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Discussion in 'Some Assembly Required' started by Pilbara, Feb 15, 2008.
Absolutely brilliant, mate. I'll take two!
Need a bit off tweaking, but it seems like a plan that can work.
KELVIN! Will you buy a fookn CAMERA? (And learn how to use it?).:huh
Lookn' good bloke! Keep it happenen!
You are the man.
What a cazy as shit project. I always had the pre-conceived idea that all BMW owners were slipper wearing, pipe smoking old bizzy bodies, i think you have smashed that concept Pilbra!!!! Mate, awesome to see someone thinking outside the square and going for a design that will take some REAL riding. Keep it comingman, waqiting with baited breath for the installments.
Yep. Sheared the vulcanised rubber bushing on my 1150GSA's driveshaft last November. Failure occurred suddenly and totally. That is there were no warning signs and it needed a recovery vehicle.
Bike had done 55k, about 30k of which was at my hands, and as much as possible on dirt tracks and gravel roads. OK my hands may not have been the kindest.
Is the front end to retain the GS feel of limited dive under brakes?
hey Pilbara, do you use an oxy set to braze or a TIG welder someone mentioned in another thread?
I had a mate now disceased that built a super single using the same technique with Reynolds? tubing.
If you TIG it do you use a shielding gas
This is an ambitious project and I wish you all the best of luck with it.
Love the idea - but I think you are going to kill yourself. Might want to do a little welding research.
<BR>I think brazing is being used here as an attractive way to tack the pieces together while prototyping.
Brazing and braze welding are two different things. Pilbara answered this in post #55. It got me looking, where I found out that at low temperatures the strength of a braze welded joint is typically stronger than the base metal.
The downside is that the weld loses strength above 200C. And you can't match colors.
<BR>Yes I read post 55 on semantics. Unfortunately a structure doesn't refer to semantics when it evaluates whether it will carry a load.
Brazing or braze 'welding' is a great choice if the joint is designed with enough bond area. If the bond area is large enough, the joint can certainly be stronger than the base material, for even the strongest of steel alloys.
The thing is, for a brazed joint, the fillet doesn't accrue to total bond area. This is especially relevant when the connection point is subjected to bend or shear loads. Many of them are in this inventive frame design.
Hello dirt rider X, the welding is all done with an oxy acetylene torch. I have heard of persons using a TIG but have never tried it myself, I would think it would be too difficult to do too, as the TIG would have a very localised heating area and the whole purpose of using bronze welding on chrome moly tube is to not overheat the material above its critical temperature. I am surprised at the misconceptions around bronze welding and the perception of weakness. This frame is not tack welded it is welded with phosphor bronze in the interests of construct-ability, safety and strength.
I have crashed my frames before on the speedway track and torn the chrome moly tubing apart and the weld still completely in tack. Again this perception of weakness is not in my experience and wonder where it comes from. I can only imagine from persons not appropriately skilled in the technique of bronze welding having had failures and this being seen as an inappropriate metal joining process. I have crash tested this method of frame building and it works...well, better than any other techniques used before being shown this method. My welding research has been done from a practical sense and proven. Not sure what is being missed here by the doubters of this. Look at all the Wasp frames, most of the pre ali or carbon GP bikes and cars for decades have been built this way. So I would suggest that the surfers do a bit of research of their own. History and any current custom frame builder of any credible note does exactly what you see here.
The proof will be in the pudding so to speak, lets see how it handles the punishment I intend on giving it and, I feel pretty safe in doing it too. There may need to be some changes along the way, but it is only metal...
Javahead, thanks for the feedback on the driveshaft, I have bought a new one so have confidence it should be good for a while. The front end is done that way because I believe that is how it should be done. I cannot achieve what I want with a set of telescopic forks and I can't afford a set of forks that will do what I want. Again I am surprised by the industry sticking with telesopic forks when they really are a poor compromise for suspending the front end of a motorcycle. It is a bit like the internal combustion engine, it really was not the best method of producing power for transportation and yet we have it and nothing else is considered appropriate. I think telescopic forks on a motorcycle are in the same league. Industry has put all its efforts into the development of the telescopic fork and have ingrained themselves into carrying on with their development, just like the internal combustion engine. Look at what you need to spend on a set of forks if you want to race competitively in the WSB >$35K! How much do you think Coma and Cyril pay for their forks? OK Redbull...and they are a compromise. Look at what I need to achieve hopefully a similar or maybe even better result. No complicated steering head with tapered roller bearings and no way, other than making a new frame or other significant expense, to change things like; rake, offset, trail etc for a fraction of the cost, just a lot of head scratching. Mark my words, one day all front ends of motos will be made in a fashion similar to this and people will say, wow there is one of those old telescopic fork front end things....
I sure agree with you about the forks Kevin. In addition to what you mentioned, I'm surprised that oil damping and metal springs are still in common use for vehicle suspension. (But not really so surprised. If commodity items were designed and manufactured economically it would put 60 or so percent of people out of work.)
Out of curiosity what's the axial load capacity of the 'front strut' Heim joints?
Front at max droop and rear at about 4" compressed position.
The rear swingarm is being built in the same vein = strong I don't want this happening again...
This is very impressive stuff.
How much travel have you managed to get out of the suspension?
Also I have done a small amount of alterations to my engine and frame on my dr and I ran into a few brick walls when I went to find out about registration. How are you going to register it?
Gonna leave the drive shaft exposed?
Here's an interesting link about braze welding, if anyone is interested.
It looks like a good way to get a strong joint in 4130, as long as it isn't exposed to high temps that would weaken the filler, and in this application that shouldn't be a problem.
If I were attempting this I'd have to make some test joints and test them in the shop press and/or have them fatigue tested, but that's because I don't have the previous experience that the OP has.
Here, when someone says bronze welding, they are talking about joining pieces where the base metal is bronze.
Normalized 4130 tubing can be torch welded, or tig welded, but preheating may be required. A professional welder who is an expert in these steels would be a must have IMHO. One stray arc could cause a future crack. E70S2 would be a good choice, as opposed to 4130 rod. Heat treated 4130 would likely require heat treating the entire frame after welding.
Anyway, super-cool project. I can't wait to see how it turns out.
Anyone that knows pilbra will know that the loose nut behind the handle bars is the issue not the strength of the welds
I'm sure his first ride out will test the weld strength, wont be a matter of if he crashes more the fact asto what speed ???????
Well done K