Rebedding jack mounting plates
I had to pull my jack mount plates (T shaped steel) on my rear jack and now I am trying to figure out how to bed them. What was there from the factory was just caulk around the outer edge and at the h...
Forum Discussion
I don't like butyl tape in general, and in particular I sure don't like it for this application. It is thick and greasy and does not harden for a very long time. Those plates are loaded in shear with self tapping screws into a wood backer. They need all the help they can get.
The butyl will ooze out of the joint for a long time (like years or anytime it gets warm). That is a mere annoyance, but it lubricates the joint like grease, exactly what you do not want in a shear connection with dodgy fasteners. As the butyl oozes from the joint, the screw tension relaxes. You can go tighten them again, but the process repeats.
I would clean everything properly and use 4000 UV, Sikaflex, or perhaps even 5200 on them. The bulletproof way to do this is liberal use of the PU or PE sealant, do not coat the fasteners, put them in just snug and wait for the sealant to set. After it has gelled, pull the screws out and coat them with the same, then back in drawn up. The reason for this is you want a bond line of sealant a minimum thickness to do it's job, not completely squeezed out by fastener tension, then you want the screws to be sealed and put a bit of compression on the set sealant. This installation will be significantly stronger and watertight far longer than butyl tape (like 20 years would not be an unreasonable expectation). If you have to get them off someday for some reason, it will be some work but it is still possible.
The butyl will ooze out of the joint for a long time (like years or anytime it gets warm). That is a mere annoyance, but it lubricates the joint like grease, exactly what you do not want in a shear connection with dodgy fasteners. As the butyl oozes from the joint, the screw tension relaxes. You can go tighten them again, but the process repeats.
I would clean everything properly and use 4000 UV, Sikaflex, or perhaps even 5200 on them. The bulletproof way to do this is liberal use of the PU or PE sealant, do not coat the fasteners, put them in just snug and wait for the sealant to set. After it has gelled, pull the screws out and coat them with the same, then back in drawn up. The reason for this is you want a bond line of sealant a minimum thickness to do it's job, not completely squeezed out by fastener tension, then you want the screws to be sealed and put a bit of compression on the set sealant. This installation will be significantly stronger and watertight far longer than butyl tape (like 20 years would not be an unreasonable expectation). If you have to get them off someday for some reason, it will be some work but it is still possible.
