Switching hydraulic lines on LX brake levers

[Daxiet]

I have downloaded the tech manual on the brakes in question, they have bleed screws so I may as well bleed anyway to ensure a happy cycle. But it would be fun to let him go wizzing down a hill to find he has no brakes. Would be good technical training .

 

I agree I will be very lucky if I do the swap without getting air in the system. I couldn't get hold of mineral oil today, so the activity is on hold, probably until next week.

 

Thanks all for the feedback. No noddy badge for me, far too many of them going around today, they've become like the Zim dollar.

[GoLefty!!]

 

 

Can I get the Noddy Badge please

 

Have swopped hoses manytimes without having to bleed the system afterward.

You may be required to top up he oil afterward but no bleeding required at all.

 

When swopping the hoses make sure you tape the hose to keep the open end higher than the caliper' date=' then no air will move toward the caliper.

 

Once the swop over is completed, a few pumps of the lever should sort out the air bubbles just below the master cylinder.

 

Done, go drink some whisky

[/quote']

 

 

OK, but this is my last one.

 

 

I'm just too concerned that those bubbles stay in the system.

 

Too many geniuses on this forum, now I'm out of Noddy Badges.

 

Please send some single malt.

 

 

 

 

 

 

 

 

 

No need for concern, just care. Keep the caliper below the level of the open hose and you're fine.

air will always try to settle at the highest point in the system.

Once done, give the lever a few squeezes, with the reservior cap open and you'll see the air flwo back in the reservior.

 

I only bleed brakes once a year to replace the oil. This is necessary because of oxidation of the oil due to heat. We ride lots of hills down here in the cape. Perhaps inJHB it is not necessary to bleed the system as often.

[Dirtbreath]

 

 

 

Can I get the Noddy Badge please

 

Have swopped hoses manytimes without having to bleed the system afterward.

You may be required to top up he oil afterward but no bleeding required at all.

 

When swopping the hoses make sure you tape the hose to keep the open end higher than the caliper' date=' then no air will move toward the caliper.

 

Once the swop over is completed, a few pumps of the lever should sort out the air bubbles just below the master cylinder.

 

Done, go drink some whisky

[/quote']

 

 

OK, but this is my last one.

 

 

I'm just too concerned that those bubbles stay in the system.

 

Too many geniuses on this forum, now I'm out of Noddy Badges.

 

Please send some single malt.

 

 

 

 

 

 

 

 

 

No need for concern, just care. Keep the caliper below the level of the open hose and you're fine.

air will always try to settle at the highest point in the system.

Once done, give the lever a few squeezes, with the reservior cap open and you'll see the air flwo back in the reservior.

 

I only bleed brakes once a year to replace the oil. This is necessary because of oxidation of the oil due to heat. We ride lots of hills down here in the cape. Perhaps inJHB it is not necessary to bleed the system as often.

 

Whaaaaat?! We have such big hills here we need to bleed our brakes DAILY!

 

[jroux]

Hijacking the thread but can anyone just give a quick explanation what the air bubbles do inside the oil? And don't just say the brakes fail, I gathered that much.

[Johan Bornman]

Hijacking the thread but can anyone just give a quick explanation what the air bubbles do inside the oil? And don't just say the brakes fail' date=' I gathered that much. [/quote']

 

It causes what I'd like to call, predictive erratic behaviour.

 

The brakes are initially soft, but if you pump the lever, it firms up. If you let go and brake again 30 seconds later, the brakes are soft again and needs some pumping before working correctly again.

 

It's awful.

 

 

[bustthesickness]

As air (unlike the hydraulic fluid) can compress, this makes the

brakes feel really spongey and powerless. Any air bubbles left in will

also expand with braking heat and lock the system up very quickly. Fading occurs when the brake fluid

inside a hydraulic caliper boils.  An important characteristic of

brake fluid is that it is incompressible.  When a brake fluid boils,

gas is formed within the system that is compressible and any lever stroke

available goes toward compressing the gas instead of generating brake power.  Interestingly

enough, when a fluid is under pressure, it is very difficult for the fluid

to boil.  If a brake system is under pressure, the fluid temperature

can rise above the boiling temperature without the fluid actually boiling.  Once

the pressure is released, the fluid will instantly boil and fade will

occur.

 

 

 

[jroux]

Thanks guys, great explanation.