My brake setup uses a Wilwood aluminum tandem master cylinder (#260-8555) and a Hydratech Hydroboost. I was having a bit of trouble bleeding the brakes; basically I could not get any fluid to come out of the MC. I did previously bench bleed the MC on the car, so I decided to just start over and bleed the MC on the bench (ie the right way). When I removed the MC from the Hydroboost, I began to wonder if I was missing something:

1. Either the Wilwood MC or Hydroboost came with a 1.442" pushrod-like spacer. I never used this part and wondered what it was for. If you know what part I'm referring to, I'd like to know what its used for.

2. The Wilwood comes with a rubber boot that is supposed to be attached to the back of the unit. I didn't put it on, as I could not see a way that it would work, as nothing seems to go into the unit until after you push the pedal, and the hydroboost can't be 'tested' without a MC installed. The hole in this boot seems like it would cause a problem if the Hydroboost pushrod did not go into the hole directly. What is the boot used for if you use a Hydroboost ?

3. Is there anything that goes between the back of the Wilwood MC and the Hydroboost ? I can see a pushrod in the Hydroboost, but can't seem to be able to remove it, so I'm assuming its supposed to stay in there.

I started wondering about all of this when my problem with being unable to get any fluid to leave the MC might be caused by the Hydroboost not being able to push on the MC all of the way.

I tried calling Hydratech, but they seem to be hosed real bad due to their recent move and their phone just rings.

Thanks for anyone who has a similar setup and can remember how it went together.

-Kevin

I'm able to answer part of my own post. I found the other pushrod/spacer in the back of the MC, and it does not want to come out. When this spacer is installed, its flush (even) with the back of the MC. I guess my only question concerns that rubber boot that comes with the MC. I assume that on a normal non-Hydroboost setup, the pushrod is longer or one piece and the boot would hold it up, plus keep dirt out of the rear booster piston area? So you don't use it when using the aluminum pushrod spacer and a Hydroboost ?

-Kevin

My Wilwood master (manual application) has a long threraded rod attached to it, it goes thru the boot and threads directly into the clevis on the pedal

The rubber boot is used for manual applications. You will not use it with the hydraboost.

OK, boot not used. That makes sense as I didn't see how it will work. I bench bled the MC just now and it worked a lot better off the car, as I could get it level. I then put it on the car and still no go in getting $#%@!*& fluid to go anywhere.

I can pump and pump and nothing seems to go anywhere. I even tried one of those vacuum things that you hook to an air compressor and still no fluid to the rears. I did manage to get a few drops out of the front lines, but stopped as I wanted to do the rears first like you are supposed to.

I guess tomorrow I'll check to make sure that I can run air all of the way through the rear lines in case something got into the rear line (a bug ? ) but that is unlikely as I always had it sealed and even ran cleaner through the line I think.

I'll try to contact Hydratech again to see if they have any ideas. The problem is that you're not supposed to operate (press on the pedal ?) the Hydroboost without a MC being on the car. So how am I supposed to know if when I press on the brake pedal its pushing against the MC ?

This is driving me nuts! Its the last thing that I need to do before I can drive the car under its own power after sitting for 20 years and being worked on for the last 3 years!.

-Kevin

I think it is safe to assume the hydroboost is stroking the master.

What's not safe to assume is "is the rod pulling back far enough at rest to open the fluid ports in the master?" as in is it releasing all the way?

I'd think the way to tell would be to put the bench bleed hoses on it, and stroke the pedal a few times, see if it's moving fluid.

It can take a LONG time to get fluid out the back of a new system. I'd suggest using a mitivac on one of the back bleeders, just suck on it until the fluid starts flowing. Plain ole gravity will work too, but may take a couple days.

Jim:

Thanks; I originally bench-bled the MC on the car, so I know I was getting fluid out and back in. I could even see the level drop and then rise back up, but can't remember if it was both reservoirs or not.

I also tried the vac, but don't know how long to let it suck. I will ask a brake guy this morning, as the vac is his, and ask. I'm also going to open the rear line to see if anything is coming out of the proportional valve, as I have that too.

-Kevin

An update: With a little more time with my wife behind the brake pedal, I may finally have gotten the bleeding done. Don't know what I would have done differently, but I think I found my problem:

The primary problem was that no fluid was ever really leaving the master cylinder. You could pump all day long and nothing would happen. Wilwood told me to have someone pump the pedal about 5 times, hold it down, then crack the bleeder for a couple of seconds with the hose on the bleeder and the end in a jar of fluid. I was doing that originally, but only one pump at a time.

The problem was that after we finally got fluid to show up at the calipers, that I found two leaks where the axle hard lines connect to the flex lines. So what I think was happening is that air was flowing back into the system each time the pedal was just pumped one time and released, bring in air through the leaky fittings. By pumping several times you can charge the line faster than the air/pressure can escape through the leaky fittings.

Its bad when you have a new system and all new lines and fittings as it takes time to get everything to seat right so if you have a leak you won't know it until the fluid gets there and you can't get the fluid there to see the leak.

From now on, I'm going to pressure bleed the system if its new. Unless you have perfect seats on all of the fittings, using the brake pedal to push the fluid is a long frustrating process. So I purchased one of these today based on the recommendation of a guy who does brakes:

http://www.brakebleeder.com/product.php?pid=2

-Kevin

I found two leaks where the axle hard lines connect to the flex lines.
Just FYI, the Wilwood system uses fixed, not floating calipers.
As the calipers are bolted solidly to the brackets, there is no need or desire to use any flex lines on the rear brakes at all. Run hardlines all the way into the calipers.

Adapters are available, I just sent some leftovers to Thedugan for his, perhaps he can post the manufacturer and part number (I was gonna, but kinda forgot.) These adapters go from 1/8" NPT to 3/16 female flare, and your hardlines will screw right into them.

I'm still learning about brakes, but my calipers are Baer. I was just using a Wilwood master cylinder because I liked the look. Baer supplied flex lines, so I'm assuming they are the floating kind.

In my next project, I may look into fixed calipers, because I would like to reduce the number of connections. Baer's flex lines at least only have two connections (one at the banjo and the other at the hard line connection), but I had some flex lines made by Inline Tube that have four (4) connections as each end is separate, with the entire flex line being an AN line with ends. I like Baer's better, but would love to get rid of them entirely.

Thanks for the tip; I will consider Wilwood all the way next time or consider the pro/cons of fixed vs. floating calipers.

-Kevin