Brake Bleeding Questions

[gbranham]

This weekend is Brake Bleeding Weekend! My setup is dual Wilwood master cylinders, as supplied with the Complete Kit, and Wilwood calipers and rotors, purchased from Factory Five. I'm using the single brake fluid reservoir supplied with the Complete Kit, and have it mounted just in front of the passenger footbox, on a bracket I fabbed up, mounted to the 3/4" tube the edge of the body rests on. Pretty standard stuff.

Couple of questions:

1) I purchased a power manual bleeder that connects to the top of the brake fluid reservoir. Do I need to bench bleed the Wilwood MCs, or does the pressure of the manual bleeder connected to the reservoir preclude the need for this?

2) I've read a few posts that it's good to put a dab of brake fluid on fittings before tightening them up. I didn't do that on any of them, and I'm confident my flares are good. Is it really worth it to back all the fittings off to add a dab of fluid?

3) Also read some folks fill the power manual bleeder with fluid, and some don't. For those that don't, they just make sure their reservoir(s) stay full of fluid. I like this approach, since it seems less messy. My question is if the reservoir holds enough fluid to even get one corner bled without having to refill it?

Thanks for the help, folks. Have a great weekend!

Greg

[edwardb]

Sounds similar to what I've done successfully multiple times with a pressure cap on the M/C and low PSI. I've always "bench bled" the M/C's so can't say whether it would work without doing it. It's not hard to do and also confirms the M/C's are working properly, getting fluid, etc. I discovered a bad M/C on one build and while helping a buddy found out he wasn't getting fluid to the M/C's because his reservoir was too low. Both before trying to bleed the brakes, which in both cases wouldn't have been successful. No way I'd take the joints back apart now that you have them together. Obviously you'll be watching for any leaks while bleeding. Tighten a little more if they leak. They can stand quite a bit. If stubborn, back them off loose and then re-tighten. Good luck.

[Dgc333]

FWIW, I had a hell of a time getting all the air out of my system. I tried a vacuum bleeder, the Wilwood procedure (leave the bleeders open with a hose going into a partially filled bottle and just pump) and a pressure bleeder. Never was able to get a good pedal.

I called Wilwood in frustration and was told that many systems can only be bleed using a three person process, this process will develop more pressure in the system and will better flush the air out. This process has one person pumping the pedal and the second and third manning a front and rear bleeder. The pedal is pumped until there is pressure and the two bleeders are open simultaneously. Wilwood also told me the bias bar needs to be centered and the push rods need to be adjusted such that you can get full stroke of each master cylinder. This process finally got me a good pedal. I hope you have better luck.

I would definitely put brake fluid in the pressure bleeder the reservoir doesn't hold a lot and you can't see the level. If you suck air you will be starting over. Certainly messier but worth the clean up to not have to worry about starting over.

Also, I didn't put any of the fluid coming out of the bleeders back into the system. As such I went through 5 quarts.

[Mike.Bray]

1) I purchased a power manual bleeder that connects to the top of the brake fluid reservoir. Do I need to bench bleed the Wilwood MCs, or does the pressure of the manual bleeder connected to the reservoir preclude the need for this? Definitely

2) I've read a few posts that it's good to put a dab of brake fluid on fittings before tightening them up. I didn't do that on any of them, and I'm confident my flares are good. Is it really worth it to back all the fittings off to add a dab of fluid? Never heard of this.

3) Also read some folks fill the power manual bleeder with fluid, and some don't. For those that don't, they just make sure their reservoir(s) stay full of fluid. I like this approach, since it seems less messy. My question is if the reservoir holds enough fluid to even get one corner bled without having to refill it? Do it dry with 10-15 PSI. One caliper at a time, your reservoir won't run out of fluid bleeding one caliper.

Hope this helps.

[F500guy]

I had a few that started leaking, loosened and obviously that got the seating surfaces wet and then re-tightened and they sealed.

I did not use a power bleeder, but I did realize I have not mounted my reservoirs in the permanent home so they were elevated a significant amount above the master cylinders (5-6 inches) so that really helped the fluid flow.

[Ted G]

A couple of recommendations after you bleed the brakes:

1) test them with a hard press to the pedal.... I mean hard! (you'll be doing that once its on the road unless you have power brakes).
2) Place a blue paper towel or brown wrapping paper under each connection to make sure there are no leaks. Also do this under each caliper and bleading point. This will give you the easiest way to see any drips.

I did this and found one very small leak in one of the caliper connections and have had none since.

[gbranham]

A couple of recommendations after you bleed the brakes:

1) test them with a hard press to the pedal.... I mean hard! (you'll be doing that once its on the road unless you have power brakes).
2) Place a blue paper towel or brown wrapping paper under each connection to make sure there are no leaks. Also do this under each caliper and bleading point. This will give you the easiest way to see any drips.

I did this and found one very small leak in one of the caliper connections and have had none since.

Great tip, thanks!

[BEAR-AvHistory]

Here is what I did. Had replaced all 4 calipers & reservoirs on a 10 year old system. During the process the master cylinders apparently bled-out Tried to get a good pedal with a pump-up bleeder. Was unsuccessful after three attempts.

Based on clearances figured trying to pull the masters to bench bleed would be a nightmare. So if you masters are already install try this:

Broke the line connections between the master cylinders & calipers at the very first joint in the tubing easy enough to reach just enough so fluid & air would escape on a pedal push. Kept the reservoirs full.

Had a helper push & hold the pedal down like an old style manual bleed. Tightened the fittings at each pedal hold. Continued till just fluid was being pumped out of the joint. Locked up the fittings then finished with the standard power bleed at the calipers.

Rock solid pedal.

If they are not installed bench bleed & save a lot of effort.

[CraigS]

1- Admittedly I was using CNC MCs, not Wilwoods, but I never bench bled MCs. Just too much of a mess disconnecting a like at the MC, installing another, and then reinstalling the original.
2- I like the idea but no way I'd take them all apart to do it now.
3- I also can't imagine filling the bleeder itself. At some point you have to disconnect and brake fluid eats paint. I have not used the FFR MC but I think it will be fine. You could do a test on the LF caliper since the lines to it are the shortest in the system. Time how long the bleeder is open before it runs out of fluid. Then do you bleeding for about 1/2 that time from then on. BTW I always have a couple of cans of brake cleaner on hand and ready w/ the red tubes inserted. If you spill some brake fluid, flush it away w/ copious amounts of brake cleaner. At dealers where I worked inevitably, somebody would drop some fluid on the fender of a newish car. We would use half a can of cleaner flushing it down off the car, followed by a quart or two of water. A little bit of wax borrowed from a detailer, and no damage ever done.

[GoDadGo]

Have you simply tried to doing a "Gravity Bleed" starting with the longest run first?

• I used some clear tubing on the bleeder ends and placed the ends in a container to avoid air reentering the system.
• Please know that when I did mine, it took me two times, I lowered the rear of the car to aid the fluid flow.
• First I started with the passenger rear rear and then the driver side rear.
• Next I did the passenger side front and then the drivers side front.
• It was a bit time consuming but it worked extremely for me.
• Once completed I did a pedal pressure bleed.

Good Luck & Happy Brake Bleeding!

[CraigS]

I have also successfully used gravity. Works real nice if you have other projects around the house. Just set an alarm in your phone to check every 10,15, 30 minutes. You will find out on the first wheel how long you should allow between checks.

[mmklaxer]

There's a wilwood balance bar video online for bleeding their system. bleed front PS and rear PS at the same time. Then do front DS and rear DS at the same time.

I used a power bleeder without bench bleeding. worked, but still some squish in the pedal.

then I rebled with the wilwood method on the wilwood pedal system. rock solid.