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-   -   help! brakes again (http://www.risingsun4x4club.org/forum2/showthread.php?t=1609)

subzali 06-14-2006 09:38 PM

help! brakes again
 
:rant:

Brakes don't behave ANY differently than before.:rant: I got a NEW OEM AISIN master cylinder from Burt this afternoon, bench bled it, installed it, bled the brakes, and gave it a try.

Pedal travels fairly far on the first pump (6-8 inches), and stops the truck pretty fast when moving. Second pump travels less, harder to stop the truck (feels more like braking with the engine off), third travels less etc.:rant: (basically it is pumping up)

Engine idle gets jumpy and idles down slightly when pumping the brakes at idle just sitting in place. Pedal swooshes somewhat like before.:rant:

We think there's still a little air in the lines, but not much because the pedal isn't squishy, once it gets hard it's hard.

Questions:
1) Does it sound like the booster I yanked off of the FJ60 is also a bad one?
2) If the booster is bad, is there still a danger (as I guess there was before) of running 5 and 6 cylinders lean and burning stuff?
3) Cany somebody or everybody with an FJ40/55 describe what their brakes do? Or confirm if they observe the same behavior from their brakes?
4) Did I miss something in the bleeding procedure?
5) I had to cut the rod on the new booster, does it sound like I may be having a conflict with that?
6) Any other ideas? Wheel cylinders seem to be fine, no leakage or anything...:rant: help:(

Shark Bait 06-14-2006 11:32 PM

Probably try bleeding the system again. Have you adjusted the rears?

subzali 06-15-2006 06:04 AM

Ooh, good idea :thumb:

I was planning on bleeding the system again anyway, but I've never adjusted the rears so I should probably do that.

A couple other things I thought of: is it possible that the check valve could be clogged or something? Or the hose that runs from the booster to the engine is clogged? I'll play with the pedal travel and pumping up, but I'm really concerned about the engine idle changing while I'm pumping the brakes, I think that has something to do with the booster.

Rzeppa 06-15-2006 10:10 AM

Quote:

Originally Posted by subzali
Engine idle gets jumpy and idles down slightly when pumping the brakes at idle just sitting in place. Pedal swooshes somewhat like before.

We think there's still a little air in the lines, but not much because the pedal isn't squishy, once it gets hard it's hard.

Questions:
1) Does it sound like the booster I yanked off of the FJ60 is also a bad one?
2) If the booster is bad, is there still a danger (as I guess there was before) of running 5 and 6 cylinders lean and burning stuff?
3) Cany somebody or everybody with an FJ40/55 describe what their brakes do? Or confirm if they observe the same behavior from their brakes?
4) Did I miss something in the bleeding procedure?
5) I had to cut the rod on the new booster, does it sound like I may be having a conflict with that?
6) Any other ideas? Wheel cylinders seem to be fine, no leakage or anything...

Answers:
1) Yes, or a cracked/leaky check valve. Most likely the booster though, if the check valve were cracked and leaking you'd have a vacuum leak all the time, not just when you press the brake pedal.
2) Yes. Been there done that, burned #5 exhaust. Head job=$$$
3) I press on my brakes, I slow or stop, depending on how hard I press. I do not experience any change in idle. Change in how the engine runs when you press down on the brakes is a sure sign of a vacuum leak at the booster.
4) Probably not. Your description does not sound like you need any additional bleeding.
5) No, you usually have to adjust the rod length whenever a new master is installed.
6) Yes, adjust your rear cylinders. Having braking at a higher pedal position on the 2nd or subsequent pumps is always a sign that the cylinders need some adjustment.

Rzeppa 06-15-2006 10:18 AM

Quote:

Originally Posted by subzali
I was planning on bleeding the system again anyway, but I've never adjusted the rears so I should probably do that.

A couple other things I thought of: is it possible that the check valve could be clogged or something? Or the hose that runs from the booster to the engine is clogged? I'll play with the pedal travel and pumping up, but I'm really concerned about the engine idle changing while I'm pumping the brakes, I think that has something to do with the booster.

Your description does not fit with air in the lines. Air in the system makes for soft pedal.

A clogged check valve or vacuum hose would mean that your booster would not operate. You probably already know the procedure to test if the booster is operating, but to reiterate: Engine off for at least several minutes so there is no residual vacuum for the booster. Press brake pedal until it stops at some point. Maintain same, even pressure with foot on pedal, then start engine. Pedal should now travel down some with the same, even amount of pressure with your foot on it.

A change in how the engine runs when you press the brake pedal is almost always a vacuum leak in the booster. They can be rebuilt and kits are available. I haven't done it (yet), but there is a rebuild procedure in the manual.

mhdsummers 06-15-2006 10:29 AM

What Jeff said. My guess is your booster too. I will only add that I noticed a very slight change in idle speed when my cruiser was a two or three pumper and my booster does not leak AFAIK. After I replaced the master cylinder, adjusted, and bleed, I no longer notice the change in idle. Buy one of those vacuum pump dealies and test your booster. It should hold a vacuum. Also, I dont think the line from the booster to the intake manifold could be clogged since there should be nothing in your intake to clog it but you might as well check.

subzali 06-15-2006 09:35 PM

I tried the testing procedure last night and everything checked out okay, just like it was supposed to. I still get the idle change when pumping though, so I think I'm either going to get a new booster or get the vacuum dealy and check it out, if it's not too expensive. Adjusted one of my rear drums tonight, it seems like that made a difference.

Jeff - I read your writeup and you say there are 8 places to bleed the brakes and 8 places to adjust the wheel cylinders. I only found one place on each of the rear drums to bleed the brakes, which would mean if you have four wheel drums you'd only have 4 places total to bleed your brakes. Maybe I'm missing something?

When I tried to adjust the shoes out, only one of the four adjusters would turn. All the others were...(jammed, stuck, all the way extended,...:confused:)...what does that mean? Do I need to replace wheel cylinders now? Or does that just mean that the shoes are all the way against the drum already? I could BARELY hear dragging on either side (that Lockright is loud compared to brake dragging :D)...so any thoughts there? Thanks again guys, I'm getting it figured out...

Shark Bait 06-15-2006 09:46 PM

Matt,

It's likely your wheel cylinders are frozen. Rusted and won't move. You could try pulling the drum off and going at it from the front. Ultimately, you'll want to either repalce or rebuild the wheel cylinders. If you have the money, an alternative is to install rear disc brakes. TSM in Castle Rock makes a nice kit. Complete it's around $500 including loaded GM calipers. Rebuilding the cylinders is a PITA, but probably the cheapest way to go. If you have one that's really bad you'll have to replace it. You probably won't know until you have it apart. When you're in there you might want to replace the brake shoes. That's why it's worth considering the disc conversion. Jeff will probably pipe in and say he thinks drums stop better. Discs aren't bothered by being wet like drums are. Once you've converted to discs it's less maintenance because there is no adjusting involved.

HTH

Hulk 06-15-2006 11:28 PM

Matt,

Earlier all-drum brake 40s had two wheel cylinders per wheel -- that's what I had on my old '75. The later models had only one wheel cylinder per drum. They probably started this in '76, when the 40s went to discs up front.

So 4 places to bleed and adjust is correct for your model year.

/we have three Matts in this club. Maybe more.

mhdsummers 06-16-2006 12:18 AM

I have a number of wheel cylinder rebuild kits. Not sure how many. If you are interested email me at mhdsummers@hotmail.com.
I will be going through Golden tomorrow at 9am and then again in the late afternoon.


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