I am not a mechanic

asechrest

asechrest

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asechrest
Lately I've been sorta proud of myself. I've been doing some of my own work on my vehicle and my girlfriend's vehicle. Most recently, I replaced the font rotors on her car and had no issue. Granted, this is a terribly easy job for a good shadetree mechanic. Still, I'd never done it. Before that, I property diagnosed and replaced the vapor canister surge valve on her Malibu. And before that, I replaced her brake pads and my own, also no issue.

But the two times I've tried to help my brother with his extremely poorly maintained 2000 Ford Mustang V6, I've failed miserably. The first time was my failure to diagnose properly. We had an overheat problem that I diagnosed as a bad thermostat, but that ended up being a bad water pump. Live and learn.

He's strapped for cash and after getting a $289 quote for front brakes and rotors, tonight I told him I'd help him change them, which hasn't been done in at least 5 - 7 years. There was literally no pad material left at all on two of the four pads, and the rotors were a mess. All was going well until it was time to push the brake pistons in so the caliper would fit around the new bulky pads. Jesus they would not compress. I had the old brake pad up against the dual caliper pistons and my c-clamp attached and it was incredibly difficult to compress them, to the point of my needing additional leverage on the c-clamp handle in order to get it to twist. And even then it bent. I have not had this trouble on the three brake jobs I've done. Piston compression was relatively painless.

Eventually I was able to compress the caliper pistons enough to get around the new pads. I get everything buttoned up, have him pump the brakes, then we take it for a test drive....and I've got a spungy pedal with a large travel distance that I'm not comfortable with and braking action that seems arguable to be worse than before.

The possibilities, I guess: brakes desperately need to be bled (which I know factually is the case, but can't figure out why braking action would now be worse than before), or we damaged something when pushing the caliper pistons back in, perhaps by back-flowing crud in the brake lines up into the master cylinder. Some additional reading leads me to believe that some people suggest opening the bleeder valves when compressing the caliper pistons so you avoid pushing the cruddy brake fluid up into the master cylinder.

But, above all I'm just venting. I was really hoping to help him and after a bunch of successes with my own vehicles, I was really bummed with the hangups on this job. Sometimes it pays to just...pay for the experts to do it. Thanks for listening.
 
He probably needs a caliper or two if it was that hard to push in.

Read up on how to bleed, especially if he has ABS. Get a large container of brake fluid and flush it until clear. It can be done with one person, but it's a lot easier with two.
 
MAKG1 said:
He probably needs a caliper or two if it was that hard to push in.

Read up on how to bleed, especially if he has ABS. Get a large container of brake fluid and flush it until clear. It can be done with one person, but it's a lot easier with two.
Click to expand...

Thanks. I'll have to check on the ABS. If memory serves, the V6 Mustangs of this vintage could go either way depending on the package.

I have read up on bleeding brakes, both with two people or by yourself. We'll see what tomorrow brings, but after 3 hours in 85 - 90 degree muggy Florida evening heat, I'm really beat down. It might be a pride thing. I really wanted this to be a clean, painless job where I helped him save some money.

[PS] - Thanks for the two comments above, too.
 
asechrest said:
but after 3 hours in 85 - 90 degree muggy Florida evening heat, I'm really beat down. .
Click to expand...

The climate here can make simple jobs very frustrating. Drained and dehydrated lead to a foggy mind.

Is there a local car club you could join and build some mechanic friends who can help teach you for the cost of a beer or two and lunch? Ive done that and it really does make a difference and can be a fun afternoon.
 
Bleeding brakes is easy...

with 2 people: loosen bleeder screw, have assitant press brake to floor and hold it there. tighten bleeder screw(hand tight is good enough at this stage). Have assistant release brake pedal. Repeat until solid streams of fluid are coming out of bleeder screw... tighten it back up good when done. Keep fluid reservoir topped off throughout the process. If pedal is solid you're done

1 person cheater method(works better on some cars than others). Open bleeder screw, wait for a while as fluid dribbles out, keep reservoir topped off, tighten screw, check brakes. Continue until solid pedal.


I doubt thats the problem here though but it's worth a try before spending any more money. I suspect the seals around the caliper pistons are bad and you just need new calipers.
 
Next time try removing the fluid cap on the master cylinder. Be sure they're aligned perfectly when you're trying to compress. It's possible for the alignment to get off causing difficultly pushing them back in.

One trick is to loosen the brake line to relieve pressure but you'll typically be looking at bleeding after that.

If you ever do the rear pads on it those have to screwed in, not just compressed.

If there was signficant metal to metal action happening on his front brakes he may have destroyed his calipers already and will need new ones.

Bleeding is no big deal and is an easy one man operation if you have a vacuum pump which is my preferred method.
 
As some have said, if the pads were overly worn down, the caliper piston can get over-extended and ruin the seals/boots. Also, on some ABS systems, not a good idea to compress the brake fluid back up through the system. On some systems, the ABS valves don't like it. Not sure on that year Mustang, but I have always just cracked the bleeder valve on the caliper while compressing the piston. Bleeding takes just a couple of minutes and you can be reasonably confident there is no more air in the system.

-Brian
 
When a brake pad is completely gone, and there is metal to metal contact from the backing plate to the rotor, you can get a lot of heat transfer into the backing plate, and the piston causing it to deform. This would explain your difficulty in getting the piston to push back in the caliper, and also the spongy feel when applied as the piston is not moving smoothly in the bore. The hard to push piston should have been your giveaway that something there was fubar.

You have several choices. You can replace both calipers(should not do one side at a time), or you can try to replace the piston and coned brake piston seal. The cheapest is to replace the piston and seals. Go to Rockauto, navigate down to 2000 Ford Mustang V6 and order the caliper pistons, and caliper rebuild kit(seals). You do have ABS, but unless the light is on the dash, don't worry about that for now.

Proceed as follows:
Remove one side caliper from the hub, do not disconnect the fluid line.
Remove the pads from the caliper.
Press the brake pedal repeatedly until the piston pops out of the caliper(messy), note where, and orientation of the current seals.
Clean out all brake fluid from the caliper bore, there is likely a dust seal at the outer edge unless it's been burnt away. Clean or replace that dust seal(later step).
Use some Brake Cleaner fluid and a scotchbrite pad or 1500 grit sanding cloth to polish the inside of the piston bore. Once it's nice and smooth, clean it out with brake cleaner.
Install new seals in the bore, noting correct orientation.
Fill the caliper bore and coat the piston with fresh correct DOT brake fluid.
Crack open the bleeder valve at least two turns.
Insert the piston smoothly into the caliper bore, depress it all the way in.
Close the bleeder valve. Clean up the caliper, check or replace the dust(outer) seal now.
Insert the new pads into the caliper.
Install the caliper on the hub.
Suck out all the old fluid from the master brake reservoir and put in new fluid to near the top.
Using your helper in the driver seat, bleed the brakes until new fresh fluid comes out the bleeder valve.
~~~~~~~~~~~~~~~~~~~~~
Repeat for the other side, except you don't need to drain the master brake reservoir this time, just keep adding fluid so the level doesn't fall below the master piston. Turn the key to on but not start. Check for the ABS warning light to come on. Start the car, wait 5 seconds, the ABS light must go off. If it is not off, bleed some more fluid, you may have a bubble in there. If it is still on take it to a pro.
 
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