Topic: Front Caliper Woes

[campbmic]

My roomate has an 81 Suzuki GS450 that he has been rebuilding the front caliper and putting a stainless steel brake line in. The brake system looks very simiar to mine. When we try to bleed the brakes we pump the front brake a ton but there is no resistance building up. When I unscrew the bleeder nipple and pump the brake it does make an in and out sound. We have plenty of fluid in the master cylinder. What would cause this?

On a side note, my bleeder nipple is completely stripped and rusted, I can't open or close it or even remove it. Whats the best way to remove it so I can install a new one?

[NickC]

There is a large bubble in the lines. Crack the bleeder, hold your finger over it, and have your buddy pump. This will allow air to escape and your finger getting sucked into it will keep it from coming back in.

On yours, use some PB blaster and vice grips......

[campbmic]

I tried that, I pumped it about 100 times and still absolutely 0 resistance.

[Spanner 1]

No fluid is getting out of the mastercylinder reservoir 'cos the teeny-weeny hole in the res. ( that allows fluid into the line and caliper ) is blocked..... it's the hole nearest the brake line and must pass the smallest sowing needle in your Mom's sewing box thru' it. Don't use anything bigger. Because this is the supply passage from the m/cyl., it only allows a very slow feed of fluid into the empty lines and has to fill the brake caliper too, so it takes AGES to 'seep' down to fill all of it even with vigorous pumping. Only quick-fix IMO is a vacuum bleeder to suck the fluid down...........

[campbmic]

Do you mean when Im looking into the master cylinder its the hole nearest the brake line? And I just poke it?

[Spanner 1]

Yes, the one nearest the brake line.... looks the same size as the other hole, but narrows down to a very small opening into the cylinder.
You can see it with a magnifier glass..... just verify it is not blocked ( common problem ) by poking a smallest size needle into it. BTW, don't pull on the lever with the needle in there as the cup seal passes under the hole as soon as you move the lever ( i.e., needle tip would rip the seal )....... try that and be careful not to enlarge this opening any.

[75cb550 (kyle)]

i had the same issue on the goldwing... definately check the return hole.
if you have a huge air bubble, you can fill it up to the tip top and barely crack the bleeder over night it should gravity bleed. may even let the caliper hang since you have the SS line. i would check it from time to time to make sure it doesnt run empty....
reminds me of bleeding the slave cylinder on mid '90s Ford Ranger.... bubblesssss

[campbmic]

Thanks! Poking fixed it

[Fabricator]

I tapped an old master cylinder cap 1/8" NPT and installed a schraeder valve....  No more air bubble woes when fed a quick shot of compressed air. 

Fabricator

[Spanner 1]

Thats fab, Fab.!