Convertible top slowing down ('75 Eldorado)

[benji808]

Convertible top has been working fine for about a year. Recently it has started to slow down and/or stop moving...I may have to give it a little manual help to get moving again. I'm not hearing any clicking like a relay going in and out, so I'm thinking the motor is tired and I need to get another one. Any other things I should check before swapping the motor?

Thanks!

[The Tassie Devil(le)]

G'day Ben,

Firstly, there are a couple of things to check before going out and buying stuff you might not need.

(1)   How old is the battery?

(2)   What is the weather like?   Cool?   Cold?   It can really make a difference.

(3)   Is it better when the engine running as you operate the top?

With regards to the battery, one way to check for a depleting battery is to hold a Volt Meeter onto the Battery Terminals and read the voltage.   Then, as the top is being operated, check the Volt Meter to see how low it gets to.   Yes, this will be a two-person operation.

I have one of these Volt Meters, and one would be surprised just how much current is drawn when using different operations happen.

Plus, check the battery terminals for tightness, and cleanliness.

Bruce.

PS.   When I get a battery, I make sure that it is the biggest one I can find that will fit within the battery container.   Never have too much battery.

[benji808]

Thanks!

1) battery has a 5/21 sticker, and so appears to have been replaced right before I bought it a year ago. It registers 12.4v/13.7v with car off/on, so seems healthy. Running the top with car off can drop it to 12.0v.

2) it's cooler, but not terribly cold (50s/60s Fahrenheit)

3) no major difference with car running- it still gets stuck when trying to open (it stops shortly after I start opening; if I give it a little push to get off of that full extension it will finish by itself, albeit slowly).

Thoughts?

[The Tassie Devil(le)]

Whenever I operate my roof, I make sure that the sun has been on it for a while to allow it to warm up.

Plus, when closing the roof, I make it a point of closing it before the sun goes down.

Down around the 50's F, I would consider to be too cold for normal operation as driving around at those temperatures wouldn't be good for my health.

Bruce.

[benji808]

Do you think a new motor would allow it to operate more quickly even at the lower temperatures?

[The Tassie Devil(le)]

Not necessarily, unless your motor was worn out.

I got a new one for a friend down here, and it didn't perform any better than the one he thought was worn out.   So we put the old one back in.

If I remember correctly, I re-set the drive cabling, and as he had a broken outer sleeve, I ended up getting him a new pair of cables.

I am pretty sure I renovated his drive units, but don't hold me to that.

Bruce.

[JeffBp]

I put a new motor on my 74 Eldo after the old one failed and it did not perform as strongly as the original had done. New one is Chinese made.

[benji808]

Thank you for the input!

[TJ Hopland]

The relay can cause it to be weak also.  Its kinda an odd circuit where half the motors power runs direct through the switch then the rest runs through the relay.  If the relay has issues you get some power that back feeds through the other part of the motor so it still kinda works for a while but it basically ends up running the motor at half power and burns it up.   Its the same relay and circuit they used for the power seats.  Like many relays in the era its not a normal one.

[fishnjim]

You might try to lube the joints on the frame and see if it improves.  But those motors are canned so not able to check them. 
Inspect the cylinders for bent or leaks.
Could possibly be low on fluid, but usually you'll hear some spurting/air if low.   
Also the contacts on the switch can start to burn and need a cleaning and shot of contact cleaner.  They draw around 20-25 amps.  Not sure if '75 is on relays(?) but same thing on the high side.  That's close to the last year for ragtops.
You can check the motor amp draw vs the published specs and see if it's not putting out.
Battery should show 12.6 VDC when fully charged.  Also the cable and clamps can get corrosion and increase voltage drop to the users.  Might need a new set of bat. cables if they're crusty.

[The Tassie Devil(le)]

Sorry Jim, but these tops aren't hydraulic.   All electric and mechanical.

Bruce.

[TJ Hopland]

Here is a diagram showing how the relay only runs half the motor so its possible to have a bad relay and still have the motor sort of work.

[Steve Lomas]

I fixed a couple of these with the same issue in the past.

One was the relay behind the back seat, it worked but the wire contacts were partially burned out and not delivering enough juice, re-did the contacts and it worked fine.

On the other, the motor was very stiff to turn by hand- and it was the (nylon?) gears attached to the motor-
not sure if they swell over time, but they were extremely tight. I shaved some material off the teeth and the roof worked great after that.

As per some comments above, I'd make a new motor the last resort, I haven't found the motors themselves to be a problem in the roof, windows or seats- they seem pretty tough. usually something else.