1960 Power Top Update

[Joe M.]

After spending a small fortune and countless hours over a 6 week period, I have the power top installed and the up cycle works perfectly, but it will not bring down the folding top unless I push up near the header with one finger and apply a couple of pounds of pressure. I can see the cylinder rods trying to retract, but not enough power to get it started on its own. I have a new motor/pump and cylinders; so I am generating maximum power. It does not appear to be binding on anything as both cylinders appear to be trying to come down at the same rate, but if it is binding, I don't have any idea how to pin it down. If this is as good as it gets, I am going to be extremely disappointed.

I am out of ideas and a small fortune! (the small fortune I expected)

[Richard M.]

Re: 1960 Power Top Update

Joe,

Maybe low battery? Did you try it with the engine running and above 800 rpm so the generator is in charge mode?

Rich

[Joe M.]

Re: 1960 Power Top Update

That is a good point. I have it on a battery charger on the 10A mode; so I believe it is getting sufficient electricity. I am going to have the frame adjusted and see if that takes care of the problem. The up cycle take 22 seconds from start to finish. I never get tired watching it work!

[Thomas H.]

Re: 1960 Power Top Update

Joe,

First let me state that I know nothing of how these automatic tops work as my car has the standard push/pull manual top option. But I do know a thing or two about motors and electricity.

Your 10 amp charger may not provide enough current upon initial retraction. Rich had a good suggestion, run the car at a higher RPM and the combination of the generator and battery should provide more then enough current to get things moving.

Tom

[Joe M.]

Re: 1960 Power Top Update

That is a good idea, but the top should work correctly when the engine is not running, but that would rule out insufficient battery power with the engine off. I have a repro tar top battery which actually has a small AGM-type battery inside a plastic shell. i am not sure why it would be harder to bring the top down than raise it up.

I noticed that when the folding top header hits the top of the windshield, it really slams down hard on the top of the windshield and the two pins strike the windshield forward of the holes where they should insert. I believe that the frame needs a slight adjustment so the folding top header makes contact with the windshield about 1/2" back from the position it now strikes.

[Dan D.]

Re: 1960 Power Top Update

Joe, it could be your hydraulics are bypassing. I believe you said you had a new aftermarket pump. Could be the bypass spring is not heavy enough to pump the extra pressure needed to get it going. -Dan-

[Joe M.]

Re: 1960 Power Top Update

Where is the bypass spring located? I know several men who have used the same aftermarket cylinders and motor/pump and all tops functioned correctly. I am convinced that it is a frame adjustment that is needed to correct the problem. If I hold the toggle switch long enough, the cylinders finally retract the top, but I don't think that type of strain is good for the system.

[Dan D.]

Re: 1960 Power Top Update

Joe, the bypass valve will be somewhere in the motor/pump, usually near the output of the pump. All hydraulic systems have this safety feature or they would stall the motor or blow something up if they encountered a large overload. If you hear the motor running but nothing is moving, then you are in bypass mode. Now it could be either the bypass is set too low, or the linkage is binding or adjusted wrong as you suggest.

I am not familiar with these power tops, but I have to believe that this system, designed in 1955, running on 12V battery power, is probably marginal at best. My 57 was equipped with the power top when it left St.Louis, but it was long gone way before I got the car. -Dan-

[Joe M.]

Re: 1960 Power Top Update

The bypass valve in the Corvette pump looks like a toggle switch with two ball bearings. When the pressure gets too high, one side of the bypass toggles and the ball valve blocks the other sides. The valve rocks back and forth and the excess pressure bleeds off into the reservoir, into the air cavity at the top of the fluid. The cylinder rods are trying to move the whole time the top is trying to fold; it is not in bypass. Some part of the linkage may be binding on the way down, but it does not appear to be binding on the way up as the up cycle is smooth.