Calliper torque value

tribonnie

tribonnie

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Having replaced seals etc on brembo callipers on 1977 triple have a very slight leak. Anybody know the torque value for the two bolts that hold the two halves of the calliper together. Thanks Richard
 
the correct torque wont stop the leak, barely just past hand tight and they should seal, its only an O ring between the two halves and recessed both sides, are you sure that this is the source of the leak and not the hydraulic connection to the body of the caliper?
CLEM
I have never correctly torqued them, just banged up tight with loctite on the bolts for the body halves and lockwire for the body to fork leg bolts.
CLEM
 
CLEMTOG said:
the correct torque wont stop the leak, barely just past hand tight and they should seal, its only an O ring between the two halves and recessed both sides, are you sure that this is the source of the leak and not the hydraulic connection to the body of the caliper?
CLEM
I have never correctly torqued them, just banged up tight with loctite on the bolts for the body halves and lockwire for the body to fork leg bolts.
CLEM
Click to expand...
Clem, that’s all I did, new O ring and two white knuckles on the human torque wrench. Mistakingly l looked on the web and got all sorts of wild figures, but as the front callipers are “quite” important thought I would check. Richard
 
FWIW, Richard, it's 50Nm (source Brembo - see attachment).

But as Clem and Paul have said, that's not the cause of the problem. Either that pesky O ring has got squiged slightly out of place, or the piston seal is leaking, or the brake hose is leaking at the caliper (you did replace the copper washers? Or anneal them, at least?)

Caliper bolts.jpg
 
Thanks for info, most likely cause is miss aligned o rings after I rebuilt callipers, seals etc. will have to take apart and have a look. Richard
 
It's quite difficult to misalign the o-rings in their recesses. If the o-ring is pinched at all, the halves will not offer up to each other properly, which would be very obvious.

Most causes for leakages AFTER an overhaul are overseen corrosion residues in the piston seal groove. While the old seal had decades to form and adjust itself to the ever-blossoming corrosion, the new seal will not adapt and will therefore leak at this area.

With a hooked tool, scrape the inside of the groove, especially the area that is out of sight. Use a mirror if necessary to check that all corrosion is removed. This may leave pockets that may or may not cause leaks. If it does, well, then you're up shit creek and need a new caliper half...

Guess something like this could be bodged with Araldite or similar, but not really recommended.

piet
 
sfcpiet said:
It's quite difficult to misalign the o-rings in their recesses. If the o-ring is pinched at all, the halves will not offer up to each other properly, which would be very obvious.

Most causes for leakages AFTER an overhaul are overseen corrosion residues in the piston seal groove. While the old seal had decades to form and adjust itself to the ever-blossoming corrosion, the new seal will not adapt and will therefore leak at this area.

With a hooked tool, scrape the inside of the groove, especially the area that is out of sight. Use a mirror if necessary to check that all corrosion is removed. This may leave pockets that may or may not cause leaks. If it does, well, then you're up shit creek and need a new caliper half...

Guess something like this could be bodged with Araldite or similar, but not really recommended.

piet
Click to expand...
Aren't the caliper halves paired, like the crankcases?
I had a worn caliper piston bore and the good half didn't match up with other halves.

Paul
 
Paul Marx said:
Aren't the caliper halves paired, like the crankcases?
I had a worn caliper piston bore and the good half didn't match up with other halves.

Paul
Click to expand...

No.

Very slight alterations were made in the halves over the production run, it is important to swap a half with EXACTLY the same type. The major difference lies in the shape of the o-ring recess.

Lots of knackered calipers littering the streets... surely something to be found.

piet
 
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