YABBQ - Yet Another Brake Bleeding Question

[emmotto]

color me frustrated..

Had small leak at joint of left front brake hose and wheel cylinder. Like that for months but eventually pedal started getting soft and finally was pumping up significantly. So I replaced the wheel cylinder AND the hose on the idea that maybe the PO cross threaded the hose into the cylinder.

So now I can't bleed the brakes.

Have tried twice - bled all 4 wheels, started with the back - no air visible there, pulled the wheels and did the fronts. Got lots of air bubbles both times. Once bubbles stop, get a firm pedal that pumps just a wee bit. Put the wheels back on (take maybe 15 minutes) and pedal goes back to the floor again and pumps up.

I've checked the adjusters and they're all ok - tight and then back off 2 clicks.

Bad (new) wheel cylinder? Bad connection at brake line to hose? Bad connection at hose to cylinder? Something else? I've checked all my connections (despite including them in my questions above) and all look ok. Where can the air be mysteriously entering?

I'm considering putting my original wheel cylinder back in...

And on another note - I got a set of AllMakes brake shoes for front brakes from another vendor (RN is completely OUT of shoes until sometime mid January 2013) and they are too WIDE. When I tighten up the screw that holds the drum on they lock up the drum. Back off the screw and the drum turns. I ran a die grinder (Dremel) down the side of the shoes along the plate under the brake material and that didn't help. The size is close - these are itsy-bitsy just a bit MORE than 2" and my old shoes are itsy-bitsy just a smidgeon LESS than 2" wide. Obviously enough to make a difference...

Is it ok to grind down the side about a 1/32 or 1/16" (wearing a face mask of course)? Or do I just give them up as a bad business and cheap POS?

I've got a friend who is extremely Rover savvy coming by maybe tomorrow to lend a hand - maybe third time will be the charm...

[albersj51]

Regarding brake shoes, avoid All makes, they don't fit; too thick. If RN is out, call George at RDSparts.com and ask for Mintex shoes. They will work. You could grind the all makes, but I would return them and get the mintex.

[o2batsea]

I've checked the adjusters and they're all ok - tight and then back off 2 clicks.

No set them so that you can barely turn the (elevated) wheel by hand.

[emmotto]

No set them so that you can barely turn the (elevated) wheel by hand.

That would one click tighter - will do. Trying again tomorrow.... Thanks


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[o2batsea]

The difference between the brakes being on or off is a mere few thousandths of an inch. When they are adjusted properly and there is no air in the lines you should have a firm pedal without pushing very much at all. If the pedal is going to the floor, you have air. Bleed the cylinder farthest away from the Master Cylinder first, which I guess is the left rear, then the RR the RF and then the LF (think that's right). Do not let the level in the fluid reservoir fall too low when you do this or you will suck more air into the lines.
You really need two people for this, one to push the pedal and one to crack open the bleeders. best of luck. keep trying.

[stomper]

Just a quick thought, you did put the brake shoe springs on correctly didn't you? Otherwise you will never get a good pedal feel with one pump. Aside from that, I have nothing to add that others haven't already suggested.

[emmotto]

Just a quick thought, you did put the brake shoe springs on correctly didn't you? Otherwise you will never get a good pedal feel with one pump. Aside from that, I have nothing to add that others haven't already suggested.

AFAIK - bottom spring goes from leading shoe web to trailing shoe web using topmost holes. top spring goes from pin on leading shoe (behind web and in front of adjuster) to hole in trailing web with long part of spring wire on the leading side going to the pin.

[emmotto]

The difference between the brakes being on or off is a mere few thousandths of an inch. When they are adjusted properly and there is no air in the lines you should have a firm pedal without pushing very much at all. If the pedal is going to the floor, you have air. Bleed the cylinder farthest away from the Master Cylinder first, which I guess is the left rear, then the RR the RF and then the LF (think that's right). Do not let the level in the fluid reservoir fall too low when you do this or you will suck more air into the lines.
You really need two people for this, one to push the pedal and one to crack open the bleeders. best of luck. keep trying.

Agreed - but it's a LHD truck so furthest from the master is the rt rear, and then so on and so forth. First pump - pedal goes to the floor (brakes no worky), 2nd pump - pedal stops 1/3 from floor (brakes now worky), 3rd pump - pedal stops 2/3 from floor (brakes worky), 4th pump - no change from 3rd pump. Rinse and repeat... (next application of brake is the same sequence).

Yet, when adjusting and bleeding the brakes with wheels off, pedal would stop about 5/8 of the way off the floor on first pump and maybe pump just a little to about 2/3 - 15 minutes later back to the scenario described above. To be clear though, I did the bleeding with the Allmakes brakes in one wheel and the removed them and replaced with old shoes after I realized they wouldn't work w/o extensive modification. But I readjusted after swapping (didn't re-bleed) and seemed OK.

Tim Smith lives near by me and is kindly coming by later today to help me diagnose the problem.. I will report back later.

[o2batsea]

Agreed - but it's a LHD truck so furthest from the master is the rt rear, and then so on and so forth.

Um I think you'll want to rethink that statement. Look at the rear axle. Which side has a longer pipe coming off the t connector? That will be your furthest away, plumbing-wise.

[emmotto]

You are right! It is a longer run to the left side rear than to the right side.


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[emmotto]

Ok fixed.

2 problems -

1: brand new wheel cylinder was defective...

Leaked - upon inspection was full of metal scarf from machining and piston cup cocked. Was leaking brake fluid into drum. That's where the air was coming from.

2: top spring was put in wrong ( by me )...

I had the spring in front of the adjuster not behind it and pulling on the trailing shoe instead of attached to the post on the backing plate. That's where the symptoms of mal-adjustment were coming from.

Thanks Tim!



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[emmotto]

Just a quick thought, you did put the brake shoe springs on correctly didn't you? Otherwise you will never get a good pedal feel with one pump. Aside from that, I have nothing to add that others haven't already suggested.

And yes - Stomper - you were right!


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[stomper]

We have all been there, Heck, why do you think I asked if it was installed correctly?

[I Leak Oil]

OK, where did you buy the cylinder from and what brand?

[emmotto]

OK, where did you buy the cylinder from and what brand?

umm... our hosts... part#PLB536 - bought 10/4/12.

I gave the cylinder to Tim who is thinking of looking into having a wheel cylinder steel sleeved as an experiment, so I won't be returning it to RN. I'll have to go rooting thru the garbage to find the box with the maker's id but I believe it was AllMakes..