Rinkys

iTrader: (2)

I know, another brake bleeding question – but I cannot seem to find an answer to my question. I have a 1972 Chevelle, LS3/T56 setup, and have nearly completed a complete rebuild from the ground up. The ENTIRE brake system is brand new – never used, never bled, never seen brake fluid at all. It has a standard Chevy MC, and C5 disks on all 4 wheels. In researching how to properly bleed, the consensus was that I would have to:

1) Bench bleed the MC
2) Open the bleeder on RR caliper – gravity bleed
3) Open bleeder on RL – gravity bleed
4) Open bleeder on RF – gravity bleed
5) Open bleeder on LF – gravity bleed
6) Then pressure bleed from each caliper in the same order.

My questions are… “They” say to bench bleed your MC because if you don’t, then you push air into the hoses and lines down the line. Guess what? They are all full of air already – so is bench bleeding necessary on a brand new, never used, just built car? Second, many say to gravity feed each caliper first, but from what I know about how fluid flows through hoses – would that not lead to air bubbles being trapped at the top of all those pigtails that come off the MC? Or anywhere else for that matter? Seems to me that in order to get all that air out of the pigtails, the fluid would have to be pulled or pushed through the system rather quickly. Any opinions?
Second – I have speed bleeders on the system. I also have a Mityvac. I have heard that the two do not play nice together, but cannot verify. I guess my questions are – what is the best way to bleed a brand new, never used brake system for the first time (with speed bleeders) – considering the fact that EVERYTHING is dry?
FYI - I still have the stock bleeders, just in case...

Tom Ringlein

Kevin97ss

Bench bleeding is the right first step. In a lot of cars the master will sit inclined at ride height which can trap air in the bore that will never bleed out. That being said "bench bleeding" can be done on car and is the way I do it, the trick is to level the master by jacking the car. Hook up your recirc tubes and with slow long strokes of the pedal(all the way down-all the way up) you'll be done in five minutes. Gravity bleeding an empty system is more like priming and replaces about 95% of the air with fluid. Then you can either finish with the mityvac or have a helper with the pump and dump. Cant comment on the speed bleeders as I have never used them.

Rinkys

iTrader: (2)

Yea, that is more or less what I was thinking. I wanted to jack the rear up about 10-12" and level out the MC for a bench bleed while on the car. Was not sure though, becuase when I do this, the car will be fresh out of the body shop with a brand new show quality paint job. Underside of the hood will be detailed - so I did not want to get too happy with the pedal and spray brake fluid on my new paint. For that reason, I am researching now whether or not I want to do the DOT 3 or DOT 5 thing. Still on the fence. Think what I will do is bench bleed MC on the car, get the wife to use the Mityvac on each line while I keep the reservior full, then "pump and dump" pressure bleed at each caliper. Keep my fingers crossed for a nice, firm pedal. Somoething else, though. Once I bench bleed the MC - what will keep all that fluid from running out when I disconnect the bleeding kit and re-install the brake lines? I guess I would have to move fast and connect the line, have the bleeders open for gravity feed, and immediately start keeping the reservoir full as to not pull air into the system.

I have similiar questions about pressure bleeding the clutch MC/Slave. When I installed the transmission and new slave in 2008, I did not bench bleed the slave because I knew it would sit for 2 years while I was stationed overseas. Still working on that one.

TJR

Kevin97ss

The fluid wont pour out of the master like a faucet; it will drip at a steady rate though. There is a trick to slow it down when connecting the lines. First, only fill the master a little over half way for the bleeding procedure but make sure the tubes stay submerged in fluid. Once the "bench bleed" is done lift the recirc tubes above the fluid and allow the tubes to drain back into the master(not all of the fluid will drain out) you can either clamp the tubes or have someone hold them straight up. Fill the master and put the cap on, then let gravity drain the tubes in to a bottle, this will create a vacuume in the fluid chamber. The fluid will now just barely seep out and give you a chance to connect the lines with out a huge mess. Still use a folded towel to protect any painted surface while you work. When your ready to bleed the system open the bleeder and remove the cap from the master. Keep an eye on the fluid level but dont worry about rushing around, the gravity bleed is a very slow and time consuming process, the RR may take 20 minutes or more before you see fluid at the bleeder. It goes faster as you get closer to the master.

Rinkys

iTrader: (2)

Kevin97SS - thanks for the tips. As much as I was not looking forward to this process, I am actually now looking forward to doing this stuff myself. But anything painted Viper Orange will certainly be covered with plastic and a towel or two for sure.

TJR