1956 Power Top Limit Switch Mechanicals

[Richard M.]

Re: 1956 Power Top Limit Switch Mechanicals

Gary, I found the problem. The switches were all fine and wired correctly. It was the wiring to the solenoids that was wrong. I followed the wiring when I got the car here and recorded it and re-connected the same way. It was wrong. They had the Top cover solenoids and Soft Top solenoid wires reversed. I just swapped out the 4 wires and it's all set. Works quite well. I didn't time it but i guess it's about 20 seconds. That's what the book says it takes.

I have one sticky limit switch in the well, the "top=down" long arm toggle switch. It sticks down and doesn't return. It needs a little more TLC, just a spring adjustment inside. Then the entire system will be fully functional.

A video is loading on Youtube of the testing and operation after fully re-installed on the car.

here......

http://youtu.be/VjRZoxL4jl8

Thanks for everyone's help.
Rich

[Edward M.]

Re: 1956 Power Top Limit Switch Mechanicals

Rich;

I have been following your rebuild of the PT system both here and on CF. Absolutely fascinating; and great job.
One thing that I have been wondering is if there might be an electromechanical cylinder system that could replace the hydraulic cylinders.
Just a random thought.

Good job man, good job.

[Richard M.]

Re: 1956 Power Top Limit Switch Mechanicals

Hi Ed, Thanks for your help with some of my issues too.

One thing I learned the hard way with this '56, is that the documentation is really minimal, especially the mechanical "features" of the limit switches and brackets. I've gotten it pretty well down pat now, and I'm going to try to get it all documented when I get some spare time.

So I was wondering the same thing about electric lifts every time I had to purge the ATF to rework the pump and motor. I had it apart about 5 or 6 times to get it right. Because it was originally assembled wrong by a prior in several places I had to research much. If it had DOT 3 fluid in it it would have been scary for sure. I can imagine the guys at the dealerships in the 50's and 60's when a Corvette warranty job came in with a Power Top problem. Sick Time!

I know other folks have done some electric lifts on some "updated" restorations. I've actually done some electric engine hood lifts on some antique Jersey Skiff race boats in the past. Very noisy though, as it's a electric motor driven screw drive.

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but we used hydraulics for the custom 2-place boat trailer.
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.....
This '56 had to be original of course, so I stuck with the fluids.

Rich

[Richard M.]

Re: 1956 Power Top Limit Switch Mechanicals

I repaired the sticky "top is down"(long toggle) limit switch. Had to take it apart to clean the mechanism and bent the internal contact slightly. I re-installed it then adjusted both limit switches, in particular the "top is up"(short toggle with link) limit switch, so it comes down a bit softer onto the windshield header.

Another video here that shows it's working pretty darn close to original now, and repeatable. http://youtu.be/JJWWOiPeGIs

Rich
p.s. you may not see it for a while as the upload take a few hours.

[Gerry P.]

Re: 1956 Power Top Limit Switch Mechanicals

Great job Rich. Even though you're restoring a '56 and mine is a '57, I've copied and saved your postings as they'll prove very helpful when I start on mine. Thanks again for the great documentation.
Gerry

[Richard M.]

Re: 1956 Power Top Limit Switch Mechanicals

Okay, now that this power top is working pretty well, it's back to the details.

For that short toggle limit switch, for my testing I used a string tied to the frame arm. My adjustments to get the top to stop before the header were simply tying a different knot. Now I need to make a duplicate of the original link.

Gary Barnes had that one picture, and it used a stiff wire for the link. I can make that bracket okay, but the link is a bit confusing. It has to be adjustable so that the short toggle lever doesn't get pulled too hard. I don't want to break it with just a solid wire with a bend at the switch. I'd imagine it may be threaded at the end so it's adjustable too.

Cecil is trying to locate his switch and maybe he has the rod/link too. It'd be great to see the actual mechanism construction so I can duplicate.

I'm also going to add the 4 relays behind the division panel. I'm going to have to run a new 12G feed to that area, but getting from the dash to the trunk is going to be a new adventure for me. I haven't had the pleasure of "dash to trunk" wiring on a '56/'57 in my adventures yet.

Rich

[Richard M.]

Re: 1956 Power Top Limit Switch Mechanicals

Here's a blow-up of Gary's photo. I'm making the link bracket. It's so nice to have a reference, thanks again Gary. I'm even going to try to find some #10-32 Phillips machine screws which appear to have oversize heads that look just like those.
1956TopLimitSwitchesCrop1.jpg


I found a nice link rod I can use, threaded #4-40 from my old Radio Control spare parts bins. I put a small spring and a few flat washers, with nut and locknut.
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This should give me a good adjustment for the top-up limit switch, and keep the forces on the toggle switch to a minimum. Hoping to be a good solution until I can find the original type setup.

I bead blasted and re-painted that switch cover as it was red and white and junky looking. I had no beige so I just used a off-white I had lying around. Looks better than what it was.

Rich

[Richard M.]

Re: 1956 Power Top Limit Switch Mechanicals

Top-up limit switch link Bracket made, painted, adjusted the link and the top comes down softly onto the header. It was hard to see in the original photo, but the frame is curved there. I figured the little bracket is probably curved to match the frame, so it was a bit trickier to make, but I opted to do it that way. This top frame is a later year black frame, so I had to paint the bracket black to match.

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It works a whole lot better than the string I was using.

I got on the YT kick so I did another video clip of the limit switch mechanisms at work.

http://youtu.be/JP-WGrNgqzc

Rich

[Richard M.]

Re: 1956 Power Top Limit Switch Mechanicals

Cecil Loter found one of his original limit switch assemblies, and it had the mysterious wire link still attached. He agreed I should post the pictures here for future reference.

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End to end it is 6 1/4". The length that is between the part that would link into the bracket(at the 90* double bend), and just before the loop(where it is held by the toggle slot) is 5 3/4". It's spring steel and difficult to bend. It appears to be the diameter of typical carburetor linkage rods, IMO probably 3/32" or so.

Thanks Cecil !!!

Rich

[Cecil L.]

Re: 1956 Power Top Limit Switch Mechanicals

Actually Rich, it looks like it's closer to the thickness of a big paperclip or a wire binder retainer in the old Vette Vues Magazine binders. I don't have my calipers here but placing it over a rule, it looks closer to 1/16 diameter.

[Richard M.]

Re: 1956 Power Top Limit Switch Mechanicals

Thanks for clarifying that Cecil. I was trying to eyeball it. It seems pretty close to what I used here in fact.

I have a non-threaded rod and I may try to duplicate yours. But I'll have to use the adjustable bracket for the switches to adjust the upper limit. The slots in the bracket allow fore & aft movement. Also, the vertical slot for the switch can be adjusted. The vertical slot for the "Down" limit switch may need some movement.

Rich

[Richard M.]

Re: 1956 Power Top Limit Switch Mechanicals

Playing around in MS Paint this morning I modified the 1956 Wiring Diagram and added some notes for future "Top Gunners".

Rich
edit....yukky size so I'll put a link to a bigger view too.

1956PT_Wiring_Rev1.jpg

Downloadable link here too.....http://home.comcast.net/~richmz/onli...iring_Rev1.jpg

[Cecil L.]

Re: 1956 Power Top Limit Switch Mechanicals

Great work Rich.
BTW, if anyone needs a replacement spring loaded toggle switch, these look identical to the landing gear uplock switches on my 46 North American Navion. Of course the toggle itself will be different but the internals should be the same.
I'll look next time I'm at the hangar......pretty sure I have a new one on the shelf.
Nice to know they can be disassembled and cleaned to cure the stickiness as that is a common problem with the gear indicating system.

[Richard M.]

Re: 1956 Power Top Limit Switch Mechanicals

Okay, Here it is....the original style switch link rod. Thanks to that nice photo I duplicated it pretty closely.

P7050001.jpg

Now, more interesting info. My link measured perfectly against the original in the pic, but it was too far away from toggling the switch, so I guessed there may be a spring used there, plus also as a little shock absorber like my setup before. I chose a few and tested until I found the right one. It's 1" long and about 1/4"" OD. With this choice I'm about in the middle of both slotted adjustments in the bracket and the Up Limit Switch itself. I readjusted both switches and the top works fine as it did before.

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My 1929 to 1959 P&A 30 Book shows:

1956 Corvette 3716332 "SPRING Comp Lid Switch" 1 That must be the spring.
1956 Corvette 3716367 "ROD rr. Contl Link Switch" 1 That must be the rod.

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I think I finally figured out this switch arrangement. Thanks guys!

Rich

[Richard M.]

Re: 1956 Power Top Limit Switch Mechanicals

To close out the description of work on this 1956 Power Top System, here are a few more posts with pics.......

I fabricated a duplicate of Cecil's top limit switch link rod, installed with the spring, adjusted the limit switch, and it works fine. I adjusted the limit switch in it's slot for a gentle drop of the soft top header on to the windshield header frame.. Here are the photos of the subject parts. I also found some part numbers and descriptions in my 1959 P & A Book.

My 1929 to 1959 P&A 30 Book shows:

1956 Corvette 3716332 "SPRING Comp Lid Switch" 1 The spring.
1956 Corvette 3716367 "ROD rr. Contl Link Switch" 1 The rod.

P7050001.jpg P7050009.jpgP7050016.jpg P7050015.jpg

Since I had the system operating well, I decided to add relays to each of the 4 solenoids to increase longevity of the harness wiring and rare switches.