Bench bleeding brake capilers.
Thread Starter
Le Mans Master
Joined: Jun 2019
Posts: 5,409
Likes: 2,136
From: Loveland
Bench bleeding brake capilers.
I have never been happy with the pedal feel for the brakes. It always seemed to soft. I pressure bleed, gravity bleed, suction bleed, pump bleed the brakes and never seemed to change. Just because, I decided to over haul the rear calipers. I installed a stock caliper seal kit. The old ones were not leaking and seemed fine. I figured as long as I had it apart, I would install the new ones. Before installing the calipers I thought I would make sure they were full of brake fluid. I tipped the caliper on end with the brake line fitting pointing straight up. The bleeder fitting on the other side pointing straight up. I hooked a tube to the bleeder fitting and started filling the caliper with fluid. Very slowly. I could see the fluid making bubbles at the brake line fitting. I kept filling untill a clean flow of fluid came out,,,,, no bubbles. Closed the bleeder and sealed the brake line port. Installed the caliper. I have never had such a solid pedal before. I know there has been MANY posts on here about how to bleed the brakes. This seemed to work very well.
1968 manual brake car.
1968 manual brake car.
Safety Car
Joined: May 2004
Posts: 4,347
Likes: 1,576
From: los altos hills california
Le Mans Master
Joined: Mar 2004
Posts: 7,458
Likes: 1,484
From: Little Rock AR
Might try this if I need to bleed again. Having the caliper in your hand and being able to rotate it to get the air to the top near the bleeders sounds like it would be worth a try. Need to restrain the pistons some way. If the line was off when you filed the caliper, you still need to get that last bubble out.
Thread Starter
Le Mans Master
Joined: Jun 2019
Posts: 5,409
Likes: 2,136
From: Loveland
There are a few different brands of caliper kits on Amazon. I'm not sure about the regional. Make a block of wood, when you slide the caliper off the rotor, slip the block in. This will make it much easier to reinstall.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
2027 Corvette vs The World: Every C8 vs Its Closest Competitor
Joe Kucinski
10 Most Common Corvette Problems of the Last 20 Years!
Joe Kucinski
Drifting
Joined: Nov 2016
Posts: 1,957
Likes: 576
From: Pittsburgh PA
Why? If there is no air in the hydraulic lines and hose, and you've done careful job of sealing off the hose, there is no reason to bleed anything. Employing your bench bleeding strategy here, I would say you first make sure there are no air bubbles coming out of your lines, and then you mate the two.
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,809
From: Cool Northern Michigan
That's right. Very skeptical of this new found way.
C3 brake fluid bubbles are very special bubbles. They like to hide around corners. They like to duck-down when someone is looking. And they are somewhat sticky. They like hanging on to steel, rubber or cast iron, refusing to let go and exit the casting.
C3 brake fluid bubbles are very special bubbles. They like to hide around corners. They like to duck-down when someone is looking. And they are somewhat sticky. They like hanging on to steel, rubber or cast iron, refusing to let go and exit the casting.
Drifting
Joined: Nov 2016
Posts: 1,957
Likes: 576
From: Pittsburgh PA
well its funny this thread came up, because I have actually thought of prefilling the caliper. just because they hold so much fluid, you would still have to bleed them once installed, but it would significantly reduce the amount of air you are trying to remove. it would be much harder on the rears since the line is opposite the bleeders.
Thread Starter
Le Mans Master
Joined: Jun 2019
Posts: 5,409
Likes: 2,136
From: Loveland
That's right. Very skeptical of this new found way.
C3 brake fluid bubbles are very special bubbles. They like to hide around corners. They like to duck-down when someone is looking. And they are somewhat sticky. They like hanging on to steel, rubber or cast iron, refusing to let go and exit the casting.
C3 brake fluid bubbles are very special bubbles. They like to hide around corners. They like to duck-down when someone is looking. And they are somewhat sticky. They like hanging on to steel, rubber or cast iron, refusing to let go and exit the casting.
Safety Car
Joined: May 2004
Posts: 4,347
Likes: 1,576
From: los altos hills california
The question becomes, just how much air gets in? If you're careful and work fast and the hose or line is dripping fluid, a bubble or too at worst.
A QD fitting would be great here. No such thing I guess.
Secondarily, if you still have to bleed the caliper, then what's the point of this method? Air in the hose has to travel through the caliper to get to the bleeder valve.
Last edited by ignatz; Mar 19, 2020 at 02:07 PM.
Drifting
Joined: Nov 2016
Posts: 1,957
Likes: 576
From: Pittsburgh PA
Of course not having done it I have no objective data. I think if I were trying this I might plug things at the brass fitting. Then leave the hose in place and fill that as well so that gravity works in my favor when I put it back together.
The question becomes, just how much air gets in? If you're careful and work fast and the hose or line is dripping fluid, a bubble or too at worst.
A QD fitting would be great here. No such thing I guess.
Secondarily, if you still have to bleed the caliper, then what's the point of this method? Air in the hose has to travel through the caliper to get to the bleeder valve.
The question becomes, just how much air gets in? If you're careful and work fast and the hose or line is dripping fluid, a bubble or too at worst.
A QD fitting would be great here. No such thing I guess.
Secondarily, if you still have to bleed the caliper, then what's the point of this method? Air in the hose has to travel through the caliper to get to the bleeder valve.
i like the idea because instead of trying to push all the air out of a 100% empty caliper, you are only trying to bleed a caliper that in 99.9% full of fluid, so trying to remove very little air.
I'll definitely try it the next time i mess with my brakes.
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,809
From: Cool Northern Michigan
No thanks, don't want more grief. Motive Pressure Bleeder for me.
Safety Car
Joined: May 2004
Posts: 4,347
Likes: 1,576
From: los altos hills california
Willwood lists the piston area per bore at 3 sq-inches. I don't know what the throw on a bore is, let's say 1/2". That puts the volume of fluid in a caliper somewhere around 3 X 4 x 1/2 or 6 cubic inches. Or a cube 1.8" on a side. I guess if I went and looked at the master cylinder piston I could determine the pedal throw before the air gets completely compressed, but honestly I think one could do this job without adding much air if one was careful.
My thinking is this could be an OK procedure. Side note is that I have Willwood replacement brakes which are poorly designed when it comes to the placement of the bleeders and to get the air out due to mounting geometry I practically have to dismount the caliper anyway.
Thread Starter
Le Mans Master
Joined: Jun 2019
Posts: 5,409
Likes: 2,136
From: Loveland
Like I said. After bleeding my brakes many times and many ways, this is the first time I have a rock hard pedal. Is yours rock hard? After installing a new set of seals, it is easy to see how air could get trapped in the caliper.