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I love that herpes is the default metaphor for CR.net these days.


RJB, cool your jets.....you are getting your help so scoop the sand out of your vag and listen up.


Asking questions that have multiple answers and expecting one answer is not going to help you. So let's run back to the project planning stage for a second.

At this point I will remind you that your brakes are only as good as the traction your tire has. The single disc has the ability to lock up on a stock bike, but it takes effort and there isn't a lot of feel up at that top range. The stock drum has a lot of fade and generally any disc conversion is considered an upgrade. What you want ideally is the ability to easily use the entire range of your brakes from light touch to locked up with the maximum amount of feel.

but before we get to the good stuff I will answer your question about the cb550/450/750 dual disc conversion. You are correct those bikes did not come from the factory with dual discs. However honda at one time planned a dual disc conversion accessory kit for all three bikes and did at one time sell one for the 750 for a breif period. The forks have lugs for both discs and basically you convert a stock one sided caliper bracket to bolt to the other side by shaving one of the mounting points and making a spacer for the other. You also reverse the caliper by pulling a crush pin in the caliper so the line exits the opposite side. Search cb750 dual disc conversion and you will find tons of articles on it, the 450 uses the same caliper and fork legs but are shorter, the 500/550 uses similar pieces and the method is the same but only the wheel interchanges. The 450/500/550 forks are preferred over the 750 since the forks are shorter. We will talk about how to mount them up later.

There are two major approaches to improving your bikes braking which is what I assume what you really want to do. A lot of it depends on how the overall bike is setup. If it is closer to stock I would almost say take the weight penalty of dual discs and bigger forks just because it a) looks more impressive, b) is going to add more rideability, and C) you are understressing components which are normally used to working on heavier bikes.

But let's talk about the first approach for a second. The lightness approach or the understressing method. If your bike overall is 50-100 lbs lighter than stock or more (if that is possible) then it may behoove you to work the lightness to your advantage. The simplest way is to get a cb360 disc front end (same as the 350G) and slide it right into your trees. Since the 33mm forks are pretty spindly I would add a fork brace, a tweak bar bolted under the bottom clamp (a fork brace bolts to the sliders, a tweak bar bolts to the fork tubes in case you don't know the difference), an aluminum rim (18"), braided hoses, and a modern master cylinder with a piston size 14mm or one size larger than that. Make sure your fork springs and rear shocks are paired nicely and setup for your weight.

What you gain is braking improvement by making your overall package work less hard. The only unsprung weight you add is the fork brace, and you remove the heavy drum. You get rid of brake pressure loss due to hose flex by using braided lines, and the new master works like a new master so you probably get back some efficiency there. Plus you keep your stock speedo gauge and because the 360 one has the same ratio as the old one and you just run a cable.

What you lose is the increased rigidity of a thicker tube front end and the ability to get better parts like cartirdge emulators and cheap mass produced fork springs.


If your bike is closer to stock weight (and by now I hope you have figured out you need to be weighing your bike), then while the above approach will work it won't improve the handling, won't improve the feel too much, and you will still be stressing your components as they were stock, which means the brake will feel shitty.

Enter the neck bearing chart:

http://scandalon.com/2009/06/motorcycle-steering-stem-bearing-size-chart/

cb350 uses: Upper: 26 x 48.5 x 15.2 Lower: 30 x 50 x 14.4

Honda CB450/K1-K7: Upper: 26 x 48.5 x 15.2 Lower: 30 x 50 x 14.4

Honda CB550K/K1: Upper: 26 x 48.5 x 15.2 Lower: 30 x 50 x 14.4

Honda CB750K (1969-1978): 26 x 48.5 x 15.2 Lower: 30 x 50 x 14.4

See a pattern here? Unfortunatly what you don't see is that the stem heights are different for all three bikes, with the 450/500/550 being the closest to the cb350 stem height. You will still have to make a spacer that fits under the top clamp to allow the nut to tighten down properly, and you will have to measure that yourself, but basically you bolt the entire front end Triple trees to tires right into your 350 neck. You will also need to make new steering stops - you can buy dirt track bolt on ones, or you can drill and tap the stock stops in the clamp and put a bolt in there. either way, it is pretty easy. Now you can stop here and already you would be miles ahead of the game, however, if you got a 450 front end you can search out a hondamatic 750/ GL1000 front rim and upgrade to alloy. You can also run braided lines. Again, better springs, maybe cartridge emulators, and a fork brace. no tweak bar unless you really want it. But even stock the components on the bike will be underworked and will be an improvement over your stock 350 stuff. It is at this point if you really want to go overkill you can do the dual disc converion that many 450/500/550/750 owners have done for 40 years.

As with anything nobody is gonna write you instructions. It isn't fair to us or to you who needs to learn not just how to do custom work but how to be brave enough to plunge into custom work with little more than a well reasoned idea of how it goes together.
 

· Registered
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26,142 Posts
I love that herpes is the default metaphor for CR.net these days.


RJB, cool your jets.....you are getting your help so scoop the sand out of your vag and listen up.


Asking questions that have multiple answers and expecting one answer is not going to help you. So let's run back to the project planning stage for a second.

At this point I will remind you that your brakes are only as good as the traction your tire has. The single disc has the ability to lock up on a stock bike, but it takes effort and there isn't a lot of feel up at that top range. The stock drum has a lot of fade and generally any disc conversion is considered an upgrade. What you want ideally is the ability to easily use the entire range of your brakes from light touch to locked up with the maximum amount of feel.

but before we get to the good stuff I will answer your question about the cb550/450/750 dual disc conversion. You are correct those bikes did not come from the factory with dual discs. However honda at one time planned a dual disc conversion accessory kit for all three bikes and did at one time sell one for the 750 for a breif period. The forks have lugs for both discs and basically you convert a stock one sided caliper bracket to bolt to the other side by shaving one of the mounting points and making a spacer for the other. You also reverse the caliper by pulling a crush pin in the caliper so the line exits the opposite side. Search cb750 dual disc conversion and you will find tons of articles on it, the 450 uses the same caliper and fork legs but are shorter, the 500/550 uses similar pieces and the method is the same but only the wheel interchanges. The 450/500/550 forks are preferred over the 750 since the forks are shorter. We will talk about how to mount them up later.

There are two major approaches to improving your bikes braking which is what I assume what you really want to do. A lot of it depends on how the overall bike is setup. If it is closer to stock I would almost say take the weight penalty of dual discs and bigger forks just because it a) looks more impressive, b) is going to add more rideability, and C) you are understressing components which are normally used to working on heavier bikes.

But let's talk about the first approach for a second. The lightness approach or the understressing method. If your bike overall is 50-100 lbs lighter than stock or more (if that is possible) then it may behoove you to work the lightness to your advantage. The simplest way is to get a cb360 disc front end (same as the 350G) and slide it right into your trees. Since the 33mm forks are pretty spindly I would add a fork brace, a tweak bar bolted under the bottom clamp (a fork brace bolts to the sliders, a tweak bar bolts to the fork tubes in case you don't know the difference), an aluminum rim (18"), braided hoses, and a modern master cylinder with a piston size 14mm or one size larger than that. Make sure your fork springs and rear shocks are paired nicely and setup for your weight.

What you gain is braking improvement by making your overall package work less hard. The only unsprung weight you add is the fork brace, and you remove the heavy drum. You get rid of brake pressure loss due to hose flex by using braided lines, and the new master works like a new master so you probably get back some efficiency there. Plus you keep your stock speedo gauge and because the 360 one has the same ratio as the old one and you just run a cable.

What you lose is the increased rigidity of a thicker tube front end and the ability to get better parts like cartirdge emulators and cheap mass produced fork springs.


If your bike is closer to stock weight (and by now I hope you have figured out you need to be weighing your bike), then while the above approach will work it won't improve the handling, won't improve the feel too much, and you will still be stressing your components as they were stock, which means the brake will feel shitty.

Enter the neck bearing chart:

http://scandalon.com/2009/06/motorcycle-steering-stem-bearing-size-chart/

cb350 uses: Upper: 26 x 48.5 x 15.2 Lower: 30 x 50 x 14.4

Honda CB450/K1-K7: Upper: 26 x 48.5 x 15.2 Lower: 30 x 50 x 14.4

Honda CB550K/K1: Upper: 26 x 48.5 x 15.2 Lower: 30 x 50 x 14.4

Honda CB750K (1969-1978): 26 x 48.5 x 15.2 Lower: 30 x 50 x 14.4

See a pattern here? Unfortunatly what you don't see is that the stem heights are different for all three bikes, with the 450/500/550 being the closest to the cb350 stem height. You will still have to make a spacer that fits under the top clamp to allow the nut to tighten down properly, and you will have to measure that yourself, but basically you bolt the entire front end Triple trees to tires right into your 350 neck. You will also need to make new steering stops - you can buy dirt track bolt on ones, or you can drill and tap the stock stops in the clamp and put a bolt in there. either way, it is pretty easy. Now you can stop here and already you would be miles ahead of the game, however, if you got a 450 front end you can search out a hondamatic 750/ GL1000 front rim and upgrade to alloy. You can also run braided lines. Again, better springs, maybe cartridge emulators, and a fork brace. no tweak bar unless you really want it. But even stock the components on the bike will be underworked and will be an improvement over your stock 350 stuff. It is at this point if you really want to go overkill you can do the dual disc converion that many 450/500/550/750 owners have done for 40 years.

As with anything nobody is gonna write you instructions. It isn't fair to us or to you who needs to learn not just how to do custom work but how to be brave enough to plunge into custom work with little more than a well reasoned idea of how it goes together.
 

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quote:Originally posted by kenessex

Geeto,
I still contend that a properly set up drum is not as crappy as you think. Have you ever actually ridden a 350/360 with a properly set up ( adjusted, bedded, lubed) front drum? I agree that most drums and single piston disc brakes are crappy.

Ken
Yes I have. Many times. And T500 drums, and BMW drums, and triumph drums.

When it comes down it I would rather have a dual disc than a drum for 2 reasons:

1) much easier to service. If both have been standing for 15 years obviously the drum is easier to get back to functional, but in terms of service on a system that is in regular weekend use - the disc setup doesn't require me to remove the wheel to change pads, the fluid is easy to change out with a length of hose and a 10mm wrench (instead of a drum brake tool), and the parts are much easier to get.

2) easier to improve. For me to make the drum better I need to know someone who can reline drums, I need to have a basic understanding of how levers work, understand how spring rates work, understand how to tune in brake drag. for me to mod disc brakes, there is all of that, plus little projects that don't require as much knowledge like braided lines and disc drilling. Each has its own science, but something about discs feels easier to understand since, well drums are a dying art.
 

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26,142 Posts
quote:Originally posted by kenessex

Geeto,
I still contend that a properly set up drum is not as crappy as you think. Have you ever actually ridden a 350/360 with a properly set up ( adjusted, bedded, lubed) front drum? I agree that most drums and single piston disc brakes are crappy.

Ken
Yes I have. Many times. And T500 drums, and BMW drums, and triumph drums.

When it comes down it I would rather have a dual disc than a drum for 2 reasons:

1) much easier to service. If both have been standing for 15 years obviously the drum is easier to get back to functional, but in terms of service on a system that is in regular weekend use - the disc setup doesn't require me to remove the wheel to change pads, the fluid is easy to change out with a length of hose and a 10mm wrench (instead of a drum brake tool), and the parts are much easier to get.

2) easier to improve. For me to make the drum better I need to know someone who can reline drums, I need to have a basic understanding of how levers work, understand how spring rates work, understand how to tune in brake drag. for me to mod disc brakes, there is all of that, plus little projects that don't require as much knowledge like braided lines and disc drilling. Each has its own science, but something about discs feels easier to understand since, well drums are a dying art.
 
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