triple clamp dimensions - USD forks swap

[silviocross]

Hi everybody,
I found out a good set of WP upside-down forks with radial brake calipers and anodized triple clamps, so I can finally substitute the old stock forks on my K75.
I have at the moment materials, lathe and milling machines but my bike is unfortunately far away from where I live now. I will move back to my bike in ~ 2 months, but then I won't have a lathe anymore (damn..).

Does anybody have some dimensions of the original steering head/triple clamps assembly/frame so that I can design and machine the required components for the swap?

thank you,
Silvio

[Laitch]

Welcome, Silvio.

What year was your bike made and which model of forks is on it now?

[silviocross]

Hi Laitch,

thank you for joining the thread, it's a 1989 K75 (no fairings, no rear disk brake).
Front forks are standard at the moment.

have nice day,
Silvio

[Dennis de Vries]

Maybe a stupid thought, but how about getting a used original triple clamp of ebay and work from there?

[silviocross]

Hi Dennis,

yes this was the original idea. But since the plan is to trash my original clamps as well, if possible I would avoid buying another set only for measurement purposes... 

[Laitch]

It's early here; I had a late night; I haven't had coffee yet.

If you were intending to trash your original clamps—from which you want dimensions—what's the plan? Buy aftermarket clamps? Wouldn't you need dimensions from those?

Doing this project from a distance, depending on measurements of unverified origin, and working in a time-driven state of desperation seems a trifle unwise. Maybe things will become clear to me in a while.

It's coffee time! :sip:

While you're resting, here's a chart to read that is on the K100 forum. If it's not helpful, at least it's colorful. :giggles

[silviocross]

I'm going to trash the original clamps in order to mount the new set, so of course I can take measurements from them.
My problem is that I will have my bike in two months, and while it will be easy to take measurements I won't have the tools anymore.

Before buying another triple clamps set I thought that maybe somebody had a disassembled bike in its garage.

[rbm]

I haven't a K75 triple tree to measure but I do know of someone who installed an USD fork on their K75; they used a complete Ninja ZX7R front end.  Requires different 52mm steering head bearings, but stem length is right on.  Uses Standard 20mm axle just like K75/K100, only needs wheel spacers.  Uses 52/34mm roller bearings.  You'd need to turn stem down only few 1/10 mm to size it for the bearing (Press out steering stem, turn on lathe, reinstall in lower triple).  You'd be advised to pin the stem to the lower triple for security after reassembly.  Standard Nisin brakes fit 320mm disks on K75/K100 wheels.  You'd have to adjust caliper offsets to be sure they are centred over the rotors.  I got the following response below when I asked the same question you just did:

Pivot Stem:
Length from top of lower triple clamp to top of threads:  176mm
Length from top of lower triple clamp to where tapering begins:  128mm
Diameter (to fit inside bearings):  28mm
Note that I ignored the portion of the steering stem that goes into the lower triple clamp
The K1200 axle is 20mm dia. and the k1100 axle is 25mm dia.

Frame:
Steering head length: 165mm
Steering bearing seat diameter:  52mm (BTW, this matches the outside diameter of the bearings I bought for the 1992)
Standard headset bearings (upper/lower) are 28 I.D. X 52 O.D. X 16 thick

[silviocross]

This is what I was looking for, thank you very much!

[silviocross]

Here the (not finished) result!
Thank you!

[The Mighty Gryphon]

Very classy looking.  The pinstripes really look good and I like how the taillight is worked into the tail cowl.

Beautiful job!

[Lewisrags2517]

Hello Silviocross. Could you do a little build thread with pictures or a thorough build by writing it down as I want to use USD forks on mine but I was intending to used Yamaha R1 forks.

Regards Lewis