$lim's Money Machine Rebuild/Pimp my OCC Chopper

kdaddy1980 · Mar 12, 2014

so ive been in close contact with my buddy slim,that i sold the chopper, and hes been getting little modifications and upgrades.just put a set of dual exhaust pipes on it and now he wants a new paint job. so im breaking it down and doing a full rebuild on it.
good thing we decided to do a full inspection because i found the frame cracked completely off in one spot and almost cracked in half under the engine mount. he has the bracket style mount for his engine and i will be converting it to a tube/post type bracket, homemade, since i accuired my bada$$ welder lol

heres a before picture, and i will be updateing with pics of the damage and repairs as i go along

join me for "Slims Money Machine Rebuild/ Pimp my OCC Chopper" .shft.

kdaddy1980 · Mar 14, 2014

so heres where the frame cracked completely off. its where the front tensioner is bolted through the frame , im going to beef it up and maybe even weld the bolt in the hole so it doesnt crack the frame again.

the kickstand had cracked completely off and the frame was cracking right in half under the engine. ill be welding a plate on the frame before i weld the kicstand back on, as well as welding the engine mount plate to the frame

heres how she is sitting at the moment. on my homade workstation, which is a rolling trash can, and old shelf, and a vise lol
started sanding and welding, doing all the metal work before i paint

kdaddy1980 · Mar 19, 2014

Welded up the bottom of the frame with a steel plate.heated the sides of the plate and rounded them down to weld them to the frame.still getting used to my stick welder but I think I got it dialed in to the thickness of this bike. Welds are getting better as I get aquainted with it.

GearNut · Mar 19, 2014

That frame tube where the kickstand broke off looks rusted inside. Was/ is it?
Have fun learning that welder, melting metal into useful things is fun!

outlawbiker · Mar 30, 2014

Ive been very careful about what i have had to weld on my OCC. In the past Ive experimented with MIG welding chromoly bike frames in "structural" areas of the frame only to cause catastrophic failure and pain when crashing. And from the photos those look like some serious problems with the frame, your repair work looks good. I just say be careful.

Im very good at welding,and love it,but im no scholar or professor. Awhile back i had the idea of doing a rear suspension on my OCC and because of the structural integrity i needed to make sure i was going about it right. so anyways,from what i read and was told, stick or ARC welding can run too hot on our bike frames,and MIG flux core or gas could do the same. what happens is the alloy (side note: our frames are an alloy,not steel or iron) that our bike frames are made of doesn't like the heat,and when it cools,becomes super brittle near the weld and under the right conditions break, also you maybe able to weld a different metal to chommoly,but the differences between the 2 could cause the weld to fail. I was told the only way to do it right is by using a TIG welder with chomoly filler rod or by brazing. i dont have any of this equipment so i never started the project and i didnt want to take the chance cutting up my only OCC bike to find out if ARC or MIG would of failed.

What i was tought may or may not be fact,or i got some facts wrong,but MIG in the past has failed me on structural parts of the frame,and this information i found later made sense to me now. I hope it all works out for you,but i thought i should mention this because i dont want to see any of us getting hurt,when those frames fail,the crashes are quick hard and painful.

good luck,and happy welding

Henshooter · Mar 30, 2014

From previous experience a stick is definately too hot and apart from blowing holes in your weld areas and frame you will certainly render the strength of the frame close to Nill , you might get lucky and run some decent beading but each and every time I did this with an ark many years ago withing weeks the area would fail and usually quite catastrophically , the best and only way to correctly weld a bike frame is with a tig and chromoly fillers and or as suggested braising , despite what I've said it looks to be a sweet repair job ,
Just keep an eye on the extent of rusting in the kickstand repair ,it looked fairly eaten out and full of rust and you don't want that to fail when under way, a thin pole like that will go through flesh like a chop stick to barbecue pork ,trust me from experience it is quite the painful experience and just as bad a sight for the bystander

Overall the repair looks great but heed the warnings given and be very carefull ,keep a watchful eye on the weld spots

Regards Henshooter brnot

Theon · Mar 30, 2014

My Softtails been done with the stick.
Wasn't the fanciest chrome moly frame, does it make any difference to strength of weld with varying grades of steel?
I reweld all my welds, and mostly use a slow tacking vertical up type weld giving a second or two between tacks. I've had no welds fail as yet, but do worry a little at times, as I did a major rework of the two main tubes, sleaving what I could, However I was also sure to add an extra tube and gusseting for reinforcement.
It's quite painful work with a buzz box, but with an inverter welder, set around 65A to 75A, one with a digital display is the go for reproducing consistent welds.
The TIG is obviously the go, and All I really need is a bottle of gas. And something for sharpening my tip.

Pelican Pete · Apr 8, 2014

My first build was an OCC chopper. When the hub self destructed (actually it was my fault) my frame broke in the same place as yours. It is not surprising because it is a "hard spot" (sudden change in structural continunity).

The hard spot is where the oval tubing is resting on the side of the rectangular tubing. Square & rectangular tubing is great stuff for structural design, but you want to put the stresses on the edges and not on the flat sides, unless you use a doubler plate. Notice that on the OCC, only a small portion of the round tube is resting on the corners of the rectangular tubing, and the rest of it is on the soft flat side of the rectangular tubing.

The OCC has 2 such joints at the top and bottom chainstays. I think the bottom joint takes the worst beating because it is alternately in tension and compression. The weight of the rider puts the bottom joint in tension, then when the clutch grabs, it probably goes into compression since the chain is trying to pull the hub forward.

This is easy enough to fix using a soft toe bracket. Soft toe just means long tapered ends with a big radius to minimize stress concentrations.

I did a quick and dirty fix on my OCC by brazing in an angle bracket to spread the load. I used a bent bracket from the local hardware store, which was probably a bad idea, because it has already been hard bent at the factory, so it is kinda like covering a weak spot with a weak spot. It would have been better to use a short piece of angle bar since it is rolled to an angle and not bent.

I think a better way to fix it is to braze on a Tee bracket, on the top and bottom of the joint. It can look stylish with tapered ends and a big radius in the corners to gradually ease the stresses.

My favorite way to attach things to a bike frame is to make welded assemblies with saddles or doubler plates to braze on the frame. I agree with the comments above about welding. It is often touted that MIG and TIG welds are stronger than the parent metal, but as mentioned, the weld can lead to failure outside the weld, probably because of the heat, but also because the area outside the weld may not be adequately protected by the inert gas. For critical welds on a thin bike frame or tank, it is a good idea to fill the inside with inert gas before welding.

Excuse me for ranting; I couldn't see how to express it in fewer words; thanks for your patience and I hope your project works out well.

kdaddy1980 · Apr 22, 2014

i built a tube type mount to hopefully take down some of the vibrations.

i welded the engine mount bracket to the frame with some supports. the welds are big and ugly but nevertheless seem strong and will hold good.