Question: Installing new Front Pads

[gnb]

Can I just use a C Clamp to push against the old pads to push the piston flush into the calipers to make room for the new thicker pads?

Or do I need to open the bleed plug to relieve the pressure while compressing the pads /pistons back into their bores??

The Chilton book does not address this and shows pressing the piston back into the calipers. There are differing opinions - some say it is better to open the bleeder plug to relieve the pressure prior to pushing the pistons back into their bores.

Thanks,

Nate

[DevinSixtySeven]

that works fine, unless youve added fluid to the reservoir as the pads wore down, in which case youll need to remove some fluid from the reservoir.

-sean

[gnb]

Sorry , I am a bit slow on the uptake .

Do you mean it is fine to just press the pistons back into their bores? Or do yuou mean I need to open the bleeder prior to pressing the pistons?

Just don't want to wreck my ABS system.

Thanks

Nate

[sequoiasoon]

Depends on the school you learned at. Many new school places do not want to take the chance of pushing contaminated fluid back into the system so they open the bleeder and let the pressure out. If you plan on flushing lines which is recommended every couple years anyway this is probably a good time. Opening the bleeders every now and then keeps them from totally seizing

Others are on the why bleed if you don't have too, "I've busted bleeders and had to get new calipers", it's faster, they just do it so they can make labor profit on rebleeding side, it invites contamination because your opening a "sealed" system.

I've done both. If I am alone and it has to be done ASAP that fluid is getting pushed back in (and sometimes out the master cylinder). If I know I have reliable help (I didn't get the Motive bleeder yet) than I'll use the opportunity to at least flush some of the old fluid out. Kinda like a drain and fill on the tranny. Removes some of the old fluid and contaminants but not all. Not as good as full flush of system but better than not doing it at all. My preference is to open bleeders but sometimes you do what you have to do to get the job done.

[LGL002]

Originally Posted by gnb

Sorry , I am a bit slow on the uptake .

Do you mean it is fine to just press the pistons back into their bores? Or do yuou mean I need to open the bleeder prior to pressing the pistons?

Just don't want to wreck my ABS system.

Thanks

Nate

What he means is when you compress the piston back into the caliper (bleed port not open) the brake fluid will back towards your master cylinder. If you've topped off your brake fluid as the old pads wore the excess fluid will overflow your master cylinder. If it's reasonably close to the top you'll need to dip or ? some of it out before you compress the piston with the clamp. Another thing is DON"T remove both calipers at the same time or you'll push the piston out of the second caliper when you press the other one inward. This description is without using the bleed port option.

[Bbbutch]

Wether you compress the caliper pistons back in with the bleeder open or closed use the old brake pad in between your C clamp and the pistons so that you don't do damage to the pistons.

[akauth]

Originally Posted by gnb

Can I just use a C Clamp to push against the old pads to push the piston flush into the calipers to make room for the new thicker pads?

Or do I need to open the bleed plug to relieve the pressure while compressing the pads /pistons back into their bores??

The Chilton book does not address this and shows pressing the piston back into the calipers. There are differing opinions - some say it is better to open the bleeder plug to relieve the pressure prior to pushing the pistons back into their bores.

Thanks,

Nate

Nate, if you've got anti-lock brakes or you've got over 100,000 miles on the vehicle or it's been a long time since you've flushed the fluid, loosen the bleeder prior to compressing the pistons. This will keep dirty fluid from going backward into the system. More important the more miles you have and/or the more miles between a flush.

In general it's best to pop the bleeders always *but* recognize that you'll introduce air into the system and will have to bleed. If you can't bleed afterward, the vehicle will be in a dangerous condition (potentially). You should always bleed after replacing pad/shoes but I'll admit I've been lazy a couple times and not done it and it came out fine. (And I've had the reverse be true too).

If you don't have anti-locks it's not at big a deal since replacing parts aren't an arm and a leg if they go bad so the cost of laziness is less.

Number one rule - the cleaner the fluid the longer all the parts last. The cleaner you can keep the fluid the better but failure to do so gets a lot more expensive when you have anti-locks (or a very expensive vehicle). This means the fluid only goes one way - from the master cylinder to out the bleeders. The only way you can do that is to pop the bleaders. But popping frozen bleeders can open a can of worms (but it's the right thing to do) if they're frozen.

The other thing that can happen is that if you've filled the brake resevoir too much when the brakes were just about "done", pushing the fluid back in can cause it to overflow. Popping the bleeder stops this and prevents dirty fluid from going back into the resevoir where it can then help to wear out the master cylinder prematurely.

Alan

[gnb]

Thanks for the responses !

I have a Motive Products power brake bleeder and should receive by next Wednesday an adaptor to fit the Toyota master brake cylinder. Also ordered several liters of ATE Super Blue brake fluid (Dor 4 and Dot 3 comparable). BTW, The Motive Products bleeder really works like a charm. Did my old volvo a few years ago with it and it works like magic (it's due again this summer).

My plan was to replace the pads and rotors this week-end and bleed and flush the brake system next week-end.

Do you suggest I wait and do it all at once ? Or will pressing the old fluid back up the system and not flushing the whole system for a week be harmfull ? Is it the dirt/residue in the old fluid that is harmfull to the system or is it the potential for damaging seals that may occur by pushing fluid back up the system on ABS equipped vehicles ? Or is it both ?

I am told that as long as you are pressing the piston into the calipers with the bleeder valve open that NO AIR can enter the system. Is this true? I am a bit reluctant to completely trust this theory. I was prepared to attached a rubber hose to the bleeder nipple and submerge the other end in a bottle full of fresh brake fluid- wouldn't this work? Of course, there is the small amount of air that is present in the hose between the nipple and the bottle.

My 2002 Sequoia has 29K miles on the odometer and it does have ABS.

[DevinSixtySeven]

i have abs, 97000 miles, and have bled the brakes at least three times, including once in the parking lot of offroad solutions . it only takes a few minutes, may as well do it when you change the pads/rotors. i use the two person method and the little cup same as you with a looped section of clear tubing so i can see if it's still trapping bubbles or not, and the shade of the fluid...that ate blue will make it a snap . maybe one of these days i'll get a motive...sounds useful.

never had a problem with the abs, drained the master cylinder completely at one point (couldnt be helped at the time), got everything buttoned up just fine afterwards.

-sean

[LGL002]

It looks like you've been through this process before and I apologize for my description which was aimed at someone who may not have done any of this before. That said, unless you bleed the air out of the hose into your container of fluid you could get air back into the system. There is no check in the bleeder port so opening it to atmosphere without fluid pressure could induce air into the piston cavity as the old fluid drains out. The pressure system you're accustomed to using is the best way to go and I'd wait until you get your adapter. Fresh fluid is always the best way to go.

Larry