Seized pistons on rvf400...

[Tossi]

Went to service the front brakes. All the pistons bar one are seized lulz. I'm thinking it would be cheaper to just buy a pair of front calipers from an sp1/2? (also what other calipers are a direct replacement) As opposed to rebuilding them...

Anyone have thoughts on this?

[lukemillar]

If your front brake pistons are seized, then free them up! You don't need to buy new 2nd hand calipers that would probably require rebuilding anyway ( being used and 2nd hand )

Try clamping the piston that moves in the caliper and then get someone to pump the brake lever once or twice. It should force the others to start moving. When another piston start to move, clamp that piston as well and then repeat.

When all the pistons have started moving, then I usually chuck a brake pad sized piece of 10mm rubber flooring between all 4 pistons and then pump until they are all tight up against the rubber. This should keep them in their seals, but protruding enough so that when you split the caliper, you can pull them out easily without munting the pistons. Do this on both sides before draining the system and then clean, lubricate and fit new seals if needed.

NC30 brakes are pretty good if they are kept in good condition.

[V4beermonster]

In really bad cases I have had to weld a bolt to the piston (6pot tl1000r calipers) to remove them. Also if not leaking just deglaze the oil seals using a Stanley blade scrape the varnish like stuff from seals, refit and plenty of red castor grease to seals

[amorti]

The gold calipers off a 00-03 cbr900, 03-04 cbr600rr, vtr1000 sp1/2, are really nice kit.

The pistons are teflon coated aluminium and so don't corrode. I got a set that looked rough so f*k but they cleaned up and work perfectly without even a full strip. Even the seal grooves are anodised, so corrosion can't easily get a hold there like it can on most calipers that are finished, then machined there.

You will want the relevant matching master cylinder, or if not easily found any 5/8" will be much closer than the RVF's 14, which is not really suitable. I have tried both combinations, trust me.

[Tossi]

Thanks for all the advice lads! Ill try go for a rebuild i think but i am quite tempted by the gold calipers (thanks for the info on the cbr600 ones btw)

What do you mean about the master cylinder? Need to get a different one if going down the road of replacing the calipers?

[Neosophist]

Thanks for all the advice lads! Ill try go for a rebuild i think but i am quite tempted by the gold calipers (thanks for the info on the cbr600 ones btw)

What do you mean about the master cylinder? Need to get a different one if going down the road of replacing the calipers?

Depends on the calipers you fit but yes it's preferable to match the calipers with the master cyinder.. the size of the piston that pumps the fluid in the MC varies between bikes, so if you use the wrong size you lever feel and braking effect will be all to cock.

[Tossi]

Kewl. I'm just gonna split and bring the calipers down to local place to blow out the pistons as i dont have an air compressor or vice and piston pliers etc haha

Cheers lads