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only one disc caliper working - symptoms?

  • Zaddict
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24 Jan 2020 16:20 #817795 by Zaddict
I was trying to diagnose a new clunking from my front end and noticed only one of the disc rotors is getting hot. I was in an accident a few months ago and am only just now starting to ride again - the noise could be a result of damage from that. I'm wondering if the clunk might be related to only one disc caliper activating (e.g. causing the whole wheel to become off balance). I'm thinking probably not since lots of bikes come with only one disc, but I don't know. It does seem the noise is related to the brakes as I only hear it when they are activated (not when, for instance, I try bouncing against a wall...but maybe that's because I can't get enough bounce without the brakes applied). Has anyone had any weird front end noises when compressing or extending the shocks that turned out to be related to the brakes not working properly?

1990 Zephyr zr550 B1
Wiseco 615cc kit
zx550 cams
SPII ignition system
Kerker stainless steel race exhaust with 1.5" competition baffle
K&N Air Filter...

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  • Scirocco
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24 Jan 2020 18:02 #817803 by Scirocco
Replied by Scirocco on topic only one disc caliper working - symptoms?
If only one disk rotor getting hot the break caliper Piston is locked or stuck in his movement. Over the time dirt and gung will growing up in the grooves where the Piston seals and dust coves sits. Moisture will enrich in the brake fluid (hydroscopic effect) and react with oxidation of the aluminum caliper Body.
I use a fine flat Dremel brass brush to clean the grooves, it´s a must to do deep cleen Procedere!!!

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26 Jan 2020 17:06 #817993 by Zaddict
Replied by Zaddict on topic only one disc caliper working - symptoms?
Alright, even I thought the idea was a stretch, but looks like fixing the brakes got rid of my mysterious front end clunk. The pads on one side were slick; they must have gotten soiled somehow. Now both discs are getting hot, bike is stopping on a dime and no more mystery clunk. My best guess is that there's a tiny bit of play in the axle, and when only one caliper was grabbing it was torquing the front wheel enough to make that little bit of play clunk. Or maybe it was something else. In any case, for anybody out there in a similar situation looking for things to try -- make sure both calipers are working...

1990 Zephyr zr550 B1
Wiseco 615cc kit
zx550 cams
SPII ignition system
Kerker stainless steel race exhaust with 1.5" competition baffle
K&N Air Filter...

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  • Street Fighter LTD
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26 Jan 2020 22:29 #818004 by Street Fighter LTD
Replied by Street Fighter LTD on topic only one disc caliper working - symptoms?
Check steering head bearings are adjusted / not flat spotted Just to be safe


Original owner 78 1000 LTD
Mr Turbo Race Kit, MTC 1075 Turbo pistons by PitStop Performance , Falicon Ultra Lite Super Crank, APE everything. Les Holt @ PDM's Billet Goodies . Frame by Chuck Kurzawa @ Logghe Chassis . Deep sump 5qt oil pan. RIP Bill Hahn

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13 Feb 2020 08:15 #819165 by Zaddict
Replied by Zaddict on topic only one disc caliper working - symptoms?
Just adding some info for posterity. The "give" that was creating the clunking sound turned out to be a bad wheel bearing. So while making sure the brake calipers were both operating got rid of the clunking symptom, it didn't do anything for the underlying problem. The front axle shouldn't have any play at all. Here's the relevant wheel bearing thread:

www.kzrider.com/forum/5-chassis/612248-w...shot?start=40#819020

1990 Zephyr zr550 B1
Wiseco 615cc kit
zx550 cams
SPII ignition system
Kerker stainless steel race exhaust with 1.5" competition baffle
K&N Air Filter...

Please Log in or Create an account to join the conversation.

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