Hi guys, On my '41 Ford with a straight axle, dropped spindles, Caprice Disc Brakes on the front. I have had a vibration in this Rod since I bought it. Sent the axle to Phoenix to re size the king pin hole, re bushed the spindles, New King Pin set, Some improvement, new tires in the front at several times, wheels are Phat Five from U S Wheel, (now obsolete). Wheels are Lug Centric. Added front PanHard Bar also Steering Damper from Pete & Jake's. Some improvement..... Had the drive shaft balanced and straightened, .060 out. More improvement! STILL have some vibration at 55 MPH but not all the time. WHERE can I go now??? HELP!! PLEASE, Don
I've had the same problem with vibration at that speed. Could be bad motor mounts or harmonic balancer? Posted using the Full Custom H.A.M.B. App!
First is the vibration in the steering wheel only or throughout the hole car? If its in the steering wheel only that narrows your problem down to the front end components only. If throughout the whole car, then that opens it up to a lot more. If its in the wheel only, start by putting two completely different wheels and tires on the front, then drive and see if it goes away, if not, you've eliminated wheels and tires. Take it a step at a time, eliminating each item as you go. Usually if all susupension is good, it will be a wheel and tire or balance issue. If its througout the car, this could be rear wheels and tires, balance, ect. or driveshaft, rear axle problems, wheel bearings ect.
Typically a vibration at 55MPH is a tire balance problem. As others said, start there and go down the list. Normal troubleshooting starts with the last thing you did before the problem started but since it has done it since you got the car it could be anything.
Try to see if it is mph or rpm related. Try and duplicate the vibration in a lower gear at the same rpm. RPM relates is more likely a driveline issue than tire/wheel etc.
I have had a 55 mph vibration on two different cars. Both small front tired with straight axles and radial tires. F-1 steering on one and Corvair cross on the other. No the dampner bandaid didn't help. My attempts included tire pressure, rotating the tires about the rim to get closer balance and playing with toe adjustments. Both cars had the kingpin bushings done correctly. First car had bias plys and switching to radials did help some. Neither car had reversed or shallow back spaced wheels. Though I got both cars much more drivable, avoiding bad roads and 55 mph seemed the best cure.
Also check your rims to see if they straight and true. Lift the car up and get a gauge that will set on the floor. Rotate the rim and tire and check for out of round condition and for a bent rim condition by using a makeshift gauge to check it. A floor stand with a pencil taped to it works. I just had this same problem on an old ford wire rim. check both the rim and the tire.
One more check that no one above has mentioned, at the peak of the vibration, lift your foot completely off the accelerator. If the vibration ceases the problem could be in the rear end. Maybe a slightly bent axle or bearing wear. To double check, as you are coasting, engage your brake very slightly and you should notice it in the peddle. It wont be real obvious, you will notice it though. Good luck to you.
If you don't have a positive traction rear end !! Jack up right rear wheel and get in car and slowly run it up to 55 mph on the jack . Making sure it is well supported of course, if it still shakes you'll know its driveline or tire balance . We used to balance tires that way - it includes the brake drum and axle in balancing . Maybe somebody out your way still does that
Actually, 27.5 MPH indicated would equal 55 MPH wheel speed. A differential will multiply the speed of the spinning tire by a factor of two, if the other wheel is not turning. To check the driveshaft, you do need to see 55 MPH on the speed-O-meter, but then your wheel will be spinning at 110.
Check to see if it is driveline related by driving down a grade at 55 and when it vibrates kick it into neutral and coast. If it goes away, it is engine related. If it continues to vibrate it is driveshaft to tire related. Given what you have said I would suspect out of round or bent wheels.
Is there somebody up your way that can check your tires for run-out and possibly shave them if necessary?
Find an old time tire shop that has one of those machines that goes under one tire at a time and spins the whole assembly on the car. They can balance not only the tire and wheel that way, but everything that rotates, rotor, hub, etc. When I was going to run my car at the BP Drags I knew I would be going faster than I normally drive so I wanted everything to be perfect. I took my 27 to a local tire shop and they spun each wheel and balanced them for me. As soon as I drove out of the tire shop I could feel the difference in my steering wheel, it had no vibrations at all and the car ran right down the road really smoothly. I also had a Toyota Corolla years ago and had new tires put on it. Immediately I had a vibration. Took it back and they tried everything but as a last ditch effort the manager got out the spin balancer. That found one side was out of balance and once they redid the weights the car was smooth again. Before you start tearing into other stuff I would do that. Don
Absolutely, I have Coker bias ply copies on my model A and had the same problem after a few miles. Had the fronts strobe balanced and trued and handles like a different car, smooth as a '29 model A can be!
Hmmm...dropped spindles on a "straight axle" with Caprice brakes? I suspect you have a lot of "scrub" at the tires. That is usually problematic. You might relieve this by switching to front wheels with less offset. Do your wheels center on the rotors, or rely only on the lug nuts/wheel studs? In concert with the above condition any runout will make wobble hard to avoid.
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