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73 eldo convert vibration

Started by TJ Hopland, May 29, 2010, 09:48:28 AM

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TJ Hopland

At highway speeds my 73 eldo convert has a annoying vibration.  It seems to be in the whole car, not just steering wheel.  Its been there as long as I have owned the car which is now 15 years.   It can be just noticeable or it can be so bad that you can hardly see through the rear view.  Its not quite so bad that you think the car is going to fall off the road but its bad enough that I really dont fell like driving it on the highway for long trips.   It can even change minute to minute.  Putting it in neutral does not have any effect.  Braking has no effect.  Slightly steering either way has no effect.    Over the years I have had 2 completely different sets of wheels and tires on the car.  Recently I replaced 2 tires with no change.  A few weeks a go I found a more old time shop that said they solved the problem by balancing the tires properly with the correct weights.   I was really excited when I went to pick it up thinking it was fixed.  I could tell it was smoother but overall did not solve the issue.  This is pretty much how its been over the years someone finds a problem, I pay to have it fixed but it really does not help.   Back when they first came out with the tire balance machine that loads the tire I paid a lot of money to have it done and they ended up finding a wheel problem so I got some other wheels they said checked out.  Same result as always, no real change.   Other than those tire things over the years I have also done 3 left drive shafts 2 rights.  The short extension shaft and bearing.  Rebuilt transmission.  Inspected final drive. Upper and lower ball joints.  Front wheel bearings replaced.  New front rotors. New calipers.  New front hoses.  No wheel covers.  Different wheel covers.  New rear wheel bearings.  New shocks all around.  Steering shock.  2 engines (one rebuilt).    All with the same result, no real change.   The car came from Texas so it has no rust on it.  I am fairly certain it has under 100K on it.   It did apparently get sideswiped fairly hard early in its life but on one has been able to find any cracks or damage to the frame or any mounts other than the front core support is slightly tweaked not allowing proper gap alignment of all the front clip parts like the grill and headlights to bumper and such.  Its not bad but if you look you can see its not right.     

My 75 hardtop is does not seem to have the issue and its a rusty pos with old tires, I even took off some of the wheel weights to fit the wheel overs.  Its not super smooth but its no where near as bad as the 73.    My other 73's are really not roadworthy.  One I drove at 55 for a few miles and it shook and rattled all over the place.  The other I only drove on a dirt road so it was really hard to tell but later I found out it had bad wheel bearings and some other issues.


Ideas on things I have not checked?
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

Dave Shepherd

I've seen this occur with the ft axle rubber damper go bad as well as any cv joint , now those have been replaced as you say so that should eliminate it. You don't say what speed this occurs, but have you tried running it ft wheels off the ground, properly supported of course, see you you can see excess axle runout, or feel the vibration inside the car, naturally a helper is required. here. BTW, do not go over 50 like this. Make sure you have no looseness in the rear suspension or wheel bearings.

TJ Hopland

Original axle had the damper none of the replacements have had one.  Original axles were thought to be worn.  Later ones were boot problems.   Speed is sometimes around 60 but usually worse at around 65-70.

Had it jacked up and in gear, there is visible run out but it did not really seem to rattle the car.  Been meaning to jack up other cars and see what is 'normal'  I dont have my 75 close by for comparison. 
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

35-709

If it is not shaking the steering wheel, and after having done all of that work, I would be looking at the rear components.  Were the rear rotors (or drums) replaced?  Do you get the vibration when the car is standing still while revving the engine up to the same RPM that it would be at if you were going down the road at 65 MPH?  Have you raised just the rear of the car and spun the rear wheels ON the car with an old HUNTER type balancer?  Could it be a rear axle stub is out of balance or slightly bent, it wouldn't take much.  Just some thoughts.
Geoff N.  
1935 Cadillac Sedan resto-mod "Big Red"
1973 Cadillac Caribou - Sold - but still in the family
1950 Jaguar Mark V Saloon resto-mod - Sold
1942 Cadillac 6269 - Sold
1968 Pontiac Bonneville Convertible - Sold
1950 Packard 2dr. Club Sedan
1935 Glenn Pray - Auburn Boattail Speedster, Gen. 2

"Cadillac Kid" Greg Surfas 15364

TJ,
If there was a difference, however slight when the front wheels were balanced,I think it would be safe to say the vibration comes from the front.  The rear end rotating pieces will usually work correctly if they are in the same county as the rest of the car, so let's look up front first.
I think you have answered your own question when you said the car had been hit. Where ever the bend in the frame exists, I would venture to say it is the cause of your vibration. If the "A" arms are out of alignment enough they would cause the CV joints to work continuously and that is an awful lot of iron rotating out of "true".   
I don't believe you said anything about having the balance of the shafts themselves checked.  Most drive shaft repair shops can check the balance for you.
Check the tabs where the "A" arms bolt to the frame and compare the two sides.
Good luck.
Greg
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-

Otto Skorzeny

I think Greg and Geoff both have valid points. Take it to a professional frame straightening shop and they'll be able to tell down to the millimeter how far out of whack things are. The new shops use lasers all over to get dozens of measurements.

The 4 wheels could theoretically be aligned with each other but not with the geometry of the car.

Now if it vibrates while sitting still and being revved high, you have a flywheel/harmonic balancer/etc. problem.

I would also put the front on stands and see what happens when the transmission is engaged. Maybe a shop near you has a dyno so that the engine and trans could be placed under load.
fward

Ask not what your country can do for you, but what you can do for YOURSELF

HUGE VENDOR LIST CLICK HERE

TJ Hopland

It has been in a body shop.  It was not a modern laser one.  Maybe that would be worth a try.   I will have to get it on the lift again and look at where I remember the damage and see if it looks like it gets back to the a arms.

The steering wheel moves but it does not seem to move any more than anything else in the car its just the first place tend to notice.

Rear is drums.  I dont think I replaced them, just had them turned.   Maybe tomorrow I will get it on the lift again and give em a spin but I would think if the axle was bent it would just cause tire wear issues?   Remember this is FWD car so the rear axle is just a solid bar with stub shafts welded to it. 

I never thought of balancing the drive shafts.  I guess I could ask how much that would cost.   I have a drive line shop that was able to do a wheel bearing for me last year.   Seems odd that there was no mention of that in the manuals or is that because when they were new they were good enough not to need it but how many remans down the road maybe they are off?

If I can get this thing to ride like a Cadillac I will dump some more money into it and drive it more often.  Right now on a nice day with the top down on city streets or in the park its great but put the top up and take it on the highway its one of the worst cars I own.

I assume the 71-76 converts should ride pretty much the same as the HT's?   My HT vibrates but its a different sort of vibration.
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

The Tassie Devil(le)

Out of balance tyres will cause shuddering at around 48 MPH.

Over 60 MPH, there has to be an alignment problem.   Especially Body Alignment, and with a Convertible, it sounds like your Chassis is seffering.

Bruce. >:D
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
'02 VX Series II Holden Commodore SS Sedan
(Past President Modified Chapter)

Past Cars of significance - to me
1935 Ford 3 Window Coupe
1936 Ford 5 Window Coupe
1937 Chevrolet Sports Coupe
1955 Chevrolet Convertible
1959 Ford Fairlane Ranch Wagon
1960 Cadillac CDV
1972 Cadillac Eldorado Coupe

bcroe

With all the stuff already swapped out, and an accident, I'd wonder about the front A arms.  Swapping a whole different suspension on from another car isn't that hard, you have torsion bar tools?  Also, a set of KYB gas shocks brought a near miraculous improvement in handling of my 79 Eldo.  Bruce Roe

Mike Josephic CLC #3877

Considering all that you have done, this may be a "long shot" but here goes.

I've owned a 1973 Eldo (coupe) since new.  What I found out early on that it is very
sensitive to they type of tires you put on -- especially in front.  The originals were
Uniroyal from the factory, they were OK but wore out quickly after about 15K miles.
The car was ordered from the factory with radials which were an option in '73.

Then, I tried Dunlops, next Michelins (the worst) and finally after suffering through
wearing those out put Firestones on it.

The Michelins especially caused front end vibration that was a real pain.  The steering
wheel would "wobble" from side to side at low speeds and the front end would vibrate
at higher speeds.  The tires also need to be spin balanced by somebody who knows what
they're doing and the correct weights used.

I would not know what type of tires to recommend to you today -- my Firestones are
about 8 years old but the car rides smooth as silk.  I'm not looking forward to replacing
them!

Mike
1955 Cadillac Eldorado
1973 Cadillac Eldorado
1995 Cadillac Seville
2004 Escalade
1997 GMC Suburban 4X4, 454 engine, 3/4 ton
custom built by Santa Fe in Evansville, IN
2011 Buick Lucerne CX
-------------------------------------
CLCMRC Museum Benefactor #38
Past: VP International Affiliates, Museum Board Director, President / Director Pittsburgh Region

TJ Hopland

The steering wheel would "wobble" from side to side at low speeds and the front end would vibrate
at higher speeds.  The tires also need to be spin balanced by somebody who knows what
they're doing and the correct weights used.


That sort of fits.    Is it because of the offset?

First set of tires when I got the car were old Montgomery Wards (like sears) glass something bias that had been sitting a long time so you could imagine what those felt like.  Car also came with some Uniroyal Tiger Paws that were worn but much newer.  I ran those for a few months while I worked on other things. I think I then went to 4 new Goodyear Regattas and when that did not do it that shop was the one that sold me on the wheel bearings and ball joints.  I remember jacking up the car there was no obvious play in those parts but I had em done anyway.    I also remember when I had 2 of those tires replaced a couple of years ago that the ones I took off were really screwed up.  The tread block was sort of in a zig zag pattern with buldges in the sidewalls.  Thinking about how bad those tires looked and that the car did not seem to really shake any different with those than the new ones.

I think I will look for a laser frame shop just to see what they can find.

I will also ask tires shops which tires they find need the least amount of balancing.     
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

Mike Josephic CLC #3877

By the "offset" are you talking about the wheel weights?  The outer weight had
a long shank on it to allow seating of the wheel cover.  The inner weight was the
standard type.

I don't know if those "long shank" outer weights are still available, but the alternative
would be the "stick-on" type that I have used on another car and they work well.
Just make sure they clean the wheel with brake cleaner or other solvent befoer applying.

Good luck,

Mike
1955 Cadillac Eldorado
1973 Cadillac Eldorado
1995 Cadillac Seville
2004 Escalade
1997 GMC Suburban 4X4, 454 engine, 3/4 ton
custom built by Santa Fe in Evansville, IN
2011 Buick Lucerne CX
-------------------------------------
CLCMRC Museum Benefactor #38
Past: VP International Affiliates, Museum Board Director, President / Director Pittsburgh Region

The Tassie Devil(le)

The CAX weights are still available.

Bruce. >:D
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
'02 VX Series II Holden Commodore SS Sedan
(Past President Modified Chapter)

Past Cars of significance - to me
1935 Ford 3 Window Coupe
1936 Ford 5 Window Coupe
1937 Chevrolet Sports Coupe
1955 Chevrolet Convertible
1959 Ford Fairlane Ranch Wagon
1960 Cadillac CDV
1972 Cadillac Eldorado Coupe

TJ Hopland

I know about the weights and they do still seem to be available just no one has them on hand and always says they can get them only to call back and say oh ya those are special order and will take a few days. 

Offset meaning the plane inside the wheel where the hub bolts to.   Before FWD that was usually somewhere near the center of the wheel.  On these its at the outside, sort of like a dually truck rim. 
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

TJ Hopland

Found a frame shop that gave it a quick check and said the frame damage is forward of the front suspension.

Went to yet another tire shop, this time one of the ones that is an advertiser in our local chapters newsletter.  They are an independent shop and handle several brands including Cooker and Diamondback.  A regular tech took a drive with me and did not think it was a tire issue so he suggested setting up an appointment to have the mechanicals checked with their old car guy.   He said the upper shock bolts were not tight and the sway bar end links were not tight.  He thought both of those things would make a difference but he thinks most of the trouble is the tires.  2 of them are Goodyear Regattas that I just bough a couple years ago.  He said that one is out of round and the other must have some issue because of the amount of weight it took to balance.  He said they both have a sort of odd wobble in the tread.   They gave me 3 options for tires 2 diamond backs and regular firestone 380's.   They think that the ride and quality is going to be about the same on all 3 tires only difference is really going to be cost and the ww size.  I really dont care about the ww size as long its there so I am thinking about the 380's.  In the past I have never liked Firestones but with these high end good years turning out to be junk and goodyear not really making a tire for this car anymore it seems I need to look for change.   One of the diamondbacks was a Firestone and the other is a Michelin. Both are 2x the cost of the 'standard' Firestone.    This shop seems to know what they are doing and they do work on older cars.  They stock the CAX weights and eldo valve stems.  THey also have various methods of balancing including on car if needed.  I really hate to throw more money into tires with no guarantee its going to solve the problem but it seems like this shop has the best chance of finding the problem if it can be found.   They want me to also get an alignment with the new tires but dont see any mechanical issues. 

Im out of town next week but the following week plan on rounding up 4 or more wheels with bad tires on them and getting them over to the shop to have them checked for roundness.  Once I get 4 decent ones I will have them put on and the alignment done and my current tires will go on the junkers or my winter beater hard top.

Any thoughts?   Anyone think I should spend 2x the money for a Diamond Back?     
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

The Tassie Devil(le)

G'day TJ,

Is there anyone in your area with an Eldorado that drives smoothly, and simply swap the wheels and tyres onto yours, and yours onto his, and see if it makes any difference?

This way, you will definitely know what is bad.   And shouldn't cost anything, as a fellow Eldo Owner would surely agree to help you.   I know, I would.

Bruce. >:D
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
'02 VX Series II Holden Commodore SS Sedan
(Past President Modified Chapter)

Past Cars of significance - to me
1935 Ford 3 Window Coupe
1936 Ford 5 Window Coupe
1937 Chevrolet Sports Coupe
1955 Chevrolet Convertible
1959 Ford Fairlane Ranch Wagon
1960 Cadillac CDV
1972 Cadillac Eldorado Coupe

TJ Hopland

I have another Eldo that is roadworthy or at least it was a year and a half ago when I parked it.  Only problem is it is currently being stored for free about a 6 hour round trip from where I currently live.  It had a vibration but not at all like the one on my convert.  I just dont have the time or anywhere to park another car anywhere near my house right now.  I have never really had the cars together in the same place at the same time, sort of a summer and winter car.  Sometimes the meet but usually in the spring or fall when I am making the swap but other things have changed so I have not even made the swap for a while.   I suppose at least short term getting that car up here may be a better deal than buying tires that may not solve the problem.   
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
80 Eldo Diesel
90 CDV
And other assorted stuff I keep buying for some reason

Otto Skorzeny

I would try to ascertain that the wheels and/or tires are indeed the culprit before blowing $600 or more.

Take car #2 out for a  15 -30 minute spin and see what it feels like BEFORE changing tires. Take notes or a dictation recorder while you drive. Swap the tires on BOTH cars.

I would drive both cars over the same route before and after the tire swap.

Does car #2 behave differently with the tires and wheels from car #1? Do the problems of car #1 now appear in car #2 where they didn't exist before?

Does car #1 behave better or worse with car #2's tires and wheels?

I know this is an all day chore but it might actually help get to the bottom of the situation once and for all.

fward

Ask not what your country can do for you, but what you can do for YOURSELF

HUGE VENDOR LIST CLICK HERE

"Cadillac Kid" Greg Surfas 15364

Guys,
Tires don't go out of balance, round, etc. and then "fix themselves. In the first post T.J said the symptoms "come and go" at Highway speeds.
T.J. my suggestion is to 1st, make sure your tires (front) are true and balanced , then go out on the highway and see what it takes to make the vibration "go away".  Is on a banked turn? On a flat turn"? Is it on an incline or decline or a combination of any of the above?
Since you said putting the car in Neutral makes no change in the vibration that only leaves the differential through the tires. 
The differential would whine and make noise if it was going bad, although you might pull the cover and inspect the internals for something amiss.
The final drive output bearings should be checked, and that really only leaves the half shafts. If they are out of alignment (with straight, meaning they are "cocked: to even a small degree, there is a tremendous amount of rotating mass to generate a harmonic vibration.
Even the frame being hit in front of the Upper A arm brackets can cause the frame to bend enough to throw the suspension and thus the half shafts out of alignment.
I hope I'm wrong and it's just tires.
Greg
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-

Otto Skorzeny

Tires don't fix themselves, of course, but certain conditions may make the problem seem to come and go. Speed, road surface, crown, etc. I wouldn't rule out a problem with the tires and wheels without further study.

Having said all that, I think the suspension geometry warrants more than the quick look it got at the frame shop. Careful measurements should be taken as Greg described earlier.
fward

Ask not what your country can do for you, but what you can do for YOURSELF

HUGE VENDOR LIST CLICK HERE