Author [ES] [CA] [PL] [PT] [IT] [DE] [FR] [NL] [DK] [NO] [GR] [TR] Topic: Weak rear brake  (Read 1543 times)

0 Members and 1 Guest are viewing this topic.

Offline Rev Ken

  • CBF God
  • *****
  • Posts: 4707
  • Growing old is compulsory; growing up is optional.
  • Bike: BMW F800GT
  • City / Town: Workington
  • Country: England
Re: Weak rear brake
« Reply #10 on: 23 February, 2020, 04:30:07 PM »
Personally I take the advice of Michelin and would get it repaired by a 'proper' garage. If you take the wheel off yourselves it isn't expensive in my experience.
Never ride faster than your Angel can fly.

Offline Crispy

  • CBF Pro
  • ***
  • Posts: 94
  • Bike: CBF1000A
  • City / Town: Manchester
  • Country: Britain
Re: Weak rear brake
« Reply #11 on: 23 February, 2020, 07:21:12 PM »
*Originally Posted by jm2 [+]
Add to your shopping list brake/clutch cleaner in abundance

Brake cleaner is cheap at Screwfix, £3.49 for a 600ml aerosol can.  :046:
A day without learning is a day wasted

Offline FLIZ

  • CBF Pro
  • ***
  • Posts: 88
  • Bike: Honda CBF1000A9
  • City / Town: North Yorkshire
  • Country: England
Re: Weak rear brake
« Reply #12 on: 23 February, 2020, 07:47:58 PM »
Holts brake cleaner same size and price at Toolstation as well.    :028:

Offline Shed

  • CBF Master
  • ****
  • Posts: 355
  • City / Town: Newcastle
  • Country: UK
Re: Weak rear brake
« Reply #13 on: 23 February, 2020, 07:53:39 PM »
« Last Edit: 23 February, 2020, 07:54:17 PM by Shed »

Offline Crispy

  • CBF Pro
  • ***
  • Posts: 94
  • Bike: CBF1000A
  • City / Town: Manchester
  • Country: Britain
Re: Weak rear brake
« Reply #14 on: 24 February, 2020, 09:23:06 PM »
Nice one Shed, will buy some of that brake cleaner, should last for years. Some of the prices you can pay for a tin of brake cleaner can be eye watering, 8 quid plus. Also you can get 5 litres of WD40 with applicator for around £23, again prices for a single tin can cost nearly half that (e.g, the one with the fancy retractable nozzle and fixed straw so you don’t lose it.)

I’ve got a weed sprayer to clean my bike. Mist spray with water, spray on some cleaner, sponge the wheels, rinse with weed sprayer (minus the weed killer) dry with chamois leather. Much cheaper than a jet washer and can be used if there’s no access to a tap.



« Last Edit: 24 February, 2020, 09:35:19 PM by Crispy »
A day without learning is a day wasted

Offline Greenfingers

  • CBF Member
  • **
  • Posts: 13
  • Bike: CBF1000 A6
  • City / Town: Oxford
  • Country: UK
Re: Weak rear brake
« Reply #15 on: 25 February, 2020, 07:26:09 PM »
It's reassuring to see there are other frugal minded people out there. The shelves in my garage are stacked with Toolstation and Screwfix consumables and I buy most of our groceries from Lidl and Aldi (although admittedly, some of their middle aisle items are junk). With a wife and three youngish daughters in the family, I am constantly battling against their lust for unnecessary cosmetics and accessories. Perhaps my loathing of rip-off brand names went too far recently, when I ordered a bulk purchase of spirit vinegar and sodium bicarbonate, to use instead of that ridiculous array of cleaning products! Anyway, still just about married!

Now, time to admit to a massive blunder. Maybe I've been out of the game too long, or maybe just bad luck:-
The CBF rear brake pads had plenty of meat left and the pistons and calipers seemed to be working as they should, but it seemed like a good idea to remove the caliper and check/lubricate all the moving parts. The 14mm bolt head near the front of the caliper was really tight to undo - so much so that I had to use a ring spanner on the end of the 14mm ring spanner to break it free. After that, it loosened up a bit and I continued with the ring spanner. I didn't bother to move the silencer out of the way and eventually the bolt came away. There wasn't really any build up of crud on anything and the sliders and pistons all seemed to move fine, so I just cleaned what I could, applied some silicone lube and went to reassemble. With the caliper bolted back into place, I went to reinsert the spring and pads, but couldn't get the anti rattle spring back in, so unbolted the caliper again and managed to fit the spring. This time after lubricating the caliper bolt, I unbolted the silencer and lowered it enough to use a socket and ratchet. The bolt went in easily, but when it landed against the shoulder, it didn't go tight. I knew something was wrong and got the torque wrench to see if 20ft/lb was achievable, but alas the bolt kept turning!

So I have managed to strip the M12 x 1.25mm thread in the caliper. This takes me back to umpteen years ago, when I found out the hard way about the incompatibility of aluminium and steel. Anyway, ordered a helicoil kit from Ebay for £12.75, which will hopefully sort it!

Offline Greenfingers

  • CBF Member
  • **
  • Posts: 13
  • Bike: CBF1000 A6
  • City / Town: Oxford
  • Country: UK
Re: Weak rear brake
« Reply #16 on: 01 March, 2020, 06:51:58 PM »
Hooray, job done at last!

The Neilsen 'Helicoil' kit worked in the end, but I did waste a couple of the thread inserts by trying to cut them to length before insertion. If you stretch or bend them at all, they don't like following the rest of the insert through the newly cut STI thread. Also, once they are engaged in the thread, it is difficult to back them out again, because the action of turning anticlockwise expands them into the tapped thread. Fortunately, this application was not in a blind hole, so it was possible to just wind them on through. In the end, I threaded the insert in from the back and cut the excess off in situ from the rear, which ensured there was a clean start for the bolt to engage from front.

Couldn't really find anything wrong with the brake mechanism. At first, the 2 rearmost pistons moved out when pressing the brake pedal, but if I held them in with 2 fingers, then the 3rd would move instead. No build up of crud or anything, so I just squeezed them in and out a few times and basted them in silicone lubricant, while turning them round at the same time.

I haven't done a proper road test yet, but the brake doesn't seem to be binding as such, although the rear wheel still doesn't seem to spin very freely. Perhaps this is more to do with the chain and sprockets?

Offline Art

  • CBF Master
  • ****
  • Posts: 877
  • Bike: SC58 CBF1000 A-6
  • City / Town: Shoreditch
  • Country: England
Re: Weak rear brake
« Reply #17 on: 02 March, 2020, 03:47:47 AM »
+1 for helicoil kits. Every time I torque down brake caliper mounting bolts and other bolts such as the gear lever cam bolt I feel as if the thread is about to strip and question if the torque wrench needs re-calibrating, I'm like really why hasn't it clicked yet. That's pretty much how I ended up with an M8 helicoil doing what it does on the gear lever cam bolt.

Happy Days

Offline Shed

  • CBF Master
  • ****
  • Posts: 355
  • City / Town: Newcastle
  • Country: UK
Re: Weak rear brake
« Reply #18 on: 02 March, 2020, 05:16:03 PM »
Slightly off original topic, but to go alongside the torque theme, a decent little pdf on torque tightening available here:

https://www.atlascopco.com/content/dam/atlas-copco/industrial-technique/general/documents/pocketguides/9833864801_L.pdf



Offline Art

  • CBF Master
  • ****
  • Posts: 877
  • Bike: SC58 CBF1000 A-6
  • City / Town: Shoreditch
  • Country: England
Re: Weak rear brake
« Reply #19 on: 03 March, 2020, 08:55:22 AM »
+1 to the POCKET  GUIDE TO TIGHTENING  TECHNIQUE

I remember back in the day our college tutor would get very vocal and very angry at anyone who didn't immediately grasp the differences in screw head torque, clamping force etc when comparing dry and lubricated threads.

 


diverse-leafy