Front Brakes don't "grab" the Rotor... - Wrist Twisters
 
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post #1 of 12 Old 09-07-2007, 02:39 PM Thread Starter
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Front Brakes don't "grab" the Rotor...

I swapped out my black calipers with '06 gold calipers I bought off EBay. While at it, I installed my new Goodridge SS lines. I bled the entire system over and over. The brake foot lever and hand lever feel right (not spongy). But the front brakes themselves just don't bite the rotors like I expect them to.

The '06 calipers already had pads on them, which are practically new with no wear. What gives? I heard something about new pads needing to be "mated" to the rotors, or cleaning off the "film" on the rotors from the old pads so the new pads will work properly? But I assume the '06 Honda pads are the same compound as the '03. BTW, the rear brake feels and grabs just fine. It's just the front that's messed up.

Anyway, any ideas on what to do?

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post #2 of 12 Old 09-07-2007, 02:42 PM
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The lines are for sure blead? how much seat time on the new pads, rotors?

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post #3 of 12 Old 09-07-2007, 03:09 PM Thread Starter
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Alright. I just bled the system again. This time, I used a Mighty Vac. I started on the left caliper. Pumped the Vac to 10 PSI, then opened the nipple... no air... just solid fluid.

Switched over to the right front caliper. Place the tube on the nipple; pumped the Vac, then I see air/fluid coming out even though the nipple is tightly shut. Ok, so air is entering the system. Tighten the brake line bolt onto the caliper, but it's already way tight. Pump the Vac again, and even though the nipple is as tight as I dare to make it.... air and fluid still escape with only 10 PSI pressure. I guess I just need to replace the nipple? Or can I remove it, wrap some teflon tape around the threads, then re-install?

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post #4 of 12 Old 09-07-2007, 03:38 PM
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you may have found out why someone was getting rid of brake parts... ?

you should be able to make that caliper bleeder fitting leak by just applying brake pressure, which is well in excess of 10psi pressure. if , in fact, it IS leaking.

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post #5 of 12 Old 09-07-2007, 03:39 PM
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Quote:
Originally Posted by Rob919 View Post
Alright. I just bled the system again. This time, I used a Mighty Vac. I started on the left caliper. Pumped the Vac to 10 PSI, then opened the nipple... no air... just solid fluid.

Switched over to the right front caliper. Place the tube on the nipple; pumped the Vac, then I see air/fluid coming out even though the nipple is tightly shut. Ok, so air is entering the system. Tighten the brake line bolt onto the caliper, but it's already way tight. Pump the Vac again, and even though the nipple is as tight as I dare to make it.... air and fluid still escape with only 10 PSI pressure. I guess I just need to replace the nipple? Or can I remove it, wrap some teflon tape around the threads, then re-install?
I would think that the connection between the vacuum line and the nipple is where the air is coming from otherwise you would have brake fluid leaking out every time you squeezed the lever.

Problaby just take some 600grit sand paper and lightly go over both sides of the rotor so the pads have a good surface to mate to. But if that doesnt work after serval miles I would recommend that and new pads cause the other rotors could have been damaged and you not know it.

Quote:
Originally Posted by bucky View Post
you may have found out why someone was getting rid of brake parts... ?

you should be able to make that caliper bleeder fitting leak by just applying brake pressure, which is well in excess of 10psi pressure. if , in fact, it IS leaking.
+1

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post #6 of 12 Old 09-07-2007, 03:58 PM Thread Starter
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I took the bleeder valve off my old caliper, which just so happened to have teflon tape around the threads. I took the bleeder valve off the "new" caliper, and noticed it had no teflon tape at all. I wrapped new tape around the old valve and installed. Bled the system again 2x both sides. Brake lever feels even better than before. Just as I installed the Master Cylinder cover, getting excited to test the brakes on the road again.... Mother Nature decided to let the rain come pouring down....

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post #7 of 12 Old 09-07-2007, 04:02 PM Thread Starter
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Quote:
Originally Posted by bucky View Post
you may have found out why someone was getting rid of brake parts... ?
Maybe, huh? But the Seller had other '06 919 parts for sale, incl. forks, rearsets, exhaust etc., so I don't think he was just getting rid of bad brakes.

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post #8 of 12 Old 09-07-2007, 05:18 PM
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I think Bucky thought that it was leaking out of the caliper when the nipple was tightened.
Yes you can wrap,(obviously), Teflon tape on the threads. Just keep it off the sealing seat. Vacuum bleeders will suck air from anywhere it can, through the threads,nipple connection, even the hose at the pump.
If it is the nipple leaking, replace it. the other owner might have damaged the seal.(over torque)
As far as the pads. Let them re-seat. should take about a 100 miles or so.
Old pads have the wear pattern from the other owners old rotors. The new rotors have the wear pattern from your the other pads.
The two don't match. thus surface area is limited.
You can block sand the pads flat, but the pads will still need to bed into the old rotor pattern.
Just be careful for a little while and let things settle in.

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post #9 of 12 Old 09-07-2007, 07:07 PM
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The pads could be contaminated with fork oil or other fluids. It will soak in, dry up, and not work worth crap. My mighty vac always leaks around the nipple and looks like there is more air than there really is coming out. I always have to snip the end to make it fresh and fit better.

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post #10 of 12 Old 09-07-2007, 07:25 PM
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Quote:
Originally Posted by xrmikey View Post
I think Bucky thought that it was leaking out of the caliper when the nipple was tightened.
Yes you can wrap,(obviously), Teflon tape on the threads. Just keep it off the sealing seat. Vacuum bleeders will suck air from anywhere it can, through the threads,nipple connection, even the hose at the pump.
If it is the nipple leaking, replace it. the other owner might have damaged the seal.(over torque)
As far as the pads. Let them re-seat. should take about a 100 miles or so.
Old pads have the wear pattern from the other owners old rotors. The new rotors have the wear pattern from your the other pads.
The two don't match. thus surface area is limited.
You can block sand the pads flat, but the pads will still need to bed into the old rotor pattern.
Just be careful for a little while and let things settle in.
Rob I'm 99% sure that xrmikey has got it right. I've swaped same pads between different rotors several times and I always have this problem to begin with. You just have to wear the old pad pattern into the new rotor pattern. Make sure you do some riding for a while where you know you want have to do any emergency stopping.

Congrats getting it done! If I don't find anyone to ride with tomorrow morning I think I'm going to install my new Galfer lines.

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post #11 of 12 Old 09-07-2007, 08:10 PM Thread Starter
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Quote:
Originally Posted by royalchoppers View Post
The pads could be contaminated with fork oil or other fluids. It will soak in, dry up, and not work worth crap. My mighty vac always leaks around the nipple and looks like there is more air than there really is coming out. I always have to snip the end to make it fresh and fit better.
I was thinking that, too. The Seller shipped the parts, with fluid still in the lines. So the newspapers he packaged it in were a little soaked (but not too bad). Nevertheless, maybe some fluid got onto the pads.

I'm gonna do a little riding in the morning and start "bedding in" the pads (that's the terminology for it, aparrantly), per xrmikey's suggestion.

Hey Jim, I can ride in the morning, but I have to be back by 9:30am latest! Not sure where we can go in a couple hours ride, though.

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post #12 of 12 Old 09-08-2007, 07:18 PM
 
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Yeah, I'd say just clean the rotors / pads really well with brake cleaner and give the system some time to bed in. I had the same problem for a few dozen miles when I swapped on some Galfer pads.

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