Showa fork bottom swap questions

[Syscrush]

I'm looking at picking up a set of Multistrada 1000DS forks to swap onto my CBX - it's hard to find good USD forks that are as long as the forks on the old bikes, and the Multi is an almost perfect match.  If I go this way, it'll be modified internally to take out a couple of inches of travel (i.e. move the stop bump about 2"), re-sprung, and re-valved.

But I'd also really like a set of radial calipers.  I can't help notice that these are 43mm Showa forks, and a set of bent Showa GSX-R 43mm forks with good bottoms, calipers, and master cylinder are not much more money than just a set of calipers and pads.

I have seen a few 916 and other Ducati superbikes with Showa forks that have been swapped to radial brakes by swapping bottoms from other radial-equipped Ducatis, but the GSX-R parts are so much more readily available and inexpensive.  Also, it's hard for me to imagine that Showa is cutting different threads onto 43mm forks sent to Hamamatsu than the ones they send to Bologna.

Does anyone know what the story is on swapping non-Ducati Showa bottoms onto Ducati Showa forks?

Thanks,
Phil.

[Speeddog]

I've not swapped fork bottoms, but I've been told by Eric at Clubhouse Motorsports that it's not very easy.

My advice would be to equip those Multi forks with a set of axial-mount 4-pad calipers.
Those would be appropriate brakes for a CBX, and no parts mix-n-match necessary.

[Syscrush]

Thanks Speeddog.

I'm not really concerned about if it's difficult or not, I won't be doing this myself in a home shop or anything.  It would be done by my suspension guy - he has done these kinds of swaps plenty of times and has his tools and technique - the question is if the parts will fit.

I appreciate the advice, and I agree that good axial calipers would work every bit as well as radials.  By the same token, some revalved Bandit 1200 RSU forks would work every bit as well as the Multi USD's. But my only reason for going to USD forks is for looks, and the radial calipers are an important part of the look I'm going for.

[Speeddog]

Fair enough. 

RaceTech sells aftermarket sliders, I believe they're manufactured in Italy.

You may want to E-mail them, see if they can tell you.

[Syscrush]

Fair enough. 

RaceTech sells aftermarket sliders, I believe they're manufactured in Italy.

You may want to E-mail them, see if they can tell you.

Thanks for the pointer!

I was thinking about contacting the Italian company selling aftermarket bottoms on ebay since they should know, but given my past experiences with RT customer service I think that they're a much better bet.  Great idea.

[Syscrush]

TNK is the company that makes the tubes sold by RT.  I've contacted them through their website, I'll update with any info I get.

But I probably won't go this way, since I've learned that the USD forks from a Triumph Tiger 1050 are the correct length and come with radial calipers.

[Syscrush]

A customer service rep at TNK is being extremely helpful.  Through him, I learned that GSX-R Showa BPF forks from '08-on are 41mm, not 43mm.

I'm leaning more towards either the Tiger 1050 forks or the KTM Duke 690 forks instead of the Multis, but I'll update here with whatever info I end up gleaning.  If I go with the 690 forks, I'd have to buy them first and then spin off the bottoms and measure the threads, then my new best friend can tell me what other bottoms would swap on.

If I ever do end up in the market for aftermarket fork tubes, you can bet I'll be sending some euros to TNK.

[caperix]

Sorry to dig this up from the dead,  but I have been wondering the same thing.  I was able to swap the lowers from a Buell XB with the 43mm showas onto a set of '06 GSXR 600 forks with the 43mm showas.  They were a pain to get loose & I have not finished yet, but the threads are the same.

[Syscrush]

And I'm sorry I let it die.

What I've learned about forks and threads for bottoms & caps is that the same brand will tend to use the same thread for the same dia (not guaranteed, but it's a good bet), while different brands will not.

I ended up going with RSU forks from a later CBX (39mm instead of 35), fitted with AK20's.  And new tubes from TNK.  They're still in GA, should arrive in a few weeks.

[zippsub9]

For anyone interested I just completed swapping caliper mounts on my SBK front end swap from a '12 848 Corse to a '10 Monster 1100 with '08 1098 internals.  The fork bottoms were swapped so that I keep the same offset for rotors and no need to shim out to 15mm offset from 10mm.  I also took the opportunity to powdercoat the caliper mounts as well.  The rebound needles are different external, but no change to the adjuster.  THe reason for the 1098 internals is the stock spring rate is 1.00 in lieu of .94 on the 848 and they were also black DLC coated to boot.  Pics to come if anyone is interested. 

This was done in my garage with a heat and vice clamp.  Not hard, no need for special tools either to break apart forks, just some 550 cord and a ratchet strap.