Convertible Top Cylinders

NOT A T5 · Sep 17, 2018

Hi Guys, after heaving the convertible top frame back into place I thought why not hook up the cylinders and hoses. I knew from the past one of them leaked a little but found out they both leak, one more than the other. It's the "Top Down" fittings where it screws into the nylon on top of the cylinders. Bottom fittings have no leaks. Turned out that the nylon threads are stripped, so what can I do here? I know there's a lot of pressure, should I be searching for a good used pair or go aftermarket? Is it possible to repair the nylon threads? These cylinders are original to my 71. I looked at aftermarket cylinders but they vary so much in price. Do the aftermarket cylinder have nylon threads as well or are the threads all aluminum? Thanks for any input!

rackerm · Sep 17, 2018

Hi Guys, After heaving the convertible top frame back into place I thought why not hook up the cylinders and hoses. I knew from the past one of them leaked a little but found out they both leak, one more than the other. It's the "Top Down" fittings where it screws into the nylon on top of the cylinders. Bottom fittings have no leaks. Turned out that the nylon threads are stripped, so what can I do here? I know there's a lot of pressure, should I be searching for a good used pair or go aftermarket? Is it possible to repair the nylon threads? These cylinders are original to my 71. I looked at aftermarket cylinders but they vary so much in price. Do the aftermarket cylinder have nylon threads as well or are the threads all aluminum? Thanks for any input!

I had one that had a stripped Nylon fitting. I managed to get an another fitting and thread it in. I also used a Hydraulic sealant and attach the hose fitting end to it, and then I wrapped it with a plastic tie strap to hold it all together, but it's a Rube Goldberg, a shameful hack job and I just should replace it before it leaks again.

All that said, you don't want to end up with a mess from a leaky fitting and end up with ATF fluid all over your nicely restored floor pans and quarter panel(s). The installation of new ones is not hard but is certainly easier when you don't have to drain the lines and remove the old ones first.

I think you are better off replacing them now. Keep in mind I read that it is recommended that they are replaced in pairs to be sure that the hydraulics operate uniformly and in sync with each other. You don't want one cylinder to move up/down faster than the other and possibly create roof frame binding from uneven up/down motion.

mudbilly · Sep 17, 2018

My cylinders & hoses have failed enough times that I needed to do something when I redid my trunk and interior and didn't want to have to deal with the mess again.

I built a lexan box for the pump.

Also totally enclosed the lines in shrink tube.

and built lexan cylinders for the hydraulic cylinders

Silicone caulk around all of the interfaces........

Spent many hours working on this. Sure hope it works if I have another failure....

Carolina_Mountain_Mustangs · Sep 17, 2018

Wow you must be a Lexan distributor, lol. I have had mustang convertible since the 70's and never had line or cylinder blow. KNOCK ON WOOD.

The pressure in the system if very low in fact or the plastic lines would fail for sure. When you close the top do not let the top frame contact the windshield frame before you let off the switch. If you hold the switch then the pump does build pressure because nothing can move any farther.

Also when the car is sitting always release the top clamps to allow the seals to breath.

I would think that a sheet of plastic taped around the cylinder to drain fluid into the quarter panel would work also.

Early mustang power top was an option. I think the pumps are the same from 64 1/2 - 73.