Ducati Monster Forum

Moto Board => Tech => Topic started by: rule62 on June 21, 2009, 03:08:04 PM

Title: Fork Bottom Swap?
Post by: rule62 on June 21, 2009, 03:08:04 PM
How difficult is it to swap fork bottoms.  Say from 17mm axle to 25mm, or different caliper mount spacing?  What's involved?
Title: Re: Fork Bottom Swap?
Post by: Buckethead on June 21, 2009, 03:11:26 PM
Quote from: rule62 on June 21, 2009, 03:08:04 PM
What's involved?

Dark magic.
Title: Re: Fork Bottom Swap?
Post by: A.duc.H.duc. on June 22, 2009, 05:22:01 AM
Quote from: Obsessed? on June 21, 2009, 03:11:26 PM
Dark magic.

That's nearly the truth.
Title: Re: Fork Bottom Swap?
Post by: Buckethead on June 22, 2009, 05:28:26 AM
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.
Title: Re: Fork Bottom Swap?
Post by: ducpainter on June 22, 2009, 05:54:04 AM
Quote from: Obsessed? on June 22, 2009, 05:28:26 AM
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.
Title: Re: Fork Bottom Swap?
Post by: dlearl476 on June 22, 2009, 08:57:38 AM
Quote from: Obsessed? on June 22, 2009, 05:28:26 AM

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.
Title: Re: Fork Bottom Swap?
Post by: Speeddog on June 22, 2009, 10:07:56 AM
Quote from: painter on June 22, 2009, 05:54:04 AM
I've seen ducvet do it a bunch of times.

I've never done it, so there you go.  ;)
Title: Re: Fork Bottom Swap?
Post by: ducpainter on June 22, 2009, 03:22:06 PM
Quote from: Speeddog on June 22, 2009, 10:07:56 AM
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.
Title: Re: Fork Bottom Swap?
Post by: Charlief on June 22, 2009, 04:59:28 PM
Quote from: painter on June 22, 2009, 03:22:06 PM
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. 
Title: Re: Fork Bottom Swap?
Post by: rule62 on June 22, 2009, 06:02:39 PM
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.
Title: Re: Fork Bottom Swap?
Post by: Speeddog on June 22, 2009, 08:16:52 PM
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.