XT M785 brake bleeding problem
Just bleeding my brakes for the first time, I can’t get the caliper syringe to push the oil into the system, it just resists and leaks around the edge of the tube/bleed nipple interface as I push harder.
Bleed nipple is open 1/4 turn, I can make oil come out of it but not in. Using the syringe on the caliper as instructed.
I couldn’t get the pistons fully in without opening the bleed nipple a little bit, which is weird. this issue maybe related? can you get an airlock?
Any ideas?Posted 4 years agobinnoMember
I’ve had issues in the past, my solution:
1. Remove syringe piston and lube rubber plunger part with mineral oil. Test it to make sure it slides up and down nicely as it does expand if used before.
2. Load syringe with oil and mount to calliper bleed port (once air has been squeezed out).
3. Open the bleed hole at least 1/2 a turn, you can go a bit further it won’t hurt the system at all. You need to this part to make the oil flow. no idea why they star a 1/4 turn?
4. it will slide on up smooth as (obviously given that the lever has the funnel attached, little plunger removed, and lever is not pressed in or anything.
5. run a fair amount of oil through, tighten up nice and tight at the calliper bleed port and your done at that end.
BTW – if you then bleed down you can test what I’m saying about opening up the bleed post more than 1/4 – no oil will come down if it’s to tight at this point. ease it open till is flows nicely – then you know how much to turn the threads in the future.Posted 4 years ago
As already stated the lever syringe does need to be without the plunger for the oil to enter unrestricted, as per our guide which has already been linked above.
This is a problem with all syringe plunger seals where the mineral oil will cause it to swell. We’ve tried syringes from multiple manufacturers and the results are identical unfortunately.
A neat little trick is to remove the plunger from the injection syringe before use and lubricate the seal with mineral oil before drawing fluid into the barrel.
It might sound counterintuitive to use the very fluid that causes the swelling to lubricate the seal, but during use it will help.
Good luck.Posted 4 years agoshortcutSubscriber
You don’t need a syringe to bleed Shimano XT. You take out the pads, put in the yellow spacer. Attach small ring spanner to the caliper bleed screw, add pipe and bottle to recieve fluid. NOTHING NEED GO IN AT THE CALLIPER END.
Remove the screw in the top of the resevoir on the lever, screw in the yellow funnel, pour in Mineral oil. Bleed from the lever end by pulling the lever and allowing oil to pass through the system via the now open bleed nipple, tighten up bleed nipple, release lever – repeat.
When its all good, pop the plunger in the funnel, replace the screw, pads etc. go riding.
Easy.Posted 4 years ago
That is an alternative way of doing things and it’s how the older Shimano brakes are supposed to be bled.
Pushing fluid upwards by injecting at the calliper is certainly faster and as air rises it should be more effective too.
However to get the best of both worlds and to do a thorough job you are advised by Shimano to do both.Posted 4 years agoMister PMember
You should always bleed XT brakes with the little silver screw wound out. Then after bleeding you can wind it in and it actually does something. It basically increases the volume of the master cylinder so by winding it out you get more fluid into the system. Winding it back in reduces the volume of the master cylinder again. If you bleed them with it wound in, winding it out afterwards does very little.Posted 4 years agoiaincSubscriber
You should always bleed XT brakes with the little silver screw wound out. Then after bleeding you can wind it in and it actually does something. It basically increases the volume of the master cylinder so by winding it out you get more fluid into the system. Winding it back in reduces the volume of the master cylinder again. If you bleed them with it wound in, winding it out afterwards does very little.
I didn’t know that but very useful tip and makes a lot of sensePosted 4 years agobigdrewMember
Bit of a hijack but it is along the same lines.. I am having the same trouble with SLX brakes. I take it they don’t think this silver screw that is causing trouble on the XT’s.
I can get them to feel solid with a 10mm Allen key as a spacer but as soon as I put pads and disc in it is pretty soft. Any ideas?
Pads are about 1/2 worn but I am assuming this shouldn’t effect it at all?Posted 4 years ago
Sounds the same as me bigdrew, lever felt solid with the yellow plastic spacer in but once pumped out for the pads was quite spongy. I did actually ride yesterday and I’m still alive, definitely a bit spongy and bite point is closer to the bars than I would like, but I can’t be bothered bleeding them again for the time being.Posted 4 years agojairajSubscriber
Have you tried new pads?
I thought my M785 needed a bleed as they felt spongy and the lever travelled back to the bars.
My pads where very worn out too so I tried that first and the lever feels fine now.
Maybe the reservoir volume is small and they cannot self adjust enough to compensate for the worn pad width?Posted 4 years ago
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