Author Topic: Rebuilding front calipers  (Read 335 times)

Online VirginiaJim

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Rebuilding front calipers
« on: November 12, 2018, 10:15:31 am »
Gonna be rebuilding the front calipers with seals and such.   Anyone have a good method of keeping the brake fluid in the main line from draining all the way out?  I don't want the master cylinder to lose all it's fluid either.


Ok, clamping not a good idea on these lines.   Gonna try plugs...


https://www.amazon.com/High-Temp-Silicone-Rubber-Tapered/dp/B00XYD2760/ref=sr_1_1_sspa?ie=UTF8&qid=1542045609&sr=8-1-spons&keywords=silicone+plugs&psc=1
« Last Edit: November 12, 2018, 11:00:38 am by VirginiaJim »
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Offline Y0ssarian

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Re: Rebuilding front calipers
« Reply #1 on: November 12, 2018, 12:38:22 pm »
I usually use a plastic "sandwich" bag. Push the banjo fitting into the corner and wrap it tightly with a rubber band.
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Online VirginiaJim

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Re: Rebuilding front calipers
« Reply #2 on: November 12, 2018, 01:55:29 pm »
Good idea.  Thanks.
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Online VirginiaJim

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Re: Rebuilding front calipers
« Reply #3 on: November 12, 2018, 01:55:48 pm »
What's the best way to get all 4 pistons out?

Maybe splitting the caliper and doing it that way with compressed air? 


Best way appears to be to push out the pistons on both sides before you disconnect the brake line leaving a gap between both sides.   Then remove from the line and then take the caliper apart.  Using a piece of bicycle tubing to protect the pistons, pull them out.   I've inserted links for a 4 piston caliper rebuild for anyone interested.



« Last Edit: November 12, 2018, 05:04:23 pm by VirginiaJim »
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Offline Y0ssarian

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Re: Rebuilding front calipers
« Reply #4 on: November 12, 2018, 05:03:03 pm »
Yeah; use a rubber-tipped blowgun and GENTLY pressurize it (each half). When you do that only one piston will pop out...barely engage that piston back against its seal (not even into the seal; just against it), put a piece of scrap wood like a paint stirrer or a piece of yardstick...I mean meter stick...on the outside of the caliper to protect it and use a C-shaped pair of welding vice-grips or a C-clamp to hold it and blow again. Did I mention you want do it GENTLY? I'm almost sure I did!


edit: You can do it with fluid pressure but that pumps a lot of fluid down to the calipers and risks making a huge mess of paint-stripping brake fluid. I prefer to take the caliper off and away from the pretty bits.
"They couldn't hit an elephant at this dist-"
- Last words of Gen. John Sedgwick, spoken as he looked out over the parapet at enemy lines during the Battle of Spotsylvania in 1864.

Online VirginiaJim

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Re: Rebuilding front calipers
« Reply #5 on: November 12, 2018, 05:24:54 pm »
Yeah, I'll definitely keep it away from me.
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Offline gPink

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Re: Rebuilding front calipers
« Reply #6 on: November 12, 2018, 06:21:06 pm »
.
Thank God for good men willing to do extreme violence.

Online VirginiaJim

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Re: Rebuilding front calipers
« Reply #7 on: November 12, 2018, 06:52:01 pm »
Hey, look at me.  I'll probably melt if brake fluid gets on me.
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Offline maxtog

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Re: Rebuilding front calipers
« Reply #8 on: November 12, 2018, 07:51:17 pm »
Hey, look at me.  I'll probably melt if brake fluid gets on me.

No, but your paint will...
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Offline Y0ssarian

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Re: Rebuilding front calipers
« Reply #9 on: November 12, 2018, 08:34:57 pm »
Any time you're dealing with brake fluid keep a spray bottle full of water and a pressurized hose or a gallon "jug" full of water nearby. If even one drop gets on something painted, powder coated or plastic spritz it with the spray bottle RIGHT AWAY and flood it with the hose. Lightly spritz the master cylinder cover and sides before you open it (not enough to drip into the reservoir), and spritz/flood it after you tighten the screws to close it, then flood everything from there down (on our Connies that's the inner fairing panel). Put a fully wet towel under the master while you're working on it. I hate the look of painted master cylinders with the top part "chipped" away.


edit of an edit of an edit: Sorry for all the edits; the brain gears are rusty with age.
"They couldn't hit an elephant at this dist-"
- Last words of Gen. John Sedgwick, spoken as he looked out over the parapet at enemy lines during the Battle of Spotsylvania in 1864.

Online VirginiaJim

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Re: Rebuilding front calipers
« Reply #10 on: November 13, 2018, 04:58:38 am »
In all seriousness, I know about that and even have some 'scars' on the top right black cover under the master cylinder.  This will be the first time I've gone in depth on replacing seals on a 4 piston caliper.
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Online VirginiaJim

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Re: Rebuilding front calipers
« Reply #11 on: November 25, 2018, 12:37:45 pm »
The shudder/judder appears to be gone after the caliper rebuild.  Up to this point I've changed rotors and pads to no avail.   It never felt like a warped rotor.  It felt like the pads were gripping and letting loose at the same time.  Kinda hard to describe.


In rebuilding the calipers, I split them.  It's easier to do that way.  There was no Ah Ha moment when replacing the main seal or dust seal.  I had one piston that seemed a bit dirtier than the others though.  The original seals did not appear to be hardened by time but they weren't as supple as the new ones.


I'm pleasantly surprised that this fixed it.  I'm still working on getting that last bit of air out of the line as the brake lever still isn't as firm as it was before.
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