Bleeding 74 brake question...

[igasper10]

Some people have said that the only reliable way to bleed our C3's brakes is to have them pressure bled. That's pretty pricey around here, so I just wanted to know what was so bad about bleeding them the standard way? i.e. someone in the car pumping the pedal while you go from wheel to wheel. If anyone has any tips for this type of manual bleeding, please reply. Thanx--

ian

 

[igasper10]

Also,

How much "wobble" are the brake pistons supposed to have inside their bores? I'm not talking about straight, linear motion. When I took off the old pads I noticed that I could move the pistons so that the face that puts pressure on the pads during operation was about 10 degrees or so off from being flat against the pad plate if it would have been there. Is this normal?

Also,

What's the order for bleeding? Is it rear left inner screw, rear left outer screw, rear right inner screw, rear right outer screw, front right (1) screw, front left (1) screw?

ian

 

[ronkellogg]

brake bleeding question

you can get a power bleeder for around $50 and do it yourself. I used it last night when I replace the master cylinder on my 79. It works great and would also be good for just changing the fluid.

motiveproducts.com

 

[GTR1999]

You can still use the 2 man method, I used it for years. You must have 0-.003" runout in your rotors, good hoses and calipers. If the hoses are more then 5-6 years old replace them at the next brake service or now. They collapse internally over time and will give you fits. If you have a small compressor you can make a pressure bleeder from a piece of steel that fits over the M/C in place of the cover. Glue a piece of rubber on it to insulate between the M/C and plate and drill and tap for a air fitting over the M/C chamber. I use a C clamp to hold it on and use about 5-8psi to bleed the system. works good. I have a Motive bleeder too but haven't used it yet.

 

[MaineShark]

Those "speed bleed" bleeder screws (with the check valve) are a lifesaver. Like $13/pair (you'll need three pairs - one for each front caliper, and two for each rear) from NAPA, and worth every penny!

I let mine gravity bleed for a while, to clear out the old fluid. After that, I did the ol' pedal-pump method (but with the speed bleeders), and things went well. I'm going to make myself one of those pressure bleeders, one of these days...

Joe

 

[igasper10]

Also,

How much "wobble" are the brake pistons supposed to have inside their bores? I'm not talking about straight, linear motion. When I took off the old pads I noticed that I could move the pistons so that the face that puts pressure on the pads during operation was about 10 degrees or so off from being flat against the pad plate if it would have been there. Is this normal?

Also,

What's the order for bleeding? Is it rear left inner screw, rear left outer screw, rear right inner screw, rear right outer screw, front right (1) screw, front left (1) screw?

ian

Any answers to my "wobble" question?

Also, my Chilton manual says that the order for bleeding is rear left inner, outer, rear right inner, outer, front LEFT, front RIGHT. It didn't make sense to me that the caliper closest to the M/C wasn't the last one bled. Is this correct???

 

[igasper10]

Also, I'm using a vacuum pump as my vacuum bleeder. If I have everything hooked up right (i.e. air tight seal around bleeder screw, other end of hose submerged in bottle of fluid) will I be able to hold a pretty constant vacuum pressure??? The first time I tried it, as soon as I would pump the vacuum the pressure would go up and then immediately go back down to zero because I had too big of a hose on the bleeder screw. Now that I've solved that problem I'm wondering what the gage will read with it air tight at both ends.

ian ;help

 

[c4ever]

I continue to go the old fashion manual route. Bleed from the farthest point first. Right rear , left rear , right front , left front. One of these days I'll get the speed bleeders.

Carlo

 

[GTR1999]

"wobble" is runout,caused by a worn or warped rotor-most times. Could be play in your bearings. Do you have an indicator? You need to know what's happening there and it takes more then observing by eye. You have to determine runout through 360* then check the end-play of the bearings which should be around .001-.003" although the GM books spec up to .008"(too much). Turning your rotor most likely will not correct the problem,you'll still have runout but not as much.

 

[MaineShark]

I think he means lateral play, not longitudinal play. In other words, the piston rocks side to side, not in and out.

As far as how much is acceptable, that I don't know.

Joe

 

[81LT4]

Be sure when you bleed the rears, you t off the vaccum line
and bleed both valves at the same time! if your useing the pump.