Ceriani fork seal replacement - HELP

P

pewe

New member
So decided to resurrect the Laverda.
Failed MOT on leaking front fork.
Story so far - demounted the fork but I'm blowed if I can undo the 6mm hex bolt holding the piston assembly at the lower end - the one that's buried up in the slider.
Various and increasingly extreme methods have failed to dislodge it.
Last one involved a broad bladed screwdriver down the tube held very tightly by a sash clamp and then the ratchet gun on the other end - still no effect.
Coming to the conclusion someone has used silicon or similar to seal it and locked it in as well.
Last resort will be to drill it out but it may just rotate as I'm doing it.
So ANY suggestions gratefully received.
TIA, Pewe.  :(
 
Pewe, probably blue Loctite, actually a good idea to use it on reassembly but my guess is it was done up too tight using a rattle gun. Try some local heat on the screw itself using a micro propane/butane torch. It won't transfer well with the screw clamped to the mass of the slider so you'll need to leave the heat running for quite some time, 10-15 minutes at least.
If you do have to drill it out be REALLY careful not to damage the slider.
I'd be tempted to find a local engineering shop and have them do it.
And use a new soft copper washer when you put it back together, helps with sealing.

Ken
 
Thanks for the quick reply, Ken.
I'll try some heat.
B*ggeration factor - the rattle gun's just run out of juice - something tells me this job isn't going to get any easier......
Aware of the problems associated with drilling it out - once started down that route there's absolutely no going back!
Cheers, Pewe.
 
Pewe, thinking about it, you could actually replace the seal without dismantling the fork. A couple of little holes drilled into the top of the seal then screwing self-tapping screws into the holes, pop the seal out with a cheap automotive body impact puller tool.
Remember a few things, though.
1. Be sure you remove the circlip above the top seal. Can be hard to see sometimes.
2. Depending on which Laverda you have, you may have 2 seals, one above the other (most '70s triples). You don't need to put them both back, one is quite enough. If you can get the seals out without damaging them, cut the neoprene part off a couple of them and use them as spacers, below the top (actual) new seal. Reduces stiction a lot.
3. Replace the external wipers too.
4. Make sure whatever seal you're replacing the old ones with isn't one designed for sealing a rotary shaft. They have a lot more spring tension and static friction. Check with whoever you buy the seals from and be sure you're getting seals for use with a sliding shaft.

Ken
 
Had the same problem. Solved by giving the head of the bolt a hard smack with a drift, then came out easy with the rattle gun.
 
Guys, great advice thanks and the dismantling is now sorted.
An afternoon session with the heat gun (narrow nozzle) played up into the allen bolt recess for 10 mins or so (hot to touch above the allen bolt location), a set of sash clamps compressing the sliders by 3.5" (90mm) and a fully charged rattle gun saw them come out no problem. Like the suggestion about the bolt head a p*sser with a punch & hammer before attempting to dismantle - should have remembered that one.
Interesting about using only one set of seals but I think I'll stick with the two per side - the pessimistic side of me says I don't want to risk having to do them again.....
Thanks once again and safe riding, Pewe  :D now
 
The advantage of using 2 seals is that the outer seal will act as a dirt scraper and will protect the inner seal from any crap that gets past the rubber dust cover. So the 2-seal setup should last longer before it leaks. But as Ken says, some people like to leave one seal out to reduce friction.
 
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