Avid Brake Bleeding: issues with syringes

[Nautonier]

I was attempting to bleed the levers on my Avid X0 Trails yesterday and had massive problems with huge runs of air bubbles coming into the syringe while I was at the 'creating a vacuum' stage. Ordinarily this is a good sign, as it means air bubbles are being sucked out of the reservoir/lever, but in this case, the bubbles were coming from the where the hose joins the syringe. I could see that lower down where the hose was attached to the bleed port, there appeared to be nothing coming through at all.

Much frustrated buy the never-ending stream of air bubbles and not being able to get a vacuum before running out of syringe travel, I tried swapping syringes and the same thing happened. These are brand new syringes from an Avid bleed kit I purchased recently. I also tried a Rockshox syringe I had lying around and it malfunctioned similarly.

I've bled Avid brakes before and not had this problem - what I am doing wrong? Is it possible that there isn't any air in the system and that cranking on the syringe really hard just pulls air through the hose join? In this case, why are my brakes feeling spongy and needing the contact point adjustment dialled all the way out to stop the levers coming all the way in to the bars (ie no brakes)?

 

[ctguru]

where are you in Melbourne?

I can give you a couple of new syringes to try

 

[99_FGT]

I was attempting to bleed the levers on my Avid X0 Trails yesterday and had massive problems with huge runs of air bubbles coming into the syringe while I was at the 'creating a vacuum' stage. Ordinarily this is a good sign, as it means air bubbles are being sucked out of the reservoir/lever, but in this case, the bubbles were coming from the where the hose joins the syringe. I could see that lower down where the hose was attached to the bleed port, there appeared to be nothing coming through at all.

Much frustrated buy the never-ending stream of air bubbles and not being able to get a vacuum before running out of syringe travel, I tried swapping syringes and the same thing happened. These are brand new syringes from an Avid bleed kit I purchased recently. I also tried a Rockshox syringe I had lying around and it malfunctioned similarly.

I've bled Avid brakes before and not had this problem - what I am doing wrong? Is it possible that there isn't any air in the system and that cranking on the syringe really hard just pulls air through the hose join? In this case, why are my brakes feeling spongy and needing the contact point adjustment dialled all the way out to stop the levers coming all the way in to the bars (ie no brakes)?

I did the same the first time I did it, and turned out I hadn't cracked the bleed port enough (needed to be like half a turn, which was a PITA since I don't have a 6mm spanner)

 

[Nautonier]

I did the same the first time I did it, and turned out I hadn't cracked the bleed port enough (needed to be like half a turn, which was a PITA since I don't have a 6mm spanner)

With these ones (well the lever end anyway), the bleed screw is removed completely so the issue is not with getting the dot fluid to freely flow from the system into the syringe.

 

[Nautonier]

where are you in Melbourne?

I can give you a couple of new syringes to try

I'm near St Kilda, thanks for the offer. I'm off to NZ for a couple of weeks (with spongy brakes), but might have a look into it when I get back. Really need to get them sorted and would like to be able to do this kind of maintenance myself.

 

[ctguru]

does it still suck air when you p'prep' the syringes?

i.e. not attached to brakes, just clamping bleed attachment and sucking syringe back to degas the DOT fluid

 

[pink poodle]

hopefully you haven't over vaccumed and popped the seals inside the lever....

 

[yuley95]

Are you bleeding the whole system or just the lever? If just the level, I would try doing the whole system from caliper up.

Doesn't really take much longer and will ensure no air in caliper or line.

By 'pushing' the fluid up through the line and into the lever syringe you should at least confirm that there is no blockage

 

[Dozer]

I know what you're going through, it feels like the pull of the syringe is too easy and it's actually creating an air volume in the base of the syringe. You need to pull slower and more gently, sounds pathetic I know but it's the only way to avoid the extra vacuum. The only way I could cure that problem was to use the bleed kit with the professional syringes. They have more resistance and are more reliable. The standard syringes work okay but the dearer syringes are better.

 

[Nautonier]

does it still suck air when you p'prep' the syringes?

i.e. not attached to brakes, just clamping bleed attachment and sucking syringe back to degas the DOT fluid

Not sure, will try that for sure.

I wasn't aware that the 'pro' kit came with better quality syringes. I'm being pretty gentle on them, maybe not gentle enough.

I was just doing a lever bleed, I didn't have time to do the full system bleed, but will have a go at it when I get back. The thing that puts me off doing the full bleed is having to take the calipers on and off, as it always seems to take forever to get them perfectly aligned again with the minimal pad clearance they have.

 

[mitchy_]

Why would you remove the brake?
Remove the wheel, pads and fit bleed block. Bleed, refit pads and wheel.

As doper said though, you can't do it hamfistedly, need to gently pull a vacuum on the system.

 

[Broken Bones89]

You need the Avid Pro bleed kit with these syringes, I have a set at work and they're worth their weight in gold. Stock Avid ones have one place and one place only, in the bin.

 

[Nautonier]

View attachment 305273

You need the Avid Pro bleed kit with these syringes, I have a set at work and they're worth their weight in gold. Stock Avid ones have one place and one place only, in the bin.

That looks infinitely more quality than the crappy syringe I have. The other thing that happened is that it actually leaked a lot of fluid as I 'gently plunged' the syringe to push fluid back into the lever. Rubbish.