Endless Bench Bleeding....

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San Jose Steve
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Endless Bench Bleeding....

Post by San Jose Steve » Mon Dec 24, 2018 1:01 am

I went all out to bench bleed my new MC. Rigged up my reservoirs above the vise mounted MC and made new lines running from the 3 outlets to a can of fluid. I can’t seem to keep the reservoirs full as they slowly drain into the can. I’ve never bench bled before..... is this normal? Anyone see anything wrong with my setup? This is not what I expected to happen. -Steve
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Re: Endless Bench Bleeding....

Post by fp55scca » Mon Dec 24, 2018 7:31 am

--Steve, bench bleeding is just a process of getting all the air out of the MC before mounting in the car. Given your setup, you may already have achieved it.

--Instead of using three brake lines from the MC, try isolating one of the circuits at a time. It helps to have back pressure from the circuits not being tested in order to check each circuit independently. Remove the brake lines from the MC. Insert a 10mm x 1.25 bolt into the rear circuit of the MC (the single port at the front of the MC). Just lightly, don't damage the tapered seat. You could also lower your reservoir. It's a gravity feed, and you don't need that much pressure.

--Now hold your (rubber-gloved) fingers over the front brake ports of the MC, and slowly actuate the rear plunger of the MC with a suitable probe. As you continue to plunge, you should begin to feel pressure at your fingers as the fluid is forced through the MC. When you feel pressure at your fingers, release one of the ports while continuing to slowly depress the rear plunger of the MC and you should observe a free flow of brake fluid without air bubbles. Reverse your fingers until both fronts are air free. Don't let your reservoir empty.

--Now insert two 10mm x 1.25 bolts into the front circuits, remove the bolt from the rear circuit and repeat the procedure until you feel pressure from the rear circuit and observe clear, bubble free fluid at the rear circuit.

--Install the MC, and proceed with your normal brake bleeding on the car.
Jim Scurria
Norfolk, VA

1972 Fiat 124 Spider
1971 Spider - SCCA FP-24
1974 CSA Abarth Replica
1981 Fiat Spider Ratrod
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Re: Endless Bench Bleeding....

Post by bartigue » Mon Dec 24, 2018 12:23 pm

If you have fluid flowing through everything then you’re done. Mount it and hook it all up and bleed it to the calipers.

I never bench bleed by the way. I use a power bleeder and gravity and my foot. Less messy and maybe takes two more minutes per caliper.
Brad Artigue
1969, 1969, 1970, 1979, 1980, 1981, 1982, and 1982 124 Spiders
1969, 1970 850 Spiders
77 X1/9
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