Front Caliper Rebuild

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Of course the brake is leaking, best time for it in the middle of riding season. At least I know why the lever was mushy. I never saw any fluid dripping but when I took off the wheel there was definitely a mess. So it wasn't leaking much.

I'm going to be fighting the screw in plug for a while, it's soaking in PB Blaster right now, but I suspect heat will get involved at some point.

I'd like to get the parts ordered while I wait and I don't know if I need pistons yet. I don't know if this brake has even been rebuilt. I don't think SS pistons were stock, I'm trying to remember what the pistons on my other bike looked like when I rebuilt those brakes. Luckily I bet I have pictures somewhere on this forum.

Until I've looked I wonder if anyone can tell from this pesky poo picture if these look like SS pistons? They have a little muck on them but I sure don't see any rust. I can't imaging steel pistons not corroding at some point.

What's your guess?


 

Larry S

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I just finished my calipers and it wasn’t too bad getting the plug out. I used a heat gun and the “special “ tool and they came right out. Rebuild kit says to heat to 100 degrees Celsius before attempting to use tool as the pins may break. I also had to use compressed air to get the inside pistons out. Good luck.
 
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Soaked a bit in PB Blaster.


Mounted it back on the fork leg since I don't have a vice anymore. Heated it up with the heat gun and got it about to 100˚C. Plug came out with just a little effort. Far less than I thought it would.



I put the brake pads back in, outside pad in normal position but the inner pad out of position so that the inner piston would move more. And it worked. The inner piston came down. But then the outer one didn't really want to move much. So a good tap and it came loose. I then just removed the outer seal and both pistons fell out.


Can you guess which side was in the ultrasonic cleaner first?



The stainless pistons cleaned right up and look almost new. I doubt chrome ones would look that good.



So why was it leaking? The seals didn't look in bad shape but there was gunk in the seal groove and I suspect it caused the light weeping. New seals (along with stainless plug and stainless bleeder) on the way so it should be back to new soon!



It spend a bit of time in the ultrasonic cleaner with heat and the caliper looks probably better than when new. I've got a few days until the order from Old Britts shows up so I'll find some other projects to work on in the meantime. Because you know there's always other things that need tending to...
 

Craig

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Hard to see in photos , are the seal grooves pristine , I had to use a wooden chop stick to get the stuck on crap off , no ultra-sonic though , also I wrapped the SS bleeder threads with Teflon tape to help avoid seizing , not sure it would be an issue, just couldn’t stop myself ....
 
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Swooshdave says. "......I don't have a vice anymore."
Gosh, that sounds all wrong! First of all, we are all entitled to a few vices. Beer, women, Nortons, to name a few.
And if he meant no viSe, well that is all wrong too!! Hard to work on a stubborn old Norton without a vise.
 
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They do look excellent after cleaning!
what fluid do you use in your ultrasonic tank?
 
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Hard to see in photos , are the seal grooves pristine , I had to use a wooden chop stick to get the stuck on crap off , no ultra-sonic though , also I wrapped the SS bleeder threads with Teflon tape to help avoid seizing , not sure it would be an issue, just couldn’t stop myself ....
They are now. There was stuck crap and I think that's what was causing the leaking. If you look carefully at the seals you can see the dents where the stuff was pushing on them.

I now have the grooves pristine from careful scraping. The ultrasonic cleaner did not get that stuff off. I felt like when the dentist scraps the plaque off my teeth.

I think either anti-seize or teflon would work on the SS bleeder valve.
 
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Swooshdave says. "......I don't have a vice anymore."
Gosh, that sounds all wrong! First of all, we are all entitled to a few vices. Beer, women, Nortons, to name a few.
And if he meant no viSe, well that is all wrong too!! Hard to work on a stubborn old Norton without a vise.
Thanks for the catch. Unfortunately we can't edit our posts anymore so you will need to suffer with my spelling mistakes.

My one vice is relying too much on spellcheckers.
 
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They do look excellent after cleaning!
what fluid do you use in your ultrasonic tank?
Simple Green Pro (the PURPLE stuff!) and water. Do not use the green Simple Green as it will eat the aluminum. The ultrasonic cleaner heats the fluid to about 140˚F which helps too. I probably ran it for about 30 mins (it goes in 8 min cycles).
 

motorson

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I went with the stainless pistons as well. When I took mine apart the threaded cover was corroded on the back side. I opted for the stainless steel cover as well as the stainless pistons. Now I feel like it will last longer with less maintenance.
 
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I went with the stainless pistons as well. When I took mine apart the threaded cover was corroded on the back side. I opted for the stainless steel cover as well as the stainless pistons. Now I feel like it will last longer with less maintenance.
Yup, since I already have the SS pistons I made sure to get the SS plug and SS bleeder valve.
 

springs75

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I recently rebuilt my calipers and Installed new stainless steel pistons. After they were done, one of them seeped right away and I found that the new piston had cut the seal. Had I read the technical article on Old Britt beforehand, I would have known to buff the edge on the new SS pistons. Although it is a chamfered edge and looks smooth, there are still fine machining marks. Learned my lesson.
 

cliffa

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They are now. There was stuck crap and I think that's what was causing the leaking. If you look carefully at the seals you can see the dents where the stuff was pushing on them.

I now have the grooves pristine from careful scraping. The ultrasonic cleaner did not get that stuff off. I felt like when the dentist scraps the plaque off my teeth.

I think either anti-seize or teflon would work on the SS bleeder valve.
I spent hours scraping out the seal grooves in mine. Even after boiling it on the stove there were really hard crusty deposits in them. It's the best reason I've seen to change the brake fluid annually.
 
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