trackin xv750

It does not matter wether its a caliper mount or a fender mount i think. It was not designed to handle the amount of stress wich such a tiny drum will give on such a lump of metal. I totally agree with teazer and the chalk part, but for some reason i think the only thing chalked with this idea is the line around a dead body....

dont trial and error on brakes man.. if it snaps, your cable gets tangled up and everything is smashed to shit.
 
one could argue about the fact that the caliper mount is very tough and such, but it gets its strengh from the 3d boxed shape wich you've taken away, it now is just a piece of alu and not the strong part as designed by manufacturer. If i would have this problem, i'd make a clamp around the fork leg with a boss on it out of steel or highgrade alu. It's not like you're fabbing a odometer onto it, Its your life.
 
Bert Jan said:
It does not matter wether its a caliper mount or a fender mount i think. It was not designed to handle the amount of stress wich such a tiny drum will give on such a lump of metal. I totally agree with teazer and the chalk part, but for some reason i think the only thing chalked with this idea is the line around a dead body....

dont trial and error on brakes man.. if it snaps, your cable gets tangled up and everything is smashed to shit.

it doesnt matter whether it was a caliper mount or a fender mount? is that a serious statement? you think the engineers put the same amount of thought into the fender mount as the caliper mount? dumb. the arm is exactly the same as before i touched it.. i just cut the end that wasnt needed off. im not saying you're wrong, im not saying you arent making good points.. but dont say the arm for a caliper is the same as the fender mount, the fender mount is very small, thin and quite frankly, looks like a fender mount. this is a large, thick arm, which im sure the engineers put a little more though process into when designing.
 
Bert made a pretty good point - look at aluminium structures that are made to bear the kind of stress you're putting on that point. Aluminium does not take shear well.
 
MJPriceisright said:
it doesnt matter whether it was a caliper mount or a fender mount? is that a serious statement? you think the engineers put the same amount of thought into the fender mount as the caliper mount? dumb. the arm is exactly the same as before i touched it.. i just cut the end that wasnt needed off. im not saying you're wrong, im not saying you arent making good points.. but dont say the arm for a caliper is the same as the fender mount, the fender mount is very small, thin and quite frankly, looks like a fender mount. this is a large, thick arm, which im sure the engineers put a little more though process into when designing.

Well, first of all, don't call me dumb cause i aint. its a language thing i guess. I meant to say that it's not a good idea to put the brake arm on either one of them (the fender mount or caliper mount) because they're both not designed for the force you're applying.

My point about the shape of the caliper mount is relevant. I'll try to explain. The caliper mount wants to bend when brakes are applied. The force you'll put on it will give the caliper mount completely different stress-points then the force they were originally designed for.
the more material you remove (between the stress points or not is irrelevant) the weaker the structure will get. PERIOD.

Think about a cardboard box with the lid folded close or open. The lid does not help to keep the groceries in, but it does help to keep the box strong when closed.

A 'V' piece of steel is way stronger than a flat piece for the same reason.
A hollow pipe is stronger than a massive one with the same diameter for the same reason.

IMHO it's not smart to remove material when the only argument to be made is 'i dont need it'. You might not, but the force you'll apply on it this way will negatively benefit from the removal of material.

I'm not going to lecture you any more because i'm no proffesor either, but i've got my basics in construction pretty dialed and i don't like your solution. Change it or ignore my worries, i really don't care. No hard feelings ;)

i've subscribed to see where it goes :)
 
I wouldn't have called you dumb if you had specified better the first time. Now that you clarified yourself I understand your concern, and I knew about the different direction of force might be a risk factor with it installedw like this. A before and after pic would have cleared things up for you about the cutting material off. I took about an inch of length off the tip and just sanded it with a file to make sure it was flat on either side.. So I'm completely aware that the more I take off the less strength it has. Thanks for following along, I love the insight from fellow members. Even if it's arguing.
 
yeah for right now im gonna leave it this way.. i need to get the axle made first, then ill make the decision at a later date.. trust me ive been thinking about the things you've said, and a friend has taken a look who is an engineer has addressed the stress direction that the arm will have.. which will be different as you said before.. he thinks it will hold up strength wise, but has no comment on the stress direction. maybe ill put some football gear on and drive in the grass and hammer on the brake a few times and see how it turns out. HAH.
 
MJPriceisright said:
maybe ill put some football gear on and drive in the grass and hammer on the brake a few times and see how it turns out.

And he's calling ME dumb... ;)

I think that a fairly cheap and important upgrade would be to replace the washers with a piece of tube with a thick wand. Best would be to make one on a lathe, so you have it as big as possible. Ideal would be to make it touch the whole of the mount, instead of just a little bit (like the washers do now). It will reduce the torsion tremendiously. Might also consider changing to m10 bolt maybe?
 
On the pics, i spotted another hole, under the one you're using for the m8 bolt. Wouldn't it be possible to use that one? Because there's material between the hole and the leg (the hole you're using now is on an extended piece of alu wich could break.)
You could fab a piece of metal between the mount on the drum and the lower bolt hole, would be MUCH safer. If you make the red bar as thick as the washers you're using now you wont have to use any washers in between, making it even stronger.

Edit: Like this;

Schermafbeelding2013-01-16om183107_zps45f15b21.png


The red bar is a piece of steel, the blue part is a piece of steel welded on to the red piece in a 90* angle and has a small hole with threads in it, to accomodate the cablestopper/adjuster. The light green is your innie, dark green outie. The red piece can be made shorter/longer, this is just an idea. Shorter would be better by the way, would be nice to put the drum arm behind the fork leg. cleaner.

Even nicer would be, (but i cant see if that would work for you) to put the brake arm as horizontal as posible so that the cable is behind the fork leg ;)

Last piece of advice; measure twice, cut once.. Dont chop (more fork) unless youre 100% sure its the way to go. Would be a bummer if you decided the drum does not brake enough and you want calipers again........
 
haha! yeah oh for sure, that was just for mock up purposes, going to definitely have a large diameter bushing made.. do you think the bushing should have a arm welded to it that runs down to the lower caliper bolt hole? was doing some thinking that maybe that would help, bracing to the larger/thicker area down by the axle.. thoughts on that? ive attached a really shitty picture to try and put it into perspective.. thanks bert for keeping this in check, i appreciate you following along.
 

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The existing bracket is most likely to break because the forces act in a forward direction where the "arm/extension" piece is tall but not in the direction of the force. We're talking a simple aluminum casting and they don't have a whole lot of strength in bending.

The lower hole would be a much safer option.

I'm guessing that the lack of braking force will save that bracket and that it will take so long to slow down that a redesign will be on the books. :) The builder isn't dumb, he's just stubborn like the rest of us that get an idea in our heads and want to see where it goes. He'll work it out.

His design criterion was to keep the front end looking clean and simple, so the question is how else can that be achieved? Maybe a single large diameter disk or a rim mounted Buell arrangement or something from Berringer perhaps? Maybe two smaller diameter disks and small body calipers?
 
MJPriceisright said:
haha! yeah oh for sure, that was just for mock up purposes, going to definitely have a large diameter bushing made.. do you think the bushing should have a arm welded to it that runs down to the lower caliper bolt hole? was doing some thinking that maybe that would help, bracing to the larger/thicker area down by the axle.. thoughts on that? ive attached a really shitty picture to try and put it into perspective.. thanks bert for keeping this in check, i appreciate you following along.

Well, that would be better, but, like teazer also said, the piece will prolly break. So, if you're going to use the lower hole with a bar (as i uploaded) no extra bushing is requird right? if not (its hard to see from the pics) a tube welded onto the bar will be better than a loose tube for sure. A thick enough bar would be golden/strongest. You could even drill speed holes in it or give it a mill-diet.
 
teazer said:
The existing bracket is most likely to break because the forces act in a forward direction where the "arm/extension" piece is tall but not in the direction of the force. We're talking a simple aluminum casting and they don't have a whole lot of strength in bending.

The lower hole would be a much safer option.

I'm guessing that the lack of braking force will save that bracket and that it will take so long to slow down that a redesign will be on the books. :) The builder isn't dumb, he's just stubborn like the rest of us that get an idea in our heads and want to see where it goes. He'll work it out.

His design criterion was to keep the front end looking clean and simple, so the question is how else can that be achieved? Maybe a single large diameter disk or a rim mounted Buell arrangement or something from Berringer perhaps? Maybe two smaller diameter disks and small body calipers?

That would be a single disk (one mount is gone and 1 is cleaner than 2) but the rims dont accept disks. would be a lot of work to find wheels that fit and have the right looks aswell, not undo-albe, but a lot of work...

I would try to score a wheel that looks kind of the same as the rear wheel and has a disk option. That's the closest i guess, next to riding with the drum.
 
bert a guy on here makes a rear to front conversion that comes with adapters etc to run a front disk. i dont have a problem buying that conversion, but yes like teazer said i had in my head of running dual drum and keeping things as clean as possible.. so we'll see.. i will make the bar and bushing, mount it up and go from there. an also like teazer says, if the thing doesnt stop, well ill be goin back to the drawing board.
 
I've been following your build as I'm building a XV500, regarding the debate on your front drum conversion I would have gone with using the caliper mount for the anchor for the drum brake, the reason being that the caliper mount will take the rotational stress of the drum brake. Obviously the drum brake won't be as effective as twin discs but it will not be too far away from the standard single disc. The reason for this is the coefficient of friction and rotational forces. Drum brakes can be as effective and in some cases more so than disc brakes for many reasons. The rotational or turning forces from your drum brake will be no greater than the forces from the disc brake, this is due to fulcrums and levers. The anchor on the brake mounting plate is a lever in essence that reduces the actual force transmitted to the caliper mount and will not be too far away from the forces applied by disc brake calipers. .
 
yeah we have established most of the elements here.. but the big concern is the new angles of pressure applied, which will be different now that im bracing a drum with it. essentially it could twist and break.. definitely going to do some bracing using the large caliper mount hole. going to start with the crappy drawing i had made up.. steel brace running up to a bushing welded at the top, having two points bolted to help reduce the twist.
 
Karlloss said:
I've been following your build as I'm building a XV500, regarding the debate on your front drum conversion I would have gone with using the caliper mount for the anchor for the drum brake, the reason being that the caliper mount will take the rotational stress of the drum brake. Obviously the drum brake won't be as effective as twin discs but it will not be too far away from the standard single disc. The reason for this is the coefficient of friction and rotational forces. Drum brakes can be as effective and in some cases more so than disc brakes for many reasons. The rotational or turning forces from your drum brake will be no greater than the forces from the disc brake, this is due to fulcrums and levers. The anchor on the brake mounting plate is a lever in essence that reduces the actual force transmitted to the caliper mount and will not be too far away from the forces applied by disc brake calipers. .

I'm sorry? You talk alot but dont say much. I really dont understand what youre trying to say.
 
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