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Sever driveline "Shakes".

Started by 66dave284, December 19, 2023, 06:00:37 PM

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66dave284

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

davez

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

CharlesTurner

Shaking at specific speeds is usually wheel/tire related.  Steering box wear would normally cause sloppy/loose steering.
Charles Turner
MCA/SAAC Judge

jk66gt350

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.

gt350shelb

Some where some one is driving their collector car for the last time but they don't know it . Drive your car every time like it could be the last memory of it .

mikeh

#5
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

Coralsnake

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.

The original Influencer, check out www.thecoralsnake.com

Bill

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
Instead of being part of the problem, be part of a successful solution.
HOW TO IDENTIFY A FORUM TROLL
https://www.saacforum.com/index.php?topic=16401.0

Coralsnake

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
The original Influencer, check out www.thecoralsnake.com

pbf777

#9
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.

     

Coralsnake

I guess you could try some steel wheels and see what happens
The original Influencer, check out www.thecoralsnake.com

Royce Peterson

Many of these cars got a vibration damper attached to the tailshaft of the C4 if they vibrated. Maybe this is one of them?

1968 Cougar XR-7 GT-E 427 Side Oiler C6 3.50 Detroit Locker
1968 1/2 Cougar XR-7 428CJ Ram Air C6 3.91 Traction Lock

gt350shelb

also not uncommon if using stick on wheel weights for them to come off
Some where some one is driving their collector car for the last time but they don't know it . Drive your car every time like it could be the last memory of it .

66dave284

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 

Side-Oilers

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!
Current:
2006 FGT, Tungsten. Whipple, HRE 20s, Ohlin coil-overs. Top Speed Certified 210.7 mph.

Kirkham Cobra 427.  482-inch aluminum side-oiler. Tremec 5-spd.

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