67 Firebird 5th Gen Brakes W/Wilwood Parts -- Help needed

[67FirebirdKiller]

Hello PT, I need help, bad. This is an email I've sent to wildwood twice now. I really hope someone can help and honestly I never thought I'd have ask for help with bleeding brakes...


Good morning, I bought your Tandem master cylinder part #260-8555, connected to a tuff stuff 9” dual diaphragm (part number throughSummit racing TFF-2224NC) booster and run through your prop valve part number260-13190 with 3/16 copper-nickel brake lines. I have bench bled the master 4times and checked all fittings for leaks… it has been gravity bleeding itselfat the calipers (calipers are 2010 Chevy Camaro SS brembo 4 pot, bleeders arepositioned up) but it is still pushing air into the system for some reason. Weconnected clear hoses from master to the prop valve to check for air leaksafter bench bleeding and it still pushed air into the prop valve and not surewhy. The master is not leaking from the push rod area at all. Is it normal tosee the fluid going in and out of the master when the pedal is pushed in andout (fluid out when pushed obviously but then gets sucked back in whenreleased)…?? I have never had such a hard time bleeding brakes on any car untilthis set up. I called on Thursday 6/1 and spoke to Derek and he told me to justbench bleed the master, which we have done over and over and reinstalled andattempted to bleed. A quick checklist of what I have triple checked and donebefore sending this email:

Master cylinder bled, multiple times
Bleeders are positioned up
Pedal rod makes full 1” stroke
Fittings are not leaking air and have correct flares and aretorqued tight correctly
Removed and blew out prop valve and reinstalled (thisallowed the system to start gravity bleeding the 3rd time around)
Prop valve is set to wide open for rear to bleed, we alsotried half open and every setting in between besides closed
We attempted to use a pneumatic bleeder to remove all air atbleeders and just continues to suck air
Attempted traditional bleeding with pedal down, bleeder open
Attempted to pedal siphon bleed by open bleeder pedal down,then close and pedal
Attempted mityvac bleeding with grease on fittings toeliminate pulling any air through threads, continues to pull air


I don’t know what else to do, this was bought brand new, Ibelieve the master is defective as we found the master to still force air intothe system after being fully bench bled.

[dontlifttoshift]

Is there a foam gasket in the booster where the master cylinder bolts up? If the master bottoms on this and forms a seal, it will push air into the master with every stroke.

[67FirebirdKiller]

Is there a foam gasket in the booster where the master cylinder bolts up? If the master bottoms on this and forms a seal, it will push air into the master with every stroke.


Donny it does not have a gasket, just the normal rubber boots on the master and around the boosters push rod.

[67FirebirdKiller]

I got off the phone with summit and they are going to send me a replacement prop valve (SSBC A07071) and I'm going to swap out the master and current prop for the SSBC prop and an S10 master cyl... unless someone has any idea?

[dontlifttoshift]

So there is a rubber boot on the master?.....where it connects to the booster? Remove that. The pushrod side of the master needs to be able to "breathe" If it is sealed, when you release the pedal the air that is between the booster and depressed MC piston has to go somewhere and the path of least resistance is right past the rear piston seal into the master cylinder.

[chpr1972]

Years ago on a 79 GP I had this same problem. I used a pressure bleeder at the shop and tried foot bleeding. An old mechanic came over and I opened up the rear brake lines and he pumped the brake pedal with them open 3 or 4 times. Then the brakes bleed right out. He explained that air was caught in the system and bleeding with the foot and pressure bleeder didn't force the air out of where it was trapped! Go figure

[67FirebirdKiller]

So there is a rubber boot on the master?.....where it connects to the booster? Remove that. The pushrod side of the master needs to be able to "breathe" If it is sealed, when you release the pedal the air that is between the booster and depressed MC piston has to go somewhere and the path of least resistance is right past the rear piston seal into the master cylinder.


I'll try this, I didn't think of that. Thanks for the suggestion.

- - - Updated - - -


Years ago on a 79 GP I had this same problem. I used a pressure bleeder at the shop and tried foot bleeding. An old mechanic came over and I opened up the rear brake lines and he pumped the brake pedal with them open 3 or 4 times. Then the brakes bleed right out. He explained that air was caught in the system and bleeding with the foot and pressure bleeder didn't force the air out of where it was trapped! Go figure

It does seem like it has air trapped in it, I'm going to try a few different things tonight and see where I get

[67FirebirdKiller]

well I've had no luck at all. Called wildwood and I'm supposed to get an RMA to send the master back. about 25 hours wasted on this. Very disappointed. Going to install an S10 master for now.

[67FirebirdKiller]

May have figured it out. I never noticed it before since I always put my prop valve lines to master on loose then tighten the master down, last night I went to take off the master to box up and send out and I noticed the master wasn't leaking even though it was full (I randomly took off the prop lines sooner)... as I unbolted the master, it began leaking, so I tightened it back up with the lines off and noticed it was squirting off and on as I bolted the 2 nuts tight which is a master plunger/booster rod pre load issue I believe. I took off the master completely and just slid it onto the the booster and noticed it had some resistance from being flush just before making contact with the surface. Never even thought about that issue as this was sold as a complete unit for the car. Would residual pressure cause wacky unbleedable soft pedal problems like I'm having? I was thinking of shaving off some material on the rod insert pin in the master tonight and try one more time before sending the master back to wilwood...

[dontlifttoshift]

Yep clearance required. .020 - .025" between the pushrod and the piston in the master cylinder.

But that really doesn't jive with this


but it is still pushing air into the system

[67FirebirdKiller]

Yep clearance required. .020 - .025" between the pushrod and the piston in the master cylinder.

But that really doesn't jive with this


You're absolutely right and I'm hoping the air I saw in the tube was either air not bled out or air getting past where I had the tube connected to the fitting..

[67fenix]

I really hope you figure this out because I'm having the exact same problem on the exact same P/N master cylinder. Its extremely frustrating. I called Wilwood today and they also told me to bench bleed it again but it didn't work.

[67FirebirdKiller]

So tuff stuff emailed me back and told me to remove the push rod slug included with the master cylinder. With that being said...

I wish I could say it was solved. After rebleeding and removing the slug I had one good pedal...the first one after doing above and then nothing. 35 hours now. Had it. If take F'n drum brakes over this ****. 5 years and 33k grand and I cant drive the car because of brakes. Ready to part it out.

[dontlifttoshift]

Take the lid off the master. Have someone stroke the pedal slowly. Observe what is happening in the reservoir.

If you took the slug out, how did you get a pedal at all? Unless you have a long pushrod coming out of the booster.

[67FirebirdKiller]

We figured it out last night around 2 am. By process of elimination. There was something wrong with the prop valve... whether machined wrong or what but it was causing weird fluid flow and pressure problems.

[TheJDMan]

Hang in there, this stuff can be frustrating as hell but the payoff is worth the effort. I spent two weeks trying to bleed my simple manual brake system also using the Wilwood tandem MC. Once the car is operational the real fun begins sorting out all the small bugs that will inevitably pop up.

[lsa1stgen]

so the new proportioning valve fixed your problem? is the new one a wilwood? haveing same problems

[67FirebirdKiller]

so the new proportioning valve fixed your problem? is the new one a wilwood? haveing same problems

I ended up removing the prop valve and running a T'd line from master to the front calipers and got nice front brake pedal feel, the next step is to put in the SSBC single line in/out prop valve for the rear and bleed them. The problem I see with the other wildwood with 2 in 3 out is that all the fluid enters it into the same chamber causing some kind of air/suction issue---I'm not really sure, but this is just a problem I had, I'm sure thousands of people have had zero issues with them but it just left me bitter towards that particular one now after all the wasted time.

[lsa1stgen]

I will give that a try. We have the same set up and same problems.

[dontlifttoshift]

with 2 in 3 out is that all the fluid enters it into the same chamber causing some kind of air/suction issue

That is not how it works. The rear fluid and front fluid do not cross paths in the proportioning valve.

Is it fixed?