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Why won't the hydraulic trunk pull down actually pull the trunk down?

Started by chrisntam, May 20, 2019, 12:34:55 AM

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chrisntam

After installing weatherstrip in the trunk (last year), the pull down mechanism isn't pulling the lid down (ever since the weatherstrip was installed).  The weatherstrip is down in the channel as it should be and the profile is the same as what was removed.  What was removed was very weak and thin (worn out).

The search function provided minimal information about why the lid won't pull down.

I have a video camera connected to the smart phone and am watching/learning how the mechanism works.  Not getting in the trunk, actually watching it from the outside is a lot easier.

The existing cylinder "appears" to be working, cylinder must be vertical to test it, one end in a vise, I pull on the other end (about 4 to 6 inches), it slowly retracts closed.  I have an extra cylinder that a local shop is rebuilding, so far they've put two new seals in it - it no longer leaks - but it needed more hydraulic fluid in it, they are doing that now, I should get it back tomorrow.

There's a spring inside the cylinder that keeps it closed.  When pulled open, the spring wants to close it, but fluid travels through an orifice, which slows the closing.

But my trunk doesn't pull down beyond the initial latch.  I can push the lid down a bit and I can see the latch getting lower inside the trunk, but it's not doing it on it's own.

Can the spring grow weak and not have the umph to pull the trunk down?

The cable is free and moving in the cable housing.

The latch mechanism is free and moving.

I have an entire replacement system from a donor car, I replaced the latch mechanism with the one from the donor and it appears to work better, but when closing, it makes kind of a snapping noise I think it shouldn't make.  I can't imagine the trunk closing and making that noise when the car was new, but I don't know.

For those with a working mechanism, is it noisy - snapping, clanging noise?

For those that don't work, what did you do to "abandon" the mechanism?

Any ideas what part of the mechanism actually pulls the trunk down?
1970 Deville Convertible 
Dallas, Texas

cadillacmike68

I'm not touching this one besides the following:

My old 1970 always gave me fits. It would release fine but never pull down correctly. IF I remember there is this arm with a rubber roller up under the front right side of the decklid which gets moved by the trunk as you lower it until the lock gets to the latch in the center rear. Then "something" would grab and pull the trunk the final inch or so. That's what never worked right for me.  The manual should have some adjustment info, but I'm not certain.

The later electric ones were much simpler. Even if I eventually install an electric release, I'll never try to retrofit the pull down on the 68.
Regards,
"Cadillac" Mike

The Tassie Devil(le)

One thing that has to be correct is that the cable that goes across the trunk floor from the lock to the tensioning cylinder has to be free to move internally, and any rustiness within is a no-no.

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

Scot Minesinger

Chris,

Just to be sure I get this, the trunk worked fine.  Then you replaced the weather stripping on the trunk and the pull down stopped working correctly?  Or did a shop (as opposed to you) replace the weather stripping on trunk and then it stopped working correctly?

In the past when I replaced weather stripping on all three of my 1970 Cadillacs I had to adjust the latch so it would not close all the way to gradually compress the rubber, then a week later adjust half way to original point of closure, and finally two weeks later adjust back to original tighter original close position. 

Was the trunk latch adjusted?  Maybe it is trying to close against too much rubber weather strip un-compressive resistance?  Maybe the shop messed up the close mechanism?
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

chrisntam

The trunk has never really pulled down like "I" think it should.  I think the weatherstrip install (I did it) compounded the issue.  I'm adjusting the latch to the point where the noise isn't horrendous and the trunk is latched, but the trunk lid is still high.

It'd be nice to know how well these worked back in the day.

My suspicion is the spring in the cylinder is fatigued and can't pull the lid down.  I wonder how much force a new spring generates vs. a 50 year old spring...

With the lid closed though, the spring would be in it's "relaxed" condition...

I headed to pick up the re-sealed cylinder, I'll put in in the afternoon and report back.

chris.
1970 Deville Convertible 
Dallas, Texas

"Cadillac Kid" Greg Surfas 15364

Chris
The end of the pull down is anchored by a tab on the right rear inner fender. That often tears loose and needs to be welded. I suggest you take a look.
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-

chrisntam

Hi Greg,  hope to see you in Louisville?

I'll check both ends to make sure nothing is torn or otherwise adulterated.  I hadn't noticed any issues there though.

I got the resealed cylinder back, it's pretty, I'm about to put it on, but I'm not really expecting anything different.

If new cylinder has no effect, I'll install the other cable...

Let's hope for the best!
1970 Deville Convertible 
Dallas, Texas

chrisntam

Well, the mosquitos have arrived, need some insect repellant...

>:(
1970 Deville Convertible 
Dallas, Texas

"Cadillac Kid" Greg Surfas 15364

I’m over in Kauai looking at the weather reports bAck home in SA and May we we’ll stay here a while longer.
Won’t make the GN this time. Taking a break and going to work on my hot rod.
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-

"Cadillac Kid" Greg Surfas 15364

Another “point of wear” is the roller/ramp adjustment. If there is too much wear in the roller or the ramp is bent full travel is not possible.
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-

chrisntam

Quote from: "Cadillac Kid"  Greg Surfas 15364 on May 20, 2019, 06:19:48 PM
I’m over in Kauai looking at the weather reports bAck home in SA and May we we’ll stay here a while longer.
Won’t make the GN this time. Taking a break and going to work on my hot rod.
Greg Surfas

Yeah, you should wait another month or so for it to really get hot!

;)
1970 Deville Convertible 
Dallas, Texas

chrisntam

The welded tab on the wheel well is firmly attached, I'll check the bell crank for wear.  I looked at my extra bell crank, the black roller was similar in size to what is on the car now.

I installed the resealed cylinder in and the trunk closing is working acceptably for now.  Still readying the car for the GN, will move to other issues, but I still don't think it's right.  Perhaps a combination of 50 years worth of a bit of wear on all the moving parts.

The trunk shuts still with a pretty good "clank", and doesn't noticeably "pull down" on it's own.  It doesn't move down on it's own after the clank.  If I push down on the trunk, I can see (using my wireless camera) the cable pulling down at the latch just a bit more, tightening the trunk to the body.

The guy at the cylinder rebuild place said the spring was pretty stout, he didn't think it would lose any force.

In the near future, I'll install the other cable to see if that changes anything.  Anyone know a good way to clean and lube a cable while it's in the housing?

Having that wireless camera sure is nice, you can see what is going on without having to get in and out of the trunk.  It also allows you to shut the trunk slowly to see what is going on.  About $40 at Amazon.

1970 Deville Convertible 
Dallas, Texas

The Tassie Devil(le)

Quote from: chrisntam on May 20, 2019, 07:21:30 PM
.......Anyone know a good way to clean and lube a cable while it's in the housing? 
I slightly freed up the inner cable in my '72 by liberally spraying it with CRC, and also belting it with a rubber hammer in an attempt to dislodge any rust within.

Got it moving better, but it finally moved even better when I found that there was a broken strand of wire inside, and managed to extract it, well, part of it.

I am going to replace the inner cable when I can get ends to swage onto the wire.

Obtained a replacement complete cable, but that one isn't any better.

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