major Wilwood brake bleeding issues! 10+hrs in
 

I have the following setup on my '69 Chevelle and am having a nightmare bleeding it.
Wilwood master with brake booster
14.25" front Wilwood 6 piston calipers
11.88" rear Wilwood 4 piston calipers
custom lines with prop valve

It simply seems like the master isn't moving much volume at all. This is a new brake system 100% from end to end with no fluid in it. We went to all corners (furthest first) and it took a very long time to get the air out in the system (still some air in there) about 6 months ago and easily 2 quarts of fluid put into it (3-4hrs time). I finally took off the Wilwood master cylinder and bench bled it where I could see plenty of fluid moving as I would make the stroke happen. Then put it back on the car and as I am a small biz owner I finally had time to work on it again now that summer is over. We did the same process over again and same crappy results. We even used a power bleeder the 1st time... (not the 2nd time though).

I'm guessing the rod inside the master is too short and isn't pushing the piston far enough? The shop next door to mine suggests that it is fine... and I should take some washers and space the master further forward away from the firewall as the back port may not be fully closed which is making this happen. They said it has happened to them a few times and once you are able to bleed the system you can remove the washers and all is good.

Does this seem logical? Or should I put a longer rod inside the master itself.

Dont guess, buy the tool and check pushrod to master cylinder clearance. Adjust as needed and get it perfect at .025" with a feeler gauge.

After that, with that master, rear port is rear brakes, make sure that is right.

Finally called Wilwood and the pushrod inside the master cylinder has an adapter "cup/extension" that sometimes they said needs to be cut down. The tech said for power brakes one doesn't need a shorter pushrod... only for manual style brakes.

I will have time this week to try it again.

Thanks for info as well dontlifttoshift!

Yep, the Wilwood master is built with a deep hole like a manual master cylinder would have and includes an aluminum slug to make up the difference for a power booster.

Some power boosters have a long pushrod. Some have an adjustable pushrod and some you have to machine the slug shorter to make it work.

We check and adjust every single booster and master before installing. We do the same on every car that comes in with brake issues.

It was missing the aluminum slug. Installed one and bled the brakes within 30 mins. Feels great now.