Avid Juicy 3.5 bleed problem

vladtheexhaler

My rear brake had developed a distinctly spongy feel so I though I'd have a go at bleeding it myself. It took me a couple of attempts but I got it to a stage where it actually felt better than when the bike was new and a quick spin up and down the street confirmed that they were working well.

However, during a ride up at Arrochar at the weekend it quickly became evident that the brake works very well for a short period but rapidly loses all power allowing me to pull the lever all the way to the bar. I'm not talking about long steep descents with loads of braking but after about 5 seconds of moderate braking I may as well have no brake. Upon stopping I pumped the lever several times which got it working again but then the same thing happened once I tried to use the brake.

Does the fact that I can pump the lever back up suggest that there is still air in the system and needs bled properly?

*AL*

vladtheexhaler wrote:

Does the fact that I can pump the lever back up suggest that there is still air in the system and needs bled properly?

Yes.

Have you viewed the bleeding video's on you tube ?

nicklouse

sounds like air.

vladtheexhaler

*AL* wrote:

vladtheexhaler wrote:

Does the fact that I can pump the lever back up suggest that there is still air in the system and needs bled properly?

Yes.

Have you viewed the bleeding video's on you tube ?

Thanks.

II watched a couple of vids and followed the instructions that came with the kit.

I bled the brake with the lever wound out quite far from the bar as advised and there was immediately plenty of resistance at the lever but when I wound it back in again the lever was touching the bars and needed pumped up. Does the lever position during bleeding make a difference?

*AL*

vladtheexhaler wrote:

Does the lever position during bleeding make a difference?

I haven't bled 3.5's but when I bled my Ultimates the lever had to be secured tightly against the grip to isolate the master cylinder whilst you bleed the calliper.

Then you release the lever to bleed the brake line up to the master, and then finally the master is bled.

vladtheexhaler

*AL* wrote:

vladtheexhaler wrote:

Does the lever position during bleeding make a difference?

I haven't bled 3.5's but when I bled my Ultimates the lever had to be secured tightly against the grip to isolate the master cylinder whilst you bleed the calliper.

Then you release the lever to bleed the brake line up to the master, and then finally the master is bled.

Yeah I did that. It's just that instructions advised that the reach position of the lever should not be set so that the lever has little travel before hitting the bar. I wound the reach pretty much all the way out to be on the safe side which may have been a mistake!

cat_with_no_tail

Have a look at the instructions online here.

Pay particular attention to the bit about strapping the handle to the bar.

Also, silly question, but had you de-gassed the fluid properly before starting?

vladtheexhaler

Cat With No Tail wrote:

Have a look at the instructions online here.

Pay particular attention to the bit about strapping the handle to the bar.

Also, silly question, but had you de-gassed the fluid properly before starting?

Those instructions are a little more detailed than the ones that came with the unofficial kit I procured from ebay.

I did de-gass the fluid, however, when I removed the strap from the bar I just allowed the lever to fully extend rather than holding it and letting it return slowly as the pressure pushed it out.

I'll have another bash tonight.

*AL*

vladtheexhaler wrote:

Those instructions are a little more detailed than the ones that came with the unofficial kit I procured from ebay.

I did de-gass the fluid, however, when I removed the strap from the bar I just allowed the lever to fully extend rather than holding it and letting it return slowly as the pressure pushed it out.

I'll have another bash tonight.

Try THIS vid.

It's the proper Avid video, it's pretty much fool proof.

cat_with_no_tail

Yeh, there are some other versions of the bleed instructions that are actually produced by Avid that are awful and would couse all sorts of problems if used.

Those are about the best ones I've found and I think are the same ones that come with the "official" bleed kit too.

I think if you just let the lever snap back that's probably where the problem comes from.

Good luck