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Shade Tree Mechanic
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I test-drove and bought a '48 Fleet yesterday.
From about 20 mph on up to 45 or 50, the entire vehicle shudders violently. I mean the doors are bouncing and all kinda weird stuff. It certainly doesn't seem like simple tire balancing issues.
Could this be a driveshaft or axle issue? I grabbed wheels and rocked for bearing slop, checked for loose components and whatnot, just can't imagine what would cause this.
This car is still in Seattle, and I'm in the San Jose area, so I can't work on it or see it at the moment.
Thanks for any wisdom in advance!
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Joined: Jan 2002
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Does it have old bias ply tires, and was it sitting for quite a while, and was it was kinda cold in Washington?
Older bias tires get what we used to call "flat spots" from sitting around - especially when it is colder out, especially when they get older. When you start driving on them, it can feel like the whole world is falling apart, magnitude 9.3.
How we used to deal with this is by driving at lower speeds for a couple of miles. Once they get warmed up from road friction, they will smooth right out, and life is good.
Or maybe it's something completely different. But from what you describe and the checks you made, it's a good bet you have just learned about Flat Spots.
Chevy Guru
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Shade Tree Mechanic
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Shade Tree Mechanic
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Yep, skinny bias plies, cold in Seattle, certainly sitting.
You know, flat spots crossed my mind, but there are no cracks in the tires, and they felt quite soft and pliable, so I didn't give the flat spots any further thought.
But I bet you're onto something.
I guess I will probably lift the car when not in use so I can avoid these issues down the road.
Can't wait to get the car in-hand and get to the bottom of someof these issues.
The tappets seem quite noisy too, so I'll check adjustments and see if they get any quieter.
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You normally can't see Flat Spots - but you can definitely feel them for the first few miles.
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You might want to check to see if a spark plug wire has come off.
RAY Chevradioman http://www.vccacolumbiariverregion.org/1925 Superior K Roadster 1928 Convertible, Sport, Cabriolet 1933 Eagle, Coupe 1941 Master Deluxe 5-Passenger Coupe 1950 Styleline Deluxe 4-Door Sedan 1950 Styleline Deluxe Convertible 2002 Pontiac, Montana, Passenger Van 2014 Impala, 4-Door Sedan, White Diamond, LTZ 2017 Silverado, Double Cab, Z71, 4X4, White, Standard Bed, LTZ If you need a shoulder to cry on, pull off to the side of the road. Death is the number 1 killer in the world.
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FF, Jack it up. Hand spin the tires to see if the fronts have any out-of-round or blance problem. The balance will manifest itself by the tire going back and forth until it settles down. Rock the wheel in and out to check the king pins, etc. As to the rear wheels make sure the car is SECURE and run it in gear to turn the rear wheel(s). Notice any shaking. Observe for any out of round condition. You may have to block the dominant right rear tire in order to check the left (rear). You can tell a lot about the car's shudder by going through this simple test. You can do this test one wheel at a time if its more convenient. It may even be safer to do so. Ray is right on if the shudder is coming from the engine. Good luck, Charlie
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Speaking for myself...I've left my car sometimes for years at a time, and never experienced flat spots...Bias ply, and pretty old...The only issue I worry about is if these old tires might fly apart at higher speeds...A loose plug wire you'd probably notice even at idle...Maybe check the harmonic balancer...?
But, I would suspect the drive line...Like a bad u-joint...Might try getting up to speed and push in the clutch and "coast"...See if that makes any difference...
1947 Fleetmaster Sport Coupe VCCA # 47475
If it's not wearing a Bowtie...It's not properly dressed...!
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Joined: Jan 2014
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Shade Tree Mechanic
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Shade Tree Mechanic
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Yes, I did the 'coasting' thing, and it still shook.
All plug wires connected, she purrs for the most part, save for what is probably a valve adjustment needed for some clickety tappets. Are these solid lifters or hydraulic on these ol' 216's?
Flat spots on all four tires would definitely cause the wild ride that this thing is exhibiting. The doors sound tight when it's going down the road, but they literally flex in and out rapidly while the whole body shakes! It's quite the sight.
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Solid...Flat spots I would think would give you "bumpy" ride, rather than a "shaky" ride...
It also sounds like maybe front wheel alinement...When you get it look to see if all the tires are the same brand...Maybe someone nailed a curb or bent something in the past...
Last edited by kevin47; 01/27/14 04:07 PM.
1947 Fleetmaster Sport Coupe VCCA # 47475
If it's not wearing a Bowtie...It's not properly dressed...!
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Joined: Jan 2014
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Shade Tree Mechanic
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Shade Tree Mechanic
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Hey Kevin, you're not too far from me (a few hours).
Let me know if there are any shows you go to where I can get a look at your car!
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Oil Can Mechanic
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Oil Can Mechanic
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Don't forget the torque tube bushing, although 20 mph seems a bit slow for this to show up. From poor memory, as a 13 year old, seems this shows up 45 to past 65. They can shake you pretty hard.
Luck to you - - -
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Check the wear pattern on the tires, too. That might give some indication...If it's worn front end parts...King pin slop is pretty obvious to see..
1947 Fleetmaster Sport Coupe VCCA # 47475
If it's not wearing a Bowtie...It's not properly dressed...!
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Back in the 60's I used to have trouble with flat spots on bias ply tires in cold weather, even on the "modern cars" I was driving at the time. Like previously mentioned, they usually smoothed out after a couple miles. I would imagine that on the '48 the shocks are low on fluid and that makes the situation even worse. Bad King pins combined with no shocks and flat spots will give you quite a rough ride!
Ed
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