How to fix or not to fix leaking brake caliper

AndyAndyAndy

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I just got this new rear brake caliper (no warranty), put it on bike and it is leaking. It is not really leaking, it is "soaking" through the metal. When I apply pressure on a break, it will leak right around the place where body meets the mount. I can't see any crack or anything. Brake fluid just appears there.

Do you thing I could JB weld it? Would it hold? Price of JB weld is the same as price of this new caliper, so I don't know which way really to go.

2021-01-17_201728.png
 

I74

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That sure looks like a master cylinder to me.

If it is as cheap as JB weld, I would just get a new part, & keep that as spare parts. ;)

Traditional JB weld - 2 part is some pretty good stuff, & the 2 part ''small tubes'' pack ,, should be less than 5 bucks.

Fixed lot's of alum. fuel tanks ect. ect. with it over the many years.
Also have fixed cracked heads & blocks, ect. ect., & a few master & slave cyls. with the stuff also
Versachem also makes a 2 part ''titanium weld'', that I like also.

Key is to ''rough'' scuff up the area, & have that area ''super clean'' & ''dry'' also.

I use isopropyl alcohol prep pads for final cleaning.

Would also let that set up & cure for ''at least'' a couple of days, @ at over 70*f.

What brake fluid are you running ?

I would recommend DOT 5, if you are not using it already.

If you are not,, definitely get the other stuff out, by flushing & bleeding it with the DOT 5 ect.

Running DOT 3, you would be just asking for trouble, with those ''cheap ''- ''far east'' seals ect.

At least use Valvoline Syn power ''full synthetic'' DOT 3 - 4.

Seals ect. would probably hold up with that stuff, & it's cheaper than DOT 5.

You can get small bottles of that @ the Auto stores for around 5 bucks.

My 2 cents.

I
 
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AndyAndyAndy

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I though that difference between higher DOTs it's just a higher boiling point?

That sure looks like a master cylinder to me.

If it is as cheap as JB weld, I would just get a new part, & keep that as spare parts. ;)

Traditional JB weld - 2 part is some pretty good stuff, & the 2 part ''small tubes'' pack ,, should be less than 5 bucks.

Fixed lot's of alum. fuel tanks ect. ect. with it over the many years.
Also have fixed cracked heads & blocks, ect. ect., & a few master & slave cyls. with the stuff also
Versachem also makes a 2 part ''titanium weld'', that I like also.

Key is to ''rough'' scuff up the area, & have that area ''super clean'' & ''dry'' also.

I use isopropyl alcohol prep pads for final cleaning.

Would also let that set up & cure for ''at least'' a couple of days, @ at over 70*f.

What brake fluid are you running ?

I would recommend DOT 5, if you are not using it already.

If you are not,, definitely get the other stuff out, by flushing & bleeding it with the DOT 5 ect.

Running DOT 3, you would be just asking for trouble, with those ''cheap ''- ''far east'' seals ect.

At least use Valvoline Syn power ''full synthetic'' DOT 3 - 4.

Seals ect. would probably hold up with that stuff, & it's cheaper than DOT 5.

You can get small bottles of that @ the Auto stores for around 5 bucks.

My 2 cents.

I
 

I74

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Location
Cedar Rapids IA
There is a variation of what the different stuff is made of.

Regular DOT 3, if you get it on paint,, will eat right through it like paint stripper, ''more like a solvent''.

If you get DOT - 3 on your hands ect.,, ''it burns''.

Valvoline Syn power DOT 3-4 is ''full syn''., & DOT 5 , is silicone,, & they don't attract moisture like DOT -3, & ''way better'' on seals & stuff also.
Also won't eat paint, especially DOT - 5.
 
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