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1966 Series 60 Fleetwood: Shaky at 40mph and up

Started by 69Deville, January 27, 2023, 01:56:54 PM

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69Deville

My recently acquired 1966 Series 60 Fleetwood starts to feel shaky at about 40mph and gets worse as its speed increases. I have replaced the tires, idler arm (had a new one lying around), and stabilizer links. Its been inspected at a Les Schwab when the tires were installed and they thought everything looked good even though it shakes exactly the same after the new tires were installed and the front bearings were repacked.

When it is shaking, the steering wheel is rocking back and forth about an inch in each direction. The shocks seem to be good although the air ride is disabled and it has regular shocks in the rear.

Looking for guidance as to what suspension or steering components it could be.

Thank you!
-Dave
1969 Cadillac Deville Convertible
1966 Cadillac Series 60 Fleetwood
1996 Cadillac Fleetwood Brougham-sold :(

kyle242gt

Sounds like you can rule out wheel trueness and balance (but you could try rotating front to back to see if anything changes).

Similarly, sounds like you can assume bearings are okay (easy enough to test rocking the wheel with the car in the air).

It could also be idler arm, balljoints, tierods (also easy to check by rocking the wheel in the air, or by having a helper move the steering wheel and looking for play in the various points).

Absent that, my guess is front shocks.
Kyle Hage
1967 Coupe DeVille

James Landi

Sounds like you can rule out wheel trueness and balance (but you could try rotating front to back to see if anything changes).

Kyle mentioned "wheel trueness" and I urge you to check this out for yourseidlf. I had a similar issue decades ago, and spent hundred of dollars on the front end, alignment, parts, pitman and idler arms, and service. The service manager told me that "It's an old car,with high mileage, and you'll need to live with it." I discovered the issue when, months later, my wife was driving  behind me and I could readily see in my rear view mirror, that the passenger side  front rim was bent, it wobbled as she drove down the road. (When I asked her, she remembered that she had clipped a curb some months prior). Jack up each front side, and spin each wheel...train your eye on the tire tread that would normally contact the road.  If one of your steel wheels is bent, you'll detect it.   Hope this helps.

fishnjim

Mileage?
Any good front end shop should be able to sort this out. A bent rim should show up on the spin wheel balancer.  I assume they did that?  I don't know many shops left with the old bubble level balancers.
My gut says ball joints, that's when you get the "flutter" but if I could tell over the internet, I'd be clairvoyant.   You can jack the front wheels off the ground about an inch and there's a tool to check the ball joints, and tie rods or play.
Could even be in the steering.  Check the "rag joint" on the steering column.  It's a buck-3-98 part.
Once one thing gets loose it works on all the other parts til they get bad, so you got to spend some jack to get it straight again.  Frankly I wouldn't drive it like that.  Minimal cost to replace all the working parts int eh suspension.
If you can't find suspension parts at the local parts store, try rareparts.com

James Landi

"Any good front end shop should be able to sort this out. A bent rim should show up on the spin wheel balancer."

Often, it's the case that a tech will put a wheel on a dynamic balancer and not pay close attention to the possibility of a bent wheel.  You may be correct Mr. Fishnjim, but I suggest this member not overlook what may be a very obvious, and inexpensive fix.  Cadillac front ends tend to "dance" at certain speeds, and sometimes a tire that's delaminating can create a difficult to diagnose front end dance at certain speeds--- this guy says the "shakes" start at 40 and get worse with additional speed.  Bent rim or perhaps a defective tire would be an easy circumstance to eliminate.   Hope this helps, James

cadillactim

Move front tires to back and back tires to front. Now see if vibration is felt more in the seat than the steering wheel. If so, it is a tire/ wheel problem on one or both in the back. If no difference check driveshaft in addition to front suspension.

Tim
Tim Groves

"Cadillac Kid" Greg Surfas 15364

I would definitely look at the drive shaft. Carden joint wear is common and causes an increasing vibration and sound as the speed goes up
Greg Surfas
Cadillac Kid-Greg Surfas
Director Modified Chapter CLC
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

badpoints

I would assume a shop could find any bad ball joints or tie rods. I would check the a frame bushings.

69Deville

Thank you everyone for your thoughtful responses!

I will be checking the rag joint, A frame bushings, replacing the shocks, and will check the ball joints. I did have new tires put on this week which did not improve the condition. The car needed them so I started there as the ones one it had been sitting for years with only minimal usage.

I'll report back next weekend when I have time to put it up on the jack stands. The car has 76k miles and only been driven 6k since 1980 so I am sure I will be waking up lots of gremlins along as I bring her back to life.
1969 Cadillac Deville Convertible
1966 Cadillac Series 60 Fleetwood
1996 Cadillac Fleetwood Brougham-sold :(