cozzykim Posted April 25 Report Share Posted April 25 (edited) I had to grind two of these off with a 'dremel' type tool. Result, I now need two new tyre valves ASAP. Edited April 25 by cozzykim 1 Quote Link to comment Share on other sites More sharing options...
andygo Posted April 25 Report Share Posted April 25 I use the metal ones but put a dab of silicone grease on the threads. That sorts it out. You obviously aren't checking your tyre pressures every week, lol. 2 1 Quote Link to comment Share on other sites More sharing options...
cozzykim Posted April 25 Author Report Share Posted April 25 3 hours ago, andygo said: I use the metal ones but put a dab of silicone grease on the threads. That sorts it out. You obviously aren't checking your tyre pressures every week, lol. I haven't been driving it every week, that's the problem. 🤨😄 Quote Link to comment Share on other sites More sharing options...
Carmine Posted April 25 Report Share Posted April 25 Metal valve caps have been used for years without issue - wonder if the plating used on the valves or the caps has been cheapened and now they corrode? Quote Link to comment Share on other sites More sharing options...
Bike Loon Posted April 25 Report Share Posted April 25 Bad to use... Corrosion - This happens because most of these caps are made of a steel, where as most valves are either brass or aluminium. With the static electricity generated by the wheels going round you get a galvanic corrosion reaction between the two differing metals and they corrode together. Also I have seen on bikes where the base of the tyre valve has got damaged with some of the heavier metal caps as the weight puts stress on the valve as the wheel rotates at speed 2 Quote Link to comment Share on other sites More sharing options...
red rocket Posted April 25 Report Share Posted April 25 Yep, quite a well known issue. I managed to buy some realistic chrome effect plastic ones complete with Porsche crest which I had on the 987. Fortunately I managed to remember to remove them before I sold the car and they'll be going on the new 981 when I get it next week. 1 Quote Link to comment Share on other sites More sharing options...
BBB Posted April 25 Report Share Posted April 25 2 hours ago, Bike Loon said: Bad to use... Corrosion - This happens because most of these caps are made of a steel, where as most valves are either brass or aluminium. With the static electricity generated by the wheels going round you get a galvanic corrosion reaction between the two differing metals and they corrode together. It’s nothing to do with static electricity, it’s just due to the difference in reactivity of the two metals, but they must have an electrolyte solution between them (usually humidity). 1 Quote Link to comment Share on other sites More sharing options...
nelmo Posted April 25 Report Share Posted April 25 Also not a good idea to have that weight on the valve. It's not a lot but when the wheels are spinning that fast, the centripetal force can be enough to damage the valve stem. Quote Link to comment Share on other sites More sharing options...
cozzykim Posted April 26 Author Report Share Posted April 26 11 hours ago, BBB said: It’s nothing to do with static electricity, it’s just due to the difference in reactivity of the two metals, but they must have an electrolyte solution between them (usually humidity). 👍 Electrolysis, the bane of my previous working life with high voltage water cooled inverters. 😉 1 Quote Link to comment Share on other sites More sharing options...
EXY Posted April 26 Report Share Posted April 26 I wonder if rotating the wheels to use gravity, a squirt or two of Plus-Gas (NOT WD40) and a little time wouldn't have done the trick. I have metal caps fitted to my trials bike which were regularly under water and never had an issue but I do use grease as per @andygo Quote Link to comment Share on other sites More sharing options...
Carmine Posted April 26 Report Share Posted April 26 21 hours ago, BBB said: It’s nothing to do with static electricity, it’s just due to the difference in reactivity of the two metals, but they must have an electrolyte solution between them (usually humidity). With a dose of road salt. Quote Link to comment Share on other sites More sharing options...
cozzykim Posted April 26 Author Report Share Posted April 26 1 hour ago, EXY said: I wonder if rotating the wheels to use gravity, a squirt or two of Plus-Gas (NOT WD40) and a little time wouldn't have done the trick. I have metal caps fitted to my trials bike which were regularly under water and never had an issue but I do use grease as per @andygo I put two lots of penetrating oil on them, about a week apart, got two front ones off with no damage but the rears were still corroded on solidly. I even tried warming them up with a gas soldering iron to shock the corrosion bond with differential expansion, no luck. Quote Link to comment Share on other sites More sharing options...
EXY Posted April 26 Report Share Posted April 26 46 minutes ago, cozzykim said: I put two lots of penetrating oil on them, about a week apart, got two front ones off with no damage but the rears were still corroded on solidly. I even tried warming them up with a gas soldering iron to shock the corrosion bond with differential expansion, no luck. I will never forget while stripping the rear axle of a Suzuki quad. Took both of the outer captive nuts off and clamped the axle vertically in a large bench vice. While standing on the bench I proceeded to blatter one end with a sledge hammer, after around 30 minutes I was punctured so admitted defeat. I fashioned a funnel from plasticine, filled it with Plus-Gas and went to bed. The following morning I went into the garage to refill the funnel and the axle was lying on the floor, wasn't sure if I should be pleased or p*ssed-off Sounds like you were lucky with the front or unlucky with the rear. 1 Quote Link to comment Share on other sites More sharing options...
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