I took my '56 pre-unit frame apart last night and started scoping out a way to disect the thing... after a few minutes alone with it in my garage, I decided that I needed to remove the bulky rear swing arm mount... So I cleaned the grime and paint off, and noticed that the mount, along with several other steel parts (over tubing) were pinned and brazed together. So I drilled the pin out of the lower part that had to come off first before I removed the swing arm mount, heated the hell out of the thing to get it to expand and then whacked it with a hammer... when it didn't budge, I decided to try and twist it off... that's when the thing snapped it two! Now these parts appeared to be forged steel... but now I clearly know at least the lower part is cast. Anyway, does anyone know if all the parts on these early Triumph frames are cast? Like the neck? I'm not planning to "chop" it... but how did guys rake them out back in the day? Now that I've fucked the thing up... I'm going to just whack it off just above the swing arm mount and graft on a whole nuther piece of tubing... which brings me to the next question. When building custom frames, what size tubing do guys use? The lower rails are 1" o.d. .065... and the other tubing is a standard size (I'm sure) also... So do I keep the same size tubing down below? I want to stay away from a welded and smoothed out frame, and am almost to the point of making an entire new frame if this shit isn't workable. Sam!
Sam, Sam, Sam, higher heat and bigger hammer! Actually you must melt the braze competely, it sounds like it was not melted. Castings generally do not do well with impact. My guess is "back in the day" they did not change the casting and brazed parts, they cut off the tubing and then welded to a short stub. Maybe if I see it in person I can make more sense of it. Tubing size would seem to be more of an aesthetic choice, and I think it should match the rest of the frame. 1-inch cshould be plenth strong as long as it's braced and welded properly, which I know you will do. Save those broken pieces and i can confirm of they are castings or not.
So are these cast parts strong enough? Or did people have problems with them cracking and braking? Then again, they probably didn't heat them up red hot and then try to bend them in a vice after haven' whacked them with two pound sledge. (under normal riding conditions) Sam.
You of all people I would think can fabricate replacements out of steel plate. (and drill holes in them like the spring mount on the rat racer.)
Not sure how the Trumpet guys did the front end rake bit. On our Honda Scramblers we cut out a piece of the frames top tube a couple inches back of the steering head, heated the lower tube and bent the frame back until the cut area was pulled together. A little chamfering on the cut before the heat and pull-back was done. Then the top tube was welded back together. Sometimes we'd reinforce across the cut area with a piece of strap or some thin wall tubing cut, heated & wrapped around the frame top tube. Welding those into place made us feel a little better, but the guys who simply welded the top tube didn't seem to have any problems. Seems like the cut was 1 1/2" or so. The cut done to slow the quick steering Hondas down in the steering dept so stability on the top end was improved. Runnin patrol roads and all that....
I've cut a few old "trumpets" and I usually lengthened the down tube and raked it either behind the neck casting or in front of the "seat post". Works great and keeps from messing with the cast areas. Hope that helps. George
A lot of frame builders, these days, are using thicker wall tubing. It doesn't deform during bending quite so much. You may want to stick a length of smaller tube - in your cut/weld spots just to be safe. You probably were already thinking that, though. Right?
Sounds like they were made the same way as British bicycle framesand Morgan front suspension were (and still are) made.
Dumb questions: Are the forces a "chopper" frame receives under "normal" use less than say, a "rat rod" chassis? Translation, which is crazier for a novice welder to do... weld up a chopper frame and hop on and ride it, OR, weld up a T/A chassis and hop in and drive it? Thanks, J
The cast parts on the old British frames weree "malleable iron", brazed into the tubing. Good iron with consistant crystalline structure.. People didn't rake frames "back in the day" They raked frames in the disco days when profile and "style" counted for more than performance and handling . I have been thinkin...trad hot rods today are descended from lakesters and the stripped down racers of the 30s and 40s...when removing weight and surplus parts made for better performance...high performance was the goal... So why is any HAMBr interested in choppers? Where performance is far far down on the priority list and profile and FASHION are the goals? Just a question.
my old man weld up my 66 trump frame when i cut it up 20 years ago and he had me cut the top tube under tank where it can hidden, and he had me make a long plug for inside the tubes and a little slice here and there in the down tube let it bend easier and then weld the slices back up, since then I've learned to even appreciate a front brake(even though a springer only looks right with a spool hub), I now that he just zapped it with the old lincoln tombstone buzz box and I went down the road, ride the hell out of dude
[ QUOTE ] I have been thinkin...trad hot rods today are descended from lakesters and the stripped down racers of the 30s and 40s...when removing weight and surplus parts made for better performance...high performance was the goal... So why is any HAMBr interested in choppers? Where performance is far far down on the priority list and profile and FASHION are the goals? Just a question. [/ QUOTE ] That's why you'll never catch me dead on a chopper or a channeled "hot rod"... and I pretty much think of "Kustom's" along the same lines... So, I agree wholeheartedly about what you be layin' down! Sam!
Reason I ask is I wanna convert a swing-arm bike to a hard tail... a bit more envolved than a rake... Yo, I gotsta have a choppa to go wit my west coast chppers hoodie, yo... (Kidding about the clothing statement, but not the hardtail...) We all have different ideas of what BITCHIN is...
You might want to search the web for "sif bronze" or "sifbronze" welding or brazing to find out how some of the brit bike manufacturers "glued" their fames together. Some MC restorers and high end bicycle frame manufacturers still sif bronze braze their frames together, and there have been a number of discussions in Classic MC mags by those who feel this is better than tig or mig welding frames.
Reading your list of problems I'd say your already over your head. Not that you shouldn't try new things but find some qualifyed help before you start cutting up hard to replace parts. Those old frames were put together by a process called Furnace welding. Proper heat controll and fill rod is the secret of dissimuelar metals being welded secusfully. In this case Brazed. There were several hard tail kits made years ago. Most came with same size tubing as the front half of the frame. The good ones had a slip in bung welded on the ends so you just slipped it inside your frame and Plug welded and then a perimeter weld. In your case I'd stay with same size tube and same wall thickness. You could however do like we do when lengthning dragster chassis. Get a piece of tubbing same wall thickness but with I.D. same as your existing O.D. then bologna slice and slip over then plug and perimeter weld it together. Good Luck! The Wizzard
I was just rememberin, those Triumph iron frame lugs were made by Qualcast, a big foundry in Birmingham. The last few years of Triumph brazed frames sometimes had, instead of pins to align the lugs, just a couple little spot welds on the edges. You can weld malleable iron with nickel rod in a forge, but it's not too successful usually...in my experience it takes a lot of luck
[ QUOTE ] Reading your list of problems I'd say your already over your head. Not that you shouldn't try new things but find some qualifyed help before you start cutting up hard to replace parts. [/ QUOTE ] I appreciate you help... and concerns, Wizzard. But when you have access to 3D CNC machines and/or a mill, lathe... and file... those erreplaceable parts aren't as hard to find. But I will end up using the NHRA approved sleve inside a tube method, with rosette (plug) welds to graft the new tube on. I will also use this method to make the lower rails that extend to the rigid rear section. I'm doing this because I want to retain those *cast* pieces that bolt the lower rails to the front down tube. I know it seems finiky, but those parts are an integral part to the feel of my bike. So, did they ever have a problem with these cast parts breaking? Sam!
Sam, I have read about cast bits breaking - during desert races. I have never seen them break myself, and my experience around these bikes is at road-racing events and a shop or two. You are more likely to tweak tube, than to bust the cast. I would try to keep heat away from them, while working on the frame, just because. Shouldn't be any trouble for you, though...
Actually dusty knuckles... I seem to attract heat all the time. I also appreciate the help from all of you. I'm used to working with old Ford stuff... so it caught me off guard that a part that looked as it did was cast... Sam!
[ QUOTE ] and the stripped down racers of the 30s and 40s...when removing weight and surplus parts made for better performance...high performance was the goal... [/ QUOTE ] [ QUOTE ] So why is any HAMBr interested in choppers? Where performance is far far down on the priority list and profile and FASHION are the goals? [/ QUOTE ] Disastron, I thought chopper was short for chopped hog, where guys removed weight and surplus parts from Harleys to make them perform like a motorcycle should
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