Front Caliper rebuild

Here be mechanigeeks. Anything technical that is not a teething problem.
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Doerbird02
500cc
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Location: Monterey, CA

Front Caliper rebuild

Post by Doerbird02 » Thu May 09, 2019 12:50 am

I changed the brake fluid 6 months ago and the front is already coffee dark, rear fluid is like new. So that leads me to think the seals are bad on the front calipers. I noticed them not completely releasing and you can hear it ever so slightly when coasting the bike.

I took the left caliper off and cleaned it up with a toothbrush. Pressing the brake tells more of the tale. One piston moves freely, another slightly less and the opposite side, one piston barely moves and one not at all.

So, ordered up some new rings and will be giving the calipers a rebuild. Question is, I have the shop manual, but it doesn't give any caliper rebuild info. The main thing I need to know is what the torque spec is when replacing the bolts that hold the caliper together. Any Help?

Also, any thoughts on new brake pads? The ones that are in there are KTM and still have about half their life in them, but are glazed.
Rotweiler, Leo Vince cans, SAS and Canister removed, 2nd Flies Removed, Kev's #20 map, forks heavier springs and custom valving from KTM World, random orange anodized bits for looks
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Magic Wand
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Re: Front Caliper rebuild

Post by Magic Wand » Tue May 14, 2019 8:13 am

Hi "Doerbird02"

I did the same thing last spring.
I recommende you to split the caliper halves. Try to find info how to do the rebuild, it will save you some good riding time in the end.
It's M8 thread for the screws, so I believe I tightened them to 2 - 2,5 kg (20-25 Nm).

The brake pads:
Original IS the best - not to discuss for a second. The pads on my bike has been in place for almost 57000 km now and they are not dead yet(!) Most likely I'm not a 'hard breaking guy', I use the brake from the engine as often I can.
You can 'clean' the brake pads using a rotating bench brush. I used to do that when I had them out for some resons.
Brake caliper.jpg
How they looked like after painting :-)

/M

Doerbird02
500cc
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Re: Front Caliper rebuild

Post by Doerbird02 » Wed May 15, 2019 7:48 pm

Thanks for the reply! Calipers look great!
Rotweiler, Leo Vince cans, SAS and Canister removed, 2nd Flies Removed, Kev's #20 map, forks heavier springs and custom valving from KTM World, random orange anodized bits for looks
Image

Thirdway
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Re: Front Caliper rebuild

Post by Thirdway » Sun Jun 16, 2019 6:41 pm

Don't split the calipers. Use Ty wraps to hold back 3 Pistons, then a compressor to blow out the free piston. Take care to avoid fingers in the caliper or you will lose them. Buy a dental pick to to remove the seals. Fit new seals using Brembo lubricant. Push piston fully home. Ty wrap that piston. then do the next one. When it's all done and the fluid is in. Bleed them by beginning at the master cylinder-it gets a tiny bubble of air which will make bleeding very difficult from the caliper.

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