Author Topic: Rear Brake Arm Slipping (Read 1761 times)

crhoads · « **on:** May 23, 2013, 12:27:10 PM »

Hey everyone, was on a ride yesterday and noticed that the travel the rear brake needed to apply stopping force increased more and more as the ride went. After some investigation I discovered that the Rear brake arm is slipping on the splined shaft that comes out of the rear hub. I reset it's positioning, tightened it down, and again realized it slips down the spines when any real force is used on the brake. Curious if anyone had any suggestions for making that more solid besides just replacing the splined shaft, which I assume is a result of the "teeth" being worn down somehow. Just curious if anyone had any creative solutions.

Thanks in advance.

Gordon · « **Reply #1 on:** May 23, 2013, 12:43:43 PM »

I wouldn't mess around with trying to find a work-around solution when it comes to brakes. Be safe and replace the worn parts.

bjbuchanan · « **Reply #2 on:** May 23, 2013, 12:48:28 PM »

Is the 10mm bolt there that tightens the arm at the splines? dumb question but it would definitely do that..
Also how tight is the bolt if it is there?

MoMo · « **Reply #3 on:** May 23, 2013, 12:55:44 PM »

If it cannot be tightened to prevent slipping you will need both the splined shaft and brake arm-both must be severely worn due to the bolt not being tight-but in 40 years I have never seen that happen...Larry

bollingball · « **Reply #4 on:** May 23, 2013, 12:59:22 PM »

Quote from: bjbuchanan on May 23, 2013, 12:48:28 PM

Is the 10mm bolt there that tightens the arm at the splines? dumb question but it would definitely do that..
Also how tight is the bolt if it is there?

Just what I was thinking. Either that bolt is not getting tight or one or both of the splines are worn. Like said above don't play around when it comes to brakes. No time for shade tree repairs. Just clean it good and you should be able to see what it is. Pay close attention when resetting that you don't go into over travel.
Ken

Vinhead1957 · « **Reply #5 on:** May 23, 2013, 01:02:14 PM »

That shaft should have an alignment mark as well as the arm. I think the arm is softer material than the shaft. You might get away with just the arm replacement. You also might have a brake issue

bollingball · « **Reply #6 on:** May 23, 2013, 01:05:06 PM »

http://www.cmsnl.com/honda-cb550f2-super-sport-550-four-1977-usa_model468/partslist/F++10.html#results

Both parts in stock here but you should be able to find them cheaper.

Powderman · « **Reply #7 on:** May 23, 2013, 01:11:37 PM »

Here is the arm for $22.50USD:
http://www.partzilla.com/parts/detail/honda/HP-43410-MR5-000.html
The cam is shown as obsolete on this and the site linked below.

crhoads · « **Reply #8 on:** May 23, 2013, 01:15:18 PM »

Quote from: bollingball on May 23, 2013, 12:59:22 PM

Quote from: bjbuchanan on May 23, 2013, 12:48:28 PM
Is the 10mm bolt there that tightens the arm at the splines? dumb question but it would definitely do that..
Also how tight is the bolt if it is there?

Just what I was thinking. Either that bolt is not getting tight or one or both of the splines are worn. Like said above don't play around when it comes to brakes. No time for shade tree repairs. Just clean it good and you should be able to see what it is. Pay close attention when resetting that you don't go into over travel.
Ken

The bolt is there but after market, It has been tightened down as much as physically possible, but doesn't seem to really be "snugging up" the other side. Any idea what the original bolt size and length is? I will grab a replacement off a parts bike, but it is so strange as I have never seen this happen.

bollingball · « **Reply #9 on:** May 23, 2013, 01:17:05 PM »

find out what it is if it is just the 10mm bolt I would put a longer bolt in and a lock nut. I don't believe there is any safety issues doing that.
Ken

MoMo · « **Reply #10 on:** May 23, 2013, 01:37:43 PM »

It'd be a 6x1.0 thread, as stated if only the splines of the arm are worn try and longer bolt with a nut. If it tightens there won't be a safety issue...Larry

bollingball · « **Reply #11 on:** May 23, 2013, 05:14:34 PM »

The oem bolt may not work if a po has put what you call a after market bolt in. You need to check that bolt to see if the size and pitch is still the same.

Ken

bjbuchanan · « **Reply #12 on:** May 23, 2013, 06:03:10 PM »

Probably has the stock threads stripped out on the arm. If so use another 6x1 that is longer than what you need and do a nut bolt lock washer combo

Powderman · « **Reply #13 on:** May 23, 2013, 06:15:18 PM »

Quote from: bollingball on May 23, 2013, 01:17:05 PM

find out what it is if it is just the 10mm bolt I would put a longer bolt in and a lock nut. I don't believe there is any safety issues doing that.
Ken

If it is the splines that are damaged at all it won't be a safety issue until you stomp on that brake in a panic stop situation and it slips and you die. Go for it. If the splines are correct on both pieces the pinch bolt missing shouldn't make it slip unless you really apply a lot of pressure to bend it out of shape. You say the bolt is tightened as tight as physically possible. Does it have shoulder on the bolt preventing it from closing the gap further? If the gap is pinched closed it doesn't matter how long the bolt is.

bjbuchanan · « **Reply #14 on:** May 23, 2013, 08:07:22 PM »

He said before the bolt doesn't really do anything as far as tightening it down and closing that gap. I'm not suggesting ghetto rigging it but if the hole is hogged out from cross threading or improper bolt choices are being narrowed down

bollingball · « **Reply #15 on:** May 23, 2013, 09:05:05 PM »

Quote from: Powderman on May 23, 2013, 06:15:18 PM

Quote from: bollingball on May 23, 2013, 01:17:05 PM
find out what it is if it is just the 10mm bolt I would put a longer bolt in and a lock nut. I don't believe there is any safety issues doing that.
Ken

If it is the splines that are damaged at all it won't be a safety issue until you stomp on that brake in a panic stop situation and it slips and you die. Go for it. If the splines are correct on both pieces the pinch bolt missing shouldn't make it slip unless you really apply a lot of pressure to bend it out of shape. You say the bolt is tightened as tight as physically possible. Does it have shoulder on the bolt preventing it from closing the gap further? If the gap is pinched closed it doesn't matter how long the bolt is.

Powder that is why I wrote this

Ken

bollingball · « **Reply #16 on:** May 23, 2013, 09:07:43 PM »

Just a thought. You do have the bolt going in the correct side first

Ken

bollingball · « **Reply #17 on:** May 24, 2013, 04:28:10 AM »

Quote from: bollingball on May 23, 2013, 09:07:43 PM

Just a thought. You do have the bolt going in the correct side first
Ken

EDIT IF someone (PO) started the bolt into the threaded side first then the bolt would tighten up as tight as you make it but it would not clamp the arm just as you described.
Ken

MoMo · « **Reply #18 on:** May 24, 2013, 05:56:37 AM »

Quote from: bollingball on May 24, 2013, 04:28:10 AM

Quote from: bollingball on May 23, 2013, 09:07:43 PM
Just a thought. You do have the bolt going in the correct side first
Ken

EDIT IF someone (PO) started the bolt into the threaded side first then the bolt would tighten up as tight as you make it but it would not clamp the arm just as you described.
Ken

good idea Ken, that is one I've never seen but I sure can imagine it being done...Larry

crhoads · « **Reply #19 on:** May 24, 2013, 05:56:10 PM »

Hey everyone, so just to fill everyone in. I did some more testing, and investigating. The bolt was going in the right way, and it would "snug" up. Just not enough to make a difference. I think it comes down to the fact that the brake arm teeth have been worn down slightly. I think the safest and best bet is to just replace it with another brake arm. Does anyone know off the top of their head if most of the arms are cross compatible? will it take a 750 arm or a 550 arm from another year etc? I would assume so, but thought I would ask before heading to a junk yard or ebay.

Thanks again for the input.

crhoads · « **Reply #20 on:** May 28, 2013, 03:17:06 PM »

In case anyone is curious and for future searchers here is the current brake arm.

Powderman · « **Reply #21 on:** May 28, 2013, 03:56:42 PM »

Can't really see if the splines are gone enough to make it slip from that top pic. Did anyone suggest taking a cut off wheel and widen the pinch gap if the splines in the arm are not gone? What does the shaft look like as far as splines left? I was picturing in my mind a bolt and nut and not the bolt threading into the lever itself. what happens is the ears get bent so when the are touch during tightening they are squeezed together enough. I imagine there are lots of bike with similar spine patterns and lengths of brake arms that a used one can be sourced easily. New ones are no the pricey.

MoMo · « **Reply #22 on:** May 28, 2013, 06:31:08 PM »

No wonder it slips!!!!...Larry

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Author Topic: Rear Brake Arm Slipping (Read 1761 times)

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