Brake trouble + Lexus = Bad.

So im pulling out of my driveway this afternoon around 6, and im pulling forward to make room to back up and get out of there. SO im inching towards our Lexus, and as im about 2 feet away i start applying brakes..... You know... to stop. and NOT hit the Lexus. Well God, being the almighty asshole that he is, decides to make my brakes not work, and now ive got a dent in the Lexus' trunk lid the size of a grapefruit (good thing i got teh damn thing lifted, or i woulda hit the trunk AND the body....)...

SO anyways.


Brakes worked fine from there on out, in terms of i backed up, and stopped, to survey the damage. And all subsequent applications of the brakes work perfectly, considering my 33x12.50 tires.



So im thinking the first pump of the breaks didn tgenerate enough pressure on the calipers. Thus no stoppage.


Reasons this happened are cause air in the brakelines or similar, correct? Bleeding my brakes should solve the problem?

Let me know what you think.

TO make it all worse, my mom is going psycho, th inking my Jeep is unsafe, and at any minute a wheel is going to fall off. She even suggested we take it down to the dealership to have it looked over... Not only is this a big hit to my pride, but its also a big hit to the trust factor that parents are supposed to have with their children.



What should I do? Bleed the brakes? Im out 550 clams to get them a goddamned trunk lid.

If you don't know the last time your brake fluid was bleed or changed then I'd have it done. My neighborhood garage charged me $60 to do a flush. I watched and they sucked out all the fluid out of the master cylinder, then refilled it.

They then went around and used a power bleeder to get all the air out and make sure new fluid flowed.

Don't forget the rubber brake lines break down from the inside, I see you have a lift, i hope your lines are relatively new. Sounds like you need to do a complete system check.

Booster?

Could it be that your booster has a split in it or a leak in the vacuum hose? I would suspect them at low rpm.

Since I dont remember the last time the fkuid was bled or changed....
And the fact that it had the symptoms of air in the lines (pressing pedal, but no stopping) I think thats what im going to do.

Seems a lot easier to pay someone to do it for me, make sure i get it done real thorough, especially since time is running out, and i have a Lexus trunk lid to fix.

i agree with your mother. seems unsafe to me that the brakes didnt work. why all of a sudden did your brakes not work???

Did it just not stop, or did the pedal sink? If it just didn't want to stop, I agree with Hosshoffer - sounds like bad vacuum or a bad booster.

Air in the lines will cause a spongy pedal, but it won't really sink, and I wouldn't expect it to fail to stop, especially since there is rarely air in ALL the lines at once. If the pedal sank, suspect the master cylinder. Sometimes a worn-out master cylinder will do this on the first application of brakes, and then kind of "wake up" afterwards. But if so, it will get worse, and more unpredictable. Check all your brake lines and your fluid level too, because sometimes a cracked line will intermittently open and close and cause this kind of thing just before it fails completely.

Here are some quick booster checks:

Get in the car, with the engine off, and pump the brakes till the pedal is good and hard. Now, with your foot still on the brake, start the engine. The pedal should immediately sink part way down. If it doesn't, or doesn't do it immediately, you have a booster problem. Now let off on the brake, and stop the engine. Push the pedal a few times again. You should feel boost for a couple of pedal strokes before you run out of vacuum.

Finally, start the engine again, let the booster fill, then go a way for a few hours. When you come back, push the pedal. If the booster and its check valve are good, you should still have boost.

Air in lines or manual brakes!

If you have air in the lines the pedal will feel spongy and not stop well. If you have a vaccum leak then the pedal will be firm but require3-4 times normal foot pedal pressure to stop. I see people come into the dealership all the time threatening to sue because there brakes don't work. After we check it out, if its a vaccum leak we just take them on a test drive and then hit the brakes hard and when it stops they have a curious look on there face like "WHat the hell" then we explain it to them. Its SOOOOOOO much fun watching them look like there going on The first drop on a mean rollercoaster. Just Rambling sorry!:bunny:

Did you , by any chance, take off/put back on the calipers just previous to this accident? I remember having compressed the pads to get mine off and putting them back on. I went to drive down the street and got a few quick heart beats the first time I hit the brakes. Pumped the pads back into position, checked the reservoir level and everything was fine.

XJ_MAC said:

Did you , by any chance, take off/put back on the calipers just previous to this accident? I remember having compressed the pads to get mine off and putting them back on. I went to drive down the street and got a few quick heart beats the first time I hit the brakes. Pumped the pads back into position, checked the reservoir level and everything was fine.

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Nope didnt touch the brakes at all.


IM going to run more tests today, thanks for the advice, ill let you know what happens with the booster.


This is exactly what happened:

I pressed the pedal, it went to the floor, no stoppage.

I reverse, to survey the damage, it stops on a dime.

booster is working perfectly, so far as i can tell. I did the test suggested, and the pedal dropped after I turned on the engine.

89xj said:

i agree with your mother. seems unsafe to me that the brakes didnt work. why all of a sudden did your brakes not work???

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I wholeheartedly DISAGREE with my mother, in that she thinks a wheel is going to fall off, lol!

Boz88xj said:

I wholeheartedly DISAGREE with my mother, in that she thinks a wheel is going to fall off, lol!

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It won't fall off but if you don'f fix the brakes it might be knocked off

Seriously, this sounds either like a leak in a line (check very carefully all around and sniff for fluid) or a bad master cylinder.

If it's a leaky or cracked line, one thing you might do is start the engine and then push really hard on the pedal. Simulate a panic stop. If the lines are healthy it will be all right. If one is about to part, it will probably do so, and better in the driveway than on the road.

If the lines pass the test, try pushing softly but steadily on the pedal, and see if the pedal gradually sinks. It shouldn't. If it does, and there is no loss of fluid anywhere, it's a bad master cylinder.

Ok, ill try the panic stop.

WHen you say "gradually sinks" how far are you talkin about? All the way?

And is this with the car on or off?

Stop blaming God for your problems and maintain your Jeep properly. Your the kind of people that brake down on the trail and don't know how to tell a bad muffler bearing from a stuck piston return spring.
Try talking to God instead of cursing Him, things will surely change.

Pounding on the pedal did nothing. I tried it repeatedly.

I did notice a spot of oil, but upon examination i found that its not brakefluid.

TTT and an update:

I had my cousin take a look at my Jeep, givin it a once over, and we decided together that it is in fact the MC going out causing my problem.

Brakes work 100% now, no doubt. problem is, what happens when MC decides to not create pressure again, and im careening off a mountain cliff at 60MPH?


So im going to replace it, and do a once over my entire vehicle before I go to camp for the summer.


Whats involved in changing out the Master Cylinder? Easy Job? Not too difficult? Time isnt a problem, as long as it doesnt take me more than a week... Cause thats all I have.


What do I need to buy? Just a master cylinder? I see some remanufactured ones pretty cheap on Kragen, are they worth it? Or should i pony up the big bucks?

Quick question:
Do I have power brakes?

I dont even know, hehe.

88 cherokee.

You do have power brakes. All XJ's do. The booster is that big black canister behind the master cylinder.

A master cylinder is a pretty straightforward job. REmove, discard, replace. In theory it's rebuildable, but I would not recommend this for a novice. I can't judge the quality of rebuilt versus new in this case, but my one experience with a "rebuilt" on a Mercedes suggests that you should opt for new if you can afford it. Make sure that you cap the brake lines so they don't get junk in them (the rubber caps for bleeders work nicely for this), and if there's a gasket or o-ring between MC and booster, make sure that is renewed. Make sure you have plenty of brake fluid when you do this job, because you'll be doing a lot of bleeding (or rather your brakes will - we hope you yourself won't bleed too much, though a little is said to build character ).

It's advisable to "bench bleed" the MC before you install it, or at least before you hook up the lines. This means it should be filled with fluid, and as much air as possible bled out, before you hook up the lines, otherwise you'll just push air down the lines and have to bleed and bleed and bleed some more.

Even if you have bled the MC, now might be a good time to do a brake fluid flush, and bleed the entire system. I think this has been discussed in a couple of other threads here recently.

Oh, and spring for a QUALITY flare-nut wrench (7/16 x 3/8). S-K, Snap-on, etc. I like the S-K tools I get at a local auto parts store. Lifetime guarantee, good fit. Even Craftsman is aiming a little low these days. A flare-nut wrench must fit perfectly and have no flex at all. A good flare-nut wrench (or if you're feeling expansive, a set of them) will pay for itself on the first job, and be a lifetime resource saving you from hours of frustration, munged-up fittings, and language that will make your mother condemn your Jeep as a bad moral influence!

Thanks for the info Matt!

I appreciate it!

Ill let yo know how it all goes, along with any questions I have!

forgiven said:

Stop blaming God for your problems and maintain your Jeep properly. Your the kind of people that brake down on the trail and don't know how to tell a bad muffler bearing from a stuck piston return spring.
Try talking to God instead of cursing Him, things will surely change.

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haha I just read this post.

Oh man, thats funny.

Thanks for the tip Jesse Jackson, but its hard to talk to someone you dont beleive in. My comment about god was a joke. A way to get overteh fact that I just rearended our Lexus.

I do maintain my jeep. One of the only things I DO do religiously. It was bad luck, simple as that. if it had happened 2 seconds later, it woulda been into a brick wall, and no problems. but with my luck, my stopping pad was a Lexus.


But whatever. Im fixing it today, cause thats what I do. Fix whats broken. Ergo, MAINTAINING my jeep. Well I guess thats not really maintaining. But whatever.