Brake bleeding bubbles

Message

wapam · #1 Unread post by **wapam** » Thu Jun 07, 2007 5:08 pm

I bled my brakes and noticed at first bubbles about 1/8" in diameter coming out the tube then some about the size of a pin head (very, very small). Do I need to keep pumping until these very small bubbles are gone or do I just need to get the bigger ones out?

Thank you.

#2 Unread post by **Sev** » Thu Jun 07, 2007 5:37 pm

Get ALL the bubbles out ideally. Every little bit of air that's in there will need to be squished before you start to actually brake. So the more you get out the better your brakes will be.

wapam · #3 Unread post by **wapam** » Thu Jun 07, 2007 5:45 pm

[quote="Sev"]Get ALL the bubbles out ideally. Every little bit of air that's in there will need to be squished before you start to actually brake. So the more you get out the better your brakes will be.[/quote]

Thanks Sev.

Any idea how long it should take to get all the bubbles out? Seemed like I pumped and pumped but never did get all the tiny bubbles out. Should I just keep pumping and pumping?

slimcolo · #4 Unread post by **slimcolo** » Fri Jun 08, 2007 11:23 pm

Tiny bubbles in my brakes;
Kinda scary gives me the shakes!

( to the tune of Tiny Bubbles in my Beer)

tim conroy · Sat Jun 09, 2007 2:29 am

Keep going till all the bubbles are out.It may take a while and a couple of can of fluid if you have not done it in a while.Did you put some into a small container first and then put your bleeder hose in the brake fluid to keep it from backing up?You need to do this to keep the flow going in one direction.

wapam · #6 Unread post by **wapam** » Tue Jun 12, 2007 4:06 pm

Well, here is what I did, let me know where/if I went wrong:

Removed master cyl. cover.

Attached clear hose to left caliper bleed valve and put other end in container with enough brake fluid in it to cover end of tube.

Pumped brake lever a few times, held it and opened the bleed valve.

Continued to pump lever and fill mast. cyl. until clean fluid and no bubbles were coming out of tube.

Held in lever, closed valve.

Repeated on other side and filled mast. cyl. to proper level.

My concern is that the brake lever seems to travel a long way before the brakes start to engage. I would guess that total travel of the brake lever at the end is around 2 1/2-3" and the brake lever stops less than an inch from the grip. The brakes seem to work great and definately stop the bike so maybe all this concern is for nothing.

Here is an article that says you don't have to keep opening and closing the bleed valve:

Motorcycle Repair: brake bleeding

(Last paragraph of "Brake bleeding 101)

Anyway, thank you for reading this.

wapam · #7 Unread post by **wapam** » Wed Jun 13, 2007 11:28 am

Anything wrong with my procedure?

Thank you.

BuzZz · #8 Unread post by **BuzZz** » Wed Jun 13, 2007 5:25 pm

Your procedure sounds fine. I would go back and bleed both sides again, just to be sure. Air can hide in crossover lines and other fittings so rocking and moving the bike around between bleedings can sometimes help.

What kind of bike is it? Cruiser levers move alot farther than sportbike levers. As long as you're not squeezing it to the bar and the brakes are working well, you should be safe.

thespirit · #9 Unread post by **thespirit** » Fri Jun 15, 2007 5:06 pm

If I am changing lines, I will sometimes try to bleed them for a while, then let it sit overnight with the master cylinder cap off (and a rag over it to keep crap out) and tap the brake lines once in a while... This seems to help get a lot of the bubbles out as they will work their way up to the master cylinder.

Another good way to bleed brakes is by using a brake bleeding kit.. It's nothing more than a hand pump with a canister under it. You fill up the canister with fluid and then pump it into the caliper up to the master cylinder. It seems to work the few times I have tried it.

wapam · #10 Unread post by **wapam** » Wed Jun 27, 2007 12:21 pm

Well, I have bled my brakes three times and the lever still feels mushy and seems to travel a long way before engaging the brakes. When it does engage, the brakes work great, stop the bike no problem. The lever doesn't feel right, but the brakes work fine. Maybe this is normal for this bike???

I have pumped new fluid through the system and I see no bubbles coming out. I have let the bike sit overnight with the brake lever taped half way engaged and the MC cover loose.

Are there any "tests" to tell if the problem is in the master cylinder, calipers, or brake lines other than trial and error??

Bike is a '85 Nighthawk 650.

Thanks for all your help.