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1980 Eldorado shake

Started by steve punzo, July 06, 2014, 09:44:52 AM

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steve punzo

  80 eldo shaking/shimmying between 65-70 mph. No issues at lower speeds.   More an entire car issue than a steering wheel issue.   Thoughts?

TJ Hopland

What sort of frequency / rate is the shake?   Is it fast enough that its a buzz or is it still kinda a shake?

Have you messed with tires?  Rotate, balance to see if there are any changes to the issue?   How old are they?

Have you jacked each wheel off the ground and gave em a wiggle to see if you have any major bearing or suspension issues?

Does your air ride work correctly?   The rear suspension geometry is a little funky on these cars so if your shocks are shot and you are not maintaining the correct ride height you get rear 'bump steer' which is pretty wacky the first few times you have it happen. 
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

steve punzo

Thanks TJ,  I'll fwd this to my mechanic. Recently purchased the car and this is the first time I've had it up in that range. Only has 18K on it, so anything is possible  Also hearing an occasional sound like the tires are rubbing against the wheel well, but that has been ruled out. Don't know what that could be or if that has anything to do with it. 

steve punzo

Tires are brand new but they are 215 and the eldo calls for a 205.  Could that be a cause? I didn't think so because it wasnt happening at lower speeds

TJ Hopland

Overall the suspension and wheel bearings and such are very similar to more modern cars so your shop should not have too much trouble checking out the basics.   Most FWD cars use a McPherson strut which is both the shock, spring, and upper pivot for the front wheel.   These cars use a torsion bar.   The front suspension on these is almost identical to what is used on the 87 and up GM 4x4 trucks so again a typical shop should not be that confused looking at it.   

The 215's should be alright.  They may not have been an option in 80 but later in the body style that size came with a touring option package.  Seems like my 80 had 215's when I got it.   I ended up with 205's because they were in stock and cheaper than special order 215's.   Even with the 215's I don't remember anything being that close that you should have rubbing going on. 

There should be a light on the dash that says level ride that comes on when you first start the car or when the load changes, you may also hear a noise from under the hood especially with the engine not running, this is the compressor filling the air shocks.   The compressor is mounted on the forward part of the left fender.    If you have say a 200+ pound person sit or stand on the rear bumper and turn the key on that should be enough to make the compressor run and level the car if it still works.   The manual gives specific dimensions and points to measure from but if its sitting level its likely pretty close.   Usually if the air ride is not working the back end will sit quite low and bounce a lot especially with rear seat passengers, cargo in the trunk, or even just a full tank of fuel.   These cars have an independent rear suspension that is similar in many ways to a front suspension (just like most cars starting in the 90's).   As the suspension moves the rear wheels slightly steer which is a very strange feeling.  These days most cars have a setup like that but back then it was pretty unique.   
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

76eldo

Steve

How severe is this?  Could it be wheel balance?  Does it seem like front or rear?  And steering wheel shake?

The level ride is (was) working.  The tires are almost new.
It is possible for a steel belt to shift in a tire and that car did a lot of sitting around.
Ill look for the receipt for the tires. Ive had that car up to 70-75 mph with no vibration or shake.
Better pull the hubcaps off and check the tightness of the lug nuts.
The wheels were off to inspect the brakes and to take photos. I am sure they are tight but please check them before driving it again. Anything is possible.

The suspension Including air ride Nd front end was inspected by me and by a Cadillac dealer before your purchase.  Please let me know what you find out.
Brian Rachlin
Huntingdon Valley, Pa
I prefer email's not PM's rachlin@comcast.net

1960 62 Series Conv with Factory Tri Power
1970 DeVille Conv
1970 Eldo
1970 Caribu (?) "The Cadmino"
1973 Eldorado Conv Pace Car
1976 Eldorado Conv
1980 Eldorado H & E Conv
1993 Allante with Hardtop (X2)
2008 DTS
2012 CTS Coupe
2017 XT
1956 Thunderbird
1966 Olds Toronado

TJ Hopland

#6
Quote from: 76eldo on July 06, 2014, 12:13:50 PM
The tires are almost new.
It is possible for a steel belt to shift in a tire and that car did a lot of sitting around.

Almost new but it did a lot of sitting around with the new tires?   Or perhaps are these are just tires with very few miles on em? 

Tires in the last 10 or so years don't seem to age like tires from 20 or even longer ago.   Like most people here in my lifetime I have driven cars with 20+ year old tires and not had any sort of issues, vibration or failures.   In the last 3 years I have had 3 sudden failures of tires between 5 and 10 years old.  In 2 of the 3 cases they had very few miles on em and had spent most of their lives indoors so they were not weathered.   I'm not saying that is the issue here just saying it in hopes of saving others the hassle or possibly safety issues with newer old tires.       

While Brian is looking for more info on those tires you can just look at the date codes on the tires.  Its a 4 digit number that is stamped in rather than raised like the rest of the numbers and letters.   First two numbers are the week number, last two the year so say 5209 would mean a tire that was made the last week of December of 2009.  5009 would be early December.  0110 would be first week Jan 2010.   Pretty simple. 
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

bcroe

Quote from: steve punzoTires are brand new but they are 215 and the eldo calls for a 205. 
Could that be a cause? I didn't think so because it wasnt happening at lower speeds   

My 79 Eldo runs 215s, no problem.  I would try swapping some tires; that found an
early problem for me.  Bruce Roe

steve punzo

  Thanks TJ:

Brian, took it Mohegan Sun last night.  First real highway ride I've taken it on. Up to 65mph was ok, but somewhere between 65-70 car started to shake.  Rear passengers felt it too. On a scale of 1-5, I'd call it a 3. Not a complete rattle, but something all 4 of us felt.  I kept it at or below 65.  When I started it for the return trip, the Ride Level light came on for around 20 seconds. Again, the magic number seemed to be 65-ish.  When I have him install the BCM,  I'll tell him what happened and have him diagnose.

Thanks Guys 

steve punzo

TJ,
   come to think of it, it did feel more like a buzz than a shake 

76eldo

Probably just tire balance.
The tires were on it when I bought it but I assume they were balanced.

Level ride light coming on when you start up is normal. The system senses a change in load in the car and adjusts accordingly.

Brian
Brian Rachlin
Huntingdon Valley, Pa
I prefer email's not PM's rachlin@comcast.net

1960 62 Series Conv with Factory Tri Power
1970 DeVille Conv
1970 Eldo
1970 Caribu (?) "The Cadmino"
1973 Eldorado Conv Pace Car
1976 Eldorado Conv
1980 Eldorado H & E Conv
1993 Allante with Hardtop (X2)
2008 DTS
2012 CTS Coupe
2017 XT
1956 Thunderbird
1966 Olds Toronado

TJ Hopland

The level / ride height stuff would not cause a buzz sort of a feeling other than the compressor itself running which you would not feel with the engine running.    Sounds like that is working anyway so its not the issue.   

I was trying to get an idea of the frequency of the problem, more of a buzz means its a higher speed thing.   Sounds like a good close look at the tires its going to be a good first step.   Have the shop get the thing on the lift and give em all a good wiggle to make sure there is not something wrong with the suspension (sounds unlikely).   Then assuming the date code on the tires are less than around 7 years throw them on the balance machine.  A good tire tech will give em a visual look while they are spinning up and down on the machine to look for things like a bent wheel or some funky tread thing.   Its certainly possible to get a wacky tire or a bent wheel to balance on the machine but obviously when you put it on a car and drive it things won't be right.

Tire issues can be somewhat inconsistent because it can depend on how each tire aligns with others.  Sometimes more than one tire can have a minor issue but they can align with each other and make a big vibration.   You can also have 2 big issues and they can align in such a way that they cancel each other out.   You go around a slight curve and change the relationship between the two and things change.    You can also get strange combos of a tire / wheel balance issue when they combine with say a out of balance drum or rotor.  Sometimes just removing the wheel and putting it on oriented differently will change things. 

Has this car got the wire wheel covers?    Those things weight a ton and a half so there could be something there contributing to the issue too.   
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

steve punzo

TJ, thanks for all the info.  Yes to wire wheel covers

TJ Hopland

You will be amazed how heavy those wheel covers are.   Each spoke is an individually cast piece.   If the tires all check out it may be worth a test drive without the covers to see if that makes a difference.   Its kinda a pain to remove them because the locking spider thing usually rattles if you don't have the covers on so you have to remove those 3 nuts to get that spider off then re install and torque the lug nuts. 

Not sure how you would fix the issue if it does turn out to be the covers and they are not obviously damaged. 
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