Getting a bad vibration starting around 55 mph that gets worse up to 65 then gets less intense at 70+, but still there. Very annoying. Feel it in the seat, steering wheel — whole car. Tires are 4 yr old B.F. Goodrich Silvertown bias-plys. Just had all 4 rebalanced. Rims are true. Tires didn't show any signs of trouble on the machine. Run the exact same tire on the '57 Fairlane with no issues, so doubting that's the trouble.

Replaced:
— shocks
— universal joints
— trans mount
 — engine steady rests

Driveshaft does not have any weights. Would y'all have that checked next? Being so short I didn't think that would be an issue, but I want to get this thing cruising smooth. Car has not been on an alignment rack in over 40 years, but nothing has been changed/messed with in the front end. Could use A-arm bushings. Wheel is off center but doesn't pull. Very few miles put on it until recently. 

Thoughts?

Kent — Round Rock, TX
'56 F-100  | '56 Crown Vic  |  '57 Fairlaine 500  |  '57 Thunderbird

  Did this vibration start a little and has got progressively worse? I would go back and check the basic things, lug bolt torque, maybe a thrown wheel weight, other repairs. Do you know if the tires are rolling the same direction as before the wheel balance? Some times this can affect a tire that sits in one position for along time, then starts rotating the other direction. Back in the 70's I had a Hunter on the car wheel spin balancer. If you know of someone who has one that could save a lot of time tracking down this problem and have a very accurate wheel balance because it spins all the rotating parts, drums etc. There are probably not many of these spin balancers around now. Should have kept mine. Hope this helps.   Part of the problem,  Cav Man

 

I've just recently gotten the car on the highway. It sat for 20 years and needed a lot of work to get it going again (including tires). I had them re-spun just the other day and they checked out ok. No flat spots. I wish I could find a shop that had that 'Hunter' machine you're talking about. Would take care of any drums that were out of spec as well.

Dad said it used to run just fine down the highway, so I'm guessing it's either tires or front-end related. The A-arm bushings look pretty crusty.

I have a '57 fairlne 500 with the same wheels/tires. I'll swap them out and see if that changes anything.

Kent — Round Rock, TX
'56 F-100  | '56 Crown Vic  |  '57 Fairlaine 500  |  '57 Thunderbird

Your problem is wheel balance. Myself and 2 of my friends had the same problem after having their wheels spun balanced. I have a old fashion bubble balancer and I was taught to use it by an old time mechanic. I balanced the wheels on my bubble balancer and problem solved.  

Is the driveshaft yoke tight in the rear of the transmission?  Either a worn yoke or rear transmission bushing can cause a vibration.  Rebalancing the tires using a Hunter spin balancer is also a good suggestion and worth pursuing.
 

Lorena, Texas (South of Waco)

Mr. Eaton —
I recently replaced the output shaft bushing. The rear seal started leaking soon after the trans was overhauled and upon closer investigation the bushing showed excessive wear and appeared original. The new one removed all slack in that area. The yoke was fine with no grooves.

You know anyone with one of those balancers in the central TX area? I'm just north of Austin in Round Rock. 

Kent — Round Rock, TX
'56 F-100  | '56 Crown Vic  |  '57 Fairlaine 500  |  '57 Thunderbird

I chased a similar high speed vibration in my 55 Tbird for a long time.  Could never find a shop with an old school spin balance machine. I was about to give up and accept it when I bought new wheels.  I was running the original steel wheels.  I replaced them with modern aluminum wheels and remounted my old tires.   To my surprise, the vibration immediately went away.  My steel wheels looked to be OK and were balanced off the car.   I have no idea why my steel wheels did this.  All I know is the vibration is gone.

Most folks seem to say rims are my issue. I tend to agree. Will post my findings. Thanks

Kent — Round Rock, TX
'56 F-100  | '56 Crown Vic  |  '57 Fairlaine 500  |  '57 Thunderbird

Before you go crazy replacing your rims, take the tires off the car and wash tires and rims front and back. ( As I said, "A old times taught me to balance tires")

I ran the car on stands up to 70 and didn’t feel what I feel on the road. Minimal vibration from the drivetrain spinning up that fast. I guess that rules out driveshaft, mounts, etc.

What I do see are very wobbly rear tires and questionable rims. Hard to determine if both are at fault. YouTube video below:

https://youtu.be/E2q_aya7AkI

Thoughts?

Kent — Round Rock, TX
'56 F-100  | '56 Crown Vic  |  '57 Fairlaine 500  |  '57 Thunderbird