Bottom triple clamp on top?

I'm in the process of messing around with a 90/6 that I'm going to have to "fix" from pretty much top to bottom (read: expect lots of questions from me, lol!). One of the things I'm wanting to do is drop the ride height by lowering the triple trees on the forks. I was lucky enough to have been given a pile of parts with this thing and an extra lower clamp was included. I have seen reference made to using the lower as an upper, but no specifics on how it's done.

So then, what needs to be done to use the bottom clamp on the top?

Thanks for any info!

There are a few threads that discuss this already.

I did this on my R90/6 over the winter. A friend hadled the machine work.

I believe he made 2 short tubes same OD as the fork tubes and milled the ends flat (perpendicular to the sides of the tubes). Then clamped these in the triple clamp to establish the plane to mill in.

At least that's how I understood it.

I kept most of the large reinforcing "rib" at the front of the clamp and had to switch to allen screws and counter sunk the heads into the reinforcing bar to make it work. The studs removed easily with double nutting them. This is neccessary as the original studs aren't long enough.

I had it media blasted to give it more of a "cast" texture and not the smooth "machined" look.
Then I sprayed a rag with aluminum spray paint and rubbed it into the brace.
Looks like it could have been a factory piece and not as "aftermarket" of some of the others.

The first pic is my visual for explaining what I wanted to do.
Then a few pictures of the clamp. Sorry, none of the bottom.

I figured there were probably already discussions about it, but I couldn't come up with a set of search terms which would yield the results I needed. Thanks a bunch for posting up the pics of your project though, it is exactly the kind of thing I needed!

That is a nice handling of the question... the project is "simple" in concept, but not so easy to do... after removing the pipe from the middle (heat and use a very strong press) , the center are must roughly duplicate the thickness of the original top plate, so it has to be milled down to the minimum thickness that can still hold the original large nut.

This has been done many times, but it takes some custom milling, and most folks opt to simply buy a custom top clamp as supplied by Toaster Tan, or by San Jose (CC products).

Very nicely done pkboxer.

Excellent. I have done a couple of them but not nearly as nice.

Nice job PKBoxer. Not to toot my own horn but.......I think I invented the recessed acorn nut on the bottom clamp trick. Almost all the metal is left and enough threads are there for the tube. I used a double stepped method to match the nut exactly. An added bonus is that the forks aligned perfectly. I used clip-ons with my application. I must say I like the look better than the aftermarket ones...and I think it's actually tougher. Big difference on the road when combined with a good fork brace.

Thanks, yeah Mattfish, if you notice, I used your photo as my example to show what it should end up looking like.

I didn't do actual work but I think my "guy" milled out the head tube and didn't press it out.

I just think these can look more stock than the aftermarker ones.

They are very nice though, not criticizing them

Just food for thought as far as making a bottom tree into a top tree. I don't think I would mill off the clamping surface except for that real thin bit. Better grip on the tube I am figuring.

Recessing for the lock nut? Don't you just about have to?

I wonder if you could swap stems and use a R65 stem (the lock bolt threads on the INSIDE of the stem. That's where they get the room for the 'real' top tree on a R65 out of the same length stem as the other bikes). Of course, how that tree holds on to the stem is super critical so there would need to be material there in order to make sure the tree is up agin the stem. It seems to me that the tree up against the stem would be stronger than the load transferring through the lock nut?

I even left the steering stops and used them to bolt my gauge bracket to. My design is snug to the tube and to the nut. I also left the flanges behind that the headlight ears used to cover. As you can see in the picture I used larger diameter clip-ons that fit over those (even more clamping power) with spacer tubes over the forks to clamp solid there. Didn't know about the R65 stem design. Of course if you had one of those, you would probably also be using the top clamp that came with it.

I was tempted to do this myself a few months back. If only this was posted back then. Thanks for sharing.

Great input everyone! I'm debating if I can manage it on my benchtop mini mill or if I should farm it out... I think my mill could do it, slowly, but I need some more tooling....

I dredged up this old thread just to ask in any of you know where I can get a lower triple clamp like the one shown above (the one in the second post of this thread; it is a lower triple clamp that has been machined to use as an upper triple clamp). I have located a stock lower triple clamp, but the local machinists I have talked to so far are not really interested in doing the job.

my top clamp is a bottom clamp.

Where did you get it machined? And how much did it cost?

You could ask at BMW Euro http://boxermetal.com/ His name is Chris.

Chris could do it but I wouldn't be surprised that it cost more than a readily available top brace. This modification was popular not too many years ago but we don't hear about it too often anymore. The cost and rarity of /5 braces may be why. I had a /5 brace to make a upper from and a local mechanic talked me out of it because he needed it to fix a customer's bike.

That looks familiar. It would be less expensive to buy one than to have it made. To do it yourself, why not?

The R65 trees hold the tubes closer together than the bigger twins. They won't work. There isn't much purchase between the lock nut and the tree. The load HAS to get to the stem somehow. Via the locknut in this case. The R65 setup offers a lot more surface area for that load to transfer. I wonder if top trees that clamp on to the stem improve handling? Clamping onto the tubes seems to make a big diff!

It should, YOU made it.

Apart from a cosmetic excercise is there any real point in having a meatier top yolk? If you bend and twist your forks without a top yolk, wheel and mudguard stay fitted the linear deflection is a few millimeters at best. Put the wheel and mudguard in place and it's negligible. The forces at play on the top yolk is linear, the steel yolk is more than capable of handling them. Has anybody had one buckle?

I signed up for the expensive San Jose top yolk and mudguard bracket a while back and can honestly say they made no difference at all to the bikes handling.