Miraculous Brake fix


Delori
03-25-2005, 09:44 AM
My wife's 95 Jimmy has been acting up for a while in the brake department. A few months ago, the brake pedal started fading while sitting at a stop sign or stop light. Nothing real bad, dropped about 3/4 after 30 sec and a quick pump would get you to the green.

After reading up about a few things here, I decided to change the pads. That worked!!! for about a month.... This last week I've been driving it because she was afraid to and we both need cars. Growing up in WI, I figured if it got worse, I might be able to handle it better then a CA girl. :biggrin:

Well last night on the way home it happened. Cruising down the highway at about 65-70, all came to a complete stop and fast. I slammed on the breaks and the pedal went to the floor! Then the ABS kicked in, pushed the pedal back to about 50% and a ratcheting clicking sound from under the dash... :uhoh:

Well, I stopped without hitting anyone and the rest of the way home the brakes are back to normal. I told my wife about it and she was so glad to get her truck back, but I told her no way! I still didn't trust it and wanted to drive it a few more days. I pulled out my book and started looking to see if there was something I should have reset after changing the pads, but didn't see anything.

On the way in to work this morning I was hard on them. Started out braking normally, then pounding them a bit when it was safe and all seems great.

So my question to anyone, what happened? Why does it seem so much better now?

Please fill me in with your thoughts,

Delorian

rlith
03-26-2005, 08:30 AM
First, have you checked your brake fluid level lately? Is it low. You actually sound like you have some air in the lines. That said, I'm cutting and pasting a small write up I did at www.sicgmtrucks.com and a few of the other boards... This might help you as well...

Cut and pasted-------------

We all replace brakes. (Well, most of us do anyway). It's a fairly simple procedure.

One thing that we often overlook when changing the front brakes out are the rear brakes!!!!

Yes, the rear shoes can last up to a 100k or better with proper servicing. But the problem is they occaionally need adjusting. Typically the average fellow when changing the front brakes completely forget about adjusting the rears.

Why do I need to adjust the rears after all this time? You might say. Because of load! Typically cars/trucks use a 60% load on the front and 40% load on the rear for stopping. If you start changing pads, the rear needs to be adjusted to maintain that split. If you don't adjust them, the load starts increasing to the front casusing all sorts of problems.

What problems? Prematurly worn pads, warped rotors, liquified pads, heated brake fluid, longer stop time, et-al .

Ever take a drive after you've just installed your new front brakes and start smelling burning asbestos? More than likely it's because you didn't adjust the rear shoes.

To adjust the rear brakes is a relatively easy process. (No backing up doesn't always do it) If your adjusters are in good shape, simply lift the back end of the truck off the ground (jack under the pumpkin) and spin the wheel. Stick a flat head screwdriver through the adjusting slot and using it like a pick, pry UPWARDS. Prying upwards causes the adjuster to move counter clockwise which spreads the shoes. For evertime you PICK the adjuster wheel, turn your wheel on that side a rotation or two. You should hear just the slightest rub inside the drum and feel feather resistance. Repeat this process on the opposite rear wheel.

Now if your adjusters are rusty your best bet is to simply replace them, but you can still try to adjust them.
Pull your wheel and drum, move the adjuster lockout (will move about a 1/4 inch) Using a fladhead screwdriver and a hammer, start tapping on the adjuster wheel tooth until it breaks loose. For every 1/4 inch you manage to move the adjust wheel, put the drum back on and rotate. Same as above, feel for feather light resistance and rub. Repeat this on the opposite wheel.

Put your wheels back on and go for a test drive. You will now notice that your brakeing is far superior to what it was.

Better braking, better wear on the front brakes, and safer overall...

Delori
03-28-2005, 09:34 AM
Well, Friday during some running around during lunch I felt like they were starting to fade again and on the way home they were as bad as before.

So after looking at the manual and seeing I need a code scanner to bleed the brakes, I decided to bite the bullet and take it in. Sat after, $500 dollars later and a new master cylinder they seemed good, but after running around on Sunday for a bit they started it again. Sitting at a light, the peddle started dropping.

I bought it into work today so I can call Wheel works and complain and take it back but they feel good again this morning.

Is there a break-in time on a new master cyl for the seals to swell or should I take it back to them? I don't want to wait to long but not sure if they can fix it if it's not doing it now...

Thanks for any help,

Delorian

rlith
03-28-2005, 02:09 PM
You do NOT need a code scanner to bleed the brakes..They charged you 500 bux for bleeding? That's BS... Again, did you adjust your rear brakes?

Delori
03-28-2005, 02:13 PM
Yes, the rears are fine, just like you say. $500 for a new Master cyl. (476.83 to be exact)

what else could it be?

rlith
03-29-2005, 05:36 AM
Have you rechecked your fluid reguraly to see if it's getting low? Your issue may also be the brake booster itself. The main diaphram inside may be shot, but as a cheaper test, replace the check valve at the hose going into the booster... If that doesn't cure it, look to the brake booster

Delori
03-29-2005, 11:43 AM
Yes, the fluid looks good and there are no wet spots around the lines or anything.

Thanks for recommending they valve and booster next, I'll check them out.

Any idea how much the booster is going to set me back?

94 Jimmy
04-04-2005, 01:02 PM
Something like this has happened to me on two occasions, both involved the wheel speed sensors. The one that sounds like what your experiencing happened when the sensor line rubbed through and allowed water to get into the wheel sensor. The ABS computer thought that one wheel was locked because it wasn't getting a signal. It would release that brake trying to unlock it, which had the effect of giving a soft pedal.
I have a 94 Jimmy and shorting A-H(I Think?) on the diagnostic plug reads out the ABS codes, you might try that. If you have that type of diagnostic plug instead of the OBDII plug, go to the car parts store and get a code reading tool, it looks like a little pickle fork (not the suspension tool, a real pickle fork). It has little tines spaced to short out the pins on the connector to recover the codes A-B for ECM codes on the check engine light, A-H(?) for ABS codes on the ABS light ect.
There's a procedure in the Haynes manual for clearing the codes if you need to. The manual and tool shouldn't be more than $25 and if you need a new sensor the front hub is about $85. If you need it changed, buy it and take it to the mechanic, he'll double the cost then charge you to put it in.
Hope this is some help
See ya
94

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