Fork Bottom Swap?

[rule62]

How difficult is it to swap fork bottoms.  Say from 17mm axle to 25mm, or different caliper mount spacing?  What's involved?

[Buckethead]

What's involved?

Dark magic.

[A.duc.H.duc.]

Dark magic.

That's nearly the truth.

[Buckethead]

I was looking into it last year, and responses varied, but it was universally agreed that it is a huge pain.

Ostensibly they screw on, but they're a really finely machined thread that can get messed up easily. They're also probably loc-tite-ed on there and will require heat, which may or may not also destroy the threads.

I'd say PM ducvet or speeddog.

[ducpainter]

I was looking into it last year, and responses varied, but it was universally agreed that it is a huge pain.

Ostensibly they screw on, but they're a really finely machined thread that can get messed up easily. They're also probably loc-tite-ed on there and will require heat, which may or may not also destroy the threads.

I'd say PM ducvet or speeddog.

I've seen ducvet do it a bunch of times.

[dlearl476]

Ostensibly they screw on, but they're a really finely machined thread that can get messed up easily. They're also probably loc-tite-ed on there and will require heat, which may or may not also destroy the threads.

One more thing: judging from my experience with putting Gold Valves in my '99 3-way adjustable 20mm forks, and putting the SS 3-way adjustable forks on my Monster, you'd have to make sure the bottoms were similar.  The OEM forks attach the cartridge via a bolt that goes up from the bottom of the fork, which is where one of the adjustments is on the new 25mm axle forks.  I don't really know how that would impact a switch as I haven't had the new forks apart, but I think it would be a show stopper.

[Speeddog]

I've seen ducvet do it a bunch of times.

I've never done it, so there you go. 

[ducpainter]

I've never done it, so there you go. 

He's got this really sweet rig that somehow turns the tube while the lower is held in the vise.

[Charlief]

He's got this really sweet rig that somehow turns the tube while the lower is held in the vise.

yup he does....  He put Stefan's forks together at the end of the suspension clinic. 

[rule62]

The reason I ask, is that I always see sweet deals on adjustable Ducati forks (eBay), but they've got different bottoms on 'em.  I mean, a pair of forks from a 916 for a hundred bucks, and the only reason I don't bid is because the caliper bolt spacing is off, or the axle is a different size, or the fender won't bolt up.  There's gotta be a way.  Me and the boys out here in the Valley of the Sun are pretty adept at turning wrenches, but this is something we haven't tackled.  I've seen write ups about swaping forks from other bikes, eg. GSXR, but never about replacing/removing/swapping cartridges/fork bottoms/uppers.  It's almost like the first reply to this thread is really what it takes.  If anyone has done this stuff... it'd be awesome if you could post up some specifics.

[Speeddog]

AFAIK

Well, there's 2 different fork diameters on Monsters, 41mm and 43mm, that's the slider part that you're thinking about swapping.
Sliders and uppers are not interchangeable between those.

I suspect that the cartridges won't swap between any adjustable and any unadjustable forks.
I could be wrong there.

Unscrewing the bottom casting from the slider requires a special tool to grab the slider.
They're not very thick, and they have to remain round and smooth during the procedure, otherwise they're scrap.

The thread is very fine where the slider and lower connect, and there's generous Loctite applied at original assembly.
There's a very small setscrew installed to also keep them from unscrewing, which is also Loctited.
All lowers are cast aluminum, so the fine threads are delicate.

They're 'mission critical' parts.