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+--- Thread: The return of the Oscillation (/showthread.php?tid=4228)
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The return of the Oscillation - misterprofessionality - 08-01-2023
Well, the Oscillation in the front end of my CB has returned. It's going to the shop very soon, don't worry, I am not going to try to fix this myself.
Small recap: Last year I replaced my front brake discs because i was feeling a rythmic oscillation in the front end under low speed front braking. This is a classic sign of a warped brake disc. after replacing them both, I was happy to report that the oscillation went away. However, over the course of many months the oscillation slowly returned. It's been less than a year at this point and it's already back, leading me to believe there's now something wrong with the bike itself that's re-warping the new discs. Everything I know how to measure seems to be aligned with regards to the front forks ect, but then I don't know much. Another interesting symptom I noticed is that one of the four brake pads in the front calipers is wearing out much faster than the other 3...even though they were all changed at the same time. odd.
As said above this is definitely going to a shop because everything I work on is a disaster, but I'm still curious. What does the knowledge base at large think could be causing these discs to warp?
RE: The return of the Oscillation - GoldOxide_imp - 08-01-2023
Are the discs discoloured? Heavily glazed?
RE: The return of the Oscillation - misterprofessionality - 08-01-2023
nope. they look like normal discs with around 10k miles on them.
RE: The return of the Oscillation - The Gecko_imp - 08-01-2023
(08-01-2023, 03:54 AM)m in sc_imp Wrote: the bleedback hole in the master cylinder is partially blocked.. (the little one when you look in the reservoir) OR,(more likely) the lever isn't allowing the master cyl to return all the way. I have seen both situations before on other bikes, especially when a replacement lever was used. there needs to be a few thou of clearance between the lever and the piston on the master cyl (0.002"-0.005" minimally) or it will always have residual pressure that can cause this exact issue. 0.02
cool m in sc, makes a lot of sense (and I wouldn't have found that explanation). At the same time I wonder, could it also be that a quality problem (e.g. with none OEM pads) ?
RE: The return of the Oscillation - max - 08-01-2023
Three questions;
1; has the bike been put away with water between the pads and the disk?
2; did the wear on one pad occur in the previous situation?
3; are the pistons in the affected caliper with the most worn disk moving back freely ( flexible seals ) from the disk after releasing the brake lever ?
My honda hornet developed some uneven braking after the bike was put indoors with rain water under the pads and developed slight rusty patches overnight.
RE: The return of the Oscillation - emptysea - 08-01-2023
I get weird stuff happening with brakes - oscillations, squeaking, etc. I have my shop guys look at it to be sure it's nothing major and that it's safe to ride and then I just go back to riding. If the bike stops, I figure my bikes works better than most Harleys and I just keep on riding it. I wish I could be of more help. Hopefully, your mechanic will set things true.
Also, wasn't 'The Return of the Oscillation' the 3rd studio album for the Zombies?
RE: The return of the Oscillation - GoldOxide_imp - 08-01-2023
(08-01-2023, 05:17 AM)EmptySea_imp Wrote: I get weird stuff happening with brakes - oscillations, squeaking, etc. I have my shop guys look at it to be sure it's nothing major and that it's safe to ride and then I just go back to riding. If the bike stops, I figure my bikes works better than most Harleys and I just keep on riding it. I wish I could be of more help. Hopefully, your mechanic will set things true.
Also, wasn't 'The Return of the Oscillation' the 3rd studio album for the Zombies?
lol - not quite, but can see the point.
More impressively, few people can relate to The Zombies.
RE: The return of the Oscillation - misterprofessionality - 08-01-2023
(08-01-2023, 03:54 AM)m in sc_imp Wrote: the bleedback hole in the master cylinder is partially blocked.. (the little one when you look in the reservoir) OR,(more likely) the lever isn't allowing the master cyl to return all the way. I have seen both situations before on other bikes, especially when a replacement lever was used. there needs to be a few thou of clearance between the lever and the piston on the master cyl (0.002"-0.005" minimally) or it will always have residual pressure that can cause this exact issue. 0.02
Ok...this all actually sounds really plausible EXCEPT the master cylinder was taken apart and cleaned thoroughly and a rebuild kit was applied (new seals and new piston and such) at the same time as when the discs were replaced. I actually didn't mention that in the original post because I didn't think it was relevant until I read your post. The brake pads were also replaced at that time and of course the lines were thoroughly bled and all that. It seems like that procedure would have cleared a blockage or funny business in the master cylinder would it not?
(08-01-2023, 04:33 AM)max_imp Wrote: Three questions;
1; has the bike been put away with water between the pads and the disk?
2; did the wear on one pad occur in the previous situation?
3; are the pistons in the affected caliper with the most worn disk moving back freely ( flexible seals ) from the disk after releasing the brake lever ?
My honda hornet developed some uneven braking after the bike was put indoors with rain water under the pads and developed slight rusty patches overnight.
1) no not in recent years. The bike was taken out of typical commuter rotation before all this started happening.
2) now that you mention it i believe it did.
3) they are. They were moving ok with the previous discs and at that time they were even taken apart and cleaned out and reassembled with new rings. They are currently moving smoothly near as I can tell.
(08-01-2023, 05:17 AM)EmptySea_imp Wrote: I get weird stuff happening with brakes - oscillations, squeaking, etc. I have my shop guys look at it to be sure it's nothing major and that it's safe to ride and then I just go back to riding. If the bike stops, I figure my bikes works better than most Harleys and I just keep on riding it. I wish I could be of more help. Hopefully, your mechanic will set things true.
Also, wasn't 'The Return of the Oscillation' the 3rd studio album for the Zombies?
Yea im definitely not gonna let it go. The oscillation only occurs at low speeds but that doesnt mean it's hot happening at higher speeds. The frequency is just too fast to feel. It's causing some undue stress on at least one of the brake pads by my observation and more than that its just bugging the heck out of me when I stop.
RE: The return of the Oscillation - dave - 08-01-2023
When was the last time you had your front tire replaced? Did you do it yourself? If a shop replaced your tire there's a chance they bent your rotor(s).
RE: The return of the Oscillation - misterprofessionality - 08-01-2023
I dont change tires myself. Last time i tried thati nearly diedof exhaustion.
This was what I thought caused it last time, but they haven't been replaced since the discs were replaced the first time, so a tire change has not had the opportunity to bend the discs this time around, meaning it likely wasn't the cause the first time either.