Its rear brake pad replacement time again

[peterRT]

Hi Spyder lovers", it's brake pad time replacement again. I have done this before and I am fimiliar with what to do I just put a pic of my rear wheel brake pads and always one wears out more than the other

 

[Bfromla]

There are few variables some can be fixed to help that

 

[Highwayman2013]

Clean the parts that slide and grease them with disc brake grease.

 

[BLUEKNIGHT911]

The pads are good till 1mm - imho they aren't near that yet ….. Mike hyea:

 

[peterRT]

Yep thanks guys for your replies and I think when I put the new ones on I will apply grease and I will just hope to get a few more weeks out of the pads yet I just keep inserting 1mm wire and when it is at its limits I will then put on the new pads

Regards Peter

 

[RICZ]

My wife saw this and told me I should comment. So don't chew on my ear for this....
Brakes turn energy into heat and dissipate that heat into the atmosphere. The thinner the friction material, the less efficient they are to dissipate heat. For that reason, I change pads when they become only halfway worn. A pad that thin is going to go bye bye real fast. If it were me and I had new pads at the ready, I'd put them in. Why risk brake fade and gouging the rotor.
Before installing new pads, put a piece of sand paper on a flat surface and give them a few stokes and bevel the leading edges. Clean the rotor with brake cleaner or alcohol. Then use some 400 grit sandpaper or Scotchbright pad on them.
My dad taught me to mind the brakes more than the engine, saying; You can always make it go, but if you don't mind the brakes, you can't always make it stop. Wise man my dad.

 

[Little Blue]

Brake Pads

Just curious, how many miles are you getting? Do you think the pads are the problem? .....:thumbup:

 

[BajaRon]

Maybe it's just me. But it's hard to tell from the pictures exactly how your pads are wearing. They appear to be wearing pretty evenly. Mike is right. You still have a fair amount of wear left on those pads. They are not as thick as a standard automotive pad to begin with. Even 1mm leaves you with enough pad to be safe. As long as they are wearing evenly, of course.

Beveling the leading edge will not help to make your pads wear evenly. Beveling is intended to reduce brake noise. And is only recommended for new pads before installing them. The bevel (if done correctly) would be gone by now on your pads in any case.

Highwayman is right. Clean and smooth all of the sliding parts and apply a very light coating of Anti-Seize. Just in the area of contact between the sliding parts. There are many good products out there. Either of these 2 are good choices.

 

[BLUEKNIGHT911]

My wife saw this and told me I should comment. So don't chew on my ear for this....
Brakes turn energy into heat and dissipate that heat into the atmosphere. The thinner the friction material, the less efficient they are to dissipate heat. For that reason, I change pads when they become only halfway worn. A pad that thin is going to go bye bye real fast. If it were me and I had new pads at the ready, I'd put them in. Why risk brake fade and gouging the rotor.
Before installing new pads, put a piece of sand paper on a flat surface and give them a few stokes and bevel the leading edges. Clean the rotor with brake cleaner or alcohol. Then use some 400 grit sandpaper or Scotchbright pad on them.
My dad taught me to mind the brakes more than the engine, saying; You can always make it go, but if you don't mind the brakes, you can't always make it stop. Wise man my dad.

IMHO , the brake pad manufacturer took the HEAT thing into consideration ….. however if the Pads are some kind of Chinese knock-off - all bets are off ….. Merry Christmas ….. Mike hyea:

 

[peterRT]

Hi Guys and thanks I will take on board what all of you said,

Regards Peter

 

[IdahoMtnSpyder]

IMHO , the brake pad manufacturer took the HEAT thing into consideration ….. however if the Pads are some kind of Chinese knock-off - all bets are off ….. Merry Christmas ….. Mike hyea:

:agree:

Brakes turn energy into heat and dissipate that heat into the atmosphere. The thinner the friction material, the less efficient they are to dissipate heat. ..... A pad that thin is going to go bye bye real fast. If it were me and I had new pads at the ready, I'd put them in. Why risk brake fade and gouging the rotor.

I'm going to quibble with your wife. The pads definitely play a part in getting rid of the heat that results from converting the kinetic energy of the moving vehicle by use of friction. However, the pad itself dissipates very little heat to the atmosphere. There just simply isn't enough interface between the pad and ambient air to conduct heat. In addition to providing friction, pads have two roles, one as insulators and the other as thermal conductors. In the insulating role they provide resistance to the friction heat at the disc/pad interface from being transmitted to the pad backing steel and on to the caliper piston and brake fluid. So in this case a new full thick pad will provide more resistance than a worn thin one. So if you want to maximize this benefit change the pads at 3/4 of original, not at 1/2. But that's a ludicrous idea. So what is the minimum thickness that the brakes will function well at? How about the thickness at which brake squawkers start making noise? And we all know that is way less than 1/2 of original. Unfortunately, Spyder pads don't have squawkers, do they?

In the other role as thermal conductors thickness times resistance/distance equals total resistance. A thinner pad will allow more heat to move into the backing plate and piston. Since the heat moves faster through a thinner pad it won't get as hot as a thicker pad. The temperature of the contact surface of a thin pad and rotor is most likely less than with a thick pad, so the detrimental effects of heat will be less on a thin pad than a thick one.

In any case, the specific heat, i.e., the capacity to absorb heat, of the rotor will be much higher than the pad, and the thermal conductivity of the rotor will be much higher than the pad. Subsequently, the heat generated at the rotor/pad interface is going to preferentially move into the rotor which is designed to transmit that heat to the ambient air as efficiently as practical. As Mike says, you can be sure the brake system designers have accounted for thin pads and heat, and with a safety margin at that. So from a practical viewpoint the only heat generating aspect of the brakes we need to be aware of is how hard we brake. There is a limit, like riding brakes for miles on end on a downhill coast.

Now, I'm going to offer up a totally heretical viewpoint, and that is gouging of the rotor may not be bad at all. Think of crossing a mountain from the valley on one side to the valley on the other side. It's pretty intuitive to recognize that the surface area of the mountain is greater than the surface area of a plain the same width. And so it is with grooves in a rotor. Once a brake pad has worn down enough that the pad material reaches the bottom of the groove you have more surface contact area between the pad and rotor. More surface contact area equals more friction area which equals more braking effect. But from the time the pad is new and flat to the time it conforms to the groove you will have less braking effect. I've never been overly concerned about grooves in the brake rotor.

Now, I suppose, a good brake system design engineer who has all sorts of laboratory test equipment, and intimate knowledge of the thermal and friction properties of brake pads, and powerful computer programs to do all the calculations, might just be able to blow my arguments to smithereens. :dontknow: My argument is based on my own thought process and Google searches!

 

[Peter Aawen]

:agree: with most of that, but Idaho, I do wish you hadn't spilled the beans to the rest of the riding/driving public re that 'trade secret' about grooves in the disc enhancing braking like they can do, even with your caveat, cos you REALLY MUST be EXCEPTIONALLY careful with your braking demands throughout the entire 'bedding in' or 'conforming pads to the not flat disc surface' period!! :banghead:

With the modern brake pad & disc materials most commonly found on road going vehicles (where users generally expect their brakes to last for at least some tens of thousands of miles, not just saaay, 500 laps around a race track or a fixed & fairly limited number of aircraft landings etcbefore replacement....) that can mean you've effectively gotta practice tippy toe-ing your vehicle around for maybe as much as few hundred miles (depending on what caliper/pad/disc combination you are running) before it's safe risking it out on a public road where you've got all those other people, vehicles, & a bunch of what's effectively immovable objects to contend with... ie. things that might suddenly require somewhat more braking effort than you have just yet!! :shocked:

But you're right, the brakes on our Spyders (and most motor vehicles) are REQUIRED to work pretty much as well at the manufacturer's recommended wear limits as they do when nearly new, and there's fairly generous safety margins built in too! So while there's a lot of merit in doing the cleaning & bevelling stuff on new pads that you refer to RICZ, changing your pads out too early is sorta like changing the oil every thousand miles instead of as per the recommended schedule..... it's probably not going to hurt too much (altho any maintenance does have risks & will impose some wear on the non-replaced components! :sour: ) but you are wasting a fair bit of your time & money for no appreciably measurable gain.... :lecturef_smilie: But it is your Spyder (or your Wife's) & you are perfectly entitled to use whatever maintenance schedule & practices you will with it! :thumbup:

 

[BajaRon]

The whole idea of a friction braking system is to (YES) convert kinetic (Moving) energy into heat, thus slowing you down.

One key to getting this done is to move the heat away from both the pad and the rotor contact surfaces as efficiently as possible. This allows these 2 surfaces to continue making heat and accomplish their job. Once a certain temperature at these 2 surfaces is reached (heat saturation), no more heat can be generated, and you are essentially left with no brakes at all, even though there is still plenty of pressure being exerted on the pad/rotor assembly. This is why you get bus or large truck accidents where the driver states; 'The brakes went out'. Yet when the investigators check the brakes, (once they have been allowed to cool) they work just fine. As the brakes approach this 'Temperature Failure' point, they begin to 'Fade' which causes the driver to push harder on the brake peddle and hasten the complete failure point.

But heat related brake failure is not really pertinent to a Spyder rider. As our brake system is way over designed. I've never heard of a heat related brake failure on a Spyder. But the scenario does illustrate how important it is to move the heat away from the contact surfaces.

There are 2 places that the heat goes. First, to the rotor which acts as a heat reservoir. Second, to the remaining pad material (which is not a great conductor of heat) to the metal backing plate, to the caliper piston, to the caliper and brake fluid, (one reason the boiling point of your brake fluid is important and why water and other contamination, which lowers the boiling point, is also important). All of these components act as heat wicking agents and dissipate to the ambient air.

Just a quick note here as to why semi-sintered and fully sintered brake pads work better than the organic pads that come on the Spyder. Sintered means Copper Alloy material which is embedded into the brake pad. Not only does it grip the rotor better. It also transfers heat through the pad material to the other components better, thus, the pad remains cooler than an organic pad, and able to generate more heat. Which translates into longer pad life and better stopping.

Because the pad material, even with a sintered brake, is not an excellent heat conductor. Brake pads of any kind will actually transfer heat to the backing plate more quickly and efficiently as they get thinner. This is one reason brake pads wear more quickly when new, and actually wear more slowly as they become thinner. So, when you have 1/2 of the pad material left. You actually have more than 1/2 the brake pad life left. At the same time, it is also true that the non-rotor brake components will heat up more quickly (caliper/brake fluid, etc.) with thinner pads. If these brake components do not have enough heat reservoir reserve, then you can experience brake fade or even failure. But again, not an issue with the Spyder.

As for grooves in the rotor. You are 100% correct that these provide additional surface area (once the pads mate completely). Additional surface area will increase braking. However, it's not all good news. One of the things that you want is equal braking at both left and right wheels. It is very difficult to get matching grooves on both rotors. So the wheel with the most heavily grooved rotor will have more stopping power, creating unequal braking. Another thing you want from your braking system is evenly generated heat with even heat dissipation and cooling. Uneven heat generation and cooling creates problems of its own. And this is what you will get with grooved rotors.

Minor scratching or grooving is not usually any problem at all. Because we are talking grooves which are small enough to make no real difference. But if you have grooving deep enough to make a difference, it's s difference you do not want.

 

[RICZ]

Now that I did get my ears chewed, I was going on the assumption y'all knew that it's the rotor that dispels most of the heat into the atmosphere. What I was pointing out was that a too thin pad transfers more heat to the caliper and there's the risk of boiling the fluid. I have seen this happen - although not to me.
Disc brakes are a huge improvement over drums that have about 85% covered by friction material, with only about 15% doing the cooling. Whereas, disc rotors are covered about 15% and the other 85% does the cooling. Hence better braking and resistance to fading.
Re those who scorned my replacing pads at or slightly below the halfway mark; Do you wait to replace tires when they are way past the wear bars because there's still some tread there? FYI, I replace tires well above the wear bars, don't scold me for that too. It's my money and my life that I'm protecting and I did not appreciate the snarky comments. Posts can be worded in positive ways, rather than rubbing someone's nose in it. We are here to help and get help.
That theory about gouged discs is an interesting one and I'd like to see a side-by-side comparo of the braking performance between smooth rotors and gouged ones. I bet you would too.
Peace.

 

[BLUEKNIGHT911]

Now that I did get my ears chewed, I was going on the assumption y'all knew that it's the rotor that dispels most of the heat into the atmosphere. What I was pointing out was that a too thin pad transfers more heat to the caliper and there's the risk of boiling the fluid. I have seen this happen - although not to me.
Disc brakes are a huge improvement over drums that have about 85% covered by friction material, with only about 15% doing the cooling. Whereas, disc rotors are covered about 15% and the other 85% does the cooling. Hence better braking and resistance to fading.
Re those who scorned my replacing pads at or slightly below the halfway mark; Do you wait to replace tires when they are way past the wear bars because there's still some tread there? FYI, I replace tires well above the wear bars, don't scold me for that too. It's my money and my life that I'm protecting and I did not appreciate the snarky comments. Posts can be worded in positive ways, rather than rubbing someone's nose in it. We are here to help and get help.
That theory about gouged discs is an interesting one and I'd like to see a side-by-side comparo of the braking performance between smooth rotors and gouged ones. I bet you would too.
Peace.

I caution against equating Brake Pad thickness with Tread depth …. they are not nearly same .,. the difference between 4mm and the effectiveness of 1mm aren't much as long as there is enough brake fluid to counteract the thinner the Pad ….. Ron wrote a lot of info and I agree ….. But to simplify - brake pads are designed to work under many different circumstances and vehicle weights ….. Pads for vehicles used in Racing won't work ( safely ) on normal vehicles.... WHY ? … because they MUST heat up to work within their design parameters..... Racing pads on the street won't stop 98% of the veh's used there.... most street pads will fade Badly if towing a large trailer down a long hill ( ie in the mountains )…..On Spyders, changing pads way before it's necessary is only an added expense and serves no positive results ….. jmho …. Mike hyea:

 

[IdahoMtnSpyder]

I was going on the assumption y'all knew that it's the rotor that dispels most of the heat into the atmosphere.

I trust you have heard what happens to both parties when you ass-u-me!

What I was pointing out was that a too thin pad transfers more heat to the caliper and there's the risk of boiling the fluid. I have seen this happen - although not to me

I wish you would have written this earlier. Then I would have known you think the same as I do with regard to this point!

Re those who scorned my replacing pads at or slightly below the halfway mark; Do you wait to replace tires when they are way past the wear bars because there's still some tread there?

Sorry if you feel like I was scorning as that wasn't my intent, although I suppose I was ridiculing your early replacement. To make the tires vs. pad more accurate I would say the wear bars are equivalent to brake pad squawkers. The product design is based on using them to the prescribed wear point and still retain the intended performance. The real question then becomes does early replacement buy sufficiently improved performance to justify the cost of early replacement? I'm inclined to say no.

 

[RICZ]

The real question then becomes does early replacement buy sufficiently improved performance to justify the cost of early replacement? I'm inclined to say no.

I'm sure you are right, but you see, you are dealing with a guy here who is super OCD when it comes to his vehicles and errs on the side of caution. But I will wear jeans for so long that my wife has to tell to get fresh ones out. Your apology is accepted, thanks.
Mike....I used to race sport cars and you are right about race pads have to warm. The same with race tires. It's also good practice on cold days to take it easy (no matter the vehicle) for a mile or so to warm and soften the tires. Cold tires have diminished grip.

 

[Little Blue]

Rear Brake Pads

Just curious how many miles are you getting on the Rear Pads?
Would it be about 25,000 to 35,000 miles?.......:thumbup:

 

[IdahoMtnSpyder]

Just curious how many miles are you getting on the Rear Pads?
Would it be about 25,000 to 35,000 miles?.......:thumbup:

Mine were completely worn out at just over 26,000 miles. One rear pad was paper thin and one front one had just started to make metal to metal contact.

 

[RICZ]

Just curious how many miles are you getting on the Rear Pads?
Would it be about 25,000 to 35,000 miles?.......:thumbup:

If you are asking me, I'm on my first Spyder, got it last February and don't have many miles on it. But I can tell you that my car, a 2007 with 93K miles, still has the original pads and there's more than 50% meat left.
I had a service truck that weighed 10K pounds - 6K on the rear axle. I turned it over to the buyer of my biz at 140K+ miles and he added another 100K and it still has the premium replacement brakes I installed at 17K miles. The original ones were, as the Scots would say, crrrrap.