Author Topic: excessive brake travel  (Read 4931 times)

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Offline 78whiteorbs

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excessive brake travel
« on: June 12, 2013, 08:30:59 PM »
got a 78cb750 K8 almost on the road. Back brake pedal seems to have mucho excessive travel before stoping the back wheel. Shoes look good to my eyes, adjusted the brake rod nut all the way in but still the pedal goes way further than it should. Any ideas fellas?

Offline scottly

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Re: excessive brake travel
« Reply #1 on: June 12, 2013, 08:43:23 PM »
Pictures would help, but my first guess is the brake arm needs to be removed and reinstalled offset by one spline, so the end of the arm is further rearward.
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Offline SohRon

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Re: excessive brake travel
« Reply #2 on: June 12, 2013, 11:25:51 PM »
It sounds like you may not have the pedal installed correctly. Check for index marks like in the following pic...

« Last Edit: June 12, 2013, 11:59:20 PM by SohRon »
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Assembling my '74 CB550: http://forums.sohc4.net/index.php?topic=86697.0
Assembly of the Right-hand Switch (a rebuilder's guide):  http://forums.sohc4.net/index.php?topic=80532.0
Installing stock 4X4 exhaust: CB500-CB550 K: http://forums.sohc4.net/index.php?topic=82323.0
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Offline 78whiteorbs

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Re: excessive brake travel
« Reply #3 on: June 13, 2013, 05:25:21 AM »
thanks for the picture, I will check that out. It is way off and travels like 5 inches maybe . When i first got the bike it was stuck and upon removing the wheel everything looked to be in good shape just a little corrosion that I sanded out. I tried just moving the arm and not the pedal with the rod off and it travels a few hours on the clock. I know these are pretty simple ,gonna investigate more this evening .

Offline bailboy

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Re: excessive brake travel
« Reply #4 on: June 13, 2013, 05:53:19 AM »
I had a similar problem on my k3. Mine was due to a bad brake stay bar.   Connecting the rear brake to the swing arm.  Check for any play in that as well.  When you brake does it grab and shoot the lever back up?

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Offline 78whiteorbs

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Re: excessive brake travel
« Reply #5 on: June 13, 2013, 12:59:48 PM »
havent rode it and will not with this problem , so I cant answer if it shoots it back up or not . Will take another good look today maybe I overlooked something simple.
When I first got the back the back brake was locked and I smacked it with a mallet and it loosened enough to be moved around. When I removed the back wheel for fresh rubber I cleaned everthing that looked crusty - slapped it back on and pedal goes very far....

Offline Dave Voss

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Re: excessive brake travel
« Reply #6 on: June 13, 2013, 05:10:36 PM »
You may need to remove the rear wheel again to inspect the brake parts inside the drum.  The brake shoes pivot at one end, and expand outward at the other end when the lever arm is rotated.  It sounds like one or both of the shoes may not be positioned correctly, and it is requiring excess rotation of the lever arm shaft to cause the brake shoes to engage the drum.  It is also possible that the pivots are damaged, broken, etc.  I would agree with you about not riding it in this condition, if anything is out of position or damaged such that it could become loose, it could cause the wheel to lock up while spinning, and that could ruin your day.
-Dave Voss
(past) '78 CB550K4
(past) '75 CB550K1
(now) '95 R1100RSL

Offline 78whiteorbs

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Re: excessive brake travel
« Reply #7 on: June 14, 2013, 12:23:08 PM »
well, I found something very obvious cant believe I didn't see this....
looks like some welding went on here... not sure why though , is there suppose to be a brake stop here on a 78?

have a look.



do I need a new right footpeg /brake stop as well?

Offline 78whiteorbs

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Re: excessive brake travel
« Reply #8 on: June 14, 2013, 12:26:31 PM »
I was paying so close attention to the engine I completely overlooked this . Looks like this might have been done possibly to clear the exhaust???  The exhaust is a 4-1 from what I thought was an F model. at least the header looks it .  Well at least the engine is running great now, sigh....one more thing

Offline strynboen

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Re: excessive brake travel
« Reply #9 on: June 14, 2013, 12:28:44 PM »
bay a new pedal/arm..that one vill bent or breake  its soft  black iron..
« Last Edit: June 14, 2013, 12:30:42 PM by strynboen »
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Offline 78whiteorbs

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Re: excessive brake travel
« Reply #10 on: June 14, 2013, 12:29:48 PM »
this nut was held on with silicone...


Offline mono

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Re: excessive brake travel
« Reply #11 on: June 14, 2013, 12:36:16 PM »
bay a new pedal/arm..that one vill bent or breake  its soft  black iron..

really a +1 to that -- i think it would be OK for normal use , but if you really stood on it it may bend.

other than that, I would say that even though it's abnormal, if it worked before it should work again.  I would agree that you should pull the wheel and see if everything inside is adjusted correctly.  are you using new brake shoes (I assume yes, but worth asking)?   and since it's been "customized", you may need to adjust it's position a little differently.

... I guess you could always shorten the rod that goes between the levers ;)

Offline 78whiteorbs

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Re: excessive brake travel
« Reply #12 on: June 14, 2013, 12:45:01 PM »
I will be getting another one that's easy . Try to find a good pic to see if I am gonna need any other parts. Also trying to figure out why it was modified. If it was to run the 4-1 exhaust then I might have to do some tweaking. It looks like the brake are might not clear the pipes on it if it were not cut, someone else I am sure knows this....let's here it ! what exhaust is this ?








« Last Edit: June 14, 2013, 01:31:40 PM by 78whiteorbs »

Offline mono

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Re: excessive brake travel
« Reply #13 on: June 14, 2013, 06:15:37 PM »
Yeah I think it was done to clear the exhaust.  Obviously a new stock one isn't going to work for you.  I would suggest maybe just fabbing up a new one or correcting the not so good job the PO did.  You may also be able to extend the "axle" that the brake lever uses and put a spacer on it to run a stock lever.... just ideas.   

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Offline mono

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Re: excessive brake travel
« Reply #14 on: June 14, 2013, 06:17:26 PM »
And is it me, or does that peg mount look long also?   Gotta say he didn't do a *bad* job... definitely some creative solutions there.

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Nic

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Re: excessive brake travel
« Reply #15 on: June 14, 2013, 08:18:15 PM »
If it was my bike I'd piss that ugly exhaust off, get a new pedal and new shoes. Even though the shoes still have plenty of meat on them with all that brake travel yours are kaput.

fendersrule

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Re: excessive brake travel
« Reply #16 on: June 14, 2013, 08:30:05 PM »
So glad I have my 4-4 exhaust. :)

Offline scottly

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Re: excessive brake travel
« Reply #17 on: June 14, 2013, 08:43:46 PM »
Looks to me the brake arm on the rear hub needs to be rotated clockwise on the splined shaft a notch or two. Have you looked for index marks there yet?
Don't fix it if it ain't broke!
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Nic

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Re: excessive brake travel
« Reply #18 on: June 14, 2013, 08:47:07 PM »
Looks to me the brake arm on the rear hub needs to be rotated clockwise on the splined shaft a notch or two. Have you looked for index marks there yet?
Doesn't matter, travel is travel n that's worn out shoes.

Offline scottly

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Re: excessive brake travel
« Reply #19 on: June 14, 2013, 08:51:43 PM »
Looks to me the brake arm on the rear hub needs to be rotated clockwise on the splined shaft a notch or two. Have you looked for index marks there yet?
Doesn't matter, travel is travel n that's worn out shoes.
Not necessarily. A member went through the same thing only a few weeks ago; the arm on the hub was improperly installed.
Don't fix it if it ain't broke!
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Nic

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Re: excessive brake travel
« Reply #20 on: June 14, 2013, 09:01:21 PM »
Looks to me the brake arm on the rear hub needs to be rotated clockwise on the splined shaft a notch or two. Have you looked for index marks there yet?
Doesn't matter, travel is travel n that's worn out shoes.
Not necessarily. A member went through the same thing only a few weeks ago; the arm on the hub was improperly installed.
If the brake arm moves more than you want it doesn't matter where it is located on the spline, it will still translate to too much travel on the pedal. The OP said he had 5" of travel regardless of the correct lining up of the dots. I didn't look at that because once he said 5 inches of travel, well say no more.

Offline scottly

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Re: excessive brake travel
« Reply #21 on: June 14, 2013, 09:16:49 PM »
The OP said he had 5" of travel regardless of the correct lining up of the dots. I didn't look at that because once he said 5 inches of travel, well say no more.
The OP never checked the alignment of the hub brake arm that I read. Looking at the pics, you can see that the arm is pointed about 4:30. It should be closer to 6:00-6:30.
Don't fix it if it ain't broke!
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Nic

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Re: excessive brake travel
« Reply #22 on: June 14, 2013, 09:21:58 PM »
The OP said he had 5" of travel regardless of the correct lining up of the dots. I didn't look at that because once he said 5 inches of travel, well say no more.
The OP never checked the alignment of the hub brake arm that I read. Looking at the pics, you can see that the arm is pointed about 4:30. It should be closer to 6:00-6:30.
Come on mate, so if he puts the arm on at 6 o'clock the travel will be gone? Hardly. If anything, he will have more travel.

Offline scottly

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Re: excessive brake travel
« Reply #23 on: June 14, 2013, 09:32:15 PM »
When the brake is applied, the arm will be approaching 3:00. The way it's now clocked won't allow enough adjustment to remove the play. I learned this lesson the hard way, on my C200 90, about 40+ years ago. ;)
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Re: excessive brake travel
« Reply #24 on: June 14, 2013, 09:38:30 PM »
When the brake is applied, the arm will be approaching 3:00. The way it's now clocked won't allow enough adjustment to remove the play. I learned this lesson the hard way, on my C200 90, about 40+ years ago. ;)
Yeah I see where you're comin from, the problem is, if you place the arm further back and then push it towards the rod you have removed the travel but the cam in the hub is now approaching full leverage and can become stuck, it's not a recommended fix, you should replace the shoes when travel is excessive. I hope this explains my point about 5" of travel n how it doesn't matter where you put the arm??? If you have that much travel you need new shoes.
 

Offline scottly

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Re: excessive brake travel
« Reply #25 on: June 14, 2013, 10:15:10 PM »
Yes, if the cam goes "over center" the shoes are worn out, but if the levers on both or either ends of the actuating rod are miss-aligned, there will be no way to adjust the play out, even with new shoes. The OP needs to post pictures of the angles of the arms at both ends of the rod.
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Offline 78whiteorbs

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Re: excessive brake travel
« Reply #26 on: June 15, 2013, 08:08:20 AM »
Hmmm, well I am gonna get some new shoes to eliminate that from the equation. Trying to get this pedal business sorted though. Toosh, better than an engine problem though.

bollingball

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Re: excessive brake travel
« Reply #27 on: June 15, 2013, 09:19:34 AM »
I have the same bike and have my wheel off at the moment for a new tire,bearings,brakes and all the other things back there. If you need any pictures let me know. You see that threaded hole on the foot peg post that is where the adjustment bolt should be it screws in from the bottom and the brake arm rest on the bolt head and a jam nut goes on top. I have all ready told you what I think in your other post. You also need to take the splined pivot shaft out to clean and grease it up. I think I will take HondaMans tip and put in a zerk in for this shaft. Have you had the sprocket carrier off? There is a large o-ring on the hub that is very important it is to lock the carrier on to the hub. The carrier should be very hard to slide on or off. When you get it lined up with the cush rubbers you should have to jump on it to lock it on. ;) Thanks to HondaMan for this tip and many others. If you don't have his book you should.
Ken

Offline 78whiteorbs

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Re: excessive brake travel
« Reply #28 on: June 15, 2013, 01:25:22 PM »
Appreciate the suggestion. I don't think I will be replacing the exhaust. Bike runs great engine wise so just this one little bit and it'll be back online. I might have a better look and see what the best solution should be.  Could be a combination od pedal being off a bit at pivot shaft and the hub shaft ad well and plus the angle of the pedal after it was welded could be way off. Bottom line though is that at the rear wheel that shat should not move but so much till the brakes engage say from 6 to 5 o'clock sound right?

bollingball

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Re: excessive brake travel
« Reply #29 on: June 15, 2013, 02:39:01 PM »
Just make sure the welds are good and you trust your life with them. Maybe you can heat the pipe enough to bend it in enough to have more room for the oem arm?

Offline 78whiteorbs

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Re: excessive brake travel
« Reply #30 on: June 15, 2013, 03:37:44 PM »
Welds look good , clean and solid. I like the thought about bending the pipe though. Also I could procure a small slipon type muffler. I'dmuch rather run a stock m pedal..... BB can you take a pic of your stock right footpeg?. Is there a stop or any other pieces I will need?