Siezed Caliper Pistons?

[canuck750]

I am rebuilding a pair of dual bleeder Brembos for a project, the caliper brake pads, pins and retainer spring were more rust than steel, the pistons were so seized that I didn't think they would come out.

I have read of folks freeing stuck steering head bearing races by welding a bead onto the race and the cooling weld shrinks the race and it falls out of the head stock. So with nothing to loose I welded a bolt to the centre of the piston, let it cool and then with a socket and ratchet the piston spun free and then with the bolt head in a vice and few taps of the caliper body with a brass hammer and out came the old rusted piston.





The bleeders were hopelessly rusted in place, drilled and then re tapped the 6mm x 1.0 threads and fitted Speed bleeders for a test fit, they seal!

[motogman]

A cleaver and ingenous approach to a difficult problem that often results in a scrapped part.

So here is another problem for you.  Maybe you have a good idea for this brake problem. 

The bleeder broke off in one of my brembo calipers from the V7 sport.  I drilled it out and was using an easy out to try to remove it.  Guess what - I broke off the easy out so now I have a hard steel bit in the bottom of the bleeder.  Now what?

[Clancy]

Now what?

Go to the fridge.
Open a beer.
 

[canuck750]

I think your screwed

I got a tap stuck in one of the castings and it snapped off, into the garbage with it. More cutting fluid next time.

When I can find Brembo dual bleeder calipers for cheap I but them and take my chances. usually I can get the bleeder out or drilled and tapped without drama.

Call Mark at Moto Guzzi Classics, he probably has a Brembo dual bleeder body you can rebuild.

Cheers

Jim

[Antietam Classic Cycle]

I still have a few bare dual-bleeder calipers laying around. Pay shipping and I'll send you one.

[tris]

.....The bleeder broke off in one of my brembo calipers from the V7 sport.  I drilled it out and was using an easy out to try to remove it.  Guess what - I broke off the easy out so now I have a hard steel bit in the bottom of the bleeder.  Now what?

Find somebody with a spark eroder and pray to the caliper gods 

[Dukedesmo]

A cleaver and ingenous approach to a difficult problem that often results in a scrapped part.

So here is another problem for you.  Maybe you have a good idea for this brake problem. 

The bleeder broke off in one of my brembo calipers from the V7 sport.  I drilled it out and was using an easy out to try to remove it.  Guess what - I broke off the easy out so now I have a hard steel bit in the bottom of the bleeder.  Now what?

My calipers were 'sticky' and not working too well so I replaced the pistons with the alloy versions (the old chrome pistons were corroded) and new seals.

One of the bleeders in the rear caliper was stuck, I tried very carefully but it inevitably snapped off. I drilled it out but managed to damage the taper that the bleeder sits on so it won't seal.

I plugged it with an M6 bolt & crush washer and have fitted a combined banjo/bleeder on the hose fitting and it bleeds fine from that, but those 6mm bleeders are not very strong.

Don't know if this is normal but on my bike only the rear has the twin 6mm bleeders whilst the fronts have a (much better) single M10 bleeder next to the hose fitting...

[huub]

i've had good results using a grease gun to remove stubborn seized pistons
simply fill up the caliper and keep pumping.
there are loads of end tips for grease guns, i found one that seals on a grease nipple
a bit of a messy job, but at least you can safe the caliper.

[chuck peterson]

After rebuilding three sets, I've learned to very carefully put all the rusted seized calipers I can find into the round storage bin, and carefully hold the edges of my credit card while dialing my favorite suppliers...

[Mike Tashjian]

Carbide burrs in a dremel tool can remove a broken tap. Just wear gloves and take your time.  Mike

[Groover]

Good job, looks like those calipers definitely needed some patience and skills to revive them.

[Rough Edge racing]

A cleaver and ingenous approach to a difficult problem that often results in a scrapped part.

So here is another problem for you.  Maybe you have a good idea for this brake problem. 

The bleeder broke off in one of my brembo calipers from the V7 sport.  I drilled it out and was using an easy out to try to remove it.  Guess what - I broke off the easy out so now I have a hard steel bit in the bottom of the bleeder.  Now what?

 Forget about the existing hole.Think outside the box.......Drill and tap a new hole next to it. You can buy universal bleeders with an insert....One time the bleeder wasn't at the highest point so bleeding required removing the caliper and hand holding it in the correct position.....I've done this on calipers made of unobtanium...

[Antietam Classic Cycle]

Forget about the existing hole.Think outside the box.......Drill and tap a new hole next to it. You can buy universal bleeders with an insert....One time the bleeder wasn't at the highest point so bleeding required removing the caliper and hand holding it in the correct position.....I've done this on calipers made of unobtanium...

I don't think there's a place to drill another hole if you want it to be back behind the piston.

[Stevex]

Be interesting to see what state the caliper bores were in after removing the pistons.

[canuck750]

Be interesting to see what state the caliper bores were in after removing the pistons.

The aluminum bodies are fine, behind the flat O ring piston seal the caliper is in surprisingly good shape.

I have had success popping out pistons with grease if the bleeder is not seized, alternately compressed air through the banjo fitting, no luck with these (and others I have rebuilt) when the piston is as corroded as these ones were. The corrosion is not on the caliper body but the steel piston under the outer seal, this corrosion expands the piston body and works its way into the flat O ring seal making the piston very hard to get out.

As for drilling another bleeder hole I doubt the hole would align with the fluid port into the casting behind the piston and as Charlie says there ain't much meat left to tap a new hole.
Drilling out the seized bleeder with the correct bit to tap a 6mm X 1.0 thread works quite well. The one thing to be very careful about is setting the depth of the drill to not screw up the seat for the bleeder.

I wouldn't bother rebuilding them at all except that I want the correct dual bleeder type calipers for a Sport restoration otherwise I would buy the new single bleeder Brembo's from MG Cycle and be done with it. There is no money to be saved rebuilding them and a lot of work after stripping , powder coating and all new parts other than the aluminum bodies.

[rodekyll]

Chromed pistons?

[swooshdave]

I believe you can get either stainless steel or aluminum pistons? Which is better or is it a toss up?

[Dukedesmo]

I believe you can get either stainless steel or aluminum pistons? Which is better or is it a toss up?

I bought aluminium, I can't see them being either better or worse than stainless from a functional point of view but they're lighter (I also didn't see stainless for sale).

[swooshdave]

I bought aluminium, I can't see them being either better or worse than stainless from a functional point of view but they're lighter (I also didn't see stainless for sale).

Here are teflon coated aluminum. Interesting option to anodized.
https://store.bevelheaven.com/Brake-Related-Parts/Brembo-F08-P108-Piston-Kit-38mm/

Maybe SS isn't an option for the F08.

[canuck750]

I use anodized aluminum from MG Cycle

originals are steel, they rust, expand and seize

http://www.mgcycle.com/index.php?main_page=product_info&cPath=110_115&products_id=743

New seal kits

http://www.mgcycle.com/index.php?main_page=product_info&cPath=110_115&products_id=591

New pins

http://www.mgcycle.com/index.php?main_page=product_info&cPath=110_115&products_id=592

and new pads

http://www.mgcycle.com/index.php?main_page=product_info&cPath=110_122&products_id=153

[canuck750]

A quick bead blast, then into the ultrasonic cleaner and finally to powder coat them, they should last another 40+ years.



These are going on a 77 Le Mans

[chuck peterson]

Whoa, can I get a 16x20 of that bottom shot?