Front brakes dragging - all pistons moving, but are they too tight?

Discussion in 'Mechanics Garage' started by honda00, May 1, 2015.

  1. honda00

    honda00 New Member

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    Hello guys and gals,

    Thanks for your time. I have searched the forums but can't find an answer for what I should do here...

    I bought my 05 VTEC about a year ago, and discovered pretty bad gas mileage (30 mpg). I discovered that (I think) the front brakes were dragging. On the center stand with the front wheel in the air would get about a turn or so with a good kick on the front wheel. I could also hear the brakes rubbing on the discs (lightly?), but maybe that's normal. I suspected that it's one or both of the calipers full of junk, or maybe even a seized piston, and that the calipers are in need of a rebuild. By the way I'm pretty sure the discs aren't warped, and the brakes (even after long rides) would never get very hot. Anyway, I was continuing with this caliper rebuild idea in the back of my head.

    So, I finally bought all the goods and took the right caliper off (but didn't disconnect). With only the right caliper off, I got maybe another 1/4 of a turn than with both on (so we're talking 1 and 1/4 turns or so). I did the same with the right and same results. So I took both calipers off (plenty of wheel spin now!) and took the pads out and the pistons (at least the lower ones, which I can get a good grip and a thumb on) would move, but I had to give a pretty darn good squeeze (like my thumbs hurt!). The other pistons would move into the calipers with a (careful) but pretty damn firm push using the rubber coated end of a big pair of channel locks as a lever. (I also wrapped a rag around these, to be careful).

    Bottom line - all six pistons moved, but with a decent (maybe too decent!) amount of effort. At this point I wondered if the calipers needed to be rebuilt or not... the old pads were pretty shot, so I put new pads in (they were pretty tight, but I got the calipers back on, just). I gave the wheel a spin and it was very tight. 1/4 or 1/3 turn max (total) with same effort as before. I took it for a short spin around the block, and all is good, but when I got back to base I gave the wheel a spin again, and now I am getting 1/3 to 1/2 turn with the same effort as before, and (not surprisingly) the discs were pretty damn hot even after a short (3 min ride - with a few pretty good stops involved).

    So the big questions are:

    1. Should I rebuild these calipers?
    2. How easy should the pistons move in the calipers?
    3. Is the amount of wheel spin I'm getting normal or bad?

    Any input is very welcome!!!

    Thanks!
     
  2. Darth Vader

    Darth Vader New Member

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    You should get 1-2 turns of the wheel, pistons should move by hand.My guess would be caliper seals need replacing.
     
  3. FJ12rydertoo

    FJ12rydertoo Member

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    Before digging into the calipers check the fluid return hole in the master cylinder. It could be partly plugged and not allowing complete release of the hydraulic pressure from the master cylinder. This would not allow the pistons to fully retract.
     
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  4. Scubalong

    Scubalong Official Greeter?

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    If the piston have small scratch or nick it can cause the piston hard to retract.
    Best would be disassembly clean and flush the whole system. Replace bad seals if needed :thumb:
     
  5. NormK

    NormK New Member

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    My money is with FJ12
     
  6. Lint

    Lint Member

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    How is this done?
     
  7. skimad4x4

    skimad4x4 "Official" VFRWorld Greeter

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  8. honda00

    honda00 New Member

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    Thanks everyone. I'm going to give them a good clean, check the rotor bobbins, and if I'm still stuck, I'll move on and check the MC return hole. If that doesn't do it, I'll tear the calipers apart.

    I'll post back...

     
  9. ridervfr

    ridervfr Member

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    I would'nt mess with the brake bobbins unless your bike is parked along the beach its entire life, read "RUST." You could clean out your master cylinder and probe it nicely with a piece of wire you harvested from your favorite wire brush. I use a cotton swab with the tip cut off to do any aggressive scraping in there, could use an orange stick too. If your brakes need over-haul, use the orange stick to clean the smigma oot of the grooves, bent angle picks are handy too (its not groovy) this crud is preventing the pistons from returning after you release the brake lever.

    oh by the way, this bike has ABS? and I guess it has linked brakes too. In that case, you are in for a long job, its worth it though. May wana invest in an air assisted brake bleeder, Cheers and good luck
     
  10. skimad4x4

    skimad4x4 "Official" VFRWorld Greeter

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    OK each to his own but I would definitely inspect the bobbins. It's a quick and simple task to check for something which might be causing the brakes to bind! I think the sunny climate of Florida is probably a lot different from Ireland where many roads get treated to a lot road salt over the winter months. OK they may not get as much salt as we get up here in the Alps - but even before moving here, I found the bobbins on my 2007 were pretty much seized solid after barely two years daily use in the UK, which has a similar climate to Ireland. That is why I routinely check the bobbins every year.

    I fully agree that working on bikes fitted linked brakes and ABS can make brake servicing a lot more complex. That is why my first thought was to try and clean the callipers without disturbing those complicated systems. OK if things are really bad, then overhauling the callipers may be unavoidable, but my first instinct is to hope for the best. Hence the video I linked to above, shows how to clean the callipers and pistons in-situ without actually disturbing the hydraulic systems. Personally if the brakes are still binding after in-situ cleaning, then I would find the funds and let a garage sort things out, as a sticking front wheel is potentially dangerous.

    Take Care...





    SkiMad
     
  11. honda00

    honda00 New Member

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    Update!

    By the way my bike is ABS/Linked brakes. So I really don't want to get into this any further than I have to...

    Pissing rain in Ireland - surprise surprise. Anyway, I gave the bobbins a go with the bolt/washer trick as per youtube, and some of them were stuck pretty good, but I freed them all. When I mean freed by the way, I mean these things are sill TIGHT, but not siezed. Not much of a difference on wheel spin after that.

    Next: I checked the return hole in the master cylinder - all good there.

    Then: I cracked the bleeder on the RF caliper and that side definitely let up a touch. A little more wheel spin now. Did the same on the right side - a little more wheel spin. So I'm now thinking that the calipers don't necessarily need to be rebuilt. I gave the brake lever a few squeezes and no surprise - the calipers are tightened right back up, and very little wheel spin.

    So - off came the calipers and pads. I gave the pistons a good inspection, and there was about 1/8 or a little more of an inch of seriously black crappy crap around the end of each piston on both calipers, and the pistons would not go in further (in other words I couldn't get the pistons in flush with the caliper housing). So used the brake lever and pedal to push out the pistons and cleaned them up really good. Took about an hour or more. Anyway, after that the pistons went in with good thumb force, right to the point where they are flush with the caliper housings! At this point I was getting pretty hopeful.

    Calipers back on and really nice wheel spin - 2+ turns. Brakes on (in the garage) and things are tight right away again. 1/2 spin on wheel. HOWEVER a little gentle shake of each caliper with my hand and I knew they are looser than before - right back to 2 wheel spins!

    So, it's raining and 8.30pm here so I'm not going out tonight, but I am hoping that my little hand caliper shake simulated a little bit of riding - if so I should be good to go without a caliper rebuild!

    Does anyone else think given the above that under normal driving circumstances the pistons will loosen up after using the brakes?

    I'll keep the updates coming tomorrow - hopefully no rain in the AM!
     
  12. ridervfr

    ridervfr Member

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    you cleaned all the "mug" out of the grooves where the seals go? You can re-use the brake seals if your careful when you remove, if I can, I order new ones but have had ok results with many bikes just doing an inspection and re-using, you run into problems when you have corrosion and "mug" in there and it makes the outer ring of the seal look like a crator.
     
  13. Darth Vader

    Darth Vader New Member

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    The bike might just need riding, the rotors knocking the pads do retract pistons to a certain degree.
    Keep my fingers crossed for you.
     
  14. NormK

    NormK New Member

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    My bet is the little return hole is still blocked, there is nothing to return the pads away from the rotors apart from the twisting effect of the "O" ring, the slightest blockage in the return hole and it will not release. Problem is you push any crud down the hole, use the brakes and as soon as you release the lever the returning fluid, pushes the bit of crud back up and blocks the hole again.
     
  15. ridervfr

    ridervfr Member

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    fingers crossed because doing the ABS/Linked brake set-ups sucks out loud, read: pain in dah arse.

    I go for braided brake lines on every bike I owned/own. I have seen the amount of lines for the linked/ABS units and they are uber expensive and complicated to install. Your return orifice may be blocked but dollars to donuts :homer: you got mug behind the seals which prevent the pistons from sliding freely. Either way, good luck, brakes are oftenE under rated, I used to beat people on the race track by late braking, loved my EBC rotors, shameless plug :loco:
     
  16. Badbilly

    Badbilly Official VFRWorld Troll Of The Year!

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    Occam's razor is good. If that don't work oot the first time, change blades.

    If front brakes lock up at any speed you are fucked.
     
  17. honda00

    honda00 New Member

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    Well, I went for a ride this morning, and the brakes were much cooler on return - I still have just under a turn of wheel spin, I would like more, but we'll see - I'm gonna leave as is for the week and do so me MPG calculations - that will tell me if I am better or worse off than before. The return hole definitely isn't blocked.
    Thanks for all your help, I'll post back next weekend!
     
  18. honda00

    honda00 New Member

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    Update:

    After three commutes this week, things have loosened up. I am getting 2 or just about 2 wheel spins (compared to 1/2 before this operation). I can tell when sitting on a small incline (even at stop signs that seem level) that the bike "wants" to roll, which is great. That being said, the pads are still rubbing (I can hear them), but perhaps this is normal? For perspective, on the rear brakes (which have new pads also), and obviously plenty of chain resistance, I can get 3 wheel spins!

    Most importantly, the brakes are not hot at all, immediately after a 40 minute commute of normal riding. So, I guess I'm going to leave it there. I'll see if my MPG's go up, but I expect they will.

    To clear up what I did in the end:

    - I took the calipers off, but not disconnected.
    - Removed pads.
    - Pumped brakes so pistons were well sticking out of the calipers (but not all the way).
    - The pistons were clean other than the ends that touch the pads (perhaps the end 1/4 inch of the pistons, all the way around). This area had a visible, raised, ring of black crap on them.
    - Cleaned the pistons with *(%$ loads of brake cleaner, a toothbrush, and (very gently) a piece of metal (actually a thin rounded feeler gauge).
    - To turn the pistons I used a pair of channel locks with a thick sock in the jaws (GENTLY!!!!). This was necessary to get to the 'back' of the pistons to clean them as this ring of crap went all the way around the pistons.
    - Did NOT remove the dust seals or main piston seals
    - Put it all back together, rode for approx 50 miles over three days
    - All seems good, as reported above, and no leaks.

    I know that some of my techniques above are bound to get some heat (channel locks and metal feeler gauge on caliper pistons), so I'm not recommending this, just reporting!

    Thanks for the help, and I'll be back to let you know if something changes, and with a MPG report.

    Cheers from the Emerald Isle for now...
     
  19. FJ12rydertoo

    FJ12rydertoo Member

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    All disk brake pads rub a little since there is no spring to pull the pads away from the disk. It just relies on the interior and exterior seal friction to pull the pads back a tad. True with pads on 4 wheel vehicles too.
     
  20. Darth Vader

    Darth Vader New Member

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    Pads still rubbing could be the wheel isn't entered .
     
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