Mushy brake pedal

[aboyandhisdog]

I just finished putting new shoes on all four brakes.  I didn't open up the hydraulic brake lines for any reason.  But now I have a mushy pedal that isn't coming up.  I double checked to make sure that all wheel cylinders were engaged correctly with the shoes and everything looks good.  Why would my brake pedal act as though there is air in the system even though I never opened the system up?   I have 11 inch self-adjusting brakes from maybe a '72 CJ5 (I think).  I suppose the fix is to bleed everything but thought I'd better see if there could be something else I should look at first.  Thank you!

[F Bill]

Are the brakes adjusted correctly ??  If one brake is way out of adjustment the pedal can feel soft... Did you have all the shoes off at the same time or did you do a wheel at a time? If you had nothing to hold the wheel cylinders compressed it is possible air got in one that way....

[aboyandhisdog]

Bill,  I did get the shoes adjusted correctly as best I can tell.  I did the two fronts first and then took a drive and all was well.  Came home and decided to do the rears too.  On one, the pin (link)  that goes into the wheel cylinder and presses against a shoe did slip out but I placed it back in and put the dust boot back in place.  Do you mean that if a pin slips out I can get air into the system?  That would explain my problem but I don't see how it could happen.  The link just presses against the piston which is sealed.  Maybe the piston twisted when it came out at an angle???  Well, anyway, do you feel that the fix is to just bleed the system or do you think I have further problems?

[F Bill]

Some wheel cylinders have a light spring inside that pushes on the cups, If that pin fell out, it is possible IF you have that type of cylinder, that the cup may have moved enough to let in some air.

In any case, bleeding sounds like it might be the thing to do.. Try gently tapping the ends of the bleeders before using a wrench on them if you think they might be siezed , even a little heat on them has been known to bust rusty ones loose. Also make sure you use a well fitting wrench on the bleeders, like a 6 point closed end or a socket, Once you have them free, then use whatever is handiest . If they were rusted, bring one to the parts store and get new ones, a little never seez on the threads may help prevent seizing again.

If you want to rule out adjustment issues , tighten the brakes to the point you can't adjust them any tighter,then see how hard the pedal is. If it is soft, go ahead with your bleeding plan. Make sure to back off the adjusters some before you drive it.

[aboyandhisdog]

Bill, this is a big help!  When I adjusted them, I just adjusted until I felt a very slight amount of drag and after securing the wheels, they spun nice and free.  Maybe I should snug the adjusters down, check for pedal firmness, then back off adjusters until free.  Then bleed them if needed.   I'll try this.  Thank you.

[aboyandhisdog]

Okay, here is where I'm at...I put on all new shoes, drums, wheel cylinders, front and rear, and self-adjusters and brake lines on the fronts (11" X 2" brakes).   I bled all of the brakes 'til the lines were clear with brake fluid - no bubbles.  Filled up the master, cap on tight, ready to roll.  Wait, what's this...still a mushy pedal!  Yikes!  Now what, I don't see any leaks.  I didn't change out the master cylinder yet as it worked fine before I began this little project.  

1)  Can I bleed a wheel at a time while leaving the cap on the MC or do I HAVE to remove the cap?  I ask this just as a matter of convenience - it would be convenient to have the cap on after bleeding one wheel so that I can see whether it did the trick after closing the bleeder screw.  

2)  How do I determine if the MC is the problem?  Would it leak?  If so, where?  I have a MC I can put on and will some day but am trying to troubleshoot other things first.  

Any input on brakes would be much appreciated.

[F Bill]

It might be time for a quick picture of your brakes with the drum off.....The bleeders are positioned correctly at the topmost point of the wheel cylinder, I assume.

Something isn't right, just what, I need to actually look at what ya have there.

[F Bill]

If you can plug the outlets of the master somehow, you can see if the master itself is mushy...Yes you can bleed with the cap on. I have used brake line that has been crimped over to plug the fittings...you will have to bleed air out still by cracking the line, then pushing down the pedal then tightening the line, once or twice to test it.

It may leak at the pushrod end, you would see fluid after pulling back the rubber boot. Or it may leak internally and no way to see that.

Things I would be looking for in a pic  are proper contact of the shoes to the  wheel cylinder , holddowns properly attached, shoes centered, adjusters in right place, parking brake mechanism in correct place, etc..  

Are shoes arced to fit the drums or are they only contacting a little bit? Not bent or anything like that?

[aboyandhisdog]

Thanks Bill.  I've read and re-read the bleed procedures...the Haynes manual says that the brake pedal must be depressed when you tighten the bleeder.  The Jeep Universal manual makes no mention of this and it would seem that the pedal need not be depressed.  Using clear tubing and observing that there are no more air bubbles in the line, what difference would it make if the pedal is not depressed?  I am working alone so it is hard for me to depress that pedal and tighten the bleeder at the same time.  Maybe this is the cause of my problem???
Thanks!

[F Bill]

When you let up on the brake pedal before you tighten the bleeder, you can let air right back into the wheel cylinder.  If you are doing this by yourself, you will need to improvise. Either use a stick to hold the pedal down, or use one man bleeders, or go buy a pressure bleeder. Mityvac makes a setup for bleeding by yourself too. All have their pros and cons, Sometimes a bleed screw fits poorly and leaks air at the threads, and vacuum or one man bleeders will not work well unless you grease up those threads. Sometimes only a pressure bleed or two man bleed will work.

If you are using a hose into a bottle, and letting up on the pedal, you may still be letting air into the bleeder via the threads ......Try not loosening the bleeder so far and greasing the threads. Also you can get a leak where the hose pushes onto the bleeder. And of course, if the end of the hose is sticking out of your brake fluid it will let in air.

[Carls_jeep]

I never have trusted the one man bleeders. You MUST close the bleeder while the fluid is still coming out of the bleeder or just as it begins to stop flowing. Air can be drawn back into the wheel cylinder very easily. Using a stick to hold the pedal down won't work. As soon as the bleeder is opened the pressure drops to 0 and there is no flow to eliminate air in the cylinder. You have to push the pedal down to exhaust the air from the cylinder otherwise it stays in.

The one man bleeder kits work ok if the drain bottle has enough brake fluid to cover the end of the hose sticking in the bottle. I still don't like to use them. Wait for someone to help you bleed the brakes and be sure to instruct them to tell you when the pedal reaches the floor so you can close the bleeder fitting immediately.

[aboyandhisdog]

Thanks Carl,  I just did them again and this time was VERY careful to watch the lines for air and I did use a stick to hold the pedal down and then closed bleeder quickly.  I feel pretty sure all air is out but can't guarantee it.  Anyway, question...Assuming the procedure goes as it should, when does the pedal "firm up"?  Should it stay firm as soon as all air is out or will it take driving it?  I had the drums on for the procedure and I'm thinking I'll put the tires back on and drive it in the driveway.  Do you think this might help get that pedal firm again?  I'm afraid my next stop will be to the neighborhood garage!

[Carls_jeep]

When the air is out of the system the pedal will be firm. If the master cylinder is above the lines and wheel cylinders the air will sometimes work it's way back to the master cylinder but don't count on that happening.

If it's still mushy get someone to help you bleed the brakes. It's important to move the pedal through it's full travel to remove the air.

If you can't get a helper then get a GOOD bleeding kit. It's important to have a very good check valve in the line in the kit and fluid in the catch bottle with the line in the bottom of the bottle.

[dtgolder]

Try http://www.speedbleeder.com/

(sorry just typed a long reply and lost it when I switched windows...darn iPad)

Anyway have had great successs with these things along with the tubing and a bottle.

Mushy brake pedal=air in the lines or soft/need to be replaced seals.

Also, when I need to change shoes I always bleed at the same time. I figure the fluid is old enough then to warrant a flush (and I feel safer adhering to this practice)

[aboyandhisdog]

Thanks DTG, that "speedy bleeder" looks good and something I'm considering if the following doesn't work...

Carl, I think you may have discovered my problem when you mention that:   "It's important to move the pedal through it's full travel to remove the air."   A while back I modified my brake pedal to make driving a bit easier with winter boots on.  I cut down the right side of the pedal a bit to make it narrower and I cut about a 1 1/2" section out of the middle of the pedal shaft in order to shorten it a bit - to make driving a bit more comfortable by keeping my heel on the floor and not having to lift my foot from accelerator to brake.  This worked great so long as I have not needed to bleed the brakes.  But now that I do, I can see that the pedal will bottom out on the floorboard and that it is clearly not traveling the full distance.  So I am ordering a new pedal today.  I think this will solve the problem and I will let you know.  Your help has been invaluable - thank you!