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Discussion Starter · #1 ·
Hey there... just looking at getting my first bike, something I can tinker with come winter, not too pricey, and been eyeing up a '78 CX500. Seen a lot of really nicely done ones online, and Cafe Racer ones as well.

The (rather stupid) question I have is about the brakes.

I've done all my own car work for the past 5yrs so, not a mechanic but I learn quick and have some skills. When I started doing research and looking up parts and such for the CX500 to make sure I can still get them, I found a lot of brake pads, but zilch for rotors. I assumed it would be like a car... type in a year/make/model and get a list of compatible rotors... but not seeing anything on motorbike part sites.

Are they no longer available? are they supposed to last forever? are motorcycle rotors all compatible and just based on the diameter?

Saw that there was a CX500 forum... figured be the best place to find out. :D

Also, what is the max weight capacity of the CX500... I'm a BIG guy... hopefully lose some weight come Spring 2015, but just in case... better ask.

Thanks
 

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Welcome to the forum from the west coast! I'm not sure about the availability but are you certain you would need a new rotor and why?
 

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Rotors on these bikes generally last a long time.
I believe they start out at 7mm, and the service limit is 6mm.
There is no problem putting on a used rotor as long as it is not warped and falls within the limit.

You may want to check in with David Silver Spares. They may have new rotors.
 

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Discussion Starter · #4 ·
Thanks!

Not certain about the brakes... the photo in the ad looks ok (though says currently disconnected). I assumed that (like a car) they wear out every couple years.

Basically doing a research "blitz" on the bike. Since I know little about bikes, when I see one I like for sale I hop online and do a few hours of research to avoid screwing myself over buying a lemon or something. I'm more a car guy, never owned or worked on a bike before, and being a '78 I figured I'd check out a few online stores and eBay for basic parts and see what the price and availability is. I know from the ad that there are a few bits of trim missing, the exhaust ends, and a rubber hose to the air box.

Last thing I want to do is buy a bike and find out that parts are impossible to find and I'm stuck with something I'll never get running unless I spend way way too much money. I'm selling a '47 Dodge Sedan that I've had for years and now simply tired of trying to find stuff for it.

That all being said... ideally... I'd like to make a Cafe Racer(ish) bike out of it, and not really a fan of the Comstar rims. I'm not sure if the rotors are bike specific? rim specific? fork? But I assume people replace more than just the pads after 35+yrs.
 

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Discussion Starter · #5 ·
So... what do you guys do when the rotor does wear out? eBay for a used one?

Must be an alternative available for buying a new one no?
 

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I believe EBC sells rotors for the 500 (just bought one for my cx650)... or you can get on from Honda and pay north of 350 for it... lol.

Used is also an option if you are in a bind... they are all over eBay still in spec.
 

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Discussion Starter · #8 ·
Ok, so there are options then? That's a relief... I was starting to think that unless you have original rotors you're outta luck. Didn't make sense, so, glad to see that there are a few options at least.

Are there any kits/advantages to converting the rears to disc? I like the appearance more of discs... but from what I've seen so far, it's a custom job.
 

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Also, what is the max weight capacity of the CX500... I'm a BIG guy... hopefully lose some weight come Spring 2015, but just in case... better ask.
The weight of the CX with all the liquids will be around 230 kilogramm. A BIG guy on the saddle should not have the weight of more than 180 kg (~~400 lbs.).

BTW: what prevents you already to take off weight, now ?


In Your position I would measure the thickness of the rotor. If the value is okay, then I would recommend to check (repair) the caliper and the MC (better, cheaper is to buy a new one from -for example- David Silver Spares) and to install SS-lines.
 

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. . . about the brakes . . . I assumed that (like a car) they wear out every couple years.
While brake pads may wear out every couple years driver, rotors can generally last the life of a car or a bike. You will get more rotor warp with a lot of aggressive braking, of course. For a rider who habitually wears out rotors, an upgraded braking system might be in order.
 

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Throbinson what!! no comstars are you nuts you know all those café racers run comstars for a reason right? and so does everybody else unless your really handy/ or have a lot of time and money . imho leave them on :eek:
 

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If ya keep the calipers in good shape and use good quality pads, the rotors should last you many, many years... If I were getting any bike as old as these are, the first thing I'd do is rebuild the entire brake system... Be sure to get 100% of the oxidized aluminum out of the caliper seal grooves and that a good caliper assembly grease is packed in em... When you’re done you should be able to depress the pistons into the caliper easily by hand... If not, then you need to go back and clean the grooves out better... If you fail to do so, the brake will always bind on the rotor some and cause excess heat and premature wear...
 

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Be sure to get 100% of the oxidized aluminum out of the caliper seal grooves and that a good caliper assembly grease is packed in em...
What's a good caliper assembly grease?

I always thought that brake fluid - and only brake fluid - was the only permissible lubricant. I guess you learn something new every day!
 

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Discussion Starter · #14 ·
Throbinson what!! no comstars are you nuts you know all those café racers run comstars for a reason right? and so does everybody else unless your really handy/ or have a lot of time and money . imho leave them on :eek:
I like the look of the wire spoke rims with big vintage looking tires better. I like the looks of the pre-'50s bikes.

But hey, if people like the Comstars, maybe I'll make an easy sale. :D
 

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Discussion Starter · #15 ·
While brake pads may wear out every couple years driver, rotors can generally last the life of a car or a bike. You will get more rotor warp with a lot of aggressive braking, of course. For a rider who habitually wears out rotors, an upgraded braking system might be in order.
So... even if I decided to leave the comstars on, I could swap out the entire brake system... somewhat easily? Like... direct bolt-on swaps available?

This is where I really wish I was sitting in front of a bike, I could probably figure that stuff out.... I'm self/google taught for the car so, not too worried about learning on a bike, but, as mentioned previously... never owned a bike before, and just trying to figure out a few things while I'm searching to buy one. The '78 CX500 I like the looks of so pretty high on my list and within budget. Just... doing the research now to avoid potential problems.

First bike so, need something somewhat basic to work on. :)
 

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Metal Gear part #20-883.
Are those 7mm ones for a CX650? Or a late CX500?
My 82 Customs take 5mm disc: MGear Brake Disc Front Left/Right at Metalgear

Either way Tim's pointed us in the right direction for a supplier for rotors! Which makes me happy as I will need 2 for my resto bike as someone previously seems to have run the pads until metal got intimate with metal
 

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Discussion Starter · #17 ·
Well, bike I wanted and was supposed to look at was sold. Another popped online a while later, went and looked... same bike. :D Turns out the seller got the bike and then realized it was way too big for her.

I did measure the rotor with my digital micrometer... 6.93mm thick, so, should be good. Bit grooved... like a record... not too bad but, given how very little I can take off, I doubt it can be machined smooth. More aesthetics than anything else.
 

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Almost all parts for all CX/GLs are available used and usually for very reasonable prices. This is one of the endearing charms of CX/GLs! There were large numbers of these bikes made except for Turbos. The occasional part that goes NLA new and then becomes rare used spikes the interest of some creative individual who finds/creates a new source. I think it's fair to say there is not a CX/GL (included Turbos) that is sidelined longterm for lack of a part. If so, the needee hasn't looked hard enough. Buy it, you're unlikely to become the first! The internet has changed the whole sourcing used parts equation.
 

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More on the brakes - Motorcycles are light and small (even big tourers) compared to cars. MC Front brakes, in particular, have just about perfect airflow over them, unlike car brakes. But instead of using feet or a vacuum servo to operate the brakes, motorcycles use the rider's hands, which are much weaker.

The result of this is that motorcycles have a large amount of pad area relative to vehicle mass and a very low effort for the brakes compared to a car. It's almost impossible to overheat the front brake on a small motorcycle unless you're road racing or doing something really wrong. The low effort means that VERY soft pad compounds are used, which give a lot of grip but wear quickly. The softer the pad relative to the rotor, the longer the rotor lasts.

CXs have such low weight and such big brakes relative to their size that the big, heavy, hard rotors are essentially eternal. If you're not happy with the stopping power on a US CX, the easy solution is to switch to a two-piston caliper.

The only reasons to change to a different rotor are a) looks, or b) weight savings.
 

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Discussion Starter · #20 ·
The bike is now in my yard waiting for me to clear some garage space. :D

Pulled it off the van yesterday and went to bed... was a few hours to get to where it was for sale. Luckily, loosened and rotated the handlebars down and it fit perfect into an '05 Montana mini van.

Brake wise, I think having only worked on my cars, I have the thinking of rotors needing replaced every few pad changes. Guess I need to get use to the differences. :)

Only think I'd want to do to mine would be to smooth it out... just for looks... smoother/shinier. If they work though I'm happy... though definitely will need new pads. That, and the caliper isn't currently bolted on, so, there's that.

I'm not into going fast... just casual cruising. Only concern would be my extra weight on the bike (350lbs), but hoping come spring I'll have had a chance to rebuild the bike into more of a cafe racer bike and maybe shed a few pounds off it and myself.
 
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