A little backgound. Before I did my toy axle swap. I had pretty bad on the Samurai. They worked, but it took a quick double pump to get them there. I just got used to it and thats how I'd stop. Now after my Toy axle swap, I got the brakes back to the same place...taking a quick double pump to get them firm. Let off the brakes completely and then put them back on and the medal is mush. While pumping the brakes I had my hood up and good hear noises from the master cyclinder (sort of a moan). So does this mean the master cyclinder is going out the door and I should replace it? I know my options on replacing, but don't won't to fix something if it's not broken. Just wondering if its improper bleeding or something else.


Koko

2 quicky ways to check the master cylinder. With the cover off (if you dont have a master with a remote resevoir and can see the little holes in the bottom) step on the pedal. You should get a little squirt coming up. Second is to pump up the pedal and then stand on it. If the pedal goes down slowly the master needs rebuilding or replacing. 75% of the time though, if the pedal gets firmer when you pump it it still needs to be bled. Easiest way I have found is to ues a piece of clear hose on the bleeder and always start from the point furthest from the master. While youre at it keep bleeding till the system is flushed. Brake fluid IS supposed to be changed regularly.

Something I noticed on mine when I did my yota axles. With the rear pinion turned up a bit, the wheel cyls are at a pretty steep angle. I think air gets trapped on the high end of the cyl. While my brakes are a "little" soft, I don't have your problem. Have you adjusted up the rears? If not, you could be using the first stroke to get the shoes to the drum and the second stroke to do the work.
Travis..

Thanks for the suggestions guys. I've already mannually ratcheted the rear pads down to the drum. I've used a hand pump bleeder to do these and this is the best its gotten. It was like this before the swap as well. I'll try bleeding them again. Next I'll replace the master cylinder and if its not that.....I don't know what, but I'll figure it out somehow! :p


Koko

What year is your rig? Does it have the valve on the rear frame that has 2 lines in and 1 line to the axle? If so, it is possible there is a problem with it. It may have an internal leak letting fluid swap circuits. Also, my point about the slave cyls pointing up was that you would need to either raise the rear of the rig, rotate the axle, or park on a serious decline to make the cyl level to get all of the air out.
Travis..

Also, my point about the slave cyls pointing up was that you would need to either raise the rear of the rig, rotate the axle, or park on a serious decline to make the cyl level to get all of the air out.

It has been my experience that I can 'bleed' the rears by having a helper PUMP HARD when I open the bleeder as far as I can with one bite of the wrench. Even though there is a bubble stuck in the top corner, the extreme turbulance blasts it out after a couple of tries.

Something to consider about the soft (mushy) pedal..

you could be using the first stroke to get the shoes to the drum and the second stroke to do the work.

If you changed the brake cylinders for larger one the Sammi master cylinder may not be large enough to supply enough fluid in one pump. I think the moaning sound you hear is the valve in the bottom of the reservoir. This happens when you are sucking fluid out, or when fluid is being pushed back in when you let up on the brakes. The master cylinder may have to take fluid out of the reservoir each time you use the brakes. This is not normal, but is true when the brakes aren't adjusted, or possibly in your case, when the wheel cylinders' volume is too much for the master cylinder.

GeoB,

Very informative. Thanks. I'll be swapping out the MC and trying the two person bleed method there.



Koko

Something to consider about the soft (mushy) pedal..
If you changed the brake cylinders for larger one the Sammi master cylinder may not be large enough to supply enough fluid in one pump. I think the moaning sound you hear is the valve in the bottom of the reservoir. This happens when you are sucking fluid out, or when fluid is being pushed back in when you let up on the brakes. The master cylinder may have to take fluid out of the reservoir each time you use the brakes. This is not normal, but is true when the brakes aren't adjusted, or possibly in your case, when the wheel cylinders' volume is too much for the master cylinder.

I know the stock M/C is sufficient once you get all of the air out of the system. I'd throw on a new one just to be safe. Bench bleed the heck out of it, then bleed the system in the oem order specified. My brakes kicked f'n ass w/ Toyo axles on 32's. I could lock 'em up on the freeway if I tried.

Ok....I give, whats does bench bleed me?

Edit....did a quick search and found this: Bench Bleeding (http://www.pirate4x4.com/forum/showthread.php?t=257228&highlight=bench+bleed)


Koko