Front brake caliper binding?


wirld

New member
Hi All,
Looking for some advice from the mechanically minded, please...

In October I decided to upgrade my brake pads - installed a set of Ferodo sintered. I really liked them, I felt the initial bite was better and had better feedback from the front of the bike.
In November my bike went for its 10,000km service - dealer didn't find anything remiss with the brakes.
Since then I've done another 1,700km so all told probably 2000km on the pads.

Today I noticed a griding from the front during braking, got home and took off the brake calipers.
The outer pad of the left hand caliper (viewed from riding position) was worn down to the metal - the others are virtually perfect.

I imagine that the caliper pistons got stuck pushing the pad against the disk - has this happened to anyone else on the MT-07?
Are there any early warning symptoms - I honestly noticed nothing wrong with the brakes until today?
I sprayed out the calipers with brake cleaner, the rubbed a touch of anti-seize around the outside of the pistons today - is there something else I can do to prevent this happening again?
Is it possible it was a dud brake pad?
etc

Thank you for input!
Grant

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sdrio

New member
If it was a seized piston, it shouldn't have done that - it seems that the piston must be constantly applying pressure to the pad. Presumably you replaced the pad (or will replace it), did the piston move back easily?

I'm not a mechanic, so this isn't based on any kind of expertise, but wouldn't this suggest there's a problem of balance between the brakes? One of them seems to be permanently on, the other not.

If you're still under warranty, I'd take it back. If not, at best your braking must be compromised so a strip down sounds necessary.

Interesting though, have never seen anything like that before.
 

Ralph

New member
Maybe the pad it's self has been binding in the calliper, rather than the piston,
the locating peg top left on the worn pad looks a bit suspect.
 

Scim77

New member
Maybe the pad it's self has been binding in the calliper, rather than the piston,
the locating peg top left on the worn pad looks a bit suspect.
I agree. This type of uneven wear is usually caused by 4 possibilities. 1) Faulty pad material - highly unlikely. 2) Faulty master cylinder - unlikely, since this would cause all four pads to wear or at least wear unevenly in pairs. 3) Sticking hydraulic piston within that particular calliper - more likely. Check that all pistons push back with similar resistance. If not then you need calliper overhaul. 4) Pads mechanically tight in the calliper apertures or on the guide pins - most likely.
When fitting your new pads, make sure that they are a nice easy fit when you slot them into the calliper. It is important that they slip in easy. If they are tight, carefully scrape debris from the calliper pad areas, and/or file the edges of the metal pad backplates until you achieve an easy fit. Sparingly apply copper-rich grease to 'rubbing' metal surfaces of the pads. Clean the pins and refit with the anti-rattle clips.
 

Yaminator

New member
This could be air trapped in the braking hose's since changing the pads, the pad that's worn i bet it was the first pad inline with the first direct hose from the master cyclinder...??
 

wirld

New member
If it was a seized piston, it shouldn't have done that - it seems that the piston must be constantly applying pressure to the pad. Presumably you replaced the pad (or will replace it), did the piston move back easily?
It did move back in easily...at least with no more difficulty than the other pistons when I put the old pads back in until I can get a new set.

This could be air trapped in the braking hose's since changing the pads, the pad that's worn i bet it was the first pad inline with the first direct hose from the master cyclinder...??
It was the first pad inline as you guessed - but I don't understand how does air in the braking hose cause this?

Maybe the pad it's self has been binding in the calliper, rather than the piston,
the locating peg top left on the worn pad looks a bit suspect.
That's something I never even considered - I'll have a look at it this evening after work, thank you!


I agree. This type of uneven wear is usually caused by 4 possibilities. 1) Faulty pad material - highly unlikely. 2) Faulty master cylinder - unlikely, since this would cause all four pads to wear or at least wear unevenly in pairs. 3) Sticking hydraulic piston within that particular calliper - more likely. Check that all pistons push back with similar resistance. If not then you need calliper overhaul. 4) Pads mechanically tight in the calliper apertures or on the guide pins - most likely.
When fitting your new pads, make sure that they are a nice easy fit when you slot them into the calliper. It is important that they slip in easy. If they are tight, carefully scrape debris from the calliper pad areas, and/or file the edges of the metal pad backplates until you achieve an easy fit. Sparingly apply copper-rich grease to 'rubbing' metal surfaces of the pads. Clean the pins and refit with the anti-rattle clips.
Thank you for laying it out so clearly - I refitted the old pads last night as they still have plenty of life in them. But I'll refit them this evening and check for any binding in the caliper.
 
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bobh

Member
Agree with the above - pads binding in the housing seems the most likely explanation if the pistons are free. This 4-pot "blue spot" design (OK, they're not blue any more) is comparatively good at resisting piston seizure, unlike some of the 2-pot sliding caliper ones that Yamaha have used on other bikes such as the XJ6 and MT-03, which need a refresh pretty much every year.

But what sort of anti-seize compound did you use on the piston? Anything with a mineral oil base will soften the piston seals - you should only use red rubber grease for this job.
 

wirld

New member
Could this be a case of fake pads.? I mean was the replacements very cheap? EBay copies maybe??
I don't think so - they did come via Ebay, from Germany. The price was competitive but not significantly cheaper...I couldn't find Ferodo in NZ, and had used them prior.
Also the other pads show the type of wear that I would expect after 2000kms

But what sort of anti-seize compound did you use on the piston? Anything with a mineral oil base will soften the piston seals - you should only use red rubber grease for this job.
I used Permatex Anti-Seize, apparently a copper, aluminium and graphite compound. Not sure if it contains mineral oil...
Started by spraying brake cleaner all over the caliper and wiping everything down, then extending the pistons and wiping a small amount of antiseize on with a q-tip, then removing with a rag - surface feels slippery, but there's no visible excess anti-seize.
Then bled the system to check if there was any air.

Afterwards the feel at the lever was good.

Update: I went to Yamaha this morning with the buggered brake pads - they reckon 99% chance it was a stuck piston, and that by cleaning it out the problem should be gone. I didn't remove the pistons completely though - so I'll take it back to them on Tuesday to have the calipers disassembled and cleaned out completely.
 
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Deanos

New member
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Hi guys and girls.

Digging up this old thread as I see this might just be a common issue on the 07's.

I knew the pads needed replacing last week, but then the scraping started about 5kms from my house.

Changed out the pads on Saturday, but still have the "scraping / binding" sound...
I did check that everything was working when I put the new pads in, but I am suspecting a bad or sticky piston....

Lucky for me the disk is still good. I didn't touch the front brakes when I first heard the scraping...

Considering I'm going to be replacing the fluid, are there any recommendations for what to use?
I'm in Sunny South Africa where temps range between 0 and 40C....

Thanks in advance.
 


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