Bad brakes

[peteinpa]

Purposely running it dry goes against everything I've EVER done with brakes.  This goes double with ABS.

It's one thing if you change lines and have no choice, but on purpose?

If you have serious crud in the reservoir I'll tie the lever tight, suck it out, clean it out, add new, then start pushing it through.

[betoney]

@petshark - I really have no idea why he bled the system the way that he did. When bleeding the brakes and pumping the lever on the master cylinder you’re either pulling in fluid or pulling in air, so if he let the fluid run dry then the only thing going into the lines is air.  

if It was my bike, I would re- bleed and get out all of the air. 

[Lone Wolf]

10 hours ago, petshark said:

We used the simple hose-in-bottle procedure and quickly established that there were in fact air bubbles coming up.

If you look at that video with Aaron bleeding brakes, he shows putting teflon tape around the bleeder nipple threads to keep air from coming in, and from my experience a lot of the bubbles that you see cruising through the tube may not have been in your brake system - they get introduced from the gap in the threads when you open the bleed nipple screw.

I have seen that with the old "tube in a bottle" method as well as vacuum bleeders. the problem with the teflon tape is you have to pull the bleeder screw all the way out and wrap it (or have a spare ready to put in as soon as you remove the old one). Personally I wipe a small ring of grease around the brake nipple and zero air can get in, it dramatically reduces the bubbles you see - and the ones you see are from the brake system not outside atmosphere. This is a legit issue. Speed bleeder nipples come with a pre-applied sealant around the threads to combat this problem, and they sell a bottle of liquid to re apply because it wears off the threads. I just use the grease.

10 hours ago, petshark said:

... then he proceeded to just pump all the oil out and let the master cylinder run dry. When I said that I had the advice to never do that he said that you can never mix brake oils so you need to purge it completely before putting new oil in.

Did he change your brake fluid to silicone? Do you have the container that was used?  If he changed to non-OEM fluid you would of course be aware of that for future brake work. Any DOT 4 could have been used for your bleed, there is no need to get rid of existing fluid when going back with DOT 4 from any manufacturer.

BLEEDER AT THE MASTER CYLINDER

I recently pulled the banjo bolt on another bikes master cylinder and replaced it with one of these from Spiegler. You bleed it right there (in addition to the caliper bleed screw). These are also helpful for some rear master cylinders where you can't get to the high point where the bubbles rise up to.

I got mine through Revzilla, did not come with crush washers so you may want to order crush washer as well.

Edited January 25, 2021 by Lone Wolf

[Manxkiwi]

It's probably a cost thing, but I'd like to see an o ring on bleed screws. Would be a great solution I reckon.

[betoney]

12 hours ago, petshark said:

he said that you can never mix brake oils so you need to purge it completely before putting new oil in.

 

9 hours ago, BBB said:

That does sound really odd to let the MC go dry. Fluids simply displace each other so simply adding new fluid would have completely flushed the old stuff out.

I agree with @BBB a simple flush would have pushed the old fluid out. - If your old fluid was due for a flush, simply hook up the hose to the bleed nipple and pump the lever until the fluid in the reservoir gets near the bottom, fill it with fresh fluid and repeat.  I run 2 full reservoirs of fresh fluid through to purge the old fluid and then fill it and bleed on the 3rd filling. 

@petshark I always flush it from the right caliper so fresh fluid starts from the master cylinder, goes through the ABS pump and left caliper and then finally out the right caliper.  Find a method that works for you, once you do it a few times, it is VERY quick and simple.

[2and3cylinders]

 I have banjos with bleeders up at all my MC because they're the high points, I don't know if they're do much good down at the calipers.

DOT 5 silicone won't be compatible though it was good unbelievably in my 88 NT650.

I mentioned using grease around the bleed ers, and do install a Teflon taped spare bleeder or when changing banjos and or lines.

Vacuum flusing / bleeding f and r takes me maybe 40 minutes taking it easy.

 

[kilo3]

Wish brake fluid could still be tinted. What a stupid law that was.

[petshark]

On 1/25/2021 at 2:28 PM, BBB said:

That does sound really odd to let the MC go dry. Fluids simply displace each other so simply adding new fluid would have completely flushed the old stuff out.

In case you’re not doing these (and I haven’t read the full thread), there are two steps that really helped me

- pump the brake lever several times to pressurise the system, before opening the bleed screw and do this every time. It keeps the air bubbles really small and easier to remove.

- after bleeding, cable tie the lever hard to the handlebars overnight

 

Except letting the MC run dry we did everything as advised here and in the videos; We did pump the brake lever every time and I also cable tied the lever overnight which did in fact return the hardness of the lever to it's pre-bleed feel.

23 hours ago, Lone Wolf said:

Did he change your brake fluid to silicone? Do you have the container that was used?  If he changed to non-OEM fluid you would of course be aware of that for future brake work. Any DOT 4 could have been used for your bleed, there is no need to get rid of existing fluid when going back with DOT 4 from any manufacturer.

We used standard Brembo DOT 4. I bought 2 of these and also have 2 closed containers of racing spec oil that he brought for future use. Motul 6600 and another one that I don't recall but all are DOT 4.

21 hours ago, betoney said:

I agree with @BBB a simple flush would have pushed the old fluid out. - If your old fluid was due for a flush, simply hook up the hose to the bleed nipple and pump the lever until the fluid in the reservoir gets near the bottom, fill it with fresh fluid and repeat.  I run 2 full reservoirs of fresh fluid through to purge the old fluid and then fill it and bleed on the 3rd filling.

That is interesting! Do I understand correctly that the new oil pushes the old oil out without the two mixing while travelling down?

I will do as you suggest and run another 2 reservoirs to make sure that all the air is out. I don't think there is a bleed nipple on the OEM (by brembo) MC on the GT, can anyone correct me if I'm mistaken?

Edited January 26, 2021 by petshark

[peteinpa]

11 hours ago, kilo3 said:

Wish brake fluid could still be tinted. What a stupid law that was.

Never heard this one.  I love it clear, then you can tell how bad it gets when it darkens.

[kilo3]

Just now, peteinpa said:

Never heard this one.  I love it clear, then you can tell how bad it gets when it darkens.

You could alternate between super blue and clear, that way it was stupid easy to see when you flushed your lines.

[koth442]

1 hour ago, kilo3 said:

You could alternate between super blue and clear, that way it was stupid easy to see when you flushed your lines.

I'm still clinging onto my last can of blue... there isn't much left though

[Lone Wolf]

5 hours ago, petshark said:

... all are DOT 4.

... Do I understand correctly that the new oil pushes the old oil out without the two mixing while travelling down?

It doesn't matter. All DOT 4 is compatible. 

Mixing is unimportant, compared to bleeding the system dry. Bleeding the reservoir dry is an "oops".
As others have said, if you want to pull some of the fluid out of the master cylinder before commencing the bleed you can pull a lot of it out with a syringe or "turkey baster". Then fill with new fluid and start to bleed it out.

Edited January 26, 2021 by Lone Wolf

[Lone Wolf]

41 minutes ago, koth442 said:

I'm still clinging onto my last can of blue... there isn't much left though

Once a container of brake fluid is open, the clock starts ticking on shelf life.
Dave Moss says if you don't use it within 3 months to toss it (due to absorb moisture from atmosphere).

[kilo3]

20 minutes ago, Lone Wolf said:

Once a container of brake fluid is open, the clock starts ticking on shelf life.
Dave Moss says if you don't use it within 3 months to toss it (due to absorb moisture from atmosphere).

I'm so tired of hearing this.
Buy a refractometer and see for yourself. I bet you never see above 1% moisture in a previously opened can of the good stuff.
I think you can get those paper test strips too on the cheap.

[Lone Wolf]

1 hour ago, kilo3 said:

Buy a refractometer and see for yourself. I bet you never see above 1% moisture in a previously opened can of the good stuff.

Personally I will put that money toward a new bottle of brake fluid, fairly cheap.

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