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Stripped caliper mounting bolt - safety?

Discussion in 'Technical and Troubleshooting Torque' started by zeddicus, Dec 21, 2008.

  1. Hi all,

    While replacing the rear pads on my GT650R I have managed to strip part of the female thread from within one of the two caliper mounting holes. The bolt tightens up better than finger tight but will not torque to its correct setting. I was using a torque wrench, properly set, at the time. Not happy.

    I am re-considering doing the front brakes. As the manual specifies 18 - 28Nm of torque and I managed to strip the thread using 20ft/p (just under 28Nm), I don't know if I want to risk killing any bolts on the front.

    So, three questions:

    1. Given the above, would you consider this 'safe to ride'? The bolt is hand tight and the second bolt is torque'd fine, and it's the back brake after all...

    2. As a fix, would I be better off tap'ing it out and using a bigger bolt, having a helicoil fitted or simply replacing the bracket into which the caliper mounts?

    3. Could I get this fixed under warranty given I was using the correct, manufacturer specified torque ( I seriously doubt this will happen but hey I have to ask).
  2. Few Questions ..
    1. Are you the only owner of the bike .
    2.Has the brakes been done before.
    Very rare for this bolt to strip that easy it might have been weakened before ..(could also be cheap Casting it is a Hyosung ! )

    It can be helicoiled and I wouldnt ride it until its fixed there is a lot of presure on brakes..
    Ok its the rear brake and you hardly use it ..Here's a test take your rear brake lever off and go for a ride ..Then tell me you never once tried to put your foot on it ..You will be very surprised how often you unwillingly use it...
  3. Thanks for the reply Traviss. Some further info below.

    I have owned this bike from new. The brakes have been looked at by the dealer twice that I know of (for squeaking first time and wear check/squeak the second). I am unsure as to whether they have had them off but I suspect so, at least for the first check.

    I have now replaced the pads on both front calipers. Out of a total of six caliper mount bolts on the bike I had issues with only one. It may be the case that someone at my dealer has either cross-threaded and backed it out, or tightened without a torque wrench.

    The affected part is the mounting bracket (a removable part of the caliper, not the frame part the bolt passes through). I've removed the bracket and will take it down to the dealer first thing Monday to see if I can get a warranty replace and/or have them tap a new thread. Whichever is quickest as I really don't want to be bikeless!

    Amusingly, it appears my front brake calipers wear pads unevenly. One caliper wore its pads much quicker than the other, with less than 10% usable (probably closer to 6 or 7%) left. The dealer had said either 60% worn or 60% left at last service 2500km ago. The other caliper's pads have much more material however one pad has literally twice the wear of the other.
  4. I would say the thread got damaged during inspection or it was a fault in machining..
    Your front pads uneven wear is not good and I would also bring this to the attention of the dealer..Cause could be poor pad material or uneven brake bias between calipars or the pistons in the calipars are sticking ..
    Worth checking for any faults as it is your brakes..
  5. Wouldn't you have noticed the difference when you undid the bolt :?

    If no luck under warranty, price a new caliper bracket and weigh this up against cost of helicoil

    Don't know about tapping a larger bolt hole - then you'd have to also drill out the caliper hole
  6. Update!

    So I rang around 5 or 6 wreckers in Sydney. Of the ones that actually answered their phone only one (the one in Silverwater) had the part I needed... except I had to buy the whole caliper rather than just the bracket if I wanted it. $125. Sod that.

    Took the bracket down to my dealer to get their opinion on options. Apparently it's a little on the thin side for a helicoil so that's out. Could perhaps tap a new thread but potential issues with a larger bolt not fitting into the frame.

    Rod, who runs the workshop at my dealer, takes the part and says 'hold on a little bit, I'll see if they can be bought separately' i.e. separately from the caliper, and dissapears. Five minutes later he reappears with a bracket and bolts in hand and puts them on the counter.

    'Brilliant! Thank you good sir, how much do I owe you' says I.
    'No charge mate, merry Christmas' says he. Win!

    Rod also had a look at some brake pads I took down from the two front calipers. They were showing extremely varied wear (60/40 remaining on the left, 8/5% on the right :shock: ). If the same wear pattern continues with the new EBC pads Rod said they might need to look into it.

    Thirty minutes later I'm home, the back caliper is complete again and I was off to bed the whole lot in.

  7. Gotta luv a happy ending..... :)
  8. Lets play a little game :twisted:

    You took it back to your dealer thats done all the work beforehand ?
    You show him the problem / damage
    In less than 5 mins he is giving you the new parts FREE of charge ???

    IMO who ever did the last brake service stripped that thread told the 'boss' and they boggie'd it up good enough to get the bolt tight one last time.
    Ordered the replacement parts needed, and where going to replace it all at your next service with you none the wiser.
    You do work yourself, find problem, they shit them selfs and just happen to have the parts for you for free !! :shock: :wink:

    I for the life of me can't see these parts as a NEEDED stock item unless they are a regular fail item.

    As I said this is my opinion only and I could be wrong, but it all sounds just to convenient to me

  9. I don't think the bracket was new. It was clean and in new condition but it probably came off a wrecked bike that was in for repair. Either way my bike was back in action same day and thus I'm happy :)
  10. Bob, the people that sell these things have learned to be very afraid, I reckon.