Very odd brake problem 71 Satellite.

[BeepBeepRR]

All the brakes are new as with the master and no leaks. Everything is new except the booster. The brake kit came with a new booster but it was one of thos eones that stick out from the firewall. So I elected to use the old booster. Here is where it gets stupid. I'm pretty sure the booster is bad or has an internal leak. When I fired the 440 up in the satellite it sucked the brake pedal to the floor. I assume the booster is shot. Has anyone ever had a booster do this?

 

[Jerry Hall]

All the brakes are new as with the master and no leaks. Everything is new except the booster. The brake kit came with a new booster but it was one of thos eones that stick out from the firewall. So I elected to use the old booster. Here is where it gets stupid. I'm pretty sure the booster is bad or has an internal leak. When I fired the 440 up in the satellite it sucked the brake pedal to the floor. I assume the booster is shot. Has anyone ever had a booster do this?

Sorry, I have seen a lot but not that?

 

[Demonic]

Are you using a single-diaphragm drum booster on a converted to disc car? Won't work.

 

[Ernie ingling]

Suspect not enough free play in pedal closing compensating valve allowing engine vacuum to act on diaphragm and apply.

 

[BeepBeepRR]

Are you using a single-diaphragm drum booster on a converted to disc car? Won't work.

That might be the problem... Damn it.. I used the old booster.. I have the new one Ill install that..

 

[BeepBeepRR]

Suspect not enough free play in pedal closing compensating valve allowing engine vacuum to act on diaphragm and apply.

This could also be the issue.. Im going to install the aftermarket one from right stuff and see if that fixes the problem.

 

[Don Frelier]

I probably would have done the same thing

 

[mopar 3 B]

Have you adjusted the rod from booster to the master cylinder. It must not make contact with the master. Also the booster check valve to vacuum needs to be there and work or the pedal will be sucked to the floor.

 

[BB BELLA]

I had a 420sel Benz, booster was applying the brakes randomly a few times.going down the highway the car would just start slowing until I had to pull over and it wouldn't move! I felt the rims and they were hot so loosened the rear bleeders and off I went! Benz mechanic told me to replace the booster and never had the issue again so don't think it's not a possibility that the booster is the problem!

 

[BeepBeepRR]

Well, I replaced the booster with the one that came in the right stuff kit. However now I have a really low pedal. The car will stop but the pedal is almost at the floor.
I adjusted the pin as shown in another post by another guy. Anyhow I think I know what the issue is. It still has the drum brake proportioning valve. I will get a disc brake prop valve and hope it fixes the issue.

 

[BB BELLA]

does the pedal come up if you pump the brakes! if you still have drum brakes in rear maybe the residual valve to rear is bad or missing! at least the booster isn't applying the brakes!

 

[BeepBeepRR]

does the pedal come up if you pump the brakes! if you still have drum brakes in rear maybe the residual valve to rear is bad or missing! at least the booster isn't applying the brakes!

Yea the brakes were pulling down before. But now the pedal just sinks but the brakes do apply.

 

[Ron H]

I’ve had the same problem with my front disk to power conversion on my ’63 Fury for some time and no hunting down the problem yet. The pedal will sink way down; but does not engage the brakes. It does this sporadically. I can still press the pedal further and brakes work fine. I did the recommended booster checks with a vacuum pump and they all check out as they should. I installed a reserve reservoir as I have a mild cam and this did squat. I maintain 15” of vacuum when cruising. Makes no sense, ya know, if the pedal is sunk way down like this, why wouldn’t the booster rod be engaging the MC? And when I bring the pedal back up, there’s a resisting force on it to raise it and once it is back up the pedal acts as it should until the next time this happens?

 

[BeepBeepRR]

I am now wondering if I need to re-bleed the master cylinder. I do know I will install a disc/drum proportioning valve soon. I hope that fixes the issue. I did the same conversion on the 69 roadrunner and had no issues. But this 71 is being stubborn.

 

[Ron H]

I am now wondering if I need to re-bleed the master cylinder. I do know I will install a disc/drum proportioning valve soon. I hope that fixes the issue. I did the same conversion on the 69 roadrunner and had no issues. But this 71 is being stubborn.

Having done a lot of hunting down this gremlin and getting a lot of tips, it was said an MC bleed wouldn't impact the problem I've had but a good idea if there's any doubt that it wasn't bench bled properly. I had re-bled my system twice but not the MC and this didn't make a difference. There's another post up today discussing adjustment of the booster rod to MC and this is another try I'm looking to do when I find a gauge. I did a bit of adjusting but this is still a question for me as if it is set right. One question I posted is if the rod adjustment, as I made it, isn't FULLY returning the pedal if this could be a problem. When I re-did the rod having to shorten it there was some putzing to obtain brake action vs the height of the pedal. I'm wondering if there could be an issue where as it is set, if the pedal return isn't fully releasing from the booster causing the sink down...like the booster valve stays open or closed as it might be...

 

[BeepBeepRR]

Having done a lot of hunting down this gremlin and getting a lot of tips, it was said an MC bleed wouldn't impact the problem I've had but a good idea if there's any doubt that it wasn't bench bled properly. I had re-bled my system twice but not the MC and this didn't make a difference. There's another post up today discussing adjustment of the booster rod to MC and this is another try I'm looking to do when I find a gauge. I did a bit of adjusting but this is still a question for me as if it is set right. One question I posted is if the rod adjustment, as I made it, isn't FULLY returning the pedal if this could be a problem. When I re-did the rod having to shorten it there was some putzing to obtain brake action vs the height of the pedal. I'm wondering if there could be an issue where as it is set, if the pedal return isn't fully releasing from the booster causing the sink down...like the booster valve stays open or closed as it might be...

I too think that the booster might be the issue. But I'm going to get a disc/drum prop valve as well as re-bleed the master just to verify thats not the issue. Then I will have to assume the issue is with the booster. This is the booster/master combo that came in the right stuff kit. I adjusted the rod to ensure that it was properly adjusted already. So Im down to 3 culprits.

1.re bleed the master
2.booster is bad
3.proportioning valve needs to be swapped to a disc/drum type.

 

[BB BELLA]

can you see a residual valve in the rear port of the master!

 

[Jerry Hall]

I too think that the booster might be the issue. But I'm going to get a disc/drum prop valve as well as re-bleed the master just to verify thats not the issue. Then I will have to assume the issue is with the booster. This is the booster/master combo that came in the right stuff kit. I adjusted the rod to ensure that it was properly adjusted already. So Im down to 3 culprits.

1.re bleed the master
2.booster is bad
3.proportioning valve needs to be swapped to a disc/drum type.

View attachment 932692

Nobody has mentioned correct linkage. I'm looking at that on my 66, 6.1 Hemi car. It has 4 wheel power drum brakes and the petal has always been low. It stops great but the booster blew last week and hasn't been fixed yet. I'm watching this thread closely for the fix you guys come up with.

 

[BeepBeepRR]

When using that wacky booster and master I posted above.. It hooks directly up to the brake pedal. You remove the original linkage and spin the new push rod out to adjust he pedal height. I have that set up to close the contact on the brake light switch. But no matter what, the pedal is really low to the floor. The brakes are working but it would be a scary situation in a panic stop.. As I mentioned before I also adjusted the push rod coming out of the booster into the master as noted in another post. I didn't have the tool they used but was able to get it very very close.

 

[Jerry Hall]

When using that wacky booster and master I posted above.. It hooks directly up to the brake pedal. You remove the original linkage and spin the new push rod out to adjust he pedal height. I have that set up to close the contact on the brake light switch. But no matter what, the pedal is really low to the floor. The brakes are working but it would be a scary situation in a panic stop.. As I mentioned before I also adjusted the push rod coming out of the booster into the master as noted in another post. I didn't have the tool they used but was able to get it very very close.

I'm going to take it one step at a time.
Replace the booster with another stock unit and get the brakes functioning as before. Then look at the linkage to get the petal height good if I can. If that is successful, I will place the brake light switch as necessary. On all my Hemi 4-speed cars the brake petals sit lower than the clutch and makes a easy transition from gas to brake. On my automatic cars the brake petal has at least another inch of travel, except for this car. So I have some comparisons. If I find something I will let you know, please do the same.