68' GT 350 Conv. (03372) - experiencing bad "swing-away" steering wheel/column shaking between 50/60 mph. Old problem but getting progressively worse. New Cooper tires on 10 spoke wheels. Tires/wheels recently balanced and checked for out-of-round- twice! Almost complete new front-end (brakes, calipers, rotors, bushings, tie rods, etc. The front end rebuild has alignment has helped, but still cannot eliminate vibration/shaking. Any help would be valuable. Dave W
Steering box could be worn out. In the 80s my 66 would hit bumps in the road causing the front wheels to chatter until I steered in to them causing them to settle down. You also have a rag joint at the base of the column. Check that.
dz
Shaking at specific speeds is usually wheel/tire related. Steering box wear would normally cause sloppy/loose steering.
Is it an automatic ? About 10 years ago, my 70 Cougar vert automatic started doing the same thing starting at about 45 -55 miles an hour. If I remember correctly, it wasn't constant, but came and went in fairly quick cycles. Anyway after checking everything you have checked and more, it turned out to be a bad torque converter. Something I had never before heard could cause that type of vibration.
u joint or drive shaft
Could be problem with the balance job/tire/wheel assy. Happens a lot! Not all balancers & mounting adapters are created equal! I would find a shop that has the proper adapters to center wheel on balancer via lug nut holes(same as on the vehicle) vs center hole. Lug-centric balancing.
I would suggest that you go to www.hunter.com and click on the red "contact hunter" option in upper RH corner. This will give you the sales & service reps in your area. They should know what shops in your area have the proper equipment/technicians to diagnose your situation if it is indeed a tire/wheel problem.
Hope this helps, Mike
Since its speed related I would guess its something that rotates in the driveline.
Personally attacking the smaller items like u joints would be the best strategy. Although uncommon you may have a driveshaft out of balance or even a bent axle.
Agree with Phil & Pete, I'd be looking at the U-joints.
Other areas to review:
Transmission & engine mounts
Front accessories bolted to the engine, crank pulley would be a good place to start.
Harmonics can travel throughout the chassis, which may have a similar "feel" for what you describe.
Then again, if you insist on it being rim/tire related, I'd be looking at the way the wheels are mounted to the car in relation to the lug nuts. A few times, I've seen where the holes in the rims where slightly hogged out (worn), enough to not allow for a firm fit to the lugs, no matter how tight you made the lug nuts.
Bill
Oh wheel lugs...i once used 10 spoke wheel lugs on a steel rim. The car was on-a dolly.
Everytime I slowed down, the trailer and car pulled. When I did the safety check on day two each of the lugs was worn half way through. I was literally a few miles from having the wheels fall off
Quote from: CharlesTurner on December 19, 2023, 07:04:30 PM
Shaking at specific speeds is usually wheel/tire related.
+1 :)
Quote from: mikeh on December 20, 2023, 07:54:42 AM
Could be problem with the balance job/tire/wheel assy. Happens a lot! I would find a shop that has the proper adapters to center wheel on balancer via lug nut holes(same as on the vehicle) vs center hole. Lug-centric balancing.
Agreed, as I have had mostly negative experiences with the inability of the tire & wheel balancing efforts by the so-called experts over the years! >:(
But do note that most O.E.M. wheel applications are "hub-centric"; though yes, most after-market wheels will be found to be of the so-called "lug-centric" system; though this is truly only accurate, or more importantly, only provides for proper fitment (registering) is if you are speaking of "10-hole (bolt/lug) Budd rims, generally as witnessed on older semi-trucks! ;)
So what do you have? ???
Remember, that generally the rule-of-thumb is that if you feel the vibration in the seat, then it's emanating from behind you; if you feel the vibration more in the steering wheel, then it's coming from ahead of you. Assuming that your drawing a appropriate conclusion in this initial observation? :-\
Scott.
I guess you could try some steel wheels and see what happens
Many of these cars got a vibration damper attached to the tailshaft of the C4 if they vibrated. Maybe this is one of them?
also not uncommon if using stick on wheel weights for them to come off
Some great comments .... Several ideas we have not addressed - but will shortly. Steering box was replaced 5 or 6 yrs ago, but it sure demands checking out !! Discount Tire is ordering 235/60 Goodrich T/A radials to replace the Cooper's (at no charge - how's that for good service). Again, thanks for comments, very useful!!! D
Quote from: Royce Peterson on December 20, 2023, 11:38:41 AM
Many of these cars got a vibration damper attached to the tailshaft of the C4 if they vibrated. Maybe this is one of them?
Yesteryear's engineering solution to a body vibration at speed: Hang a bunch of iron underneath (a la '61 Lincolns.)
Problem solved!
Try rotating front to back and see if it changes. Did you have the wheels on it before you changed the tires? If it didn't do it then, point to the tires. If you added both at the same time. Jack it up, crank it up, put it in gear and see if the wheels are turning true on the axles. Your wheels should be hub centric but if not sometimes they can bolt up out of round believe it or not. I've had some 66 wheels that were drilled off center. If they look out of round bolted up take them off and move the wheel on the hub and give it another try. Make sure when they balance them they are not just balancing them on one side. The brand tire you have is not the most perfect tire for roundness like a Michelin but I understand you have them for looks. I've even seen rear brake drums way out of balance that caused problems (very rare) The big question is when did the problem start was it always like that or just when you changed the tires. If it started when you changed the tires then it's the tires or one of them. Call me and I can give you more tips I worked in our family tire business for a long time and used to be the one that fixed the problems. 828-308-8103 Andy