Thought I would share my experience/solution to bleeding my brakes. This is a bit crude, but hopefully it can assist others. I did a complete brake system replacement, lines, calipers M/C. My initial attempt to bleed the system, gravity method, pumping the pedal were not working so I did a little research and realized my best method would be power bleeding. Here is what I did...I considered modifying the sprayer bottle like others had done....first I needed a plate to cover the M/C regardless of what actual pressure method I used.





I salvaged a piece of 3/16” aluminium plate, drilled and tapped a hole to fit a male air line fitting. Glued some leftover rubber shelf liner to act as a gasket, as well I ground out the centre area to allow the air to pressurize both sides of the M/C. Clamped the plate to the M/C with a couple of C clamps.





Once I got the plate on I set my compressor to 20lb pressure, connected the air line.





I went ahead and followed the bleeding sequence, LR Inner,LR Outer, RR Inner, RR Outer, RF, then LF. I made sure I kept an eye on the fluid level in the M/C so it didn’t run dry. I did a bit of research and decided to use Dot 5 (silicone) mainly to protect my paint. The M/C was bench bled prior to the install. I also used stainless lines and ended up with a few leaks. More research and ended up using copper flare washers that worked great to fix the leaks. Overall this worked great, and making the plate took about 30 minutes and cost nothing.

 

Great job. It would be nice if you could fabricate a factory type cap that could use the stock bails for attaching the cap to the body of the master cylinder. That would eliminate the need for clamping and un-clamping as you add brake fluid. Again, great job. Jerry

 

Not sure that those flimsy bails would hold seal against 20psi .... but maybe at lower pressure. Drill/tap your plate at the center point of each fluid well; then install properly cut-down hex-head bolt (3/8"-16 maybe) with a groove in the head to accept the bail loops. You can adjust the bolt for proper retention of the bails. You'd need to seal the bolt threads with epoxy (?) once height is established. That might hold 5-10 psi. But if pressure is too high, the ends of the bails will eventually pull out of their pockets...and you will have a real mess....

Certainly a creative approach...

 

Those lid hold-down chains from Motive are a joke aren't they? Have to use a big clamp.
I pretty much did the same thing as the O.P. but instead of aluminum lid I used Lexan. I wanted to see inside the MC while pumping the juice to it.

The lid was cut to size at a home glass shop and can be seen in my profile > photo > album > bleeding.

 

I've always used the wife method. But I am curious as to why not supply 20 psi brake fluid to a fixture rather than air. Admitting my ignorance here, is that what the Motive Power bleeder does? Heads U.P.?

 

20 psi is 20 psi...whether air, brake fluid, gravy, chili.... Air is a lot easier and less messy than working with brake fluid. Cleans up a lot easier, too!

 

I did a little research. Seems brake fluid is what is supplied by the motive bleeder. It doesn't seem to be well thought of however. In my case I have a Wilwood MC and a spare cap so that might eliminate the sealing problems with the stock MC.

I would disagree with the 'chili' comment. Plenty'o pressure available there.

 

Exactly. I pour two bottles of brake fluid into my Motive. You DO NOT want the MC to run dry. Hence, the clear Lexan MC lid I have. Then its non-stop bleeding.

Myself, I don't get why people use only air to pressurize the MC. You have to stop and refill the MC, often!

 

The method I described....using air pressure only was a very simple process. When I started I had no fluid in the system except for the M/C. When I started I made sure the M/C was full. As I went through the bleeding process I had to remove the cover I think three times. The first time was to re-fill, as it was about 2/3 down and the other times were for just a little top up. I didn’t find removing the cover that much of an inconvenience.

 

In a different recent thread, I like the idea to use an small vacuum pump like that thread's OP used his family's electric Breast pump.

 

Air is a lot easier and less messy than working with brake fluid. With a number of brake adventures under my belt a bought the motive bleeder. After the first use i just use a big clamp on the plate and just air in the pump. You do need to watch the MC and fill it frequently as it goes down quick but it is still better than dealing with a quart of brake fluid and cleaning everything up.

 

I pour the brake fluid into the pressure bleeder also. Works like a dream and no concern about running dry.

 

Compressed air is cheap/free if ya have a compressor. The GM books always say to only use a bladder bleeding system but I think that's b/c they're hesitant to advise people to use compressed air, who may not have 'clean' and 'dry' compressed air. I've seen a lot of guys' shops with a moisture trap hanging right OFF the end of the compressor -- they won't work that way. But set up properly, with the right 'clean' air ...and care not to run er dry, I think yours is a great solution.

I've seen guys suck fluid out too using an AC vacuum compressor (with an intermediate collection cup). Just sucks the fluid right out. That works too. Quick. Lot of good solutions out there.

There's a guy on ebay who sells Lexan blanks pretty cheap. I bought a couple to make a presure cap.
https://www.ebay.com/itm/SALE-2-PACK...M/274330608958

 

I have been using the Motive bleeder for 9 years now. I use the aluminum cap they provide and use a C clamp. Before I add any fluid to the bleeder I pressurize it to about 15 psi and leave it alone for 10 minutes. If the pressure holds, I know it will not leak fluid. But out of an abundance of caution I always throw a handful of rags under the MC.

 

So When I get my car back, I am going to use an after market MC cover and add a motive adapter and use the Motive bleeder. I see people are making there own cover. Did anyone try / have good results with adding an adapter to the original style MC cover?

 

Adaptor to lid? No.
See my Profile > Photo Album > Brake Bleeding.

 

I considered it a couple weeks ago. I'm sure it could be done. After looking my old lid over very carefully I decided, for me, it was going to be more work than making a new block because:

1) Mine (81) has some vent holes in the cap I would need to braze shut. That's doable.
2) I'd need to cut/trim away the rubber but leave it around the perimeter. But I was concerned if I did that there could be the possibility the rubber 'could' slip a little when installing the bale wires (but maybe not either??). You'd need to trim the center so air would pressurize both chambers.
3) I'd need to braze or rig up connectors. (that's not hard either, but more work)
4) The metal cap isn't that thick, but I'd be confident it should hold 20 psi (but would the bail clips??).
5) I have a couple other GM cars I'd like to bleed and they have different shape M/C's ...so making one universal cover would allow me to bleed other cars, even those with round M/C's. With the corvette cap, it wouldn't fit my other GM's.

At the time I was considering modifying the old lid, I happened to read a post where another forum member indicated his aftermarket adapter would spit fluid out the edge (and onto the fender paint) and make a mess if his lid/adapter wasn't clamped down with C-clamps. After reading that I decided it just made more sense to put less work into a clear Acrylic block ...which I bought off ebay for a few bucks that could be used on other cars. Acrylic drills and taps really nice, it's the easier way to go (for me). I have some rubber I can use as a gasket. I like the idea of being able to see the level as I'm working. I've run more than a couple m/c's dry before. It just takes more work then.

BUT, all that being said, SURE I believe it's possible to modify the old mc lid with a nipple to pressure bleed. You just need to make the appropriate modifications. I would assume the bale wires are tight enough, mine fit really tight. Let us know how it goes if you proceed.

.

 

Hmmmm your making me rethink this.. Thanks for the feedback!

 

Thinking along the lines of the original MC lid, its, for lack of better term, "Domed". So, when you are filling / pressurizing the MC with a Motive tank, that dome is going to fill up also. So, you have to figure what to do with that extra brake fluid after you shut off the supply from the tank.

Just like a flat plate plate-homemade lid, its just a matter of shutting off the supply when almost done bleeding. Then allow the last few ounces to drain out at the last caliper, which would be the left front. If you remove the lid too soon, you have a hell of a mess.

But the whole trick in these homemade lids is a great seal / gasket and some good clamping force on the lid.

Maybe some day, Motive Bleeder will design a better MC lid for the tens of thousands of GM masters still out there there, that does not require crappy chains & hooks.

 

I sent the Motive back and made this with a spare cover and used the air shock pump for my Harley, worked like a champ. I never could get it right using gravity, the pedal or a mity vac but this did the trick.