Hi, I could do with some advice. I have a thunderbird 900 with a front brake problem. I have no resistance in the brake leaver. I have change the seals and bleed nipple in the caliper, changed everything in the master cylinder system, but this dose not seemed to have worked. Everytime I try to bleed the brake fluid through nothing happens, the nipple also seems to be suckling air back in, but it's not the nipple itself as I have tried it with the old and new nipple, same happened with both. Any ideas?
I have experienced this too My solution was to push the pistons in as far as possible, thus reducing the air in the system Fill with brake oil and squeeze the oil in, make sure the reservoir is full otherwise you may end up pushing air in Detach the calipers from the legs and rotate them so any air rises up and can't get trapped
If you have rebuilt the calipers with new seals , pull them apart again , pour brake fluid into pots , reassemble , pushing pistons in slowly , displace as much air as possible , bleed line by loosening the banjo Union , then move on to full system bleed ! This is painfully slow way , but it beats the hell out of pumping your master cylinder to death ... !
As above, plus, when you are bleeding the caliper hold the brake lever back to the bar then close the bleed nipple before slowly releasing the lever to its rest position, that way it can’t draw air back in past the threads of the nipple, it’s only a small amount if it does that but it makes bleeding harder.
Bleed nipples seat where the chamfered point seats in the bore. It is not uncommon to find air leakage around the threads. Solution is a good smear of copper anti seize grease to fill the threads.
The other option is to use a suction bleeder on the calipers or a large syringe and force fluid into the calipers used both these methods on suborn systems before to good effect.
If at the end of all the above excellent advice you still have a little bit of air left in the system, you might find it useful to tie the brake leaver back to the handle bar and leave it overnight.
When I replaced the brake lines on my Bonneville last year I used a cheap vacuum pump to bleed the brakes. Even for an idiot like me it was relatively simple, the back brake was done in minutes, and the front just required the brake lever to be tied overnight to get it perfect. This is the one I used, not the best quality, and it doesn't have any clips to secure the pipe to the bleed nipple, but it did the job nicely anyway: https://www.amazon.co.uk/gp/product/B077FQY2DS I plan on servicing the Street Triple brakes this year, so I've ordered a simple cheap kit with a one way value to go between the bleed nipple and the pump that hopefully should make the job even easier: https://www.amazon.co.uk/gp/product/B07K16YS49
Agreed, and make sure all the inside of the caliper is wet (so the bubbles cant stick to the sides) before you reassemble them.
Kristian Box. Welcome to the family. Yes all these little tricks work well. Myself I got some clear pipe stick it on the nipple open up a quarter turn and suck the tube till the pipe is nearly full. Then put it into a jar with enough fluid to cover the end of the pipe and hey presto works a treat. Do make sure to at least put two three reservoir through each brake to ensure all the air is gone. Do hit the upload a file button bottom right corner and show the inmates the steed. Regards Joe.
These brakes are harder to bleed as the master cyl is only 11mm dia and does not move much fluid. Sucking the fluid through from the caliper via a vacum pump will give the best results.
just an obvious thing...as I came across this with caliper refurb/then bleed on my Triple recently...make sure whatever plastic pipe your are using to bleed through is a snug fit on the nipple. Mine wasn't (initially) and so air was leaching in rendering the whole process a bit chaotic. So, in summary...have a good seal on them nips!
Thanks for all you inputs, found out the problem was a small leak in the caliper. The pistons are damaged. Anyone any ides where I can find spare pistons from?
I'm afraid I do not know bikes well enough to know if yours is particularly old or special....but for the caliper refurb on my 2002 Triple I got new pistons (and seals, as a refurb set) off of eBay. Yes, it was eBay but it was a proper triumph/brake specialist selling them...so I'd just have a Google and see what you find. Good luck. Refurbing my calipers was the best thing I've done yet. I felt like a hero!
Get stainless pistons from wemoto. https://www.wemoto.com/bikes/triump...n_and_seal_kit_stainless_steel_front_-_by_trk Or you can just buy the pistons. Clean all corrosion from dust seal groove and fit back together with red rubber grease like what comes in the kit.
