Resend my activation email : Register : Log in 
BCF: Bike Chat Forums


Brake pad uneven wear?

Reply to topic
Bike Chat Forums Index -> The Workshop
View previous topic : View next topic  
Author Message

kramdra
World Chat Champion



Joined: 28 Oct 2010
Karma :

PostPosted: 22:34 - 21 Aug 2016    Post subject: Brake pad uneven wear? Reply with quote

Getting uneven wear on pads, is it normal?

More wear happens on the bottom pot/pads, which see the disc first as it rotates. Probably a result of drilled disc eating into the pad? seems to be 0.5-0.8mm difference after 30k miles

I have rotated my pads, which should even it out. The good ones have perhaps 10k miles left, but I had to swap the other two for spare. One was down to 0.3mm at the bottom Shocked (the top of this pad was just on the wear marker 1mm). MOT is soon so will get new before then.
 Back to top
View user's profile Send private message You must be logged in to rate posts

RhynoCZ
Super Spammer



Joined: 09 Mar 2012
Karma :

PostPosted: 22:41 - 21 Aug 2016    Post subject: Reply with quote

Nope, not normal at all. Time to clean/rebuild the caliper. Some uneveness is possible between the left and right pad in one caliper, especially if it's a floating caliper, but when talking about only one pad, it should never have uneven wear.

EDIT: Rotating the pads to even the wear is wrong as well. Thumbs Up

This kind of thing should never happen:
https://www.aa1car.com/library/brake_pads_uneven_wear.jpg
____________________
'87 Honda XBR 500, '96 Kawasaki ZX7R P1, '90 Honda CB-1, '88 Kawasaki GPz550, MZ 150 ETZ
'95 Mercedes-Benz w202 C200 CGI; MZ 150 ETZ, '98 Mercedes-Benz w210 E200 Kompressor
 Back to top
View user's profile Send private message You must be logged in to rate posts

kramdra
World Chat Champion



Joined: 28 Oct 2010
Karma :

PostPosted: 23:00 - 21 Aug 2016    Post subject: Reply with quote

It is not massively uneven, 0.5mm not 3mm. However the pads only have 3mm to begin with (including the 1mm wear limit), so that 0.5mm is quite a few wasted miles. Both pads in both callipers are the same, slightly more wear on the bottom pot. Callipers were stripped and cleaned Jan 2015, I noticed some pots were slightly freer to push by thumb back then. Seals were inspected, perfect condition, cleaned and put back. Callipers and seal groves were spotless. Today I pushed the pistons half out and flossed them clean with tissue and brake cleaner, they all seem equal, much better than they used to be.

What to do? I will fit new pads this month anyway, but seems silly to do seals just before winter. Also need new rear disk, rear pads, probably new rear piston and seals. About 90 quid. Front pads and seals is another 200 quid if I use genuine Nissin parts, which I would prefer.
 Back to top
View user's profile Send private message You must be logged in to rate posts

Kickstart
The Oracle



Joined: 04 Feb 2002
Karma :

PostPosted: 23:06 - 21 Aug 2016    Post subject: Re: Brake pad uneven wear? Reply with quote

kramdra wrote:
Getting uneven wear on pads, is it normal?

More wear happens on the bottom pot/pads, which see the disc first as it rotates. Probably a result of drilled disc eating into the pad? seems to be 0.5-0.8mm difference after 30k miles


Yes it is pretty normal or at least not unusual. Basically the same reason as why a lot of calipers have smaller leading pistons.

All the best

Katy
____________________
Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing
 Back to top
View user's profile Send private message Send e-mail You must be logged in to rate posts

Pete.
Super Spammer



Joined: 22 Aug 2006
Karma :

PostPosted: 23:41 - 21 Aug 2016    Post subject: Reply with quote

Normal. I don't think I've had any pad pair that wore at exactly the same rate and it's common to find a couple of mm or more extra thickness on one side, especially on the rear. In fact, I have a drawer full of old pads for when I/someone gets caught out with pads down to metal and a wait for a new set. Better to put in a part-worn pad temporarily than trash the disc.
____________________
a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good Very Happy
 Back to top
View user's profile Send private message Visit poster's website You must be logged in to rate posts

Shinigami
World Chat Champion



Joined: 14 Feb 2012
Karma :

PostPosted: 09:52 - 22 Aug 2016    Post subject: Reply with quote

if its a sliding caliper it could be what happened with mine, one of the sliding bolts was very slightly mis-threaded/crossthreaded (couldn't tell visually). Ended up having to replace the caliper when I finally figured out the problem..

It was chewing up pads at a very similar angle to those pics
____________________
Current: Honda City Fly CLR125 2003 Honda CB600F Hornet 2008 Yamaha FZ6 S2 + 1991 Kawasaki GPZ500
"Once you realize what a joke everything is, being the Comedian is the only thing that makes sense.
 Back to top
View user's profile Send private message You must be logged in to rate posts

Fizzer Thou
World Chat Champion



Joined: 06 Aug 2011
Karma :

PostPosted: 23:52 - 23 Aug 2016    Post subject: Reply with quote

The rear pads on the Exup and the FJ12 have shims that allow different pressure on one side of the pad.It sounds like one is missing or that where the pad backing plate slides in the caliper body,that it is catching somewhere and not moving freely Question
____________________
Just talk bikes.What else is there?

Always have a 'Plan B'
 Back to top
View user's profile Send private message You must be logged in to rate posts

MCN
Super Spammer



Joined: 22 Jul 2015
Karma :

PostPosted: 16:53 - 24 Aug 2016    Post subject: Reply with quote

The Hydraulic effort from the lever will take the path of least resistance.
If a pad or piston is tighter than another on in the same circuit then that slacker/free one will wear most.

Clean out the caliper and check the pistons move together.
____________________
Disclaimer: The comments above may be predicted text and not necessarily the opinion of MCN.
 Back to top
View user's profile Send private message Send e-mail You must be logged in to rate posts

kramdra
World Chat Champion



Joined: 28 Oct 2010
Karma :

PostPosted: 21:28 - 24 Aug 2016    Post subject: Re: Brake pad uneven wear? Reply with quote

Kickstart wrote:
Yes it is pretty normal or at least not unusual. Basically the same reason as why a lot of calipers have smaller leading pistons.

All the best

Katy


This explains it, they did use a smaller piston on the bottom.

Pulling the lever without pads will move them the same amount. Very little resistance, I am quite happy they are not needing to be stripped and cleaned until after winter.
 Back to top
View user's profile Send private message You must be logged in to rate posts

Fizzer Thou
World Chat Champion



Joined: 06 Aug 2011
Karma :

PostPosted: 15:12 - 25 Aug 2016    Post subject: Re: Brake pad uneven wear? Reply with quote

Kickstart wrote:
Yes it is pretty normal or at least not unusual. Basically the same reason as why a lot of calipers have smaller leading pistons.


The standard Exup1000 calipers that I now have fitted to the FJ1200 have smaller leading pistons,which is quite obvious when looking at the caliper body

https://i1073.photobucket.com/albums/w384/Rhencullen5/FJ1200/20160612_164135_zpscciufiq6.jpg

The standard FJ1200 calipers have the same piston size for leading and trailing items

https://i1073.photobucket.com/albums/w384/Rhencullen5/FJ1200/20150621_202218_zps87slwrom.jpg

The YZF750 calipers that I now have fitted to the Exup1000 are quite distinctly six piston,where the leading pistons is smaller than the other four

https://i666.photobucket.com/albums/vv23/WiNot_Rhencullen/Workshop/20160420_165309_zpsxolnnfa8.jpg

But I have yet to see any difference in the way that the pads wear.It is more about braking forces.The FJ1200 standard calipers are known not to have a very good feel and need a lot more braking pressure on the lever,than say the six piston YZF750 calipers.
____________________
Just talk bikes.What else is there?

Always have a 'Plan B'
 Back to top
View user's profile Send private message You must be logged in to rate posts

Kickstart
The Oracle



Joined: 04 Feb 2002
Karma :

PostPosted: 00:05 - 26 Aug 2016    Post subject: Re: Brake pad uneven wear? Reply with quote

Fizzer Thou wrote:

But I have yet to see any difference in the way that the pads wear.It is more about braking forces.The FJ1200 standard calipers are known not to have a very good feel and need a lot more braking pressure on the lever,than say the six piston YZF750 calipers.


I suspect a large part of the issue with feel is down to lousy choice of leverage ratios (especially on 1980s Yamahas) and not very rigid calipers.

The leading edge of the pad will have a greater braking effect, and likely wear to go with that . Smaller leading piston is meant to result in a bit less pressure on the leading edge, and even out that braking effect

All the best

Katy
____________________
Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing
 Back to top
View user's profile Send private message Send e-mail You must be logged in to rate posts
Old Thread Alert!

The last post was made 7 years, 217 days ago. Instead of replying here, would creating a new thread be more useful?
  Display posts from previous:   
This page may contain affiliate links, which means we may earn a small commission if a visitor clicks through and makes a purchase. By clicking on an affiliate link, you accept that third-party cookies will be set.

Post new topic   Reply to topic    Bike Chat Forums Index -> The Workshop All times are GMT + 1 Hour
Page 1 of 1

 
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You cannot download files in this forum

Read the Terms of Use! - Powered by phpBB © phpBB Group
 

Debug Mode: ON - Server: birks (www) - Page Generation Time: 0.09 Sec - Server Load: 0.1 - MySQL Queries: 18 - Page Size: 77.44 Kb