Having braking issues

[69ZBFairlane]

hey there just wondering if you guys could help me out with a little advice, I own a 69 zb fairlane 500 that has the double resovoir master cylinder and the vh40 booster on the passenger side of the car,it has fornt disc and rear drum brakes on it from factory...

I have put new front rotors new front brake pads and have flushed and blown out the lines with the air compressor as it was sitting for a while with no booster in it..

Ok the problem is that when I get in the car I have to pump the brake pedal a few times to get it to firm up,then I start the car and move out the driveway and push the pedal and it goes down near the floor and doesnt slow the car very much and then I take my foot off the pedal and let it come back up and then it firms up to near the top and stops the car fine....I gravity and normally bled all the brakes put new fluid in and also bled the bleeder on the vh40 and the proportioning box on the front shockie tower and this is the best its ever been but its still not right can you please point me in the right direction any help would be at all would be awesome....thanks

[FLOORED]

Originally Posted by 69ZBFairlane

hey there just wondering if you guys could help me out with a little advice, I own a 69 zb fairlane 500 that has the double resovoir master cylinder and the vh40 booster on the passenger side of the car,it has fornt disc and rear drum brakes on it from factory...

I have put new front rotors new front brake pads and have flushed and blown out the lines with the air compressor as it was sitting for a while with no booster in it..

Ok the problem is that when I get in the car I have to pump the brake pedal a few times to get it to firm up,then I start the car and move out the driveway and push the pedal and it goes down near the floor and doesnt slow the car very much and then I take my foot off the pedal and let it come back up and then it firms up to near the top and stops the car fine....I gravity and normally bled all the brakes put new fluid in and also bled the bleeder on the vh40 and the proportioning box on the front shockie tower and this is the best its ever been but its still not right can you please point me in the right direction any help would be at all would be awesome....thanks

Are any of the brake lines sitting higher than the master cylinder or the booster ? Air may be trapped there so you will have to rebleed the brakes.
If you have rubber brake lines it would be wise to clamp the rubber lines off tho see if the pedal is firmer as this isolates the calipers and wheel cylinders from the equation.If the pedal is still bad it may be the booster or master cylinder but if the pedal is good then it is on the other side of the clamp which means wheel cylinders or calipers.If the later is the case then while you have someone apply some pressure to the brake pedal you can release one hose clamp at a time and the pedal will drop a little until you find the pedal drop more than normal and this will be the area where the problem is.I hope you understand this as you are trying to locate and isolate the problem area but if you need to ring me then you are more than welcome.

[69ZBFairlane]

hey there matt thanks heaps for the fast reply I will give it a shot 2morrow and see how I go,Ive been told to bleed the master cylinder aswell,but on my car the master cylinder and booster and are on different sides of the car and the master cylinder does not have a bleeder but the VH40 booster does have a bleeder,should I bleed the booster?If so do I bleed it before the discs and drums?

With the master cylinder if bleeding is is a good idea would bleeder nipples with some vac line feeding back into the resovoirs work as its easier to find than brake lines and fittings for a zb fairlane.Would the bleeder tightened up work as block offs?As Ive been told I can also block the outlets and pump the pedal slowly and the air will work its way out into the fluid resevoir is this ok?If not will they work just to feed fluid back to the resovoir???

I know I might sound dodgy and stupid Ive just herd so many different ways to do it ,thats if its worth doing and could fix the problem,Im still learning and any and all advice and help would be great.....thanks

[69ZBFairlane]

hey matt ,ok Ive spent most of the day bleeding everything,I bled the master cylinder,the block,the booster and all the brakes,and unless Ive done something wrong its still doing the push it down then let the pedal back up then push it again and its firm....Its really annoying me lol,Im going crazy lol.

Well the master cylinder held pressure once it was all tightened and isolated from the rest of the system.

So once I had bled all the brakes again and flushed yet another bottle of fluid thru it,I got told to try and take the line from the booster to the back of the carbie of and if the brakes stay firm the booster is fine,so I tried that and the motor reved up due to vac leak where hose was but once I covered the hole it idoled down but the brake pedal did the same thing yet again.

I havent checked the rear cylinders yet but if they are leaking would they still work as in stop the drum spining??Or leak oil everywhere??

I also herd to check all the rubber lines for crack as it may be absorbing air thru them,but if air can get in wouldnt fluid be able to get out?

Also when bleeding the brakes I get my mate to pump the brake pedal in long firm slow pushes all the way near the floor 5 times then I loosen the bleeder let it squirt fluid out while the pedal pressure goes down and the pedal is near the floor and then tighten up the bleeder before he lets the pedal come back up and then repeat it 4 or 5 times and then move to the next one and check the fluid in the resevoir is this right??

any ideas??? Im going to try the isolateing thing tommorow block all four and releaseing them 1 at a time or do I l free one check the pedal if its fine block it off again and try the next one or do unclamp them 1 after another leaving each one unblocked as I move to the next???

I NEED HELP lol!

[69ZBFairlane]

I also tried isolating where the problem is,I clamped the rubber brake line that runs into a junction that feeds the 2 metal brake lines along the diff and then clamped of both rubber brake lines to the front discs.....the result was the pedal was very firm with only about a half inch of play before it stopped and was unable to go down any furthe...


I then unclamed the line feeding both rear drums,the brake pedal dropped a little but not much at all and felt like the brake pedal should.I then clamped them bake up and moved to the front I unclamped the drivers side brake line and the pedal drop a little bit more to around the same position as when the rear brakes where unclamped and it felt like it should,I then clamped it back up and tried the passenger side brake line and all of a sudden the pedal went close to the floor??

So Then I decided to lock off the front passenger side and unclamp the rear drums and the drivers side disc and with those 3 free the pedal goes to just above half way and the goes hard as in wont go any further?

So I think its air in the front lines somewhere but Ive checked all the lines are tight and all the hoses are ok Ive bled the master cylinder,and proprtioning block and the booster and have replaced the rear brake cylinders and adjusted the rear brakes wht else is there?

Ive been told to just take the master cylinder in and get it recoed to make sure as people are saying its probably more chance its stuffed rather than the booster,what do you guys think any ideas ???

[69ZBFairlane]

Ok finally I found the problem it turns out the front disc cylinders were at some point put on the wrong side which made the bleeder face up at 11 o'clock and unable to get rid of the air ,
so all I had to do was swap them over and it made the bleeders point to 9 oclock and then bleed the front brakes and the problem was fixed I now have a frim brake pedal that doesnt loose pressure..... YES!!!!!! Thanks heaps for all your ideas guys.