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Discussion Starter #1 (Edited)
I did the 4 pot caliper conversion on my 2007 Wee including steel lines, Galfer scintered pads, and large bore master cylinder. It was awesome for about 1700 miles until a grabby front brake has occured. I'm not sure if the front rotors are warped or if the brakes are just grabbing and breaking free. grab, move, grab, move. It doesn't pulse back through the brake lever so much as grab and go.
Extremely annoying almost unrideable. I mean a very abrupt grab where the front end dives and then releases and grabs, dives and releases.
Shop I go to says rotors are warped. But they seemed unconvincing. I spun the front wheels and there is no lateral movement to the naked eye.

I'm about ready to say bye bye to the Wee. I have put a lot of money and effort into the Wee and I think dumping any more money into it might be absurd. I am that upset about this development.

Help me save the Wee. Advice or experience with this problem?
 

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It sounds like portions of the rotors are glazed. Clean them with brake cleaner and a Scotch-brite pad. Do not use steel wool. A little sanding of the pads might help too.
 

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You probably wouldn't see a small but significant rotor warpage with the naked eye. Better to check with a runout guage.
 

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Maybe try a different pad compound?? At 1700 miles the Galfers are broken in.......maybe they are the culprit??? I'm no brake expert........I would try Greywolf's procedures first, then ponder brake pad material.........
 

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Dave, another couple of possibilities are contaminated brake pads (from brake fluid or other lubricants) or failing seals on the caliper pistons. Note that the later could cause the former! I re-read your original post, and it appears that the used calipers you installed were not re-built prior to installation. If that's the case, the installed condition of the calipers is an unknown. IMHO, with a key safety system component like this, this probably is not a good idea unless you are absolutely positive they are in new or like new condition. (BTW, I am just completing the rebuilding of the calipers I got from you. Thanks again! They have been re-painted red from a caliper paint kit I had hanging around.) After hearing of your current problems, I'm going to rebuild the 06 Wee master cylinder I bought just in case before I start installing anything.:yesnod:

I concur with the recommendations of the previous posters. Do what they suggest first. If their suggestions don't solve the problem, you'll have to get into it a bit deeper.

I would recommend pulling the pads from each caliper and carefully examine them. Look for any obviously darker or glazed areas on any of the pads. If there are dark areas on the pad(s), they have probably been contaminated. Start looking for leaks around the caliper pistons. Fix any leaks by putting new seals in the calipers and replace the pads. They cannot be salvaged.

If they are glazed, again check for any leaks. If none are found, adhere a full-size sheet of 220 grit sandpaper to a flat, rigid surface, like thick glass or a polished, large-format ceramic tile. (You can get large tiles 16"x16" and larger at Home Depot or Lowes for a couple of bucks.) Hold the pad as flat as possible and sand using circular movements. Don't breath any of the brake dust- it's really bad for you. Clean the pad with brake cleaner and verify the glazing is gone. Don't remove any more pad material than absolutely necessary. Reinstall the pads in their original location, pump the lever to make sure the pistons are making good contact with the pads, and re-check the fluid level in the MC. Top off as necessary. Test ride. Hopefully the problem is now gone.:thumbup:
 

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Allowable front disc runout is .012" (.30mm). Actual disc warping is very rare. Most likely is an uneven build up of pad material on the disc...and it usually can't be seen. The cleaning described above will likely work, even if you have to use fine emery cloth on the discs.
 

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When cleaning the discs like the previous posters have suggested, back up the abrasive, including Scotch Brite pads, with a solid backing. A small scrap piece of wood will work fine. It will keep the disc surface smoother than if doing it without any back-up. It will be easier to manage too.
 

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Discussion Starter #8 (Edited)
I used scotch brite on the rotors and sand paper on the pads. Nothing seemed unusual. There are no leaks and all the pistons seem to work OK. They move in and out easily. I think it is the too hard brake material itself. I road the Wee and found some of the grab and release had diminished but still way too grabby.

I test road an 2005 SV1000 today with 5k easy miles on it. This bike I believe has the same calipers as the GXSRs I put on my Wee. I don't know what the pad material the OEM specs for this bike but there was none of the scary grabbing and feeling of locking up going on. Not at all.

I'm going to try some organic (softer) pads. Stay posted. EBC organic pads on the way.
 

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Discussion Starter #9
Cleaned up the rotors again and installed EBC organic pads part# FA158. Still a little grabby. I'm trying to 'learn' how to brake with these four pot calipers. The organic pads are far less grabby and seem to give me a better feel. Time and miles will tell.
This is so weird. I had no problem initially with the conversion. Now I feel like I have to re-learn braking and how I ride. Something seems odd? Have I gone daft?:confused:
 

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rebuild your calipers?

I think you might have a piston in the caliper sticking. I'm guessing you used used parts. So they may have sat for a long time before going on your bike. At the very least replace all the seals, and clean up the pistons. Replace them if you can.
 

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Discussion Starter #11
I think you might have a piston in the caliper sticking. I'm guessing you used used parts. So they may have sat for a long time before going on your bike. At the very least replace all the seals, and clean up the pistons. Replace them if you can.
With the calipers off and the pads still installed I applied the brakes and could see all 4 pistons move out and in freely. OK. Maybe this isn't a great test to determine a sticky piston bore but...?
 

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If a piston is dragging, the rotor(s) will be building up heat. Go for a ride and check to see if either of the rotors is obviously hotter than the other, or if both are excessively hot. Be careful not to get burned. If you know any autocrossers or road racers, check to see if they have an IR tire temperature gauge you can borrow to check rotor temps without touching them.

Replacement OEM seal kits are available from Ron Ayers and other vendors like Bike Bandit and aren't very expensive. You can also get kits with both the piston and seals from these vendors, but they are pricey. Remember that there are two different-sized pistons in each caliper half if you need to go that route. When I rebuilt the used calipers I got from you, the pistons were in great shape and cleaned-up easily. I just replaced the seals.:mrgreen:
 
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