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Old 07-18-2010, 04:40 PM   #1
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Spongy Brakes After New Rotors & Pads

I replaced my brakes the other night (rotors and pads) and bled them over and over again to make sure no air was in the system. Now they brake good but only after about 4"-5" of a spongy brake pedal. I saw a post in the General Discussion forum that mentioned adjusting the rod between the booster and master cylinder and also adjusting the "secondary brake line, "but nobody has responded to my inquiry there. Can anyone explain what these two things may involve...and what a seconday brake line even is? Could the rear brakes being out of adjustment cause the spongy feel at the pedal? How do I bench bleed the master cylinder (saw this mentioned also)?....or is that even recommended? Thanks in advance

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Old 07-18-2010, 04:43 PM   #2
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Why did you bleed the brakes? Merely replacing the rotors and pads doesn't normally require you do that. Did you entirely remove the calipers and disconnect them from the brake lines?

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Old 07-18-2010, 04:46 PM   #3
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Try replacing the bake lines. The rubber hoses at the calipers tend to get squishy over the years and can give a soft pedal as they expand from the pressure. Upgrading to some stainless lines will really help improve pedal feel and firmness.
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Old 07-18-2010, 04:49 PM   #4
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No I didn't remove the calipers. I guess I didn't need to bleed them, but its been a long time and the fluid was pretty nasty looking, and I had a couple bottles of fluid around so I wanted to try to flush it out good and try to get as much good fluid in the system as possible. Think it could be that my wife let up on the brake pedal just a tad before I had the bleeder screw tightened back down? I sure didn't see any air coming out of the lines when I was bleeding them though. Just good clean fluid. I've never messed with the 13yr old Mc though and was wondering if parts in there can go bad...
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Old 07-18-2010, 04:53 PM   #5
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Try replacing the bake lines. The rubber hoses at the calipers tend to get squishy over the years and can give a soft pedal as they expand from the pressure. Upgrading to some stainless lines will really help improve pedal feel and firmness.
Thats actually crossed my mind but my budget doesn't like that idea right now. I'm keeping the Jeep and giving it to my son one day so maybe I should just upgrade the entire system when I can afford it??...mc, booster, lines, calipers.
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Old 07-18-2010, 04:55 PM   #6
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You bled them right-rear, left-rear, right-front, left-front in that order? It's not the lines causing it, they don't just suddenly go bad while bleeding the brakes.
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Old 07-18-2010, 04:56 PM   #7
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You bled them right-rear, left-rear, right-front, left-front in that order?
Yes sir I did...end when I thought it was enough and there were no bubbles coming out of the tube that I had attached to the bleeder screw, I did it more just to be sure.
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Old 07-18-2010, 05:02 PM   #8
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If the MC goes bad, the pedal will usually go to the floor. If the booster is bad, it won't hold vacuum. My guess would be squishy brake lines still. You wouldn't believe the difference, trust me. If it's not in your budget, do it when you can. It's a very good investment, especially for safety reasons.
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Old 07-18-2010, 05:02 PM   #9
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Did you by any chance bleed them when the brakes were not mounted in their normal positions?
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Old 07-18-2010, 05:06 PM   #10
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If the MC goes bad, the pedal will usually go to the floor. If the booster is bad, it won't hold vacuum. My guess would be squishy brake lines still. You wouldn't believe the difference, trust me. If it's not in your budget, do it when you can. It's a very good investment, especially for safety reasons.
I think I will do this for sure when I can afford it. Even if they're good at the moment, they're still really old and it can only help. Thanks AzTJ

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Did you by any chance bleed them when the brakes were not mounted in their normal positions?
No everything was all buttoned up and put back together.

Another question for ya though, what about all the "shims" that come in the box with the brake pads....how will I know if I need to use any of them?
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Old 07-18-2010, 05:21 PM   #11
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I've never used shims with disc brakes. I don't see why they'd even include them.

The only thing I'd think of is some kind of leak. Were there any damp areas? Have you looked at the rears?
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Old 07-18-2010, 05:22 PM   #12
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I dunno about a shim but new brake pads often come with a new slider that slips over the top of the slider on the frame that the brake pads ride on.

I still think your only problem is the lines have not been properly bled. At this point, I would take them to a brake shop and have them vacuum bled which is a very goood way to extract all the old fluid and get all the air out. They sometimes call it a power bleed procedure.
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Old 07-18-2010, 05:25 PM   #13
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I've never used shims with disc brakes. I don't see why they'd even include them.

The only thing I'd think of is some kind of leak. Were there any damp areas? Have you looked at the rears?
No damp areas showing any leakage. I actually replaced the shoes, cylinders and all the hardware in the rear a month or so ago. Should I check them out again for anything in particular?
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Old 07-18-2010, 05:26 PM   #14
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Alrighty, if the brakes were Not spongy before you changed the pads/shoes but were after the new pads/shoes and bleed I'd have to say you got air in the system or maybe one of your rear wheel cylinders may now be leaking. Recheck for leaks, Bleed them again and go from there.
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Old 07-18-2010, 05:28 PM   #15
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if it's all new hardware then I wouldn't think about looking again. Only reason it came to mind is that the drums are usually forgotten about because they require such little maintenance. No leaks... so it's a line problem. I'd do as Jerry suggested. Or hit up an auto store for a one-man vacuum bleeder.
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Old 07-18-2010, 05:34 PM   #16
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I think it was the sliders that Jerry mentioned and not the shims as I mentioned....still have never used the sliders on the many brake jobs that I've done.


Jerry I thought about going to a brake shop....man I hate that thought though. Thats what got me into doing my own work a few years back. A brake shop chain quoted me over $700 for a brake job so I said never again. Sounds like the power bleed procedure may be beneficial though so I'll have to try to do that this week. Think I'm going to try to bleed them again tonight when I get home from work and see if I can get anymore air from the lines.....can't hurt to try again I suppose.

Jeepjones, I'm going to check the rear cylinders tonight as well and will come back tomorrow with an update.

Thanks again to the three of you for your feedback. Its much appreciated.
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Old 07-18-2010, 05:38 PM   #17
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I do my own brakes too Chris but I still pay for a power flush when the brake fluid needs changing. I normally work by myself in the garage since it's just too hard to get the wife or 19 year old son out there to help. The 19 year old son, a good kid otherwise, hates working on cars/Jeeps & it's like pulling teeth to get him out there for more than 3 minutes.
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Old 07-18-2010, 05:43 PM   #18
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I do my own brakes too Chris but I still pay for a power flush when the brake fluid needs changing. I normally work by myself in the garage since it's just too hard to get the wife or 19 year old son out there to help. The 19 year old son, a good kid otherwise, hates working on cars/Jeeps & it's like pulling teeth to get him out there for more than 3 minutes.
I'll go ahead and get the power flush done soon then.

Sounds like I'm lucky to have a wife that will get out there and jump in the mix with me. Hoping my 2 1/2yr old keeps enjoying being out there with me too. :-) Had to give him one of my little 1/4 drive socket wrenches and some sockets to let him feel like he's helping. I love it!!

Wish I lived closer man, I'd be glad to come lend a hand and I'm sure I'd learn A LOT in the process. My dad never worked on his vehicles so this is all new to me starting about 5 years ago. Thanks again Jerry
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Old 07-18-2010, 05:48 PM   #19
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My dad was an artist and never worked on his cars either Chris, his "assortment" of tools was a few tiny-handled screwdrivers, a rusty hammer, and two pipe wrenches. I dunno where my interest in it came from but certainly not from my dad.
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Old 07-18-2010, 06:13 PM   #20
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Brake fluid replacement/flush is good preventive maintenance on any vehicle. VW always said do it every two years. I've known guys with a lot of experience changing calipers and wheel cylinders who said it wasn't necessary. I prefer the fluid change.
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Old 07-18-2010, 06:40 PM   #21
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What condition are the front calipers in? How do the seals look?
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Old 07-18-2010, 07:01 PM   #22
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The shims you put behind the pads are suppose to stop disc brake squeal. They don't always work. If the rears are not properly set up you will have a low pedal the first couple of pumps and then be hard. does that happen? I have put cheapy pads in vehicles and had a poor pedal feel. What was the quality of pad? If you are sure you have all the air out and suspect master cylinder, (could happen, while you were bleeding brakes the pedal went lower than it has in years and the cup in the master cylinder ran up on some mud and damaged it) remove the lines on the master cylinder and install plugs in it, eliminating all the brakes. Hit the pedal now and it should be rock hard at the top. If not replace the master cylinder
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Old 07-19-2010, 12:44 AM   #23
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One other thing. Did you crack the bleeder when you pushed in the pistons? If not you could have pushed cr@p into your proportioning valve and also into your ABS valves which will cause this problem. I always bleed them off prior to removing the caliper, instead of using a spreader or c-clamp.
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Old 07-19-2010, 08:29 AM   #24
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My bet is there is air in the system...somewhere.

it doesn't take much.

Its really easy to let the MC go a little too far empty...and if you do have ABS, air loves hiding out in the module.

FWIW - you did the right thing by bleeding the brakes. Brake fluid absorbs moisture over time, and it does need to be replaced.

The standard recommended interval for many in motor sports is at least yearly.
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Old 07-19-2010, 01:12 PM   #25
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It could be a procedure problem.

1 --- DO NOT PUMP THE PEDAL WHEN BLEEDING! Ever try to wash soap foam down the drain in a sink? Very difficult to do. The clear water goes around the tiny bubbles.
When you pump it, the air bubble breaks up into tiny bubbles, foam - they don't come out easy. It takes a few minutes for the tiny bubbles go go back to one big one.
Always - use one steady even push on the pedal - even if the pedal doesn't seem like it's doing anything - it's still pushing the big bubble down, and eventually out. The first few pumps may not seem like it's doing anything - till it spurts out the big bubble.

2 -- And - you may have ruined the MC - if the helper pushed the pedal all the way down to the floor, any trash collected inside the MC gets jammed under the cups - especially the first few pumps. Then the front cup no longer seals, then the secondary cup makes it feel like it's still full of air even if it isn't.
Air can get pulled in on the upstroke.

Try bleeding it again without pumping it first - then have the helper push "almost" to the floor. Do it several times, the air may have to go down the brake lines quite a ways taking several pushes so have patience.
When it flows clear 10 times without bubbles on each wheel, it's done.

Many folks don't do it enough times.

I recently bought a Cherokee for $200 - owner said it had bad brakes and couldn't be fixed. A shop told him he needed all new cylinders and calipers and an MC - $600-800.
I followed the above procedure - brakes were fine. Sold it for $1000 without doing anything else to it. OK, it took about $1.50 worth of brake fluid.
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Old 07-19-2010, 01:29 PM   #26
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Funny - the order of which wheels to bleed first, second etc. ---
Different car makers call out different orders.
Remember, modern vehicles the front and rear are different hydraulic systems entirely. If air gets in the front, it cannot get in the back anyway, so it's effectively 2 different circuits.

When dual MC's first came out the were a little different (60's?) - on some, one system was left front and right rear, other system was right front and left rear. But with the advent of disc brakes they no longer worked - it gave a radical pull if one system failed the disc brake stops better than the drum.

I've tried bleeding the way the mfgr order said, and tried the opposite way - never made a difference. But it's best to do it like they say.
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Old 07-19-2010, 01:39 PM   #27
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common mistake when bleeding is to push the pedle to the floor. on a old master cylinder that part of the rod could have corosion on it. when that part traveles into the master it can wipe out the seals. ben there, done that.

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