere further Model A Forum advice and comments.
 
How old are the tires (flat spotted)??
Did it do this before the rebuild??
Backing plates tight to axles??
I think more info/investigation needed.
Paul in CT
 
Usually balance problams show above 40, tire problems (not round,belt issues,flat spots etc) show up under 40
 
I'll swap the tires from my car with my Grandpa's fordor and see if that changes anything.
 
Please keep in mind that:

1. On all vehicle Forums, with sight unseen, other "different" Model A owners, from "different" distances, are desperately trying to "guess" at the "different" causes of a specific problem with a "different" 86 year old Model A; and,

2. These "different guesses" are not that much "different" than trying to "guess" at the "different" causes of a specific "different" problem with a "different" 86 year old human Model A owner.

3. Usually a "different guess" originates from a "different" someone as to what one may expect to be a "different" typical physical condition encountered and experienced over the past 86 years with a "different" Model A.

4. Moral of this message is that ....... if you find your problem is something totally "different" .... please, don't be surprised!
 
When experiencing the vibration/shaking, if you push the clutch in do the symptoms go away?

Have you always had the vibration/shaking or is this a recent thing?
 
Dick Steinkamp said:
When experiencing the vibration/shaking, if you push the clutch in do the symptoms go away?

Have you always had the vibration/shaking or is this a recent thing?
Click to expand...

I've always had vibration/shaking but that was because of the front end. Now that the front end is rebuilt, this feels like a different vibration, i even had someone drive in front of me and look back to see if they saw my front end shimmying. There was no irregular movement detected. I don't know if it goes away when i depress the clutch, haven't tried it yet.
 
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