Rescue Rogers

there is 2 different holes in the pedal arm , non power brakes position and power, but i dont think you would get the pedal to the floor, you could look at that though

edit,

It could be the positioin if you arent getting enough throw to completely get the air out.....

540 vette

Well spoke to Wilwood again. They told me the reason the brake pedal goes to the floor when the motor is running is I don't have enough vacuum. I started another thread with that.

bradleyb66

Have you verified that the rod between the booster and the MC is adjusted correctly? My 69 was converted from manual to power by the previous owner, and has the opposite problem - brakes engage immediately, and don't feel like they have any power assist. I've narrowed it down to most likely a mis-adjusted rod, but haven't torn it apart to verify yet.

If the rod is mis-adjusted, it can also cause a soft pedal. Here's a website I found that explains it.

https://techtalk.mpbrakes.com/how-to...r-cylinder-gap

540 vette

Took the master off figured I'd bench bleed it again. Made lines for it. Pumped it a few times and nothing. Did this for 45 minutes and nothing. Noticed the rear seal was wet. Took it back and getting another new one tomorrow.

540 vette

Got another new master, bench bled it and installed it. Bled the brakes with the power bleeder then pumping the pedal. Also bled the brakes with the car running. No luck. Took the rear calipers off and pointed them vertical, bled them. No luck. I have a nice stream coming from each bleeder. No sign of air. But no pedal.

Never had this many problems bleeding the brakes. 5 hours the other day. Today another 3. Plus an hour here and there.

Now I don't know if I should take the Wilwoods off and get a stock setup, sold my old stuff.

carriljc

Do you have rubber or braided brake lines? I only ask because what I am about to propose I did on the "old" brake lines for another vehicle..... Since I was going to replace the hoses anyway, I pinched them with vise-grips to try and isolate the location of the flaw. I ended up figuring out that it was the front brakes by doing that. I was surprised that I could not narrow it down to a "corner", but I did narrow it down to the fronts. If you are willing to sacrifice the hoses you can try this. Of course, do it with the engine running and vacuum on the booster. Pick a corner, vise grip that hose, check pedal. It my be worth the sacrifice since you've struggled with this so long. Just a thought.

540 vette

Braided lines.

Something I found odd. I removed one of the rear brake hoses to tighten the fitting on the caliper and no fluid came out. When I let it hang fluid came out after a few seconds. With the pressure bleeder the fluid shoots out.

dmaxx3500

go back to basics

try gravity bleeding each caliper ,1 at a time,take the cover off the master cyl,,then starting at the RR,open the bleeder just enough to get some fulid out let it drip for 30 secs,then close it up and go to the LR,do the same,then RF,then LF,,see what you've got then

540 vette

Doing that right now.

carriljc

Oh bummer... don't want to ruin new braided lines. Well, if the gravity bleeding does NOT work, then I suggest you find some "isolation valves" that fit the braided hoses at each caliper..... I know it's extreme, but you've been struggling with this for quite a while. It will allow you to do that same thing as "vise grips" but not ruin your new braided hoses.

540 vette

How many times do I bleed them with the same results. I gravity bleed them. No bubbles and no difference. I power bleed them. Steady stream of fluid from each bleeder, no air. Pedal bleed them. And a steady stream form each bleeder. 3 different masters all bench bled, no air bubbles. Bleed them with the car running no difference.

540 vette

I was out in the garage until 2 AM. I went thru everything again. Reread all the posts on this forum and another I posted this problem on.

I checked under the dash to see if the rod was adjustable from there. No good. Took the master off and the rod was adjustable from that end. I brought it out another 3/4 inch and that seemed to have worked. Took the car for a ride and I had a pedal. I didn't have enough gas and it was late to take it for a longer ride.I will do that today to see if this solved the problem. I have my fingers crossed.

I will let you guys know how it turned out. Thanks for all the help and PM's.

slofut

Two things here, as I dealt with this last year with new wilwoods etc... Bench bleed the master with it on the car, use clear tubing from the brake line ports so you can see what air is occurring and how (sometimes you leak air at this connection giving false air). Raise the rear of the car so the master is level or a tiny bit high at the rear. Then SLOWLY bleed the master one chamber at the time carefully. Watch the bubbles, you'll have to push ...watch the bubbles slowly rise to the top of the tube, then very slowly let off the pedal in increments stopping to let the bubbles rise to the top until you have enough pedal to push the bubble over and out into the reservoir. Tedious I know, and sometimes you have to modulate the pedal, kind of tapping motion with your foot to find more air bubbles. Make sure your hose connections on the master are good and not sucking air. If you just pump the pedal slowly you just push the bubbles back and forth, never out. The last one took me about an hour to do both chambers. Lots of time sitting waiting for bubbles to rise then using the pedal to finesse them over the top of the tube. But well worth it when that pedal feels good!

2nd. Just to be sure the booster isn't in the equation, plug the vacuum hose and go for a short ride to see if the brakes are working hydraulically. I don't suspect the booster.

We were posting at the same time so I didn't know you got it solved.
Glad you got it licked after all this!!

540 vette

Good information.

Thanks for you time and help.


I want to thank everyone that helped and PMed me.

bobs77vet

how do you know you are getting full pedal travel of the pushrod into the MC?

maybe this needs to be adjusted so you are getting further penetration into the MC....seems to me I had this problem when I switched the MC on the 69....I also had the back of the vet as low as possible to bleed.

and I used the motive pressure bleeder also with two clamps on it


oops ....just read your last post. glad you fixed it, bob

carriljc

Good to know you got it fixed.

Any idea why the pushrod would need adjustment if your master cylinder was the "direct" replacement?

540 vette

I don't know. Maybe the plunger on the inside was different. I had to trade in the one I had on the car so I couldn't compare.