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Discussion Starter #1
No, Geeto this isn't a joke. But I understand that you may be on sabatical so you might not read this one.

I have no reference for how good (or bad) my 1975 CB750 brakes should be. It has stock drum in the back and single disk in the front.

I rebuilt the front brake 3 times, and replaced the piston and pads. I need to really squeeze it to make it work very well. I have bled the fluid 4 times. At what point does a good front brake engage? Is it normal for me to have to squeeze the life out of the lever to make it work well?

How about the back brake?

In general, how good is the stock CB750 braking?

Thanks again
 

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don't worry I an not on sabbitical from the forum, just from working on shit in real life. this forum is one of the few places I can keep my sanity at work.

A properly setup REAR cb750 drum should be able to lock the tire with impunity. On a nice clean road surface I am pretty sure a heavy stomp on the brakes can stop the bike with enough force to make your colon hit your eyeballs.

The front brake is another story.

A properly setup cb750 front brake will not let the brake lever come back and touch the hand grip, so if you are able to pull it back that far then you need more bleeding. The brake switch on these bikes is a notorious air trap so even being bled 4 times you can still have a bubble.

However, cb750 front brakes are known for being kinda heavy on the lever. They are a man's brake that commands a man's grip. Compared to my old norton's front disc (swapped off a 75 model commando) the cb750 is a moderatly good brake, compared to a modern anything-on-two-wheels it feels like a you are trying to slow down a fully loaded 1965 chrysler imperial by putting your feet through the floor boards fred flinstone style.

How are your lines? one often overlooked thing on a cb750 brake setup is the rubber lines. If there are any sharp curves or kinks you are not getting 100% out of your brakes. Also if there is any dry cracking in the line they are probably flexing more than they should under the pressure of fluid. Braided stainless lines make a big difference in the brake feel since you are loosing a lot less pressure to line flex.

But I think you are fast discovering why so many people upgrade to dual disc.
 

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Discussion Starter #3
Geeto,
Thanks.

As I bleed the front brake, should i be needing to refill the resevior?
 

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quote:Originally posted by mut

Geeto,
Thanks.

As I bleed the front brake, should i be needing to refill the resevior?
YES!!!!!!!!!!!!!!!!!!!!!!

if you are bleeding the M/C dry then all you are doing is putting air back into the brake lines.

One of the best brake tools a friend of mine ever invested in (which he lets me borrow frequently) is a reverse bleeder. It feeds fluid in from the caliper and fills the master cylinder. Pushes all the air bubbles to the top where they can escape through the master instead of through the bleeder.
 

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Dual brakes might be a good option for you or braided hoses. Speaking of which - Pampadori, if you have a pair of them - I'd be interested for my cb750 (I'm installing duals on it this weekend)

send me an email at [email protected] with a price...thanks
 

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quote:Originally posted by mut

Geeto,
Thanks.

As I bleed the front brake, should i be needing to refill the resevior?
Ouch ouch ouch... brain hurt... ouch ouch...


Never let the fluid level drop enough to suck in air.

Also, take the pads out. Put some sandpaper on the floor. Drag the pads around in a figure 8 pattern for 30sec or so. Take some fine grit sandpaper to the rotor. Scuff it up a little on both sides. Don't touch it with your hands. Spray the pads and rotor down with brake cleaner.

Don't touch the pads or rotor putting it back together.
Greasy hands will screw up everything you just did.
 

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quote:..........this forum is one of the few places I can keep my sanity at work.
Geets keeps his sanity HERE!!!!???!

Dude you're screwed!
 

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Mut,
Did you clean and lube the pivot pin and arm for the caliper? There is a lot of resistance to movement in that shaft.
Dual disk conversion is pretty easy, too.

Ken
 

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Discussion Starter #10
Alright, I am not retarded (most of the time). I have not been sucking air into the brake lines. I should have asked about the reservoir in a little different manner. I should have asked: When I bleed the brakes, should I bleed so much out that i need to refill the reservoir?

Ken,
I did lube the pin and arm.

I will first try to bleed enough fluid through that I need to refill the reservoir. If that doesn't work, I will re-lube the pin and shaft and maybe try the sandpaper idea.
 

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Mut,
If you lubed the pin once, that ought o be enough as long as it pivots easily by hand. Geeto is right in that some air bubbles will try to hide in the lines at various junction points such as the M/C banjo bolt and the brake light switch junction. You may need to take the m/c off the bars and change the angle on it to get the bubbles out. Also try tapping on the lines caliper junction block and M/C while you are bleeding to get the air out. You may need to run several resevoirs of fluid through it.

Ken
 
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