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Cross thread rear capiler !!!!


rjp996

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rjp996

After leaving my bike past few weeks, it started right up first time however the rear break was dragging. 

Not wanting to remove the rear wheel i removed the two calliper bolts to get it off, clean it out and grease it up...

issue came when putting it back on as space to one of the bolts is small and looks like I cross threaded it..... so calliper bolt is not straight, so capiler not right on carrier. 

 

Ive removed the calliper and yes the thread is crossed :-(

 

what to do... not sure if running a tap down it will suffice, may be a new calliper... small jobs sometime become big ones. 

 

Any recommendations to fix welcome

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rjp996

Am I right in thinking there is no difference in the rear capiler between the DCT and non DCT models, only the hanger (and parking break) differ. 

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trisaki

There is only one bolt you undo on the rear caliper ,(two on the handbrake caliper if dct , ) , the other one is basically  a fixed sliding  pin 

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rjp996

Yep, was the fixed slidepin I took out and cross threaded.... 

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trisaki

You don't need to do anything  with that as it comes off with the  caliper , just rubber lube it and slide it back in  , that was b4 cross threading it ! , s/h caliper now needed or take it off and have it retapped 

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embee

Helicoil (trade mark) will recover simple stripped threads.

If it is not a major load-bearing item (which I'd say the sliding pin isn't technically, the thread just hold the pin in the hole in effect) then if it hasn't gone right down the thread length you may well be able to recover it by running a tap through, preferably from the opposite end if possible (but maybe not), and perhaps using thread lock to retain it. High grade Loctite products are almost permanent, a bearing-fit grade will usually be difficult to remove when used on threads, but it can save a situation.

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Defender

I would try a 'thread chaser' before going to the trouble of a helicoil etc, you can make one from a bolt with the same thread and cut a slot into the thread, probably a video on this on Youtube?

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rjp996

I got hold of a second hand calliper for £35. 

Im going to try a tap on it, however looking at it I've run the thread all the way through, so the bolt is wonky, and streatched the alloy on the  back side of the thread. 

 

Lesson on learnt to not short cut taking the wheel off in such a tight spot..

 

anyhow i I get to practice on the old calliper now :-)

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embee

Sounds like the only practical solution to recover the old caliper would be to have it helicoiled, which would need it setting up in a drill stand to be able to drill the old threads out straight and true, and then tap it for the helicoil. It would be perfectly do-able but debatable whether it is financially sensible unless you can do-it-yourself, paying for it would cost essentially a similar amount to a second-hand caliper as you have sourced.

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You can buy kits on that auction site that include a drill, a tap, the coils and an insertion tool. I bought one a few years back to repair a cross threaded brake disc thread. Had to place the rear wheel onto my Clarke Bench drill (after I'd levelled up the platform). I then placed the drill bit into the drill chuck and drilled the hole out by rotating the chuck by hand. Did the same with the tap included in the kit. I then inserted the coil using the hand tool. Worked great.

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Trumpet

Erm, sorry if this comes across wrong, but I would not be advising someone who has cross threaded a part that did not need to be removed and drove it right in, to drill and helicoil. Having already demonstrated their level of mechanical ability. Especially on something as critical as a Brake.  I'd be advising them to take it to a Shop ! :muttley:

Edited by Trumpet
  • Haha 2
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On 17/04/2019 at 16:57, rjp996 said:

After leaving my bike past few weeks, it started right up first time however the rear break was dragging. 

Not wanting to remove the rear wheel i removed the two calliper bolts to get it off, clean it out and grease it up...

issue came when putting it back on as space to one of the bolts is small and looks like I cross threaded it..... so calliper bolt is not straight, so capiler not right on carrier. 

 

Ive removed the calliper and yes the thread is crossed :-(

 

what to do... not sure if running a tap down it will suffice, may be a new calliper... small jobs sometime become big ones. 

 

Any recommendations to fix welcome

 

Take the calliper off, if it isn’t already, and wind the bolt in from the other side. Use plenty of grease on it when you do.

If you have a small file, you can file a wedge shape in the end of the bolt, parallel with the bolt, so you get a cutting edge to help clear any debris out.

It works. I did exactly this on another member’s bike with the same bolt.

Edited by Grumpy Meltdown
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