5th Gen Linked Brakes ... adult supervision required!

Discussion in 'Mechanics Garage' started by Terry Smith, Jan 30, 2022.

  1. Terry Smith

    Terry Smith Member

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    My SMC had developed a small fluid weep from around the boot/clevis area, not major but enough to dribble down the bracket and a few droplets on the leading edge of the fairing. I happened to have a spare piston assembly, so I pulled the circlip out, removed the old parts, visually checked the bore for marks and found none, and proceeded to reinstall the new/old piston, circlip, boot and clevis. So far so good, but bleeding hasn't been fun.

    I have followed the manual, and bled the front centres first, then the PCV, the rear centre and finally the rear outer. Problem is the SMC does not seem to hold any pressure; when the bike is parked I can stroke the SMC fully with little resistance. With the pedal pressed, there is SMC pressure. While riding, the pedal itself is inconsistent, will feel firm on one application, then needs a little pump up for the next.

    Is this a bleeding problem? I have been working on my own so not able to simultaneously press the pedal, SMC and bleeder (although I do have a speed-bleeder which has been good).

    Suggestions welcome.
     
  2. ridervfr

    ridervfr Member

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    https://www.ebay.com/itm/312004548436?epid=1911856839&hash=item48a4eb9754:g:5WYAAOSwTf9ZXO75
    This is what I use, I am not a fan of speed bleeders, (thats just me though) could be wrong, but I stick with simple solutions to problems. BTW, I had problems with oem honda bleeders and ended up going with after market stainless steel pieces which worked out great. Not a fan of linked breaks as I think they suck out loud but your stuck with them (pretty much any new bike is gona have ABS or linked or both.) Good luck and keep us posted.
     
  3. Terry Smith

    Terry Smith Member

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    Thanks rider. I delinked my last 5G, and still have all the bits to hand if this one gives too much grief.
     
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  4. ridervfr

    ridervfr Member

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    Your welcome, I have a co-worker who I invited over last weekend to work on his seized up front calipers, funny thing was the pistons where really stuck in the bores, no corrosion on them when they were freed and the inside of the calipers were not that "mugged" up surprisingly. Their were four pistons per side and they were two separate halves. oh, btw, they were HD brakes, if I did'nt use that MityVac tool, I would have been viciously Fu*ked :Rofl: :mech: Peace
     
  5. Terry Smith

    Terry Smith Member

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    My experience with properly stuck pistons is that there is often a build-up of crud/corrosion in the grooves that the seals sit in. This forces the seal tighter onto the piston and makes for friction. With the seals picked out, I gently scrape the grooves clean with a pick and a soft wire brush.
     
  6. ridervfr

    ridervfr Member

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    Its all aboot (sic) the grooves man! seriously, I use these wooden sticks that foot salons use on wimmins (sic) to pick oot (sic) toe jam. They are called "Orange Sticks' I don't know if you have them Down Under. A wooden dowel would surfice I guess. Main objective is to use as mild a tool as you can to use as a scraping instrument, dont wana gouge up the insides. Far as the seals go, they are pretty robust and if you examine them under magnification, you can usually determine if they are going to be viable or junk. In my case, it was a happy ending to the story, my friend made it to the bike show the next day (aside from having a scare in his garage, he left the bike in gear and thought the brakes were seized up, which did not make sense based on the fact that he rode home the night before.)
     
  7. Terry Smith

    Terry Smith Member

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    Seriously dude, WAY too much information...
     
  8. ridervfr

    ridervfr Member

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    ok, Nuff-Sed.
     
  9. Simon Edwards

    Simon Edwards New Member

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    I use genuine brass circular (flat, disk shaped) brushes mounted in a dremel extension.

    I needed the extension to get through the far side of the caliper without needing to split the halves. The dremel extension is really thin compared to the dremel body.

    Real Brass is softer than the calipers and harder than the crud stuck in the groves.

    Doing it this way takes a few seconds to do each groove.

    Warning!!!! Don't use brass coated steel! It is too hard and will definitely damage the groves and cause seal failures.
     
  10. Terry Smith

    Terry Smith Member

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    I got this all sorted; bleeding was definitely the problem, specifically getting air out of the SMC. The secret is to keep the fluid moving in one direction only. Press the brake pedal to extend the SMC. Compress the SMC and crack the PCV bleeder. Close the PCV bleeder keeping the SMC compressed. Press the pedal to extend the SMC. And...repeat. If you don't have octopus arms, you'll need a helper. The brakes on the VFR are brilliant now.
     
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