De-gassing DOT 5.1 Fluid?

Anyone bleed their brakes without degassing the fluid? Does it make much difference?

I know in theory that it *should* make a difference but can’t help but think it’s a faffy waste of time.

is that where you pressurise the system to force the air out?
I’ve done this, but found if you do it too hard you force oil past the seals.
bleeedin Avids.
not literally.

Not an expert, but trapped air is the enemy of hydraulic brakes. It takes a couple of minutes to do, so why not?

I know why I should, just wondering if anyone’s got any experience of NOT de-gassing their fluid.

I have never de-gassed brake fluid on any of the brakes I’ve bled. Be it cars, bike or cycles, 20 yrs in the motor trade.

For the time it takes yes, wether it makes a difference im not sure, say with avids you draw back on the caliper siringe and you draw air from the system, you’ve air in the fluid/siringe!

Never even heard of it before now!

I’d never heard of de-gassing til I started doing pushbike brakes. I’m not sure it makes any difference, but, it doesn’t hurt to do it I figure. (degassing half a litre of fluid to do the car would be a bit more of a hassle!)

I put the brake fluid in a vacuum chamber once, and set the chamber to a pressure of 0.1mtorr. Lots of bubbles came out of the fluid during the degassing. I then used that fluid to bleed my brakes with….. Can’t say it was actually noticable when riding the bike though.

“I put the brake fluid in a vacuum chamber once…” this is why i love STW participants.

So come on then, how do you de-gas during a normal bleed?

De-gassing for a normal bleed is just when you take the syringe of fluid, close the stopper and draw the plunger out a bit. The resulting vacuum forces gases dissolves into the fluid to come out. You then get rid of the bubbles as you normally would and then resume.

Since my last post I’ve bled both of my brakes, did one de-gassed and then left the other as it was from the bottle. It seems that for Avid brakes (where you bleed by negative pressure) the de-gassing is worthwhile as when you’re bleeding the caliper/lever you need to pull on the plunger just as you would when de-gassing. If you haven’t de-gassed already you get those bubbles during the bleed anyway.

IIRC someone mentioned popping it in the freezer degasses it..