Seeking edgeucation on master cyl. install

[71CHEVYSHORTBED402]

Sure a long haul to this point. Booster and MC pending and she's ready for fenders, getting close.

I've installed MCs before, but never bench bled one before, which is what I'd like to do. But the truck won't be started for say another 2 months. Should I wait to bleed the MC until it's ready to run?

[Accelo]

You will have leaks, especially if you are using stainless, so doing the m/c install now is a good idea. Access to the fittings will never be better for that reason I recommend installing it now. I also recommend using the DOT5 so any leaks don't eat your paint.

Install the m/c and be sure all the piping connections are working and fit properly.
Confirm the rod to the brake pedal isn't too long. It will keep the piston from opening the relief port and the brakes will not retract it this is set too long.

Remove the tubing at the M/C and loosen the bottom fitting. Some bench bleed but I do it on the vehicle. I also do one side at a time; I prefer to do the rears first as you will have a longer stroke at the pedal and it will make bleeding easier. Just my attempt at controlling the mess. Remove the brake tubing and put about 1" of fluid in the side of the M/C you want to bleed. Pump the brakes till you get a stream from the port. Connect the line. Then bleed the brakes. Your brake light should come on, if you have one, when you have bled one side. Complete the other side using the same method. This way if both sides have any leaks you can deal with one at the time. Mark the master cylinder so the connect fluid is installed especially if you use DOT5 as it is not compatible with the other fluids.
You can use the bleeder kits if you like. Most the time I find it unnecessary. Once in a while no matter what you do the fluid will not make it past the piston. A Mityvac on the M/C port will typically get it started.

[Reddeye]

Based on recommendations from other threads on the forum, I did the bench bleed with the MC already mounted on the firewall, just using a basic bench bleed kit.

[jocko]

I've always bench bled in a vise before installing - easier access and zero chance of spilling/dripping/squirting brake fluid on that shiny new paint Just gotta be careful when you do install so you don't spill the fluid and defeat the purpose. That truck sure is looking purdy Tony, can't wait to see it back together!

[71CHEVYSHORTBED402]

Thanks for the info.. And thanks Jocko. Guys like you guys walked me through this.

[71CHEVYSHORTBED402]

I installed it without bleeding it. The shop gets the maiden start and they'll bleed the brakes, so up to them how they want to prep the MC.

Second MC, the first from Ecklers didn't suit the hard lines. Worked out though, I like this one better and in stock.

I'm running DOT3. There's good & bad DOT3 Vs 5, just one opinion. Plus I reused the combo. valve and cylinders. Cylinders were like new and word is combo. valves rarely go bad. See what happens.

[Steeveedee]

If the shop uses a bleeder ball, they shouldn't get brake fluid all over your new paint. I was always careful that way, but some people...

[LS short box]

I always bench bleed off the vehicle. Couple of short pieces of brake line bent back into the master.
You can plug the ports during the install. Have your new brake lines ready to plug in.
Lots of towels below the master to keep brake fluid off any painted parts.
I would completely bleed the entire system before bolting on any sheet metal.

[Steeveedee]

To add, I worked at a shop in '76 right after I got out of the Navy, and the boss would sit in the vehicle and gently tap the pedal until he was satisfied with it. We didn't completely bleed out the system. Crazy, I know, but it worked. I didn't agree with that practice, as I always like to see a complete flush of brake fluid with a brake job.

[71gmcC15]

Originally Posted by Steeveedee

To add, I worked at a shop in '76 right after I got out of the Navy, and the boss would sit in the vehicle and gently tap the pedal until he was satisfied with it. We didn't completely bleed out the system. Crazy, I know, but it worked. I didn't agree with that practice, as I always like to see a complete flush of brake fluid with a brake job.

That's not good any air bubbles will grow with heat and now your pedles on the floor and you have no brakes.

[71CHEVYSHORTBED402]

Just a thought, I replaced the MC in this about 20 years ago and didn't know about the push-button on the combo valve. I bled the brakes, everything was fine.

Hmm........