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Author Topic: How much trouble should I be having getting brake caliper piston back in?  (Read 1935 times)

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Offline fmctm1sw

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How much trouble should I be having getting brake caliper piston back in?
« on: November 03, 2007, 04:57:25 PM »
My piston will not go back in.  It was a little pitted but I sanded it down pretty good.  The piston will drop in and out easily without the rubber ring in it.  However, I cannot for the life of me get the piston back in with the ring in there.  I mean, I stood on this thing and it won't go in.  It doesn't even get to the point where any pitting is.  Is it supposed to be that hard?
« Last Edit: November 03, 2007, 05:37:06 PM by fmctm1sw »
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1973 CB350F
1973 CB350G
1975 CB550K
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1973 CB750K3 (http://forums.sohc4.net/index.php?topic=92888.0)
1984 Kawasaki KLT-250 (AKA 3 wheeler of death)
1994 Honda TRX300
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Offline Bob Wessner

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Re: How much trouble should I be having getting master cylinder piston back in?
« Reply #1 on: November 03, 2007, 05:24:24 PM »
It shouldn't be. Have you everything in the right order?
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Offline fmctm1sw

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Re: How much trouble should I be having getting master cylinder piston back in?
« Reply #2 on: November 03, 2007, 05:30:50 PM »
Yeah, it's still all apart.  I have the caliper housing with the rubber ring in it and the piston.  That's it.  I have brake fluid on everything too.  I was watching one of the phenolic (sp?) brake pistons on ebay too.  Maybe I need to pick it up.
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Quote from: 754
Dude is that a tire ? or an O-ring..??

Quote from: inkscars
This is not a pod thread
This is not a #$%* on my vacuum gauges thread
This is a help or GTFO thread.

1973 CB350F
1973 CB350G
1975 CB550K
1983 GL650I
1973 CB750K3 (http://forums.sohc4.net/index.php?topic=92888.0)
1984 Kawasaki KLT-250 (AKA 3 wheeler of death)
1994 Honda TRX300
1999 Honda TRX250

Offline Bob Wessner

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Re: How much trouble should I be having getting master cylinder piston back in?
« Reply #3 on: November 03, 2007, 05:33:07 PM »
Ah, the caliper. Your post title says master cylinder. Still shouldn't be that hard though.
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Offline fmctm1sw

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Re: How much trouble should I be having getting master cylinder piston back in?
« Reply #4 on: November 03, 2007, 05:37:29 PM »
Quote from: Bob Wessner on November 03, 2007, 05:33:07 PM
Ah, the caliper. Your post title says master cylinder. Still shouldn't be that hard though.

Ah... fixed..
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Quote from: 754
Dude is that a tire ? or an O-ring..??

Quote from: inkscars
This is not a pod thread
This is not a #$%* on my vacuum gauges thread
This is a help or GTFO thread.

1973 CB350F
1973 CB350G
1975 CB550K
1983 GL650I
1973 CB750K3 (http://forums.sohc4.net/index.php?topic=92888.0)
1984 Kawasaki KLT-250 (AKA 3 wheeler of death)
1994 Honda TRX300
1999 Honda TRX250

Offline TwoTired

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Re: How much trouble should I be having getting brake caliper piston back in?
« Reply #5 on: November 03, 2007, 06:01:42 PM »
Did you clean the gook out from behind the caliper seal in the groove?  Use an inspection mirror to check?

The "plugged" end of the piston faces the brake pad.

Cheers,
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Offline MRieck

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Re: How much trouble should I be having getting brake caliper piston back in?
« Reply #6 on: November 03, 2007, 06:09:29 PM »
 The sanding part kinda scares me.
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Offline Kevin400F

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Re: How much trouble should I be having getting brake caliper piston back in?
« Reply #7 on: November 03, 2007, 06:12:33 PM »
I think Lloyd has probably hit upon the root cause.   To elaborate upon his question, you should carefully pick the seal out of the groove in the caliper in order to clean the groove thoroughly.  I like to take a piece of solid 12 or 14 gage copper wire, bend it 90 degrees about 1/8" to 3/16" from the end, then beat the wire flat and file it to make a sharpened right-angle scraper.   This typically is adequate to get all the aluminum corrosion products out of the groove, without damaging the aluminum itself.  If the seal is hard or particularly rough from contact with the corrosion junk, its best to get a new one.  
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Offline fmctm1sw

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Re: How much trouble should I be having getting brake caliper piston back in?
« Reply #8 on: November 03, 2007, 07:16:08 PM »
Yeah, I cleaned out that groove real good.  I scraped it out and had a wire brush that fit into the caliper and scrubbed it out good.  From what I could see (I don't have small mirror though) it looked good.  Guess I'll keep tinkering with it...
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Quote from: 754
Dude is that a tire ? or an O-ring..??

Quote from: inkscars
This is not a pod thread
This is not a #$%* on my vacuum gauges thread
This is a help or GTFO thread.

1973 CB350F
1973 CB350G
1975 CB550K
1983 GL650I
1973 CB750K3 (http://forums.sohc4.net/index.php?topic=92888.0)
1984 Kawasaki KLT-250 (AKA 3 wheeler of death)
1994 Honda TRX300
1999 Honda TRX250

Offline 754

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Re: How much trouble should I be having getting brake caliper piston back in?
« Reply #9 on: November 03, 2007, 09:23:54 PM »
You did lube the piston with brake fluid, right??

A lot of screaming going on when you stick it in dry..!! :o
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Offline fmctm1sw

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Solved....How much trouble should I be having getting brake caliper piston..
« Reply #10 on: February 29, 2008, 03:57:31 PM »
Decided to pick up a new seal for the caliper for this.  The first thing I noticed was how much smaller the new one was compared to the (obviously old and swelled up) old one.  I coated it prety good with brake fluid and it only put up a little resistence going back in. 

*NOTE*  Don't have the brake line connector on the caliper pointed at your eyes when you pop the piston back in (that was pleasant)....
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Quote from: 754
Dude is that a tire ? or an O-ring..??

Quote from: inkscars
This is not a pod thread
This is not a #$%* on my vacuum gauges thread
This is a help or GTFO thread.

1973 CB350F
1973 CB350G
1975 CB550K
1983 GL650I
1973 CB750K3 (http://forums.sohc4.net/index.php?topic=92888.0)
1984 Kawasaki KLT-250 (AKA 3 wheeler of death)
1994 Honda TRX300
1999 Honda TRX250

Offline pampadori

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Re: How much trouble should I be having getting brake caliper piston back in?
« Reply #11 on: February 29, 2008, 04:46:43 PM »
the last one i did i had to beat the little f&*#er in there with a hammer.  and you have to get the thing to go in straight as possible less it won't go in.
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Offline clearcan

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Re: How much trouble should I be having getting brake caliper piston back in?
« Reply #12 on: February 29, 2008, 04:59:56 PM »
Quote from: fmctm1sw on February 29, 2008, 03:57:31 PM
*NOTE*  Don't have the brake line connector on the caliper pointed at your eyes when you pop the piston back in (that was pleasant)....

Ya I found that out the hard way too.
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Offline Burke

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Re: How much trouble should I be having getting brake caliper piston back in?
« Reply #13 on: February 29, 2008, 05:26:22 PM »
How did you remove the piston? was it stuck?
Some times if you use heat to "get things going" it can damage the seal.
I had the same problem on my 78'. New seal was needed.
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Offline fmctm1sw

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Re: How much trouble should I be having getting brake caliper piston back in?
« Reply #14 on: February 29, 2008, 08:08:44 PM »
Quote from: Burke on February 29, 2008, 05:26:22 PM
How did you remove the piston? was it stuck?
Some times if you use heat to "get things going" it can damage the seal.
I had the same problem on my 78'. New seal was needed.


This one actually came out pretty easy.  I have another one I pumped the brake lever like crazy and finally got it to push out.  I read that post about the "torch method" but I haven't had to resort to that yet...  My 400F one is stuck too though
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Quote from: 754
Dude is that a tire ? or an O-ring..??

Quote from: inkscars
This is not a pod thread
This is not a #$%* on my vacuum gauges thread
This is a help or GTFO thread.

1973 CB350F
1973 CB350G
1975 CB550K
1983 GL650I
1973 CB750K3 (http://forums.sohc4.net/index.php?topic=92888.0)
1984 Kawasaki KLT-250 (AKA 3 wheeler of death)
1994 Honda TRX300
1999 Honda TRX250

Offline Burke

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Re: How much trouble should I be having getting brake caliper piston back in?
« Reply #15 on: February 29, 2008, 08:28:27 PM »


This one actually came out pretty easy.  I have another one I pumped the brake lever like crazy and finally got it to push out.  I read that post about the "torch method" but I haven't had to resort to that yet...  My 400F one is stuck too though
[/quote]

I have used both methods,torch and the lever(if its working at the time).
The torch method is my last resort, but only on the 78' 750, gave me problems. The cylinder was incredibly hard to get in then, the brake was very tight to the rotor. But then again I was the one that sent a "Flaming Cylinder" across my work bench. Not the shining moment I would like to be remembered by. ;)
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Offline crazypj

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Re: How much trouble should I be having getting brake caliper piston back in?
« Reply #16 on: February 29, 2008, 11:40:32 PM »
Glad you like my 'torch' method of last resort.  ;D ;D
What you should do is check the piston slides easily in and out of caliper BEFORE you put the seal back in.
 If it doesn't, find out why  ::)
PJ
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