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Technical Whole Lotta Shakin' Going On

Discussion in 'The Hokey Ass Message Board' started by MrPhat40, Oct 29, 2020.

  1. MrPhat40
    Joined: Apr 30, 2007
    Posts: 91


    Dear H.A.M.B'rs,

    Drove form Indy to Knoxville, TN for the NSRA South show the first of this month. The drive down was smooth and uneventful. Not so on the return. My coupe (40Ford) developed a pretty bad shake (it was as if I was driving constantly over those warning cuts in the road that you are going onto the shoulder). This shake occurred above 55 and would not dissipate thru 75 or so. I darned not going any faster. It seemed to go away for a bit if I changed lanes. This occurred on I-75 starting in KY and into OH. But when we changed to I-74 in IN. It stopped and I could not make it return until we took some side roads as interstate was getting nuts. Then it reappeared at 40 to 45 and would not stop no matter the speed.
    Upon arriving at home I noted that the front brakes (GM single piston calipers)appeared to be locking up. After changing out the pads, replacing the calipers and turning rotors I took it for a drive, no issues. The next day I took it to the interstate shake was back not as bad but back, side roads are fine not at 65 plus.

    Took it to my friends shop who re-balanced the tires (new Diamond Back radial) They came out fine. Put it on the lift, ball joints, steering rack, u joints all seem to have little to no play.

    Put is back on the interstate. Shake time!

    The steering system is :
    Early 70's GM van going into an upper u joint, welded to an approx 16 " shaft going into another u joint which fits onto the the Mustang ll spline.

    So this afternoon I am under the beast and grab the steering shaft. I have a bit of play maybe 1/32 of an inch in the u joint closest to the GM (circa 70's van) column. The column shaft also has a small amount of play.

    Central question how much play is too much and why would this shake come on all of a sudden. I can not find anything broken or loose.

    Looking forward to your input. I am tried of this tune!
    VANDENPLAS and chryslerfan55 like this.
  2. drtrcrV-8
    Joined: Jan 6, 2013
    Posts: 1,568


    Toe-in?(alignment?) Shocks? Did you check the rear wheels/tires for balance? Just throwing suggestions... What front end are you using(clip or beam?)
  3. Happydaze
    Joined: Aug 21, 2009
    Posts: 1,292


    Any amount of play in the steering isn't good, but that usually sneaks up on you as things progressively wear /worsen.

    I'd be looking at the tires. New and newly rebalanced I'd still suspect them. Swap them, permanently or temporarily to test, or get them onto a Hunter Road Force machine which will test them under load and highlight any internally breaking down issues. The Hunter website lists tire shops which have the machine - well, the UK site does, so I'd guess the US one should too!

    chryslerfan55 and firstinsteele like this.

  4. oldsman41
    Joined: Jun 25, 2010
    Posts: 1,556


    I would go with the tires too, but one thing concerns me is slop in the column isn’t there a bearing in the gm columns that is suspect in the older years? I read something about a column problem years ago but can’t remember what maker had the problem..
  5. Sure it's not an ignition issue? Had a car that did the same thing, did what you did to no relief, finally checked the ignition. Checked all connections (disconnecting and reconnecting each one), the problem disappeared....
  6. MrPhat40
    Joined: Apr 30, 2007
    Posts: 91


    Thank you all for your input:

    Some more info: Front suspension is Heidts Mustang ll of 20 plus year old origin.
    There is a lower bearing in the column which seems to have a slight amount of play but only when i really yank on it.
    I am having the tires rechecked with a new machine due the shop that originally balanced them in a week or so.
    I do have a set of older wheels and tires which have never given me this issue. I will be putting them on shortly.

    One thing about the wheels and tires this condition just started out of the blue. When the road surface
    changed from one interstate to the other it was as if nothing was wrong? It went form a bad shake to a smooth ride no matter speed or lane.
    I will definitely look into that. Had a dist problem years ago so will recheck.
    VANDENPLAS and chryslerfan55 like this.
  7. jnaki
    Joined: Jan 1, 2015
    Posts: 6,987



    It does not matter if you have independent front suspension or an old beam axle. Any little road diversion, or going over some irregularities will throw any hot rod or normal daily driver out of whack. Your road trip as nice as it was, can create 700 miles of different road conditions and driving. Checking all suspension parts is fine but, the old time front end alignment person may be your answer.

    For any road bump or differences, may cause the alignment to go out of whack. Sometimes your tires are wearing at a different pattern and are not round. All of these can be checked by a good front end alignment/tire mechanic.

    Over the years of driving all sorts of cars, front end alignment, tire truing for getting a round tire, and suspension check is mandatory. From a 58 Impala on long road trips, a relatively stock 40 Ford Sedan Delivery, a 62 corvair, two El Caminos, several station wagons, and another 40 sedan delivery with a 327. Out of all of them, each had different shakes and “shimmy” action at speed. Usually a tire balance and alignment took care of the problem. But, there were times that the good alignment guy can check and see what is wrong.


    Some roads present different conditions. Some are crowned for drainage and could affect normal driving. But, for all of the knowledge that we seem to have, the guy that does it for a living would be the go-to guy to check everything. In our experience, the Cal Rake lowered 2nd 40 Ford Sedan Delivery with the 327 was the worst, until our expert front end alignment/tire guy took his time and got everything right. Then it was like it should be when driving your hot rod. It could be something simple as replacing a slightly worn part or a full check of suspension parts.

    Old thread on shimmy at speed:

    Everyone has a way to stop different shimmy attacks on their cars. The old axle on my first 1940 Ford Sedan Delivery was somehow aligned well and did not cause me any unnecessary wear or driving/handling problems at any speed. If we could get any speed with that reliable, Flathead motor. But, 7 years later when we purchased a modified 327 powered 1940 Ford Sedan Delivery that almost looked like my first one, it had more power, but it was not correctly set up in the driving and handling department.

    By this time, we had our own expert alignment service tech that had completely fixed the Impala, the first 40 Flathead Sedan Delivery, the 65 El Camino and now, sitting in his huge new alignment shop in the OC was our latest problem handling hot rod. A 327 powered 1940 Ford Sedan Delivery. He took it for several days and did almost everything he did on the other cars we owned. Lines drawn on the floor, measurements galore from front to back and side/side, each individual reading on his machines and calibration tools, etc.

    It looked like a doctor with all of his tools splayed out on a nice blue shop drop cloth, along side his chalk and measurement devices. Since he had a new shop, he did have some new equipment. But, he did rely on his training in the old school ways and for the last thing he tried, was to balance the wheels and tires using an old “on the car” motor set up balancing machine.

    The one thing he told me to do before I got to his shop, was to get the tires trued and round. Most people just don’t want to think that their tires are NOT round, so they skip this part of the fix.

    Then, the expert went to work doing his magic. After the long days, he told me the sedan delivery was fine and come back to his shop for a test drive. It rolled on the smooth streets in slow speeds and on the open highways past his shop at speed. No wobbles, shimmy motions or jerky handling. It drove like a sports car grabbing the road around corners and like a real car driving down the road with no external forces allowing the sedan delivery to sway or not. No, damper was necessary as the whole Ford front end was set up correctly, it just needed the fine tune by someone that had the expert skills to make it work.

    His advice was to enjoy driving such a cool hot rod and that try to avoid going over pot holes or huge dips at speed. Well noted and for the next several years, he checked everything and it was the best handling hot rod we had driven. My wife liked it so much that somedays, I was alone at home looking at her 62 Corvair and she was out doing errands or visiting friends in the 40 Ford Sedan Delivery.

    Most home builders have the techniques and knowledge, but someone who does it for a living just has those extra things that we normally don’t do or have the skills to get it done correctly. YRMV.
  8. Did you figure it out ?

    Im with @Crazy Steve, just had a unit in the shop that had a really bad shudder when driving and the customer, the dealership who looked at it before me, and myself all thought it was in the transmission , clutch pack shudder.

    had the unit shipped from there yard to my shop for a tranny rebuild. Did some testing first as I was not completely convinced and it’s a bitch to do a granny in this thing ( 20,000 lbs hyster yard forklift )
    Everything checked out good, drove it on our smooth paved parking lot and sure enough it was the ignition breaking down .

    found a bunch of chafed and corroded wiring in the harness.

    let us know what you found or if your still looking.

    the fact it’s not constant st any given speed but comes and goes does not have me convinced it’s a tire or mechanical issue.
  9. I would really be suspect of the tires and wheels... Years ago I had an OT pickup that would get a death wobble /vibration that would almost take me off the road. I took it to the 'hotshot' Bear shop in town several times and spent a BUNCH of money chasing that damned issue. Finally, I took it to an old school shop run by a laid-back old guy... He looked it over, asked what I had done to it recently (big tires and wheels), and told me to run it at least 500 miles and bring it back. I did what he suggested, then one day before work I dropped if off for him to work his magic on. He called late that afternoon and said to come get it. When I got there, he told me to take it out and run it on the hi-way, then come back. That thing was rock solid and smooth as can vibration, shake, shimmy....nothin' but one-hand driving. I went back to his shop and asked what all he had done.
    Just balance the tires and wheels (on the truck). As he explained it to me: no matter what we are told, new tires are NOT round and stable! Once mounted, they still need to flex and stretch for a number of miles before they can be ACCURATELY balanced (and trued, if necessary). Made sense to me!
    Asked what I owed him, since he had worked on for 7 1/2 hours, and he gave me a bill for 4 tire balances! I couldn't believe it...I tried to argue with him but he insisted that was all he did, so that's all he was charging me for! Couldn't believe it!
    After that, every new set of tires I bought got driven about 500 miles, then right into his shop! That guy was a genius when it came to wheel and frame work. I almost cried when he retired and closed shop.
    Morale of the story: don't ASSume your tire/wheel combo is true, run it a while, then find the best front end (not tire) shop in your area, and let them annalyze (sp)/fix it.
    YMMV, but it's worked well for me.

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