New Pad Feel

[Dinkie Diesel]

Just replaced the front pads this morning with 55,000 miles on the OEM pads. When I had the bike inspected in March they said my front pads only had 400-500 miles left. I pulled the caliper, cleaned the pistons and lubed up necessary parts with Teflon dry lube. Polished the retaining pins (should have replaced them but didn't have sense enough to order ahead of time), pushed the pistons in to their retracted positions and installed the new pads. Only took about 22 minutes.

Now I have a question:

Why did my front brake lever change the point at which the brakes start grabbing? I'm having a hard time conceptualizing this phenomenon.

From my experience in the mechanical world, a hydraulic brake or clutch is a self-adjusting system. As the pads wear the pistons come out of their hole and leave you with a pad that is within a few thousands of touching. I was also taught that a certain amount of rotor run-out was good/needed to actually throw the pads out away from touching continuously.

Since putting the new pads on I now have a lot more front brake or put another way, I don't have to pull the lever near as far before the front brakes kick in. eg. My brain says if I used to have to pull the lever in 1-1/2" and that squirted 3cc's of brake fluid in the pistons why do I only need 3/4" of travel or 1-1/2cc's of fluid now? Shouldn't that remain a constant?

Sorry, sometimes I just geek out and need closure.

 

[The Dan]

LOL Now thats a mind bender.

 

[Scooter]

Did you add any fluid to the system sometime in the past before the pads were changed? You might have too much fluid in there now although I'm not certain that should affect this. Another possibility, I know that if you change the adjustment setting on the brake handle (1-5) you kind of get the same effect...

 

[MDTurley]

Stock (OEM) pads?

 

[ardykay54]

New pads don't need as much fluid to push the pistons so your lever action starts sooner?? Was it this way when your bike was new? Just guessing. Replaced my original pads at 64,000. I think mine did the same thing too. Russ. (Don't worry, be happy!)

 

[richard buber]

Hi: --thicker pads=less piston travel=less fluid=less brake lever travel---butt been wrong before
Richard,(oldwing)

 

[Kevin_56]

My take on piston travel is that once the pads have contacted the rotor they retract and then extend the same amount whether you have new or old pads. The pistons do not know you have changed pads. Just at a different location in the caliper body. Your fluid level in the reservoir will change as the pads wear. As far as lever travel goes, it should not change. My take on old to new pads. I have changed out my fronts twice and do not remember what you are feeling. Have to love how things change when they "should" not.

Kevin

 

[vinny]

Jeff, it may be possible you had an air bubble in the calipers. When you compressed the pistons back to nearly flush with the calipers, you may have forced it out and eventually up to the reservoir. If that is the case, you would experience more pressure with less lever travel. Have you ever flushed the fluid? Be careful not to get air in the system.

 

[Dinkie Diesel]

It's not that I think there is any problem, I don't. I'm just thinking out loud here in text. I know it will be impossible to convey my point without some nice charts like Ross Perot uses but here goes. Yes, the replacements are OEM Honda parts. I did not add any fluid lately. I did flush the brake fluid when the pads were half used or less. I did not open the resevoir before pushing all the pistons back in until they were flush in the caliper. I met no resistance when doing so. After getting everything installed it required about 5 or 6 pumps of the front brake lever to make the pad touch the rotor. So, I haven't physically inspected the fluid level in the res. but I feel confident it's not under any static pressure other than gravity and the wheel spins freely.

I understand about thicker pads using less fluid but liquid is not compressable so it shouldn't matter if there's 20cc's (with worn pads) of fluid behind the pistons or 8cc's (with new pads). A worn pad should stay just as close in proximity to the rotor as a new pad, shouldn't it? So I'm back to wondering why the lever has a different amount of free-play. I did not make any changes to the adjustment on the lever itself.

I expected the first few miles to feel like the brakes are not working at full capacity until they break-in/mate with the rotor. On the contrary, they worked exceptionally well the first time I applied the front brake. I give credit to the embossed, shaped, whatever you call it, face of the new pad. I'm sure this helps hasten the mating of the friciton material to the rotor.

I'm happy as a clam, just wish I could understand what is taking place.

Hey Mr. Buber, hope you got Relentless running like it should again.

 

[tlartist]

Worth checking the brake fluid levels in the reservoirs. Usually when you push the calipers back you want to open/watch the fluid levels. Might be that.

 

[Al Gully]

Did your pads wear parallel to the rotor or did they wear tapered. I'm thinking if they wore on a tapered, the run-out on the rotors may of pushed the pads/pistons farther into the caliper.

 

[T_C]

Wow! How many miles on the OEM pads? I just bought my 04 and at 30k the back pads had already been changed and the fronts had to be done before I could pass inspection.

But I have a hard time understanding that you could push the piston from full extension to retracted without popping your cover.

T

 

[T_C]

PS One possible explanation for the change could be you had maxed out one side of the pistons. Required more fluid to push the other side before it squeezed the rotor? I had a similar situation once. Thinking back to long before your pads were worn did the brakes grab sooner or later?

T

 

[Dinkie Diesel]

Did your pads wear parallel to the rotor or did they wear tapered. I'm thinking if they wore on a tapered, the run-out on the rotors may of pushed the pads/pistons farther into the caliper.

The originals wore very even across 3 of the four pads. One pad (I think it was the piston side pad on the left) had a little more material left but still flat, not tapered.

Wow! How many miles on the OEM pads? I just bought my 04 and at 30kthe the back pads had already been changed and the fronts had to be done before I could pass inspection.

But I have a hard time understanding that you could push the piston from full extension to retracted without popping your cover.

T

I replaced the rear at 38,000, front at 55,000. I thought too that I would have to suck some out of the resevoir. I'll open it up tomorrow and take a peek.

 

[flyfisher]

Is it possible that the old pads were just worn slick or had accumulated some kind of slippery road grunge? That might explain why the new ones grab better.....just thinkin'

 

[Dinkie Diesel]

Is it possible that the old pads were just worn slick or had accumulated some kind of slippery road grunge? That might explain why the new ones grab better.....just thinkin'

Certainly plausible to believe that they may have had a glaze on them.

 

[Igofar]

It's not that I think there is any problem, I don't. I'm just thinking out loud here in text. I know it will be impossible to convey my point without some nice charts like Ross Perot uses but here goes. Yes, the replacements are OEM Honda parts. I did not add any fluid lately. I did flush the brake fluid when the pads were half used or less. I did not open the resevoir before pushing all the pistons back in until they were flush in the caliper. I met no resistance when doing so. After getting everything installed it required about 5 or 6 pumps of the front brake lever to make the pad touch the rotor. So, I haven't physically inspected the fluid level in the res. but I feel confident it's not under any static pressure other than gravity and the wheel spins freely.

I understand about thicker pads using less fluid but liquid is not compressable so it shouldn't matter if there's 20cc's (with worn pads) of fluid behind the pistons or 8cc's (with new pads). A worn pad should stay just as close in proximity to the rotor as a new pad, shouldn't it? So I'm back to wondering why the lever has a different amount of free-play. I did not make any changes to the adjustment on the lever itself.

I expected the first few miles to feel like the brakes are not working at full capacity until they break-in/mate with the rotor. On the contrary, they worked exceptionally well the first time I applied the front brake. I give credit to the embossed, shaped, whatever you call it, face of the new pad. I'm sure this helps hasten the mating of the friciton material to the rotor.

I'm happy as a clam, just wish I could understand what is taking place.

Hey Mr. Buber, hope you got Relentless running like it should again.

Open (both) of the mastercylinders and check the fluid levels. I'm betting the fluid is gonna jump out at ya! Anytime you change the pads, its a good habit to bleed/flush the fluids.
I've found the rubber diaphram sucked down onto the hole on some bikes, and so swollen that it squirted when the bolts were removed.
Do the pads and fluid at the same time. Don't forget to follow the correct procedure as well.
Since you had no resistance when pushing the pistons back in....thats an indication of air in the system as well.
Don't cut corners on brakes or safety stuff.
Just my .02

 

[robkc]

Cleaning up and lubing the pins good may have reduced some friction but I'm with Vinny that you probably had an air bubble that you worked back into the line and it migrated up to the reservoir while fiddling around with everything.

 

[T_C]

Do the pads and fluid at the same time. Don't forget to follow the correct procedure as well.
Since you had no resistance when pushing the pistons back in....thats an indication of air in the system as well.
Don't cut corners on brakes or safety stuff.
Just my .02

Plus 1 on the same 2 cents. When I bought my 04 a few weeks ago I took it to a 3rd party shop for review and inspection. They were not licensed to do a state safety inspection but warned me my pads on the front would'nt probably pass. My reply was along the order of get the things changed ... my life is on the line.
, plus I already knew that.

But since I was new to ST and I had no service manual I was hesitant to do it myself. And glad I waited after reading and being shown the proper procedure at INStoc.
Never would have expected the complexity of bleeding a cross linked brake system. But completly understand it now ... or so I think.
T

 

[Pete in PA]

We noticed this phenom. on the CBR1100XX site years ago and it's still unexplained. Push your front calipers slightly into the rotor just enough to slightly push the pistons into their bores. Pump the lever to reseat the pistons. Now go ride and note the brake action. It will be much improved. It will last for awhile also, try it.

If anyone can explain this I'd like to hear it.