idosubaru Posted July 19, 2009 Share Posted July 19, 2009 Are there any high strength sealants for use on rubber bushings that can handle 150 psi air pressure? Any experience with something like this? GD? The bushings on top of the rear XT6 air struts seal the system on the top due to the rod coming through the top of the strut. They are being strained and leaking due to the lift I put on it. I guess the top mount is being "torqued" or twisted - compressing one side and lifting the other enough to cause a leak. It's a bushing seated against metal. Quote Link to comment Share on other sites More sharing options...
RenaissanceMan Posted July 19, 2009 Share Posted July 19, 2009 If you properly clean it, the only thing that comes to mind for me is a self-priming window urethane. I made some "high performance" engine mounts for my justy once using some of that stuff. it takes about a week to dry/cure properly.. but it WORKED to say the least. -Mike Quote Link to comment Share on other sites More sharing options...
SoobieDoo Posted July 19, 2009 Share Posted July 19, 2009 Possibly one of the tougher urethanes, like 3M window weld, or marine 5200. Being a sealant, and flexible is what makes it less permanent, but is necessary. I'd use 5200. Anyone who has ever used it, will tell you it's the toughest sealant. Quote Link to comment Share on other sites More sharing options...
idosubaru Posted July 19, 2009 Author Share Posted July 19, 2009 3M says marine 5200 bonds wood and fiberglass. wonder if metal/rubber is still cool? Quote Link to comment Share on other sites More sharing options...
GeneralDisorder Posted July 19, 2009 Share Posted July 19, 2009 If they are being strained by the lift.... how is a sealant going to help? Maybe I'm not picturing it correctly.... GD Quote Link to comment Share on other sites More sharing options...
idosubaru Posted July 19, 2009 Author Share Posted July 19, 2009 If they are being strained by the lift.... how is a sealant going to help? Maybe I'm not picturing it correctly....Not sure it will, but want to try something easy first. I don't think it's "breaking" contact necessarily where the bushing seats against metal. It's just rubber disc against flat metal. But under torque it's loosening pressure on one side which allows the air to squeak through. I wonder how "pliable" new bushings are and if they're even available. Maybe just having new bushings would help. Quote Link to comment Share on other sites More sharing options...
SoobieDoo Posted July 19, 2009 Share Posted July 19, 2009 3M says marine 5200 bonds wood and fiberglass. wonder if metal/rubber is still cool? I know...stupid to only rate it for wood and fiberglass. One of the listed apps is for through-hull fittings, so that would mean metal also. I'd clean and sand everything real good, and there's practically nothing it won't stick to! Keep in mind that it is rated permanent, so cleaning it up won't be fun. I'd try new bushings first, being easier to seal afterwards if necessary. Quote Link to comment Share on other sites More sharing options...
GeneralDisorder Posted July 19, 2009 Share Posted July 19, 2009 Can you modify the lift so it doesn't put strain on the bushing? Probably a PITA but I don't think anything "sealant" wise is going to stop 150 psi air getting between a poorly fitting rubber-to-metal interface. That's a LOT of pressure - hell sometimes I have trouble sealing NPT threads against that much GD Quote Link to comment Share on other sites More sharing options...
idosubaru Posted July 20, 2009 Author Share Posted July 20, 2009 Can you modify the lift so it doesn't put strain on the bushing?yes - actually i have a piece of me that wants to do that. best bet would be to extend the rear as opposed to the top. so the top (where the bushing is) stays fixed nice and flat like stock. then extend the bottom. looks annoying but not too hard, particularly since i have spare hub assemblies and struts i can mock-up and have a machine shop make parts for, etc. just going to take some time. Quote Link to comment Share on other sites More sharing options...
presslab Posted July 24, 2009 Share Posted July 24, 2009 Yeah you want a urethane based sealant. You can use Aquaseal if you have a local dive shop, a small tube is about $5. Quote Link to comment Share on other sites More sharing options...
Scoobywagon Posted July 24, 2009 Share Posted July 24, 2009 Sika's SikaFlex220 Urethane and an Aktivator pad will straighten it out. And yes, once cured, it will take 150+ psi. Quote Link to comment Share on other sites More sharing options...
idosubaru Posted July 24, 2009 Author Share Posted July 24, 2009 hmm...someone on the XT board recommend sikaflex too. mixed bag of opinions here, some think no way sealant will hold, some say it will. i'll give the sealant a try. if it doesn't work then so be it, i'll fix it the right way and make a lower extension. i just might save my best strut bushings though, i hear this sealant is rather impossible to work with once cured! Quote Link to comment Share on other sites More sharing options...
Scoobywagon Posted July 25, 2009 Share Posted July 25, 2009 Urethane is really not a sealant. Its an adhesive. And a bloody strong one at that. Once its completely cured, and that takes a while, it will take some SERIOUS abuse. Quote Link to comment Share on other sites More sharing options...
SoobieDoo Posted July 25, 2009 Share Posted July 25, 2009 I know about all of these sealants, having them in stock at my work. You're probably going to be fine with any urethane. Aquaseal is made for neoprene, like wet suits and diving masks. Probably not rated for metal, but it could be. Sika 221 is used for HVAC and RV apps. Price will be 1/2 that of 3M 5200, with either. Sealants are a delicate balance of flexibility vs. strength. One always takes from the other...that's why epoxy is so strong and brittle and rubber cement is so flexible and wimpy. Use a urethane that you can find, not many stores will have all three of these in stock. Quote Link to comment Share on other sites More sharing options...
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