Bonneville America Forums Forums Technical Forums General Tech Rear brake wear

Almost time to change the Rear Pads Again! 18,500 miles.
Been averaging about 5000 miles. Been running the sintered pads from Brent since around 6000 miles.
I'm sure this has been discussed many times before,but.
Why does the outer pad wear much faster than the inside pad.
The pad on the inside has many miles left on it. Outside pad is just about gone

Since hydraulic pressure is only applied to the outer pad, to keep the rotor from warping, the caliper must float to allow the inner pad to provide pressure against the inside of the rotor. Apparently this is not happening as well as it is should in your situation (and mine after a quick look). The result is the outer pad providing most of the stopping force and the inner pad not providing an equivalent.
Next pad change take a good look at the pin that the inner pad rides on. Mine has developed a bit of rust so it's not moving as it should. 4-wheelers have a dust cap on the pin that holds grease to prevent this. I hesitate to put a dab of grease on it, but we'll see how it works out.

That's the piston side, right? (too lazy to go out and look)...

My guess is that because the piston presses on that side it sees somewhat greater force.

Mike-Not to sound rude or anything do you use the front brakes? I've gotten almost 10,000 out of my rear pads. Are the pads dragging or anything? I had a sticky caliper on a truck of mine & it would wear pads out quick.

Yota rude? Getouttahere Yes I do use the front brake.
In fact I use the front brake 80 % of the time.In straight line stopping I never use the rear.
I bet if we do a survey we will find your 10,000 is not the norm at all. More like 6000 is the norm.
We have had many discussions on this board in the past about lousy rear brake wear. Where were you hidding all that time.

Probably shaving his back...

I can't keep up with every thread.....

I had to replace the originals at 5000. Now with an additional 7000 on the sintered that I got from Brent, they still have a lot left.
When you replace them, look at the calipers and see where all the sliding parts are. The bolts for one and I believe some flat places. Put a film of white lithium grease on all the sliding parts. It's heat resistant and water proof. I've done this on all brake calipers, as well as the contact points on drum brake shoes, for the last 30+ years.

I have a theory... well, actually something I was taught by the USAF concerning disc brakes. This may or may not apply to our brakes, and several of my mechanic friends say this is not the case, but....

I was taught that the piston seals in the caliper not only provide the seal needed to apply the brake pad, but that they actually twist slightly during application. This twist provides enough force to withdraw the pistons slightly once the hydraulic force is released. That in turn, allows the pad to move away from the rotor.
Over time, as the piston seals are subjected to heat, brake dust, tar, rocks and various insect parts, they are no longer able to twist and the pad remains in slight contact with the rotor which increases wear. It was a required practice to rebuild the calipers every time you changed brake pads.

Again, this may not be the case with our brakes, but I have had the same experience with one pad wearing about twice as much as the other....

This isn't to start an arguement, just something to think about....

Grump: You are correct....as long as it is a square cut o-ring sealing the piston.

less wind drag when clean shavin'.

I had to replace my original rear brakes at 11,000 miles....fronts at 15,000....can't imagine why yours wear out twice as quickly...

Forgot to add this but...I live in the flatlands. I don't use the brakes much.

Mike,
LOL man.

5K on the rear pads? You must really be heating up the brake fluid! Move to some flat lands and you'll get a lot more miles outa em. Or don't ride WOT all the time! Never have I changed pads and not noticed one with more wear than the other. At least our pads are under 20 bucks per axle (organics that is) and a breeze to both inspect and change. I stopped with the miles thing long ago...

Mine wears un-evenly too - I never gave it a thought 'til now ...

I'm at 18300 miles and on my third set - I think they are made off special putty that looks hard-wearing until fitted to the bike

This is because the caliper is a cheap s**t design - if the caliper is in good order, i.e. it is not binding on the pins, then the pressure will be the same on both sets of pads - however, the sliding pins seize up and consequently, the piston pad does all the moving. If you take the caliper off, and squeeze the pads together, you will see what I mean. Just more crappy "built-to-a-price" engineering!

BTW, changed my rear pads a7 6200 miles - both worn evenly ('cos I stripped and copaslipped everything) there was at least 0.002 mm of pad left!!

All the best

Jan

PS anyone going to the bike show @ NEC this year?

Hiya Jan
How's the job hunting going?
Hope you get sorted soon. If you haven't already!!

Have you been to America / are you still going - what's the position there?

I'm going to the NEC - I usually go on the Thursday (usually quieter - don't know why??)
Talking to a mate who goes on the last day looking for bargains. I want to have a good look round without spending it looking at trade stands so even if I have to go a second time for 'the bargains', a second entry fee could very easily be saved on the price of a new lid.
Hopefully the 'popular' sizes will have gone leaving only dustbin sized ones for blokes like me with .. ahem .. generous sized heads ...

I changed my OEM pads at 6,000 for the fun of it. They were barely worn. I was suprised based on all this coversations here. I have 2004 TBA.