Serfas FP-50 plunger broke
05-31-23, 07:45 PM
#1
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Thread Starter
Serfas FP-50 plunger broke
The plunger of my Serfas FP-50 broke off. It's the part that the o-ring fits into. It does not look like it's replaceable. Also Serfas does not sell this item as a replacement part. Part of the plunger is still in the shaft, (i.e., the shaft is the long tube that the pump handle attaches to.) The shaft is crimped where this part of the plunger sits. It's the crimp that holds the plunger in place. To remove the piece of the plunger that is in the shaft, I would have to uncrimp that part. If I can find the right glue, I think I should be able to glue the two pieces of the plunger back together. I suspect the plunger is made out of glass filled nylon, which is a hard material to find a glue for. Question: does anyone know what type of glue would work, or have any other ideas?
05-31-23, 08:32 PM
#2
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drill a small pilot hole into the plastic still in the shaft... go to the hardware store and get a countersink sheet metal screw... drill the o-ring holder/head of the plunger with a hole big enough to fit the screw through... countersink the plunger head just deep enough to fit the screw's head into it.
run the screw into the plunger head...
place epoxy on the screw threads AND in the countersink area... and then carefully twist the screw into the plastic in the shaft..
wipe away any excess epoxy.
let that sucker dry for a day or so.
put some vaseline on the o-ring, slap it all back together. and don't beat your pump up up again.
worth a try... remember to keep everything centered up and perpendicular where needed... and personally, i'd be tempted to true up the mating surfaces, or i'd make sure the faces mated up correctly to align things...... but i've got a great eye for that sort of thing... do you?
Example for design only.. your size needs will vary.....
https://accu-components.com/us/phill...d%20group%20#1
run the screw into the plunger head...
place epoxy on the screw threads AND in the countersink area... and then carefully twist the screw into the plastic in the shaft..
wipe away any excess epoxy.
let that sucker dry for a day or so.
put some vaseline on the o-ring, slap it all back together. and don't beat your pump up up again.
worth a try... remember to keep everything centered up and perpendicular where needed... and personally, i'd be tempted to true up the mating surfaces, or i'd make sure the faces mated up correctly to align things...... but i've got a great eye for that sort of thing... do you?
Example for design only.. your size needs will vary.....
https://accu-components.com/us/phill...d%20group%20#1
Last edited by maddog34; 05-31-23 at 08:38 PM.
06-01-23, 01:09 AM
#3
Clark W. Griswold
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Serfas stuff was always mediocre to pretty terrible but they at least did have a really good warranty and they would just replace the pump. You might take it back to the shop you got it from and they should be able to replace it for you.
06-01-23, 07:03 AM
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A good project for those who have a lathe. I would think glue wouldn't be strong enough. Andy
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AndrewRStewart
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06-01-23, 08:42 AM
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IMO. plain and simply, Serfas products suck. I would trash it and get a better quality pump. Lezyne and Topeak both make affordable, good quality pumps.
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06-01-23, 01:17 PM
#6
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Thanks. And there are probably others like me on this forum, but in my neighborhood I'm getting a reputation as the guy that kids bring there broken bikes to for fixing. It's a bit rewarding, but it's Huffys and other department store bikes I typically see. I was patching a tube and one of the neighborhood kids probably broke it while my back was turned.I was thinking about doing a similar fix, but as the other poster suggested, I'll see if my LBS will help me with the Serfas warranty .
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06-01-23, 05:38 PM
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@OP, consider what your time is worth.
Buy a new pump or get a used Silca off ebay and put a rebuild kit in it.
Don't mess around trying to repair that thing
/markp
Buy a new pump or get a used Silca off ebay and put a rebuild kit in it.
Don't mess around trying to repair that thing
/markp
