Inspecting rear brakes

cayuse · 10-14-2011, 12:13 AM

I had a funny 'knocking' sound coming from somewhere under my seat last week that caused a bit of concern(!).

As I pulled away from a stop I would get a somewhat regular 'knocking' sound in 1st and 2nd gear. Sometimes I thought I could actually feel it!
The frequency was very low so I figured it had almost no chance of coming from my engine (lot of wishful thinking going on) but was somehow coming from my rear wheel or chain, or maybe the cush drive. Then I paced out the travel the bike does for one chain revolution and the knocking sound seemed to match up with this distance. So, I became fairly certain it had something to do with my chain. In very short order I had the bike up on the stand and set about checking and lubing all the links.

Now, while I had it up on the stand I thought "you've never looked at the rear brakes, or the cush insert, and the rear brakes have been squeeling for awhile, so why not check that out now?"
Turns out the basic wooden jack stand (see another thread for that) doesn't lift the rear high enough to fully disengage the rear wheel so I used a hydraulic jack under the frame just behind the engine to carefully raise the bike another couple of inches so i could add some wooden blocks to the stand.

The rest was way easier than I imagined. I just disengaged the brake cable from the brake cam lever and spun off the axle nut. I put a 2x4 under the tire to take the weight off the axle and simply pulled it out. Knocking out the 2x4 let the tire fall to the floor. The axle spacers fell to the floor at this point too. Now, I could slide the wheel around enough to pull off the sprocket drum and brake 'panel' and have a look.

This is what it looked like:

The brake assembly just pulls out:

As does the sprocket drum:

The brake drum looks great. I cleaned out some powder that had accumulated.

The cush insert looked fine and there is plenty of life left in the shoes:

Of course, if I had wanted to change shoes or the cush insert I would have had to undo the wheel from the torque link and wrestled it out from under the fender. Maybe a second set of hands is advisable that point.

As it was, I was satisfied with what I saw so I put it back together. It all went back together just as easily, but I hurried it a little and forgot one of the axle 'washers', pulled the axle back out and upon re-installing realized I had one of the spacers in backwards, so pulled the axle out again. So, I actually rebuilt the assembly three times. Lots of practice! Reminds of the first time I adjusted the valves!

All of this is pretty much explained in the service manual, but I thought it would be good for the fellow newbies to see some real photographs and hear from another newb firsthand.

Oh yeah, and the knocking? GONE! I think my chain was telling me something like "LUBE ME!".
And, the rear brakes don't squeal anymore. So, a good bit of service work accomplished.

Cheers!

JWR · 10-14-2011, 12:41 AM

You did good. A little basic work on the bike and you know it was done right.

I clean my chain then apply DuPont Multi-purpose lube. It is clear and clean.

blaine · 10-14-2011, 01:31 AM

A job well done & a nice write-up. :2tup: :cool:

Water Warrior 2 · 10-14-2011, 02:09 AM

Ah yes, the old spacer trick. Almost found out the hard way one day. After re-installing the wheel with a spacer in backwards I noticed an irregular noise and could feel it getting worse. It is called bearing failure at 120 kph. Pulled into a nearby dealer and left the bike. No where near home so a hotel was on the to do list. Next morning the bike was repaired with new bearings and the spacers put in as they were found. HUH. Luckily I noticed this and corrected the situation before any damage was done. Just the idea of a wheel locking up at any speed makes my blood run cold.

Water Warrior 2 · 10-14-2011, 07:06 PM

[quote=Gz Rider]

Quote:

Originally Posted by "Water Warrior":36z7x0kp

Ah yes, the old spacer trick. Almost found out the hard way one day. After re-installing the wheel with a spacer in backwards I noticed an irregular noise and could feel it getting worse. It is called bearing failure at 120 kph. Pulled into a nearby dealer and left the bike. No where near home so a hotel was on the to do list. Next morning the bike was repaired with new bearings and the spacers put in as they were found. HUH. Luckily I noticed this and corrected the situation before any damage was done. Just the idea of a wheel locking up at any speed makes my blood run cold.

Correct me if I'm wrong but even if the bearing locked up completely, the wheel would continue to spin on the actual axle. The axle is just a large bolt going through the whole wheel. I touches the bearings but is not locked to them. Normally it appears the bearings do not slide against the axle because the friction would be too great and the friction in the bearing itself is less so the bearings turn instead.

If the bearings locked up, I would think you would get a much different scraping sound from the wheel with the locked up bearing. If that is not dealt with in short order, I would think damage to the axle would start to create a dangerous situation. That's why they tell you if you hear new/different sounds from the bike, take it in for service.[/quote:36z7x0kp]
The axle bearing and sprocket bearing(both on left side) were replaced. The sprocket bearing was generating the noise and jerky feeling. Left unchecked I would imagine both bearings would eventually weld themselves solid and create a deadly situation. As for the axle bearing spinning on the axle, yes it would for a while until that welded solid too.
With the spacer installed backwards the axle bearing doesn't just support the load but is also forced to accept a tremedous sideload when the axle is tightened up. The sprocket bearing suffers the same unwanted load but gives up earlier due to a less robust design and mechanical purpose.
I am by no means a mechanic and was truly mystified by the noise and feeling at 120 kph. After stopping safely and spinning the wheel with the bike on the cenerstand I was in more of a quandry. Luckily there was a dealer 4 blocks away and I successfully chanced a short ride at low speed. The actual repair was about $100 and a lesson learned without bloodshed. My Guardian Angel was working and I thank her.
As a preventative measure against breakdown I now replace bearings with every tire change. Every 25,000 kms is a lot of spinning for small bearings. Peace of mind is priceless and doesn't hurt.

mrlmd1 · 10-16-2011, 01:51 PM

You may have some dirt or a very small pebble that got stuck in there and taking it all apart got it cleaned out so the noise and squeal stopped.

cburgess594 · 04-18-2012, 01:47 AM

Maybe you should try to check the insides where the knocking is occurring...

apaz · 09-23-2014, 03:15 PM

Hey man, great write up. I have quite a few miles under me on two wheels, but bought a pretty good looking gz250 to ride around town and start to do some of my own work on. A "learn the engine and maintenance" bike, if you will. I got a flat, nail in the tire, and decided I would get in there and check things out also. This is a good visual and step by step process. Thanks.

ImaginativeFig · 10-06-2014, 09:56 AM

I'm always a fan of actual pictures

Braum Zoesenna · 05-07-2020, 11:43 PM

I needed money to pay for my daughter’s education. I worked at two jobs, but there was still not enough money, and then I decided to register for grand national live stream in the hope that I can earn. And to my surprise, I did it and I hit the jackpot! the main thing is to believe in your luck.

10-14-2011, 12:13 AM	#1
cayuse Senior Member Join Date: May 2010 Location: Abbotsford, BC Posts: 444	Inspecting rear brakes I had a funny 'knocking' sound coming from somewhere under my seat last week that caused a bit of concern(!). As I pulled away from a stop I would get a somewhat regular 'knocking' sound in 1st and 2nd gear. Sometimes I thought I could actually feel it! The frequency was very low so I figured it had almost no chance of coming from my engine (lot of wishful thinking going on) but was somehow coming from my rear wheel or chain, or maybe the cush drive. Then I paced out the travel the bike does for one chain revolution and the knocking sound seemed to match up with this distance. So, I became fairly certain it had something to do with my chain. In very short order I had the bike up on the stand and set about checking and lubing all the links. Now, while I had it up on the stand I thought "you've never looked at the rear brakes, or the cush insert, and the rear brakes have been squeeling for awhile, so why not check that out now?" Turns out the basic wooden jack stand (see another thread for that) doesn't lift the rear high enough to fully disengage the rear wheel so I used a hydraulic jack under the frame just behind the engine to carefully raise the bike another couple of inches so i could add some wooden blocks to the stand. The rest was way easier than I imagined. I just disengaged the brake cable from the brake cam lever and spun off the axle nut. I put a 2x4 under the tire to take the weight off the axle and simply pulled it out. Knocking out the 2x4 let the tire fall to the floor. The axle spacers fell to the floor at this point too. Now, I could slide the wheel around enough to pull off the sprocket drum and brake 'panel' and have a look. This is what it looked like: The brake assembly just pulls out: As does the sprocket drum: The brake drum looks great. I cleaned out some powder that had accumulated. The cush insert looked fine and there is plenty of life left in the shoes: Of course, if I had wanted to change shoes or the cush insert I would have had to undo the wheel from the torque link and wrestled it out from under the fender. Maybe a second set of hands is advisable that point. As it was, I was satisfied with what I saw so I put it back together. It all went back together just as easily, but I hurried it a little and forgot one of the axle 'washers', pulled the axle back out and upon re-installing realized I had one of the spacers in backwards, so pulled the axle out again. So, I actually rebuilt the assembly three times. Lots of practice! Reminds of the first time I adjusted the valves! All of this is pretty much explained in the service manual, but I thought it would be good for the fellow newbies to see some real photographs and hear from another newb firsthand. Oh yeah, and the knocking? GONE! I think my chain was telling me something like "LUBE ME!". And, the rear brakes don't squeal anymore. So, a good bit of service work accomplished. Cheers! __________________ Lovin' every minute of it. 2005 GZ250 (sold after 26000km) 2013 CB500XA Login or Register to Remove Ads
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10-14-2011, 12:41 AM	#2
JWR Senior Member Join Date: Jan 2009 Location: Louisville, TN Posts: 1,413	Re: Inspecting rear brakes You did good. A little basic work on the bike and you know it was done right. I clean my chain then apply DuPont Multi-purpose lube. It is clear and clean. __________________ Jerry Truth is there are lots of great bikes available and not nearly as many good riders out there riding them... "A man's got to know his limitations..."
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10-14-2011, 01:31 AM	#3
blaine Senior Member Join Date: Feb 2010 Location: P.E.I. Canada Posts: 3,784	Re: Inspecting rear brakes A job well done & a nice write-up. :2tup: :cool: __________________ If at first you do succeed, try not to look surprised. Login or Register to Remove Ads
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10-14-2011, 02:09 AM	#4
Water Warrior 2 Senior Member Join Date: Dec 2006 Location: Squamish B.C Canada Posts: 11,409	Re: Inspecting rear brakes Ah yes, the old spacer trick. Almost found out the hard way one day. After re-installing the wheel with a spacer in backwards I noticed an irregular noise and could feel it getting worse. It is called bearing failure at 120 kph. Pulled into a nearby dealer and left the bike. No where near home so a hotel was on the to do list. Next morning the bike was repaired with new bearings and the spacers put in as they were found. HUH. Luckily I noticed this and corrected the situation before any damage was done. Just the idea of a wheel locking up at any speed makes my blood run cold.
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10-16-2011, 01:51 PM	#6
mrlmd1 Senior Member Join Date: Jan 2008 Location: Crawfordville, Florida Posts: 2,853	Re: Inspecting rear brakes You may have some dirt or a very small pebble that got stuck in there and taking it all apart got it cleaned out so the noise and squeal stopped.
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04-18-2012, 01:47 AM	#7
cburgess594 Junior Member Join Date: Apr 2012 Location: Berlin, Germany Posts: 14	Re: Inspecting rear brakes Maybe you should try to check the insides where the knocking is occurring... __________________ “no women, no cry”
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09-23-2014, 03:15 PM	#8
apaz Member Join Date: Aug 2013 Location: Seattle Posts: 33	Hey man, great write up. I have quite a few miles under me on two wheels, but bought a pretty good looking gz250 to ride around town and start to do some of my own work on. A "learn the engine and maintenance" bike, if you will. I got a flat, nail in the tire, and decided I would get in there and check things out also. This is a good visual and step by step process. Thanks. __________________ Gotta love a one nut fix.
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10-06-2014, 09:56 AM	#9
ImaginativeFig Senior Member Join Date: Jan 2014 Location: College Station, Texas Posts: 138	I'm always a fan of actual pictures
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05-07-2020, 11:43 PM	#10
Braum Zoesenna Junior Member Join Date: May 2020 Posts: 1	I needed money to pay for my daughter’s education. I worked at two jobs, but there was still not enough money, and then I decided to register for grand national live stream in the hope that I can earn. And to my surprise, I did it and I hit the jackpot! the main thing is to believe in your luck.
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