My old mule.

[shovelon]

Dunno, as you have to give some info. But the basic kit is $149.
http://2btherapy.com/index.php/bikes/brake-therapy-conversion-kit

I do have a weld jig/plate locator for fabrication and welding a disc mount to your swingarm. PM me for more information if you are interested.

Terry

[fyrstormer]

Welding definitely sounds like the best option, but I have no welding experience or equipment. I'd have to pay someone to do the work, and then pay for a paint job on top of it, and I don't have replacement decals for the swingarm. How much damage to the finish would I have to expect if I wanted to weld tabs onto the frame?

[shovelon]

Well the paint would need to be stripped about 1" away from the weld, and another area to attach a ground lead. Beyond that the rest of the paint will not be compromised.

Would be me, I would just repaint the welded tab area.

Terry

[fyrstormer]

Hmm. Would you mind terribly if I asked to see a couple pictures of your work, preferably on painted swingarms? If you can do the work, I think that's the direction I want to go in, but I'd like to know exactly how perfect or imperfect I can expect it to be. I only ask because I've tried to take such good care of the paint so far, which has been no small feat since I've been busy falling down hills and hitting moving cars on it.

[shovelon]

Hmm. Would you mind terribly if I asked to see a couple pictures of your work, preferably on painted swingarms? If you can do the work, I think that's the direction I want to go in, but I'd like to know exactly how perfect or imperfect I can expect it to be. I only ask because I've tried to take such good care of the paint so far, which has been no small feat since I've been busy falling down hills and hitting moving cars on it.

Well I don't have any pics of swingarms, but I do have pics I send to GT owners detailing mast repairs with inserts added. Along the same lines. I do more mast repairs that I care to admit.




And one swingarm I built in the late 80's


Terry

[fyrstormer]

Wow. So, um...I guess you've had time to practice. Sorry about the questioning, but I keep telling myself it's the one time I don't ask that I'll get burned. It definitely looks like you know what you're doing.

So, last question in public, and then we can talk about shipping and cost over PM: can you do 74mm post-mounts, or just IS tabs? Tabs are fine, but if I can get posts that's even better because that's the kind of brake I'll be using.

[shovelon]

Only standard tabs, sorry.

[fyrstormer]

Not a problem, just asking, thanks.

[w2zero]

Re:  the air fittings on the alignment tool.  Izzat for a nitrogen purge?  We used to flood the underside of ss with nitrogen when welding countertops on ships.

[Thunderchild]

Shovelon is one fine welder.  He fixed my Proflex 5000.  It had cracked at the seat tube.   And, he fixed my Evo at the head tube down tube junction.  There are pictures in my gallery if you are interested.  Aluminum welders are hard to find.  The good ones even harder.  My father was a very talented welder (acetylene, stick, union fixed station) at Geneva Steel for 39 years.  He would just shake his head when talking about welding aluminum. 

Thunderchild

[fyrstormer]

Don't you have to use an acid flux when welding aluminum? I remember something about needing to etch it, but on an existing part I have to think a liquid acid would be too hard to control.

[shovelon]

Re:  the air fittings on the alignment tool.  Izzat for a nitrogen purge?  We used to flood the underside of ss with nitrogen when welding countertops on ships.

Good eye. 
Actually alum does not need a purge like SS, 4130 or Ti. I use the tapered threads on coupler to expand the mandrel against the seatmast. That way I burn thru the seatmast and the molten weld lays agalinst the mandrel. The mandrel doubles as a heat sink, preventing overheating.

If I am need a purge, I can feed into the coupler and wrap alum foil around the seams to slow dissipation of the purge gas.
Here is a better pic. You can see the discoloration where the weld penetration was.


Here is a Ti seatmast that I purged, but without a mandrel. See how well the alum foil works.

[shovelon]

Don't you have to use an acid flux when welding aluminum? I remember something about needing to etch it, but on an existing part I have to think a liquid acid would be too hard to control.

Alum brazing may need flux, but in welding you are melting the base metal and adding extra metal.

[fyrstormer]

Interesting. So why is aluminum so hard to weld compared to steel? Is it because it oxidizes so fast?

Anyway, on a different note, is it possible to remove the V-brake studs from a 756 swingarm? I remember trying years ago and I was afraid I was going to break the swingarm I was putting so much torque on the stud. Ended up damaging the stud and I had to sand it down so the V-brake would fit on it again. If I'm going to get disc tabs added, I won't need the studs anymore, and I'd like to remove them if possible, but I swear they were installed with an impact wrench or something.

[DugB]

ASHBURN! I'm in Falls Church! We should ride sometime and I'll bring out one of the 'flexes! Ever head inside the beltway, e.g. to Wakefield?

Welcome!

- Doug :-)