- Joined
- Feb 1, 2015
- Messages
- 9,995
After yesterday, I probably should have moved this thread to the "Goofs and Blunders to Avoid". I picked up a grade 2 and grade 5 nut, along with an O ring and a tube each of ted and blue LocTite. When I got back to the shop, I thought that my best strategy was to use the grade 8 nut and the red LocTite. So I slipped the O ring on the shaft, followed by the piston, and some red LocTite. Then I screwed the grade 8 nut on and tightened it down. I wasn't able to get the prescribed 160 lb-ft.. of torque recommended but got fairly close. And said to myself, "good job".
About 3 hours later, I realized my goof. The cylinder end cap is held captive on the assembled piston and shaft. In a panic, I started to disassemble my assembly. LocTite starts to set in 10 minutes and fully sets in 24 hours so time was of the essence. With a 3/4" breaker bar,, I was able to crack the nut loose and I started to unscrew it. The nut was turning with extreme resistance and the sound ir was making was much like that when removing a nut from well rusted bolt.
The nut did come off but I would have to agree that red LocTite is permanent. I was able to clean up the threads in the nut with a tap and pick the hardened LocTite out of the threads on the shaft. A brush with a fine bristled wire brush and an acetone wash and the threads were ready for reassembly.
When a gland is designed for an O ring capture, it is made to allow the O ring to deform. O ring material is incompressible so the volume of the gland is usually about 15 -20% greater than the volume of the O ring. In this case the actual volume of the O ring is .038 in.^3 and the gland volume is .0275 in.^3. The result is that some of the O ring is extruded out of the cavity when the assembly is tightened. This extrusion was observed on both of the original cylinder assemblies as well as as my recent assembly. Not my ideal design, but there is an old engineering guideline, "don't fix what aint broke". The upshot though, is that the O ring on the newly disassembled shaft was totally chowdered. I supposed that I could grease the O ring with some silicone RTV but the wiser path would be to install afresh O ring which happens to be 20 miles away.
When I reassemble the piston and shaft, I will use the blue LocTite as I would have to disassemble it again in the event I needed to service the seals on the end cap. The red LocTite requires heating to 575ºF in order to break the bond and that would destroy the urethane seals as well as the temper in the aluminum piston. I do have to say the the red LocTite is a very effective thread locker, maybe second only to welding.
Tomorrow's another day and after a trip to town for an O ring, the assembly should go smoothly. It gives me some time to figure out a cheater bar for my torque wrench to give me enough oomph to reach the 160 lb-ft. Fortunately, there is no immediate need for the front end loader, only my onner drive to "git 'er done".
About 3 hours later, I realized my goof. The cylinder end cap is held captive on the assembled piston and shaft. In a panic, I started to disassemble my assembly. LocTite starts to set in 10 minutes and fully sets in 24 hours so time was of the essence. With a 3/4" breaker bar,, I was able to crack the nut loose and I started to unscrew it. The nut was turning with extreme resistance and the sound ir was making was much like that when removing a nut from well rusted bolt.
The nut did come off but I would have to agree that red LocTite is permanent. I was able to clean up the threads in the nut with a tap and pick the hardened LocTite out of the threads on the shaft. A brush with a fine bristled wire brush and an acetone wash and the threads were ready for reassembly.
When a gland is designed for an O ring capture, it is made to allow the O ring to deform. O ring material is incompressible so the volume of the gland is usually about 15 -20% greater than the volume of the O ring. In this case the actual volume of the O ring is .038 in.^3 and the gland volume is .0275 in.^3. The result is that some of the O ring is extruded out of the cavity when the assembly is tightened. This extrusion was observed on both of the original cylinder assemblies as well as as my recent assembly. Not my ideal design, but there is an old engineering guideline, "don't fix what aint broke". The upshot though, is that the O ring on the newly disassembled shaft was totally chowdered. I supposed that I could grease the O ring with some silicone RTV but the wiser path would be to install afresh O ring which happens to be 20 miles away.
When I reassemble the piston and shaft, I will use the blue LocTite as I would have to disassemble it again in the event I needed to service the seals on the end cap. The red LocTite requires heating to 575ºF in order to break the bond and that would destroy the urethane seals as well as the temper in the aluminum piston. I do have to say the the red LocTite is a very effective thread locker, maybe second only to welding.
Tomorrow's another day and after a trip to town for an O ring, the assembly should go smoothly. It gives me some time to figure out a cheater bar for my torque wrench to give me enough oomph to reach the 160 lb-ft. Fortunately, there is no immediate need for the front end loader, only my onner drive to "git 'er done".
