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Loose linkage to the transmission on my 66 Cadillac

Started by Jerry Leighton, June 25, 2019, 11:49:40 AM

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Jerry Leighton

Hello Cadillac collective minds,
    I had a most unfortunate mishap last month.  My 1966 Caddy Deville convertible decided to become self aware and drive itself backwards out of my driveway un-occupied.  Yes..it was idling in my driveway, popped itself out of park into reverse and started backing into me as i was standing behind my car.  I ran over to the passenger door to jump in and stop in but the door was locked.  By the time I ran around the front of the car to the driver's side door the old candy had overrode the parking break and rolled away from me as I was chasing after it like a dang cartoon character yelling noooooo!  Long story short my Caddy backed into my neighbor's garage doing substantial damage to my car and his garage...thank goodness for insurance.
     So, now that my car is off to the body shop for repairs, I am looking to all of your advice on preventing this from happening again.  Car's generally don't go Christine on you unexpectedly. I am going to have to inspect the rear breaks to see why the parking break did not hold (the vacuum auto release has not worked for 15 years).   Also, I recently drove my friend's 66 Fleetwood that is mechanically identical and noticed right away the at the shifter on his car is much more solid and stiff than the loose shifter linkage on my 66 vert.  So my question to you all is, what specific part's/pieces on the shifer linkage fail on these mid 60s Caddys?  and more importantly, how does one inspect and tighten the transmission shifter linkage?  Your help/Advice is much appreciated.
Kind regards,
-Jerry Leighton

TJ Hopland

Neighbor have a nicer garage than yours?   Nicer company in said garage than you have to offer?

My guess is the linkage is worn enough or out of adjustment that it wasn't fully in park so the vibration at idle was enough to rattle it into reverse.    The way to check it would be to safely gain access to the shift arm on the side of the transmission while someone is in the car operating the shifter.   Have them operate it while you watch so you can see which way is which then have them go to park.   My guess is if you then grab the arm and move it further in the park direction it will move further and actually click into the detent.   If that happens I would bet you could repeat the test and find that it would also very easily go into reverse.
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

savemy67

Hello Jerry,

I would check two things - the shift lever on the side of the transmission, and the linkage from the shift arm on the side of the steering column to the shift lever on the side of the transmission.  The reason is to determine if the problem is in the linkage (most likely), or in the transmission.

If you do not already own one, I strongly encourage you to get the shop manual for your year.  The correct linkage adjustment procedure will be described in the shop manual.  If the problem lies in the transmission (less likely), the fluid pan can be dropped, and a repair to the shift detent components can be made.

As TJ mentioned, having a helper may make checking the linkage an easier task.  Work safely when under your car.

Respectfully submitted,

Christopher Winter
Christopher Winter
1967 Sedan DeVille hardtop

bcroe

My guess...   There is nothing wrong inside the trans.  To be sure
unhook the linkage and see if turning it gives nice solid clicks in
each position. 

Check out the whole linkage for slack and mis alignment.  First get
any slop fixed.  Align by the book, my experience is Drive is right
in the center.  If so the arm from the trans should be at right angles
to the movement of the pusher rod in drive, larger or smaller angle
in other positions.  It should comfortably cover all positions. 

I suppose there is a slight chance the linkage for a different trans
is in there.  Bruce Roe

Glen

It was my impression the detents for the linkage was in the transmission.  See the attached image. 
The roller runs on the detent lever holding the linkage in place.  If the spring on the roller gets weak or the screw the holds it gets loose it can cause the problem you have.   
Glen Houlton CLC #727 
CLCMRC benefactor #104

Scot Minesinger

The loose linkage is usually the the bushing in frame is gone.  The trans linkage (at least on a 1969-70) relies on an in frame linkage bushing  easily viewed across from trans shift connection.  These bushings go after 40 years.

Normally on all these Caddys especially FWD Eldorados (1966-78 years) a sloppy shift handle on column is a bad bushing or two.
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

Jerry Leighton

Wow!  Thanks so much to you all for your very detailed advice.  When my car gets back from the auto body shop I will look into all of your suggestions to find out what the problem is and then fix it.
Kindest regards,
-Jerry

fishnjim

Sounds suspicious, like it could need an exorcism.   Life's little mysteries and lessons.
I lived on a hill, and I took spare tire off leaned it against garage to change flat, turned away, and it rolled down drive and then started to curve to miss the neighbors garage, but hit their shed about 500' away(beat chasing it through the woods), so parking on an incline and/or standing behind a running car has definite risk.   We call that potential(stored) energy.   Yours turned into kinetic energy for some reason.  It takes a bit of force to overcome starting friction - where else could it get it's energy?   
I parked the boat and truck at a service station about 4 AM to wait for my partner, and I went in the boat to arrange things.   I left the truck running(stick) on a level spot near the store by the light, and parking brake was on.   A SUV came and parked directly in front of me about 40 feet away, down slope.   Guy gets out, opens rear hatch, and my truck and boat started to roll right towards him for no reason(?).   I jumped out and jumped in and braked but not before it touched.   Must be some gravitational or magnetic attraction of metal vehicles?  Or demons...
Word to the wise: I always leave the driver door open now, if I get out with the vehicle running - like at the launch ramp.
So by analogy, your neighbor's garage is obviously in the wrong spot and was exerting a pulling force on your '66!   
There's a video on the net, of a guy launching his boat with his class A motorhome, he gets out to go to boat and all starts to roll back and completely submerges.   So you're in good company and it could always be worse.

Roger Zimmermann

There is only one thing to do when leaving the vehicle: shut the engine off and put in "P". Americans are doing almost the same like French people: they let the engine run, especially those smelling diesels and they go to buy their newspaper and baguette. Is that so difficult to shut the engine?
1956 Sedan de Ville (sold)
1956 Eldorado Biarritz
1957 Eldorado Brougham (sold)
1972 Coupe de Ville
2011 DTS
CLCMRC benefactor #101

BlackCads

I had a 1965 Buick Riviera that had a bad habit of slipping out of Park and rolling.
A transmission shop installed a new "parking pawl" and that solved the problem.
Until you can get the problem fixed may I suggest wheel chocks (available at auto parts stores) or simply 2 x 4s under the rear wheels?

Scot Minesinger

My 1965 Ford Thunderbird would never slip out of park if the standard slide away wheel was pushed to the right, which locked it in park.  This is like the brake interlock on a modern car, which usually will not shift out park unless foot is on break pedal.  If you did not slide steering column over and let the 65 T-bird run in park, like many Fords of the day it would jump into R.

I agree, shut off the engine when the car is stopped rather than letting it run.  Just too much to chance in an older car.
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

fishnjim

All my joking aside, other things to check besides linkage.
The fast and regular idle speed and condition of the park pawl(tear down required).   
The torque convertor has to spin down so the trans doesn't turn but if it idles too high, which these carb cars have for warm-up, A/C, etc. it can turn a little too fast and move the car.   
The old procedure was to check it in drive, but I don't know if that was still good for '66s.   
The park pawl can wear and not engage fully.   Anything with age and miles is more suspect for issues.   We like to think they'll run flawless forever, but reality is different.