Spongy Brakes (Brake line replacement?)

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Here of late, I've had a spongy brake pedal from time to time and could actually push the pedal all the way to the stop, with some extra force. I've been thinking about replacing my brake lines with Slee SS lines. The kit he has on his web site appears to include three lines. Do you have to buy two of these to cover both axles? What's the third line for... LSPV?

Thanks,
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livelarg said:
I have them spongey brakes too. I have heard of it from others too. has anyone solved this problem?
My last 2 months activities on my 91: New pads (rotors resurfaced), new shoes (resurfaced drum), vacum bled 2x, gravity bled 2x (LSPV bled along with), 2 new brake cylinders, new master cylinder... still soft.

V. boost is good, so I guess it's as good as it's gonna get.

Cannot panic stop to save it's life, and barely holds on the trail.
 
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super90 said:
Hmmmmm. I would swear my front end has four soft lines.
Without looking at your truck, it's entirely possible. However, to compensate for a lift, the front axle requires two soft lines, the rear only one.

I highly doubt that your rubber lines are causing a soft pedal. It's much more likely you have air in the lines, and they are tricky to bleed. If you do replace the lines, you will have to bleed the system, and if you do it right you will definitely fix your spongy pedal.

-Spike
 
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I wouldn't discount the soft lines as a source- my left front line had deteriorated to the point that it would swell on application of pressure becuse it was seperating and fluid was expnding in the layers. Hard to see unless you're looking for it...

Brakes are still not where I want them to be, but that helped a lot.
 
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I think replacing ten year old lines is a pretty good idea, regardless.

I just replaced the front calipers and two of the four front lines and the pedal is certainly less spongy. Which item made the most difference? Hard to say, but I bet if I were to replace the other two fronts and all three in the rear that the pedal will be noticably more firm.

That's the square my chips are on.

Best of luck,

R.
 
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The front axle does have 4 soft lines, two between the frame and axle and two more, one going from the axle to the caliper on each side.

The slee kit only replaces the frame-to-axle lines, but when I replaced mine it did make a difference, even though my brakes weren't too bad to begin with.

The lines from the axle to the calipers seemed to be in better condition that the others. They are a little better protected where they are. Not sure if they are the same construction.
 
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Does anyone know the diam of the master cylinder of the 80 vs. the 100 and if they are interchangeable?

If the 100's is larger, then it may be possible to swap for a firmer pedal.
 
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Speaking of LSPV, I was looking at it last night and whereas my vehicle is relatively free of under carraige rust, that thing looks like it was scabbed off the Titantic. Your alls rusted up like that too?
 

powderpig

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The problem with the 100 series is that it uses a high pressure pump instead of a vaccuum booster to boost the pressure to the breakes. So I do not think this will help much with your idea of swapping one in patpend2000. I also agree that their is 4 soft line in front. If a brake booster has been off, it may of not been set properly, or even from the factory it may need a little adjsutment is all else is great in the brakeing department. later robbie
 
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I think we all have a case of the spongy brakes here. Anyone who thinks they don't just doesn't have another car to compare with. Think of all the weight we tack on these beasts! I've also installed the Slee SS brake lines only to be dissapointed that the braking still remained "soft". I'm going to play around with the LSPV this weekend and do a few brake stand test and check distance required to stop. Maybe I'll find a nice icy road to do it on ;)

I've also bleed it numerous times following the correct order of bleed in the FSM. Short of that, I think one needs to replace all the rubber lines with stiffer (SS) brake lines to see a noticable performance increase.

Patpend2000 informed me of the "Zip Tie" trick to reinforce the rubber brake lines. It is the cheap way of replacing the rubber ones for SS one. Just wrap zip ties along the entire rubber hose. Be careful not to pinch it, all you are doing is adding a reinforcement wall around the rubber line so that it cannot expand more than it already is.

HTH
 
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rockclmbr said:
I think we all have a case of the spongy brakes here. Anyone who thinks they don't just doesn't have another car to compare with. Think of all the weight we tack on these beasts!
I'm with you chief, and do realize the 80's brake are softer than most vehicles I've driven. But lately I've notice from time to time a softness beyond the initial spongy feel. Maybe say.. after sitting at a red light or even after shifting from drive to park. On one occasion recently I was able to push the pedal to the stop with some addition pressure. I don't think I'd consider that normal. It's not all the time or even most the time... just periodically. I completely flushed and bled the system a year or so ago and everything has been operating fine (with the usual semi-spongy feel), but recently... don't know if it's a function of the colder weather, it's been beyond the semi-spongy feel from time to time.

Brake fluid level looks good. Don't know how air would get into the system if is was properly bled and worked fine before, so it had me thinking bulging brake lines or possibly something else.

:beer:
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Does the S/S line kit replace all the brake hoses ??!! All four up front and all, three?, in the rear ??!!

Unless it does, I am suspecting that we're just "squeezing the balloon" in a different spot, as in the other lines just might give more as there would be more pressure on them.

Has anyone out there replaced ALL the brake hoses ?

I am just thinking that it does not take much give on each of the individual, many hoses to total significant "give" on the entire system. Take that total brake hose "give" and convert it into master cylinder piston travel, and I bet it explains a fair amount. There are, relatively speaking, a lot of linear feet of rubber brake hoses on these rigs, and after 10+ years on mine, they have to be compromised.

I could figure out the math on all this, but I am tooooo tired this evening.

R.
 
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Rookie2 said:
I'm with you chief, and do realize the 80's brake are softer than most vehicles I've driven. But lately I've notice from time to time a softness beyond the initial spongy feel. Maybe say.. after sitting at a red light or even after shifting from drive to park. On one occasion recently I was able to push the pedal to the stop with some addition pressure. I don't think I'd consider that normal. It's not all the time or even most the time... just periodically. I completely flushed and bled the system a year or so ago and everything has been operating fine (with the usual semi-spongy feel), but recently... don't know if it's a function of the colder weather, it's been beyond the semi-spongy feel from time to time.

Brake fluid level looks good. Don't know how air would get into the system if is was properly bled and worked fine before, so it had me thinking bulging brake lines or possibly something else.

:beer:
Rookie2
I've got the exact same issue. For daily driving I really don't care cause I drive like a grandpa most of the time anyways, but when I'm towing my dad's 4500lb boat, it makes me nervous as hell! I haven't tried brakelines yet, but that's next on my list.

As far as adjusting the brake booster, how do you go about doing that? Any of you guys do that and notice a diffrence?
 
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Rookie2 said:
I'm with you chief, and do realize the 80's brake are softer than most vehicles I've driven. But lately I've notice from time to time a softness beyond the initial spongy feel. Maybe say.. after sitting at a red light or even after shifting from drive to park. On one occasion recently I was able to push the pedal to the stop with some addition pressure. I don't think I'd consider that normal. It's not all the time or even most the time... just periodically. I completely flushed and bled the system a year or so ago and everything has been operating fine (with the usual semi-spongy feel), but recently... don't know if it's a function of the colder weather, it's been beyond the semi-spongy feel from time to time.

Brake fluid level looks good. Don't know how air would get into the system if is was properly bled and worked fine before, so it had me thinking bulging brake lines or possibly something else.

:beer:
Rookie2
Whens the last time you replaced the pads? I noticed that after replacing the disks and pads that some of the mushiness went away. If I remember correctly one of the complaints from auto reviews about the 80 series when it came out was the soft brakes.
 

CreeperSleeper

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If it were me I would swap in SS lines, while the tires are off I would check the pads and rotors and do a thourgh bleeding. The difference in pedel feel with the SS lines is awesome.
 

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