replacing front disc-brake pads

[gmeddy]

hi, i've done a few searches on the topic, and looked through the FSM, and i dont see a guide of how to replace the front disc brake linnings/pads.
i've never tried to do it before, maybe it's so simple that you done need a guide, but i just thought i'd ask before pulling it apart. i've got the new linnings and i'm ready to go.

thanks.

[ARCHINSTL]

The FSM worked for me.
Tom M.

[Petros]

It is straight forward. the only issue is if it has been a long time since the calipers have been off you might want to spray penetrating oil on them (pull back the little rubber boots on the bolt shaft), and you will need a long handled breaker bar or socket wrench to get them to move.

I use a large C-clamp to push the piston back in, watch the fluid level in the master cyl. because you are pushing brake fluid back up into the master cyl. If it takes excessive force to push the piston back, the caliper needs to be rebuilt (or replaced with a fresh one). If there is no corrosion and the piston retracts without binding I have found it okay to reuse the existing caliper. This will also save you from having to bleed the brakes.

Do not allow the caliper to hang on the flex hose, use tie wire or string to hang the caliper once it is off.

[gmeddy]

yeah the fsm on here is not of much use.
BR-16 shows the disc breaks and says how you can check if they need replacement, but no tips on how to do it.
looks like i'm gonna have to go it alone.

[ARCHINSTL]

BR-17 and 18 show the procedure.
Here is also a Guide from AutoZone's site, with photos. http://www.autozone.com/autozone/repair ... 5280052402
There is also a menu on the left side of the page with more info about front and rear brake components.
Tom M.

[gmeddy]

thanks for the advice, it looks tho that the FSM on this site is missing thoes pages.
the HTML is anyway, I havn't downloaded the PDF one.
the link you gave takes me to a member sign up page.

i had a go at the thing last night, the brake pads just pop out when you push them... thanks for telling me

ok so thats no problem, but seems like i'm going to need to do what Petros said and get a big C clamp to squeeze the master cylinder in, because there's no way i'm going to fit them big fat new pads in.
the outside one was worn down to nothing, the inside one was unevenly worn, down to about 3mm at one end and 5 or 6 at the other. maybe the cause of the vibrations?
i'll post some photos soon.

the other question i had was about squeezing the master cylinder in, will it come back out when i release the c-clamp? if so that will be a problem.
do you squeeze it with the brake pad on it? or would that damage the new pad?
i opened the bleed valve to let a bit of fluid out to see if that would let me squeeze the cylinder in by hand, but it still wouldn't budge even when the valve open, i could see the fluid move a bit out and back in when i squeezed it, as i had a clear hose attached.
is that normal for me not to be able to squeeze it by hand even with the bleed valve open?

also i thinking maybe i've removed the whole caliper unit when i didn't need to?
was i supposed to be removing just the master cylinder side and then pulling the brake pads out of it, or take the whole unit off the wheel hub?

i'll see if i can get my hands on a big C clamp today anyway.

[sdoan]

Gmeddy,

There are two ways to pull off the calipers. You can pull the caliper support bracket and the caliper as a unit using the larger bolts; it sounds like you may have done this. It is much simpler to pull the caliper by itself with the smaller bolts. The smaller bolts also serve as guide pins to allow the caliper to slide as the brakes are squeezed and the pads wear.

It is pretty tough to squeeze the piston back into the caliper by hand, but it can be done sometimes. The nice thing about at C-clamp is that it will push the piston straight back into the bore if the clamp is put on straight. I am often able to squeeze the piston back in the bore while the caliper is still held by the guide pins - just by pulling the back of the caliper toward the brake disc. The caliper slides toward the disc and the piston is pushed back in the bore. Once pushed back into its bore the caliper piston should stay where it is unless you push on the brake pedal. Don't push on the brake pedal until the calipers are correctly reinstalled or it can push the caliper piston out on the ground with a bunch of brake fluid.

BTW, even though it is bigger the caliper is a slave cylinder. The master cylinder is what your foot pushes against and is bolted to the brake booster.

[Petros]

You may be confusing the terms, the caliper has a single large slave cylinder (or piston) that you have to push back in. the master cylinder is on the firewall of the car next to the distributor, it holds the fluid. You have to do nothing with the master cylinder, you have to just watch you do not over flow the fluid reservoir. When you push the caliper piston back in it will push the fluid back up into the master cylinder reservoir.

If the piston in the caliper is cocked out of square it will be stuck, if that is the case you will likely need to rebuild the caliper (kits are cheap), or get a rebuilt caliper (more expensive). You likely have damaged the seal if the caliper piston is cocked out of alignment, which I suspect is the case since your pad was worn uneven on the piston side.

Sometimes you can get it strait again by putting the large c-clamp on it the high side and push it back straight, or use a wood block and a hammer on it. It might still work okay once you get the piston aligned again, but that is unlikely. Do not use the new pads to push the piston back in, it will damage them. You can use the old pad, I used a block of wood and the clamp. If you use the block of wood and a hammer on it, it would be best to remove it from the brake flex line and put it in a vise or at least a bench (which means you will have to bleed it once you get it back together, not a big deal, but it takes two people and adds an extra step).

Good luck

[ARCHINSTL]

FSM - dunno about the HTML one; I used the PDF version and stuck it in my 'puter and it works just fine.
As to the AZ link - since I am basically clueless about 'puter thangs - maybe the reason the link works for me (just tried it) is because I am already a member of AZ and you are not - the site "recognizes" my 'puter and not yours?
Heck, just join up - there is no fee (or discount, either), and the Repair Guides section has many photos, which our FSM does not. It's really a pretty good Guide.
Tom M.

[gmeddy]

thanks for all the advice guys, and for the technical corrections. master/slave/caliper ect, all very interesting, however while i was waiting for these replies i worked out that i should have left the whole thing on the hub and just undid the little bolt like you said "sdoan". Thanks for that practical advice tho, thats what i was after from the beggining.

i'll also go and give it another go using your suggestion about squeezing it against the disc, as i dont have a C clamp just yet.

thanks also Petros for the suggestion of the cause for my uneven brake wear. i'll have a close look at the piston thingy to see if it's uneven.

i will try not to confuse it with the master and go bashing the firewall with a hammer and block of wood.

[takza]

You can use the old pads and a screwdriver to get the piston back in so the new pads will go in....usually while on the disc. When you have it apart...you need to be sure the "sliders"....the small bolts with the rubber covers...SLIDE OK. Uneven pad wear usually means the sliders are sticking?

[keith]

You need to do more than just replace the pads. But first, you can press the calipers back in with a large pair of channel lock pliers. Be sure to looses or remove the cap on the master cylinder so that air can escape as fluid is pushed back up the brake lines. I have done these with 10" but 12" or larger is better. Once you get the caliper pistons back in, you need to lubricate the the caliper bushings. These are the sleeves that the small bolts you took out went through, they have rubber boots on each end.

You can get new rubber boots and even new bushings if you want to or if they are torn up. Push the bushing, sometimes called the caliper pin, out one end. Remove the boots, clean the bore, the bushing and the boots. Coat these parts with synthetic grease or silicone grease and re assemble. This will ensure that the caliper "float" as they should and the pads wear evenly.

After re assembling the brakes, get some clear vinyl 1/8" or 3mm tubing, about 8' should do it. Cut it into 2' lengths. Get four small jars and find a way to hang them from the suspension above the calipers and wheel cylinders at each wheel. Its best if the car is up on four jackstands with all the wheels off. Position a jar above the wheel cylinder or calipers.

Crack loose each bleeder valve with an 8mm box end wrench or socket. Snug them back as soon as you crack them loose so that you don't lose any fluid yet. Slip a piece of hose over the end of each bleeder valve and stick the other end into the jar. Drill a hole in the cap to put the hose through so it won't slip out.

Now use something to suck out as much fluid from the master cylinder as possible, then refill with fresh fluid. Now open each bleeder and allow the fluid to slowly drain into the hoses and up into the jar. Keep an eye on the master cylinder and don 't let the fluid level drain out, keep it full. As the fluid in each vinyl hose turns clear, close the bleeder valve. When all four hoses are clear and the bleeder valves are closed, tighten them up, but be careful not to over tighten, those break easily. Takes about a half a quart.

Fill the master cylinder to the proper level and put the cap back on. This flushes the brake fluid out without the need to bleed the system. Fresh fluid will help the rubber components in the master cylinder, wheel cylinders and calipers last longer and the brakes will work more effectively.

On last thing, optional. New rotors only cost about $13 each. Remove the large bolts for the caliper frame and the rotors just pull off the wheel. If you had any pulsing while braking, this will really help.

[gmeddy]

mmm thanks for that.
i'm all done now, but i may pull it all again to put new flex lines on, they are looking pretty "hows ya father".
when i put new lines on i'll do the drain technique you described and lube up them bushes.

i am getting much less vibrations from the brakes now with the new pads, but there is still a little bit there.

i'll let you know how much rotors cost here.
i just priced new coil springs. $160 for a set of fronts or backs, they're same price.
I'm going to pull out my rears and measure them up, then pull coils out of a few different wrecks that are around in the aboriginal communities and see what will fit.
i'm hoping for something a bit more heavy duty to hold my saggy rear end up a bit neater/sexier.

[ARCHINSTL]

You might check shipping from the USA to OZ - the front springs here run roughly USD 78/pair. The rears for the 4WD are not available from either Toy or the aftermarket; apparently only Pedders in your neck of the woods makes new springs for the 4WD.
Tom M.