rbuswell

quote:
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Originally posted by jluetjen on Pelican Parts 911 Forum

BTW -- Be sure to "bench bleed" the MC before you install it in the car. If you don't, you'll have a heck of a time trying to get the pedal firm. The process is real easy:

1) Install a couple of clear flexible tubes from the ports where you usually attached the brake lines, and run them back into the port which usually attaches to the reservoir.
2) Fill the MC with fluid
3) Pump the MC until no more bubbles appear in the flexible tubes.
4) Cap the ports
5) Install the MC as you normally would.

Trust me, this simple process will save you considerable effort later on.
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I'm putting in a new MC in my '82 SC today and I've seen this procedure recommended several time.

1) I may be a little dense but I don't understand what sort of fitting I'd need for the clear flexible tubes to work. I assume it has to fit the threads at the brake line ports in order to build pressure so it seems it needs to be a custom made, sealed part (or is it something you buy)?
2) Also should the fluid be put in first before installing the tubes?
3) Pumping the MC means just moving the shaft in and out, correct?
4) Finally, does this recommendation still apply if I'm using a Motive power pressure bleeding system?

Your help is greatly appreciated.

theiceman

i'd say screw it and use your power bleeder , looks like more trouble than it's worth. I never replaced my MC but drained the sytem to put new brake lines in and wash out the reservoir. didn't have any problems whsover and I don't have a power bleeder watchamcallit.

mo_gearhead

I put a new M.C. in my '69 rebuild project. Didn't know about bench bleeding ...it didn't seem to matter. I used the normal "two person" procedure (one in car pumping pedal, one at the wheel cyl.)

Since my car also had ALL NEW brake lines, it was all dry (empty) and did take several trips to each wheel to finally get all the air out , but it seems to be fine.

Andy_Ash

The bench bleeding procedure might work fine for some people, but I can imagine that the practicality of doing it that way may be limited.

I didn't know that it was recommended to bleed the master clutch cylinder on the bench, but I found a way of doing it anyhow. If the master clutch cylinder has or gets air in it then the piston inside just cant pump the fluid through to the slave. The pedal has a big spring in it, and the spring will push the pedal to the floor, once the pedal is over centre.

On mine the takeoff for the clutch on the tank is higher than the brakes, the brakes are in the bottom of the tank, and the clutch about 3/4 of an inch higher. It's easy to get air into the clutch because of this. It looks like the tank has plenty in it, when in fact you're drawing air.

Secondly, if you have air in the master cylinder for the clutch, get a big piece of rag, crack the output from the master cylinder, and very carefully pump the pedal until the air is gone. You have to be careful, because you don't want to fill the floorpan with clutch fluid.

If the worst comes to the worst, there are little plastic plugs in the floor which fit from the outside, underneath, and these can be used to drain the wors of the fluid off.

Edit......

A day later I read the thread again, and realise it's about the brakes, not the clutch! Doh!

Ignore me, I'm a fool!

rbuswell

I didn't attempt to use the bench bleeding technique and went directly to the power bleeder. It worked perfectly and I finished in about five minutes (not counting jacking up the car time). I highly recommend the Motive system.

KC911

I installed a 930 m/c without bench bleeding and using the Motiv pressure bleeder...makes it painless.

Keith
'88 CE coupe