Seeping Fork Seal

[Samelak]

Very frustrating that my newly rebuilt 80 CBX fork (one side only) started to leak only after about 300 miles. I even used Honda seals. Is it time for new tubes? I do have some pitting, but it's towards the top. I also just installed a Pazzio fork brace, but I do not think it is related. Any thoughts?

[Larry Zimmer]

Any pitting on the part of the tube surface that slides through the seal will damage it enough to cause seeping/weeping/leak. If not too deep, it can be polished by hand. Should disassemble the tubes to be certain that the entire length that strokes through the seal gets 'cleaned up'. Depending upon the depth of the pitting, start with a 400 grit wet-or-dry paper lubricating with oil. (Engine oil, fork oil, just don't use brake fluid!!) Work the sand paper AROUND the tube shaft, NOT up-and-down. Polish with the course paper until the pitting is gone. Then, use progressively finer paper up to about a 1500 grit to continue to polish the tubes smoother. If you are able to eliminate the pitting, this polishing will have things working well. I would install new seals, again, just to be 'safe'. Sorry about the need to disassemble, again; but, it's the only certain means of polishing the full stroke in my experience. Good luck.

[Jeff Bennetts]

I saw a post on another MC forum I belong to that mentions a product popular with farmers and people that use equipment with a lot of hydraulics that will fill any pits in the cylinders, I'm tying to find it and I'll post my findings when I locate it.

I know some people have had success with using epoxies.

Resourced from the CB1100F forum.

Here's a pretty good technique and product to repair pitted forks that will last better than the epoxy method and look better too. From "Tourmaster" (Bob) at the Custom site. Reposted here with his permission. I really like the Cigar lighter idea for a torch, great idea. I think some smallish fine files would also help the process.

Tourmaster wrote:
Okay Gene, here goes ... our local bike shop repair guy (Hugh), who I have a lot of respect for, was very forthcoming concerning his "Pitted Fork" repair weapon of choice. Hugh has in the past used the epoxy trick, but later found that the farm and heavy duty equipment guys were repairing their pitted hydraulic cylinders with something a little more robust ... and just as easy to apply. Since using this simple product(s) over the past several years, he has had no returns from his many customers.

I took some, rather crappy, photos of this stuff at his shop this morning. It's actually a solder/braze like product that is simply melted into the offending pit area. Here's the photo of the container that holds several of the solder like wires.

Product Name: Cronabraze 92C CW1020 Acid Core


And here's the solvent/flux he uses to first prepare the area.

Product Name: Cronasolv Eagle F930


Hugh said that the supply company he gets this stuff from is Lawson Products ... here's the link: http://www.lawsonproducts.com/website/m ... enDocument
NOTE: In the photo showing Hugh's example, he was actually able to get the wire in shorter lengths contained in a smaller tube, rather that a large roll as shown this this catalog shot.

Here's their catalog for the specific items including the solder/braze wire: http://www.lawsonproducts.com/webapp/wc ... GSOLDERING

And next the solvent/flux: http://www.lawsonproducts.com/webapp/wc ... 2CPOLYMERS

I actually had a chance to watch Hugh do the repairs to my GS1100 fork tube, which had one pitted area. Hugh's method of fork tube pit repair generally follows these simple steps:

1) In my case I actually had removed the fork tube allowing him to lay it flat on his work bench
2) First clean off the offending area with a general cleaning solvent to get rid of any oil and debris
3) Using very fine emery (ie; crocus) remove any potential raised burrs, but leave the depression area of the pit as is (ie jagged)
3) Quick flush cleaning of the area again
4) Apply the flux product
5) Preheat the pit area a bit and then using a simple cigarette lighter torch melt a very small amount of the Cronabraze solder/braze wire into the pitted area.
6) Allow the area to cool and then buff the excess solder/braze material away using, again, very fine emery cloth ... buffing to a smooth finish.
7) Reassemble and cruise for many happy years of NON-leaky forks


The cost of refurbishing and rechroming heavy duty equipment hydraulic cylinders have driven machinery companies to find simple and cost effective repairs, that will stand up to the riggers of the construction and mining industries. Since these are certainly more demanding applications than us lightweights cruising around on our 750's ... I like the approach.

[NobleHops]

OK, this is freaking AWESOME CONTENT. I totally wish I had a set to try it on. I bet this would work on brake pistons too. I had an otherwise tasty piston with one big pit. Perfect candidate. I think I still have it, if so I'm going to order some of this stuff and try it.

I saw a local auto stereo installer dude with a teeny propane soldering torch, which fit in the palm of his hand. Snapped on with a trigger, full heat instantly, fine flame tip, instant off. That would work perfectly with this. I want one of those! I have no feel for my electric soldering gun...

N.