My 1968 convertible top has seal leaks at the top of each hydraulic cylinder. I see a snap ring above the seal. Is this seal serviceable? Or is it necessary to buy new/rebuilt cylinders? Aside from the leaks they work fine. Then I find that the outer pivot bolts that retain the cylinders to the male hinge are impossible to get off. The Fisher body manual says that simply unscrewing both bolts will let the cylinder down. I can't get either side outer bolt off without removing the entire male hinge assembly. Am I doing it wrong? If so please wise me up. Also if I need new cylinders what brand is best? I see them going for between $100 and $150 and of course the Fleabay specials 'two-for-$99.99'.
OK!! That is great information. Thanks Jim for those links. I tried and tried to rotate the cylinders to get it away from that outer bolt but no dice. I used a bent nose long reach needle nose pliers to leverage the bolt away but there is just not enough room. I was afraid I would damage the cylinder which is only soft aluminum. Worse, I could not imagine getting it back together like that. So I just took it all apart and once the male hinge is loose it is EZPZ to get the bolts out AND back together. Extra work for sure but I have the entire car stripped so not so bad. So you are saying the O-rings are under the snap ring? What else? You mentioned washers? How are they arranged? I do have another set of rams but they both have a bend near the ends. Otherwise they look exactly like the Firebird rams. In fact I pirated the lower hose off the set because mine was broken. Maybe I can cannibalize those for practice. Yes, I will try and fix these before I spend money needlessly. This car is going to be a money pit as it is but I prefer to restore rather than replace.
Apparently it has been 13 years since I did this, wow, time flies by. BTW, still no leaks. I can't remember how many washers were involved but it you keep track of them as you remove, it is a piece of cake to replace the O-ring. With respect to rotating the ram out, I do remember the ram had to be disconnected from the top before you rotate. I also think it had to be in a oriented in either top fully up or fully down position. I just can't remember which way it was. What I do remember is once I got the first one out, the second one took only a few seconds to remove. Good luck.
Hi Larry. I am glad you joined in as your old post was most informative. I have the cylinders out, and I managed it by banging on the sheet metal behind the bolts with a long pointed drift and a small sledgehammer. I moved it enough to let the bolts pivot and then I could twist the cylinders out. Still a struggle. The amount of interference was so little I had a brainstorm. If the bolts stick out just a little but it is enough to cause headaches on cylinder removal- why not just shorten the ends of the bolts? So I marked the 3 male hinge bolts and control arm bolt positions and removed them. I let it drop down so that the cylinder outer bolts could be accessed. Once lowered I could get at the ends of the bolts with an angle grinder. In that lowered position the male hinge jams the bolt against the sheet metal and holds it steady. I marked the bolt with a magic marker and ground 1/16" off the ends of both outer bolts. Do one side at at time with the top in the UP position or else it will be unmanageable. Once the male hinge is put back up where it belongs the cylinder bolts can be slid over enough to replace the cylinder with no drama. If you had the male hinge off completely it is super easy to take the loose bolts and grind off the ends. I tried it this way because most people would not want to remove the hinge completely to do this.
Now for the cylinder O-rings. A bit of a PITA to get the snap-ring off, the washers out [a strong tiny magnet helped], and the rest of the stuff. The very leaky side O-ring was broken and came right out. The other was hardened and very difficult to get out. So the assembly working from the eye at the top is: Snap-ring, steel cup that retains a wiper, the soft wiper, a thin steel washer that forms the bottom of the wiper cup, a plastic washer [nylon?], and then the actual O-ring. And the O-ring gets forced over those other parts to get on and off. Now I would have figured the O-ring should be made of VITON to be oil resistant. Or BUNA-N. In the old thread, Dr.Drivability said to use the green HNBR AC O-rings. I have used those for various things but I am not sure they would be better than VITON in this situation. The Harbor Fright assortment I have doesn't include this size anyway. JIMC2002 says he used 5/8X7/16X3/32 and that matches up to my measurements. In O-ring world that is a size -111. That size is pretty common too so ordering some should be easy. I took pictures of all this but I don't have a hosting site to link to. After the Photobucket disaster I never used another.
On another site I asked what kind of O-rings would be best for this application. One of the guys works in high pressure hydraulics and posted this Parker pamphlet. Parker pamphlet In real-world attainability It would be a choice between VITON or BUNA-N. The BUNA is less expensive but better sealing at lower temperatures. The VITON is more chemical resistant. HNBR is very high temperature and chemical resistant and is what they use for R-134a systems. All would be good for moderate temperatures, low pressure, and ATF resistance. In hydraulic world our 350 psi system is very low pressure. Can you guys remember what material you used? I am going to try to post a pic of the sealing assembly. [img]https://firstgenfirebird.org/forums/ubbthreads.php/ubb/download/Number/20179/filename/IMG_0557.JPG[/img] Hmmm, no good. You have to click on it. Every site is different I will keep trying.
Pretty certain I used Buna-n. They were so cheap the hydraulic shop I went to didn't even charge me. I think I removed the stack by removing the snap ring, pushing the cylinder all the way down and then putting some air to the top port. Not a lot but enough to loosen the assembly.
I could see how a 1/16" of an inch could make a difference on ram removal. I guess I got lucky on both sides because I don't remember any grinding or beating the metal. I remember removing the inner shoulder bolts, loosening the outer and then using a small pry bar to hold the outer bolt against the sheet metal while I twisted the ram out.
My engineer cousin says the Buna is better for this application too. As for the hinge bolts maybe my body is off a bit but there was no way the cylinders were coming in or out without grinding a bit off the ends. I don't think the cylinders will miss 1/16" of support. Both sides the quarter glass was down in the cavity so I took them out and fixed them. Today I put the quarter windows back in. On both sides the little wheels at the bottom that slide in the track were busted off. Re-pop to the rescue. There is a special tool to screw the threaded retainer washer. I was able to get them loose with a big water pump pliers then I used a snap ring expander tool to un-screw and re-screw. I am anal about lubrication and I added a drop of Tenacious oil on each wheel shaft. Serious bike riders will know about Phil Wood Tenacious Oil. As the name implies it stays in place and doesn't attract dirt. Then I adjusted the windows to the top. The screw-bolts are used for this. I gave them a squirt of paint so I could re-locate the nuts easier. I tried to get the glass as centered as I could in the opening and fitting flush with the top.
Today I got the new BUNA-N O-rings to repair the convertible top cylinders. I have a bunch of the VITON too so if these fail I got it covered. The assembly consists of a snap ring, followed by a wiper cup, the felt wiper, a steel washer that forms the bottom of the wiper cup, a plastic washer, and finally, the O-ring. I took the opportunity to polish the ram shaft with some 400 grit wet/dry paper and a few drops of ATF. They both came out nice and smooth and shiny. Then I cleaned them up with some spray carburetor cleaner to get all the crud off the parts and clean out the cavity where the O-ring resides. Then I wiped down the outer cylinder to get 50 years of grime off. Getting the O-ring over the end of the ram was the hardest part. It helped to secure the end of the ram in the bench vise so you can use two hands to stretch the o-ring over the big fat end. After that it slipped over the other parts pretty easy. I lubed it all with a few drops of ATF so it all slipped into place. The snap ring was as difficult to get on as it was to get off. The fat part with the hole doesn't fit between the cylinder and the shaft. Again the vise helps to hold it steady while you fight the snap ring. The snap ring pliers could not get the ring into the groove. I used an awl and a tiny hammer to persuade it into place. Once seated, everything feels good. If you hold a finger over one of the hose connection holes and work the ram, pressure and vacuum builds and I don't hear any air leaks at the O-ring. So far so good. Next is to hook it all up to the pump and test for leaks. I will build the bleeder tool that is explained in the fisher body manual. This is the parts order, snap ring ,and finished cylinders.
Test time. I hooked up the hoses, filled the reservoir, hot wired the pump to a battery, and gave it a go. You need to move the rams up and down a short distance at first to get air out. Keep doing that while you add ATF to the reservoir. You will hear air gurgling inside the reservoir. As air bleeds out you can increase the rams length but do not let it hit the stops. I discovered a good way to get all the air out while it is on the workbench. When you either extend or retract the ram, take the end of the cylinder that is going to be expelling fluid and hold it upright. Give it a moment so the air rises to the top. Now move the ram and any air at that end will be expelled along with the ATF. You will see it fly through the hoses. Do this for each end several times and you will see less and less air in the lines until it is all gone. Now, the critical part. If air is in the lines, and the cylinders get to their stops, the air gets highly compressed. When you stop the pump the air wants to expand explosivey. If the reservoir port is open, air and fluid will blast out. That is what the Fischer body manual bleeding tool is for. You take a spare plug, cut off the end, and stick a steel line through. Stick that into the reservoir and put a hose on the other end and stick it into a container if ATF. This way when the rams hit the stops, the pump compresses the air, and when you stop the air/ATF gets shot into the container. When the pump needs fluid it will take ATF back and leave the air behind. That is probably the best way to bleed the cylinders when they are installed in the car. You can't tilt the ends as I did to expel the air. But on the bench, tilting the ends up, I got all the air out with the plug open. When all the air is out, fluid can't compress, so running the pump after the rams hit the stops, the pump seizes. STOP!! That puts a tremendous load on the electrical system and will probably trip the breaker. After all this, I have NO LEAKS!!! Thank you Jimc2002 and hokie1984! Two $.13 O-rings vs $300 for rebuilt cylinders is my kind of deal! EDIT: Unfortunately now the pump is leaking so that will be fixed next. Pics are: rams good- pump leaks.
When I first started working on the power top I saw that the pump had a big leak. I took it apart and saw that the big O-ring was crooked. I straightened it out and replaced it so the leaky part was at the top in air, not fluid. That worked OK but there was still some weeping at the O-ring. While I played with the system I ordered a re-build kit which has all the O-rings, new ball bearings, new rubber feet, and a new plug. Now that I know the rams are not leaking I will go ahead and fix the pump. Do as the manual says and scribe a line on each half so it can go back together in exactly the same way. There is a big bolt on the end that has a small O-ring on it. I replaced that just because it was off but I did not open the pump. It is working so I left it alone. I cleaned the reservoir and pump head making sure no O-ring debris remained. The reservoir had gummy crud inside along the bottom. It took lacquer thinner to dissolve it way. Once all clean I wrapped the new O-ring around the pump end, and installed the reservoir half lining up the scribe marks. Tighten the big bolt, re-attach the hoses, fill with ATF, [a small squeeze bottle works great] and bleed the air out again. It works! No leaks, and the rams move smoothly. I replaced two rubber feet that were broken off. Look at the hoses- no air. If I can install the entire assembly into the car without having to disconnect anything then I can see if the top moves as it should under power.
I saw a tiny leak at the wiring where it exits the pump motor. I know there is another O-ring on the pump that the reservoir retainer bolt passes through. It seals the motor from the ATF in the pump. I found a great YouTube video where the guy took it all apart and cleaned the motor up. Power top motor overhaul Since the problematic O-ring is included in the overhaul kit I figured I would take it all apart for cleaning. When I opened it up there was some ATF inside the motor so I had to soak it all in solvent. The armature was pretty dirty so that needed polishing. The hardest part was fabricating retainers to hold the brushes out of the way while you dropped the armature back in. The video shows how to do it. Be sure to scribe lines so the parts go back together properly. The kit includes new pump balls so those get replaced too. After the pump is back on the motor the O-ring is placed on the pump shaft. Be sure to gently force it down into the groove it sits in. That way the pump gears will not chew it up. I tested it and it worked much quieter than before. No leaks. I returned the cylinders to the car and ran the pump in a container just in case it leaked. I watched as the top went up and down as it should. No leaks and the motor sounded better than before so cleaning it was worth it. Then I heard a loud SQUISH. The pass side cylinder was gushing ATF. WTF?!? Upon inspection it looks like the hose fitting at the top blew off. The threads are stripped out and the fitting came loose. I was careful not to over-tighten the fittings. I guess these guys were just too old and I will be buying new cylinders after all.
