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Author Topic: More forkin' problems  (Read 808 times)

AgentX

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More forkin' problems
« on: October 05, 2012, 04:34:20 PM »
Since my old-school fork was no longer supported with new parts, I am doing a complete swap-out for a new-style fork and disc brake.

The fork legs I have are capped by the shouldered-style top; see attached pic.  However, the lower end of the fork main tubes don't have the screw-off valve body which lets you pull the spring, etc., down out of the bottom of the tube. 

Seems to be a newer setup like the C5 fork that Ducati Scotty did such a great write-up on, where the guts have to come out of the top of the main tube. 

No problem in theory, but does anyone know exactly how the fork caps unscrew?  Looks like they have wrench flats, but are they right- or left-hand threaded?  Or is there something else I'm missing?  Is there a good way to keep the fork tube stationary while trying to torque off that top cap?

Before I go trying to hard to take something off, some intel would be ideal...  Thanks.


barenekd

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Re: More forkin' problems
« Reply #1 on: October 05, 2012, 06:52:29 PM »
Slide the fork tube down through the lower triple clamp until the top is just above the lower clamp, then tighten the clamp and unscrew the cap from there. They should be standard threads.
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AgentX

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Re: More forkin' problems
« Reply #2 on: October 06, 2012, 02:40:19 AM »
Damn, that's what I was figuring.  Thanks. 

I really want to take this fork apart to install my valve emulators while leaving my current fork in place.  I'll see if I can't find some other way to hold it still; maybe I can find another loose lower tripleclamp to use as a vice.

Edit:  I tried using a 35mm upper tripleclamp off a downhill mountain bike fork to get some leverage.  No dice.  So I took the legs to a local dealer who I know has air tools at the workstations.  They told me they'd gladly clamp the fork in a vice to wrench the top off like they usually do, and that the resulting damage would be inconsequential and cosmetic.  "Normally no problem since covered by this part here [indicates casquette on standard and fork cover/headlamp ear on Thunderbird]."

I said thanks, but I'd take care of it myself.  Clamping it back into the bicycle fork upper and putting that upper firmly into the vise to turn off the fork cap should work.

On a side note, it's sorta sad that my old mountain bike fork is probably stronger with double the travel and definitely has far better damping than my motorcycle fork...then again, I'm riding a rigid singlespeed bicycle these days.  The downhill racing fork is sitting lonely with no frame.  Maybe when I'm back to the West Coast someday...
« Last Edit: October 06, 2012, 03:25:34 PM by AgentX »

OleO

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Re: More forkin' problems
« Reply #3 on: November 15, 2012, 05:58:01 PM »
Try a bit of heat from a propane torch to warm things.
Expansion always helps me loosen tight stuff.
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AgentX

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Re: More forkin' problems
« Reply #4 on: November 16, 2012, 12:41:27 AM »
Try a bit of heat from a propane torch to warm things.
Expansion always helps me loosen tight stuff.

Wish I had one!  Tried to buy it in India but no dice.  Places I've been only have welding torches, and that's not something I have the space or need for.  Can't order compressed propane canisters through the mail, either. 

I've not checked a plumbing-specific shop, though...maybe they'd have it, although tool shops are generally a separate thing.  Division of sales is weird and very specific here, with tons of tiny shops in clusters serving one particular need, but all generally selling the exact same stuff.  The whole of the hardware district's been looking at me like I have a third leg growing out of my forehead for 2 years now, with all my requests for strange things like torches.

Not to say I couldn't find some other creative way to apply some heat at home...

Might have found a shop who has an impact tool to use, though, so I'll look into that as well.  Appreciate the advice.

Hog Head

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Re: More forkin' problems
« Reply #5 on: November 16, 2012, 03:39:09 AM »
I am installing the same YSS cartridge emulators in the old design forks right now and needed to machine a fancy spacer that screws onto the top of the pumper rod and holds the cartridge. A simple spacer would work but this is far better as it is properly located at the plunger end and does not block the holes, while holding the cartridge in place properly.

As you noted earlier it is a simple matter to cut the coil bound end of the spring shorter to compensate for the added length of cartridge and spacer

I bought a new plunger rod as mine was suspect. I noted however that old and new plunger rods differ in the top nut. The fork spring would not fit over the new plunger top nut.
No problem with my new spacer design, but this needs checking if you use a simple pipe spacer

Dear knows what these new style forks look like inside, but I would be loath to just simply drop in the cartridge per the instructions, in the event that it would not seat properly.

AgentX

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Re: More forkin' problems
« Reply #6 on: November 16, 2012, 04:48:19 AM »
Hm, a simple spacer worked well enough for me on the old-style fork.  Top nut on the pumping rod was small and I had the spacers made 1.5mm thick so they didn't cover the holes.

Your way's probably the best but I'm not capable of that kinda thing...

Hoping that once I get the caps off these new style fork tubes things are simple enough to finish the install quickly.


Darkside

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Re: More forkin' problems
« Reply #7 on: November 16, 2012, 01:40:01 PM »
Since you can't get a propane torch try a normal household blow dryer. If that dosen't work try this.  http://www.harborfreight.com/1500-watt-dual-temperature-heat-gun-572-1112-96289.html
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AgentX

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Re: More forkin' problems
« Reply #8 on: November 30, 2012, 02:31:34 PM »
So, took the fork tubes, clamped into a mountain bike tripleclamp with handlebars for leverage, to the one mechanic here I DO trust...the guy who works on our 4-wheeler.

We got a team of his mechanics to help us hold the tubes in place flat on a tabletop, while another held a big block of aluminum against the fork caps and gave it a few good whacks with a big ball-peen.  After that the caps screwed out without too much more difficulty!

It was like the ultra-slow version of an impact wrench.