Honda-SOHC
SOHC.co.uk Forums => CB350/400 => Topic started by: PaulC on November 26, 2021, 04:54:56 PM
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Evening all, after some adventure with regards to my front brake woes. I bought ant untested complete 400/4 caliper unit, when I picked up a replacemnt frontend. I've tried various YouTube methods to get the piston out; greasegun etc. Could the actual tube be blocked I.e. where the banjo bolt screws in, as I'm getting fluid through the brake cables. For information: the cables, master cylinder, banjo bolts and bleed nipples are all new. The only thing I haven't tried is heat and the caliper is currently soaking in evaporust - until my patience returns 😀
Thanks in adavance Paul
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Is the nipple loose?
You could try bleeding the system,
Then using the master cylinder to pump out the piston.
Or have I got it wrong?
Sent from my SM-A750FN using Tapatalk
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Hi JW,
I primed the brake cable with fluid before fitting it to the caliper, then grasped brake lever but it wouldn't budge. So opened the bleed screw expecting a release of air but the lever still wouldn't budge!
Is the nipple loose?
You could try bleeding the system,
Then using the master cylinder to pump out the piston.
Or have I got it wrong?
Sent from my SM-A750FN using Tapatalk
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They can get hellishly tight and need alot of effort to initiate moving, as you're finding.
When like that, probably only the hydraulic system will move it with the leverage needed. The mastercylinder will generate into the hundreds psi wise.
You could try putting a spacer onto the piston and squeezing in a vice to see if you can crack the corrosion sealing it seized, then see if it'll pump out. Sounds counter intuitive, but once moved from fully stuck they'll usually get going.
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Crossed over there ;D
If you can unbolt both caliper fitments, then use thin wire to "winkle" around into the bores to see if you can clear anything obvious.
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They can get hellishly tight and need alot of effort to initiate moving, as you're finding.
When like that, probably only the hydraulic system will move it with the leverage needed. The mastercylinder will generate into the hundreds psi wise.
You could try putting a spacer onto the piston and squeezing in a vice to see if you can crack the corrosion sealing it seized, then see if it'll pump out. Sounds counter intuitive, but once moved from fully stuck they'll usually get going.
The above suggested method has worked for me in the past - for stubborn ones in the past I used an old MIni Clutch Master cylinder to pump the pistons out.
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They can get hellishly tight and need alot of effort to initiate moving, as you're finding.
When like that, probably only the hydraulic system will move it with the leverage needed. The mastercylinder will generate into the hundreds psi wise.
You could try putting a spacer onto the piston and squeezing in a vice to see if you can crack the corrosion sealing it seized, then see if it'll pump out. Sounds counter intuitive, but once moved from fully stuck they'll usually get going.
Thanks K2 I'll have ago at that tomorrow. Would using heat help?
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Heat almost certainly won't hinder it and may benefit, there's not much risk and I'd be inclined to heat the caliper in an oven rather than direct with heat scource.
There's essentially nothing inside them, just the piston and seal and they're pretty robust anyway.
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Ive never had the grease gun fail, but then i do use the air one at work, also you can get a caliper complete with with mounting, bolts, adjuster and pads from amazon for about £66. Put cb 500 caliper into the amazon search but scroll down as there are several and prices vary a lot, if you leave out the bracket i saw one at £51
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Heat almost certainly won't hinder it and may benefit, there's not much risk and I'd be inclined to heat the caliper in an oven rather than direct with heat scource.
There's essentially nothing inside them, just the piston and seal and they're pretty robust anyway.
Best wait until the wife goes to work for that one 😉
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Ive never had the grease gun fail, but then i do use the air one at work, also you can get a caliper complete with with mounting, bolts, adjuster and pads from amazon for about £66. Put cb 500 caliper into the amazon search but scroll down as there are several and prices vary a lot, if you leave out the bracket i saw one at £51
Bryan, if all else fails that'll be my final option
Cheers
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This has never failed for me.
Get the caliper, turn it upside down, flat side down. Now get a 10mm drill and drill a bloody big hole in the dome section, get a 10mm bolt and just drive that bad boy piston right out of there. Now you say, that's left a big hole in my caliper but fear not intrepid adventurer the solution is at hand.
Get an old style sixpence and just braze that over the hole. In case it leaks then just braze a old style penny over that, if that leaks then I'm sorry but I can't help you, you're just crap at brazing.
This advice of course only works if you have a handy supply of old style currency, don't try this at home kids.
I had considered drilling and tapping the piston or trying to weld a bolt to it. Unfortunately I'm all out of old coins and my brazing is worse than my welding 😀
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If you can't get it out with a good grease gun then I would think the oil ways in the caliper are solid and must be cleared first. A good
high pressure grease gun should be able to do 1000bar which is far far higher than the pressure generated in a braking system.
We used grease guns at the pit on hydraulic nuts and locked them off at just under 1000bar.
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If you can't get it out with a good grease gun then I would think the oil ways in the caliper are solid and must be cleared first. A good
high pressure grease gun should be able to do 1000bar which is far far higher than the pressure generated in a braking system.
We used grease guns at the pit on hydraulic nuts and locked them off at just under 1000bar.
Moorey, that's exactly my thoughts, so I got the Dremel out with a fine bit and that sorted it. Thanks everyone for your advice and comments. The caliper is now sat in evaporust overnight and I'll check it's condition tomorrow. I also drilled a small hole in the piston so I could free it with a drift, which worked a treat.
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This is the end result:
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Good work...my advice was going to be to get a 'sprotor' (horrible word for a sprocket rotor!), then you wouldn't need the front brake. Or divert the build to be a speedway style bike and stick with a rear brake only!
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Damn...good work getting that thing out. Can see now why it didn;t want to shift.
I had one stuck piston on my brakes that didn;t want to shift, but it was such a nice feeling when I finally got it to budge, and I could clean out the sludge, gunk and sludge that can build up in a brake caliper given enough time :)
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Good work, they really do keep quite a grip in there with corrosion don't they.
Many of the current cars get similar affects on rear calipers with aluminium construction, no routine servicing (much advice now is to swap calipers when seized) and combined handbrake mechanism and they often get very tight with salt corrosion. They creak like an old galleon when pushed out with the assisted brake pressure on the car. Clean up fine though and reassemble with silicone grease to prevent corrosion, they work as good as new.
That seal groove will need to be very critically cleaned for the caliper to work well when rebuilding.
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At least we can get seals for the bikes, most cars now you cant get kits.
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Once again thanks for all the advice and comments. The pop when it finally came out was very satisfying, but it put up a hell of fight! 😀
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There is a recommended seller on here for stainless pistons, he is also on ebay but its cheaper direct
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There is a recommended seller on here for stainless pistons, he is also on ebay but its cheaper direct
Cheers Bryanj already purchased new one from DSS 😀
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Well done PX in finally getting the piston out - these victories along the way make it all worthwhile.
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Well done PX in finally getting the piston out - these victories along the way make it all worthwhile.
Cheers Ted - one giant step for man and all that! Front fork rebuild next whilst some parts go to the sandblaster. But still looking for bits that were missing 😀
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You were lucky, when I bought my 400 I never noticed the bleed nipple was missing off the front brake, on strip down had to bite the bullet and get a new caliper as someone had filled the threaded part where the bleed nipple went with liquid metal. I tried to clear it all out but it was too far down into the fluid ways, how they bleed the brakes I have no idea. My first thoughts when I saw the missing nipple was, not a problem drill out the old one best I can, stud extractor to remove what was let, not a problem, recut the threads, how wrong I was.
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There is a recommended seller on here for stainless pistons, he is also on ebay but its cheaper direct
Where do find his details Bryan? I'm sure I've seen a list of suppliers on here but cant remember how to navigate back to it again.
It's me age! ::)
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Click on forum at top of page then recommended sources, i think its Honda Classics
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You were lucky, when I bought my 400 I never noticed the bleed nipple was missing off the front brake, on strip down had to bite the bullet and get a new caliper as someone had filled the threaded part where the bleed nipple went with liquid metal. I tried to clear it all out but it was too far down into the fluid ways, how they bleed the brakes I have no idea. My first thoughts when I saw the missing nipple was, not a problem drill out the old one best I can, stud extractor to remove what was let, not a problem, recut the threads, how wrong I was.
Jeez, that sounds like a PITA 😀
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Click on forum at top of page then recommended sources, i think its Honda Classics
Cheers Bryan..
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My first thoughts when I saw the missing nipple was, not a problem drill out the old one best I can, stud extractor to remove what was let, not a problem, recut the threads, how wrong I was.
Well done .. always satisfying when you get those apart.
wildtapholer ... we know where your name on here come from ;D
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My first thoughts when I saw the missing nipple was, not a problem drill out the old one best I can, stud extractor to remove what was let, not a problem, recut the threads, how wrong I was.
Well done .. always satisfying when you get those apart.
wildtapholer ... we know where your name on here come from ;D
You've worked on a blastfurnace then.