Brakes-Can't get piston back in caliper

[sallanblock]

Doing the front disc brakes on my '86 Toyota 1/2 ton pickup. Had a very hard time pushing the piston back in the caliper, used a block of wood and a C clamp, had no problems this way on the passenger side but the driver side caused me to ruin my clamp. I was able to force the piston in far enough to force the caliper back in place (using a sledge hammer). I even loosened the caliper's bleed valve to push the piston in but that was of no help. Now with the caliper back in place I put the rim and tire on and naturally the tire is locked in place and won't move. Drove the car a bit and the brakes work fine but the rim got really hot to the touch and is still locked to the rotor. Is it dangerous to drive this way or will the wear of the new pads eventually allow the piston to back off the rotor? What should I do?

[KimMG]

It is dangerous.
Driving with it in this condition can cause bearing failure, warped rotor, fire, burned glazed pads, brake failure.

Replace the caliper.

Flex lines deteriorate on the inside and cause blockages, you may need to replace those also.

[sallanblock]

I can understand replacing the brake caliper if the piston is frozen in place, but if brake fluid drips from the bleed valve would that not indicate the flex hose is good and not need replacing? Also by the flex hose do you mean the flexible hose that connects the brake caliper to the brake system? Not the metal brake lines? How do I check to see if this hose is good?

[KimMG]

When you bleed the brakes, are you getting a good flow (good) or is it just dripping (bad) from bleed screw? Bad (rubber hose) flex lines (not necessarily saying yours is bad) can deteriorate on the inside and have blockages that act like one-way valves keeping the caliper pressurized and squeezing the rotor or not allowing any fluid to the caliper. They can also expand and absorb the energy required to operate the caliper.
After replacing the caliper, bleed the brakes. If you get a good flow of fuid from the bleed screw when bleeding and the caliper releases the rotor when brakes are not applied, I would say the flex lines are ok.

[sallanblock]

I honestly don't know if the flow was good or dripping. I just tried opening the bleed valve enough to get a flow, in an attempt to see if that would make it easier to get the C clamp and block of wood to push the piston in further. I did manage to get the piston in just enough to be able to knock the caliper into place. I had no such problem on the other side. The piston went in all the way with the C clamp and block of wood and I didn't even have to open the bleed valve. If the new disc pads were 1/2 inch thinner, I would have no such problem getting the caliper back in place. Is there any way I can get the new disc pads cut to try this or do you have any other suggestions?

[KimMG]

If the piston in the caliper is frozen, the brakes will not work. You need a replacement caliper. No way around this. Thinner pads will not make the caliper work.
If you opened the system to press the pistons into the caliper, you have to bleed the system. The only way to check the flow of fluid is to bleed the system.

[sallanblock]

Caliper was changed today works well but I'd like to bleed the brakes. Do you have a foolproof method for brake bleeding with only one person? Thought I could prop a piece of wood against the brake pedal and bottom of seat and start from the wheel farthest from master cylinder. Do you have any step by step guidelines?

[KimMG]

Propping a piece of wood against the pedal will not maintain pressure when you open the bleed screw.
You can buy a vacuum tool (mityvac) at your local autoparts store to bleed the brakes solo.
Then start with wheel closest to the master cylinder and work your way to the wheel farthest from the master cylinder. Left front, right front, left rear, right rear.
Do you have a manual? Did you measure the thickness of the rotors or have them resurfaced? Did you check and repack the bearings? Have you inspected the rear brakes and adjusted them properly? Sounds like you are trying to take a lot of short cuts.

[sallanblock]

I have the manual but haven't done all the things you mentioned. I've done repairs on an "as needed basis" only. I didn't know there was a tool that allowed a single man operation for brake bleeding and thought you always started from the brake furthest from the brake master cylinder. The pickup has over 216,000 miles on it so I don't know whether it's worth doing everything to keep it in tip top shape. I do notice lately the brake light inside the dash keeps coming on but it's related to the emergency brake handle vibrating out. I push it in and the light goes out. Do you think I need to check something ? I replaced the rear drum brakes recently.

[sallanblock]

Forgot to mention the emergency brake works well the way it is.

[fourwd1]

I bought one of those Mighty -vacs, didn't work too good for me for bleeding brakes. A much better choice and only a little more $ is a power bleeder from Motive Products. It pumps fluid into the MC and makes one man bleeding a breeze.

http://www.motiveproducts.com/02bleeders.html

scroll to model # 0101

Proper bleeding order is:

LF
RF
RR
LR
LSPV

[sallanblock]

In bleeding brakes, what is "LSPV"? And can you tell me how to adjust the emergency brake? While driving the emergency brake handle keeps sliding out (vibration), causing the brake light to come on.

[jbclem]

I've done alot of one man brake bleeding lately and here's what I've come up with.

The easiest way with several pieces of wood...pushing the brake pedal down as much as you can by adding more pieces of wood (even shims), pounding them into place to add to the pressure...you have to protect the seat with a thick towel or the like. What I do is pump up the brakes with my foot, then slip in the longest piece of wood and a second (flat 2x4 6-8 inches long), and then I have some 1x2 pieces I try to force in up to and including the shims. The 1st piece is used lengthwise, the others are used flat(widthwise) so it's pretty solid. Then i have to get out of the front seat without knocking the wood out of place, you have to be a bit flexible to do this. As you repeat this and get air out of the system the pedal will get higher and take fewer shims/wood. This may not sound like the perfect way to do it and sometimes it won't be enough. But it will at least serve for preliminary bleeding and if you get a hard pedal out of it then you're home free.

I've tried vacumn bleeding and the problem I had was the it also sucks air in through the bleeder screw threads since the bleeder screw is loosened. It works but when you have a problem car that where the pedal won't get hard then all those extra bubbles coming from the bleeder screw threads will drive you nuts.

I have a power bleeder setup and it's more of a messy hassle depending on how good an adaptor you have for the master cylinder resevoir(s). I had to make one for my old Datsun pickup and it was a pain to install each time but when it wasn't leaking through the adaptor it worked.

Of course the ultimate method is to find a patient neighbor who will help pump the brakes.

Hope this helps.

John

[sallanblock]

Thanks John, that's the way I used to do it by forcing the brake pedal down and against a piece of wood. But I used to start at the wheel furthest from the brake master cylinder and work my way towards the driver's wheel last. What do you say? And do you have any response to my question above regarding adjusting the emergency brake?

[thastreats]

without replacing the caliper try getting a bigger clamp take the old brake pad place it over the piston and take the clamp and twist it till you see the piston flat against the caliper if it still doesnt go down all the way and the tire still locks up you might just need to replace it..