Ok bought a power booster master cyl. combo. Was manual brakes had to buy new lines for power brakes. Put it on, bench bled m/c and bled all 4corners lots of bubbles of air came out specially the front. Back took a long time to bleed. Now here's the problem power booster works fine but pedal goes almost to the floor and if I push hard enough the brake lite comes on. Have some brakes but not good. Now what?
I'd keep bleeding. Put a 2x4 under the pedal so your helper doesn't over stroke the master and put air in. Id start by bleeding the master on the vehicle since you already have it on there. You pedal pusher needs to understand it isn't a panic stop. Just stroke the pedal slowly and steadily until down then you can close the bleeder and let the pedal up and stroke it again into a glass mayonnaise jar with the tube under the fluid so if it does draw some back in it is fluid not air. I usually can recruit one of my kids but the wife will reluctantly help if I cant get one of them. After the m/c then pass rear until no air bubbles, then driver rear, then pass front then driver front. Must keep topping off the m/c. If it runs dry start again at the m/c.
I think Texas T is explaning the same way I do it. I have my helper slowly depress the pedal all the way down ONCE and hold, NOT pump pump pump. Also what I've done and it seems to work is open the bleeder, then have your helper slowly depress the pedal all the way down, hold it, close the bleeder, release, repeat. The objective is to fill the lines with fluid, expel the air, theres more than one way to do it, and do whatever way works:TU:
Just a couple thoughts, and you may have already taken care of these. Going from manual to power means the rod from pedal to booster goes in the bottom hole in the brake pedal, supposedly the manual rod would have been in the top hole. The brake light switch has an adjustment so back it up as far as possible while keeping it in the bracket. Then adjust the rod to the booster, at the clevis, to make it long enough to depress the switch and turn the brake lights off. This can get your pedal off the floor. I'm sure you know there are 2 different master cylinders, one has little to no hole in the piston where the rod fits, the other has a deep hole, an inch or more. Boosters sometimes come with 2 rods which are interchanged to match either master cylinder. Or the master cylinder has a insert to make the deep hole a shallow one to match a short booster rod. As I said, you most likely know all this stuff and have already done everything I have mentioned. I'm just trying to be helpful. I've had this problem, it can be frustrating. Mike
This! wemt through this in the spring with the Riv. Out a new master in and got a super low pedal. Turns out the cup in the back of the master was deep. not shallow like the old master. So the pedal had to travel father before it even started to hit the master.
Could have a defective MC, I just went through that, NEW DOESN'T MEAN GOOD. I got pure fluid on all 4 wheels but NO PRESSURE on the rear, returned the MC and tried again got a full peddle with first bleed. Just trying to help. Good luck. \Johnny
This brake pedal to the floor was a common problem on rebuilt master units....I assume you bought a new one. If you have no air in the lines and still goes to the floor...bad MC...had this happen to me twice.....some unknown brand....only bought Raybestos/TRW new masters and never had the problem again.
Ok the combo I got is new from a member here who's had great success with them. It's from CPP and is there 68-72 disc conversion. It's a 9" booster which worked the second I fired up the car. The first time we bled them with a small block of wood under the pedal (which I've never done that before) the brake lite came on right away and hardly NO brakes. The second time I did it by my self with a 1 person bled kit from Napa I have a little more pedal but still goes to floor with a little more brakes and you have to push really hard to get lite to come on. Went to a power system because you had to push really hard to get it to stop. I've had manual brakes before and never had to do that. Yes I moved it on pedal arm but still had to drill a new hole per cpp' instructions so there booster arm would level out. When fronts off ground hit pedal wheels stop, but not in the rear. I TOO THINK it's the master cyl. the reservoir are the same size front and back. One more thing, Is the prop. valve on the frame the same manual drum or power drum size wise? Thanks for all the comments guys!
Not trying to call anyone a DUMMY but I helped a friend work out his problem after almost 2 weeks of bleeding I finely went over to see in person what we were dealing with, I saw the problem right away, HE INSTALLED THE CALIPERS ON THE WRONG SIDE, bleeder valve was on bottom not on top. Many years ago my wife and I attended a break thingie that NAPA put together, after all was said and done I learned AIR GOES UP, that was the jist of the preparation, A wast of time but we did get a free steak out of the deal. Just trying to help. Johnny
Yea i seen someone put calipers on wrong too once (not me). I'm not going to bled for 2 weeks ou: Like I said they were hard to push before I put on the booster.
Went out and beat the crap out of the pedal than panic stopped it in reverse got front to lock up. Than forward and got the left rear to lock up but still way too much peddle travel as compared to my former blue conv. And could not get brake light to come on. My guess is it's still the master cyl. So in the morn I'm going to get one and see what happens. What do you guys think? Mabey I'll get a new rear hose first.
Always replace the rear hose when doing brakes..that is probably the 43+ year old original. Also, if 4 wheel drums...then you have distribution valve on the frame rail...should look like a rectangle. If you have disc front..then you need the combination valve as picture below....do you have disc brakes?
The master cylinder needs to be bench bleed first while its horizontal. Then put it on the car and bleed all 4 wheels. With a new master you can bottom it out while bleeding it without damage. Used ones will usually fail it you do that.
Ok Chad ill double ck. George yes 4wheel drum and it's on the frame rail and I'll change the rear hose as fluid comes out real slow there. The fronts have been changed at some time because it just blows out there!! And Steve I did bench bleed in the vice per Cpp's instructions.
Have not started it yet but got another m cyl. today bench bled it and it said not to go more then 1" in as you bleed it and continue to bleed till I'd gets resistance and won't push in any more than 1/8" which never happened. Took and rebled the one I got in the kit and it will not give so much resistance that you can't push it in more than an 1/8" either. I will bleed the brakes again tomorrow after I change the rear hose than I'll start it once again and see what happens...........keep you posted! uzzled:
The last few Mater Cylinders I did had the same instructions about only stroking it 1 inch . That is fine for a start but you will never completely bench bleed it that way. You have to eventually get to a full stroke. Its a Brand new cylinder so there should be no debris in the bore to tear up the seal. You also need to watch for the bubbles on the stroke AND the return. When you get no bubbles on the full stroke it is bleed . Are you using the tubes that send the fluid directly back to the Master ?? The last Master I got had 2 block off fittings to bleed that I have never used.
Yes I'm using tubes :Brow: watched some U tube stuff and one guy there says he gets 1000's of calls so I watched took a rubber mallet tapped on it pumped them some more and got a gazillion more tiny bubbles but the m cyl never gets hard like they say?? mmmmmm oh well I'll put it back on and bleed it all again.
