72' R75/5 Cafe Build Thread - Leadnuts

[Padmei]

Far too much thought, patience, technology & workmanship for my liking - can you please post some pics of your cockups to make us lesser mortals feel better

Seriously I like the way you are evolving your bike to your ideas.

[Leadnuts]

Awfully nice of you guys.. thanks.

As for cock-ups... I realized that bracket needs to be 5/16" and not 1/4" to look right with that mirror... so i will be doing that again i suppose, and those aluminum rearset brakets I'm going to have to make again due to the rearset brake set up changed 3x now... rod, to cable, back to modified rod... basically I have no idea what I'm doing..haha

As for patience... the reason everything seems to be "3rd times a charm" for me is because I keep making parts before the thing that is connecting to it arrives... because I haven't got any patience.

My motto is "I call Do-Over"

Hope that makes you feel a little better Padmei.


I do think Fubar takes the cake with fab parts though... the swing arm he did for me blows me away every time i look at it

[Leadnuts]

Made some new rearset brackets last night.. this time made them out of steel. As the new improved versions wil be welded on not bolted as it solves a few problems I was having.

One was that when the bracket was bolted onto a tab it pushed the rearset levers out to a funny looking distance which was becoming problematic to align the brake rod. The new one pushes the whole assembly in about 1/2".. which combined with a right angle ball joint linkage thingy all seems to line up pretty good. Alleviating the need to engineer/fabricate a cable brake system, so thats good, right.

The other thing it does is allow me a platform for adding things that I haven't really thought about yet like exhaust supports, or a removable 2nd passenger foot peg bracket, and a mount for the brake light switch.


[IMG][/IMG]

[IMG][/IMG]

next will be the making of an extension to the rearset lever or the fabrication of a whole new one... haven't decided which to do yet. Leaning towards an all new one for a cleaner look though...

[bmweuro]

I think the way you have the cable set up your brakes will activate every time the swingarm moves up and down.

[Leadnuts]

Originally Posted by bmweuro

I think the way you have the cable set up your brakes will activate every time the swingarm moves up and down.

I was wondering that, was actually thinking of flipping the lever under so the rod is parallel with the swing arm.. think that might help? If not I do have an actuator I was thinking about installing right up near the arm pivot, came from a raask bmw set. but was hoping to avoid the extra part..

[melville]

Originally Posted by bmweuro

I think the way you have the cable set up your brakes will activate every time the swingarm moves up and down.

Looks like the pedal is free to float with the wheel moving up and down. Actually using the brake over bumps might feel a bit funny, though.

[Leadnuts]

Was looking around and found this one, and its similar to what the final set up will be like on mine. I can't imagine it not working as its done by what looks like some pro shop.



never mind i see the difference, pivot is aligned with the swing arm pivot... sigh, guess i have more work to do.

[mattcfish]

Just a bit of info, at least on some airheads, you can flip the lever over on the final drive so it points up and it still works when you pull it. Might give you a better geometry.
Love the work you are doing.

[Leadnuts]

So I made a linkage lever actuator thing in order to bring the pivot of the brake rod perfectly in line and as close to the swing arm pivot as possible... The part below is made of the cut off lever from the original brake lever the grease zert pivot and the tube in which the original pivot rotated in... At this point I'm going to say "pivot" oooone more time... pivot.

[IMG][/IMG]

Here is the assembled part.. The small arm was bit of metal I had around. Drilled a hole and slipped the axle bit through then welded around that flange area when I figured out the angle I needed.

[IMG][/IMG]

Then touched up the aluminum lever where I made the cut.. The key here was to be able to lock the arm in place on the axle. Ended up drilling and tapping a hole split half on the axle and half on the alum. lever which now has a set screw in it to form a key. I will stick a washer and nut over the end for good measure.

[IMG][/IMG]


So in the end I have a pretty nice looking actuator is I may say so.. The linkage rod is temp. just to see what I needed while i was making it. Also the foot lever is set in that angle just so you can see the parts.. Ends up taking a perfect amount of push to get that brake to engage... man that was a lot of work. Bet part is I can grease the axle, i guess.

[IMG][/IMG]

[Leadnuts]

Also got some part delivered today. Stuck them on to see what It will be like. Have a look.

[IMG][/IMG]

[IMG][/IMG]



What sort of options do I have for alternative fork nuts? Also will be modifying that 7' tall tension knob....somehow.

Thats a ToasterTan brace... You Jelly Bro?

[supershaft]

Originally Posted by melville

Looks like the pedal is free to float with the wheel moving up and down. Actually using the brake over bumps might feel a bit funny, though.

Hopefully that's how it works since most aren't perfectly centered on the swing arm pivot. I pointed out the same issue with a setup bmweuro was making. He came up with a pretty cool solution but his was with cable. I would rather use a rod too but sometimes I wonder because I think it is easier with cable.

I suspect Leadnut's setup will have less of a varying petal than the one in the photo. The one in the photo is probably a whole inch above the pivot whereas Leadnuts is further in front of the pivot but more central to the radius of the swing arm. I hope that makes sense? Pretty much the same angle BMW took. I would use a rod and some heim joints on the linkage Leadnut.

I wouldn't mind making my own hangers but with round tubing if for nothing else but looks. I want to make my controls out of real thin wall round tubing too just like BMW did with their old GP bikes. Same with the pegs.

[Jon-Lars]

[Leadnuts]

Jon-Lars... that looks nice! Mind showing the rest of that bike? Man, that would have been really helpful 11 hours ago. I feel like I just reinvented the wheel, which I know had already been around for a very long time.



Do I need to go with stainless linkage joints?



I think I have a paint scheme I like.

Toast tank and seat cowl will be a white,

Frame, headlight bucket, clip on bar sections and maybe wheels will be black. Don't know about wheels yet, as I can't decide what to do with the lower fork sections)

Seat will be upholstered black with ribs.

[Jon-Lars]

Here's a photo album:

http://tinyurl.com/R80GS-album

Check your lever ratios on the linkage. You can get sufficient pressure on the brake shoes if you keep close to the stock ratio - which is 23mm/5.3mm, or 4.34/1.

(Multiple lever ratios are multiplied to get the overall ratio)

[Leadnuts]

Originally Posted by Jon-Lars

Here's a photo album:

http://tinyurl.com/R80GS-album

Check your lever ratios on the linkage. You can get sufficient pressure on the brake shoes if you keep close to the stock ratio - which is 23mm/5.3mm, or 4.34/1.

(Multiple lever ratios are multiplied to get the overall ratio)

Is that a ratio for travel, or arm length?



Also... thats a pretty beautiful bike, painfully beautiful.