If i pull the guts out of the proportioning valve, what happens?

[Rusty knuckles]

Having a heck of a time getting fluid to my rear brakes after some minor work. I'm focused on the proportioning valve being the issue. Pedal gets hard but little fluid comes out. Think it's the little plunger in the valve and I don't have the tool. Though the brake switch appears to serve the same purpose.

So anyway, if I pull the plunger and springs out does it just make the system 50/50? I'd be happy with more rear brake anyway.

 

[WileE]

It becomes gutless.

 

[kiwigtx]

BOING !!!!

 

[Mopar Hunter]

I gutted mind for that same reason you’re having, my brakes work 100%. I replaced the O-ring on the brake switch, nothing else inside.

 

[kiwigtx]

I had one that was so badly frozen that I couldn't open it up.....just replaced it.

 

[1 Wild R/T]

I gutted mind for that same reason you’re having, my brakes work 100%. I replaced the O-ring on the brake switch, nothing else inside.

Two things to think about...
1) you no longer have a split system, fluid can flow from one side to the other so if you loose a wheel cylinder you loose everything...
2) The brake switch isn't designed to handle pressure, it is intended that the detent ball fit in the groove in the spool valve, if the spool moves off center the detent ball will trigger a light on the dash... Point of all this? The switch shouldn't see pressure...

If you want to eliminate the proportioning valve get a couple brass coupler fittings & connect the lines with the valve removed..

 

[Mopar Hunter]

Two things to think about...
1) you no longer have a split system, fluid can flow from one side to the other so if you loose a wheel cylinder you loose everything...
2) The brake switch isn't designed to handle pressure, it is intended that the detent ball fit in the groove in the spool valve, if the spool moves off center the detent ball will trigger a light on the dash... Point of all this? The switch shouldn't see pressure...

If you want to eliminate the proportioning valve get a couple brass coupler fittings & connect the lines with the valve removed..

1) Your car doesn’t have a parking/emergency brake?

2) You don’t think the brake switch can handle pressure?

The brake switch has more threads with a “O” ring than the end plug.

 

[1 Wild R/T]

1) Your car doesn’t have a parking/emergency brake?

2) You don’t think the brake switch can handle pressure?

The brake switch has more threads with a “O” ring than the end plug.

View attachment 1528970

So you'll trade a working dual system for a working parking brake? Jump in your car & try out the parking park at 30 MPH before you answer that...

It's not the threads that fail, it's the plastic switch body.... Remember brake pressure can spike to upwards of 1500 PSI in a panic stop situation... Plastic pressure switches are fine for engine oil pressure @60 PSI but.....

 

[Mopar Hunter]

So you'll trade a working dual system for a working parking brake? Jump in your car & try out the parking park at 30 MPH before you answer that...

It's not the threads that fail, it's the plastic switch body.... Remember brake pressure can spike to upwards of 1500 PSI in a panic stop situation... Plastic pressure switches are fine for engine oil pressure @60 PSI but.....

I don’t know about your brake switch, mines all metal inside. It’s a contact switch, it’s metal. The plastic, which is on the outside is an insulator. Check out the metal threads, I don’t know what brake switch you have that has plastic threads or insides, mines all metal.

If I was you, I would replace your plastic switch body.

 

[Mopar Hunter]

Plastic pressure switches are fine for engine oil pressure @60 PSI but.....

I don’t know about your car, my oil pressure sending unit is metal, what kind of car do you own?

 

[kiwigtx]

 

[Rusty knuckles]

I gutted mind for that same reason you’re having, my brakes work 100%. I replaced the O-ring on the brake switch, nothing else inside.

This was exactly the response I was hoping to hear. Thanks!

 

[davek]

Bad proportion valve? Just cant win

70 Bee new MC,new hoses,new calipers went to bleed the lines and nothing going to the back. Unhooked back hose and nothing. I just cant win with my Bee. I have always had a hard pedal so Im thinking I have been only using the front brakes. I sprayed the proportion valve with PB and hoping it...

www.forbbodiesonly.com

 

[Dave6T4]

I had the same problem when I was bleeding the brakes on my '64 Polara that I upgraded with 1970 disc brakes. All the lines and calipers, master and wheel cylinders are new. I am using a combination valve from an '80's Diplomat. The new master cylinder was bench bled. We could not get the rear wheel cylinders to bleed. The front calipers bled just fine. We undid the rear line at the combo valve, and found we were not getting any fluid there. I took the master cylinder off to rebleed it, and found a big blurp of air. I think it sucked this out of the empty rear lines. After this, we were able to bleed the rear cylinders.

 

[Rusty knuckles]

I had the same problem when I was bleeding the brakes on my '64 Polara that I upgraded with 1970 disc brakes. All the lines and calipers, master and wheel cylinders are new. I am using a combination valve from an '80's Diplomat. The new master cylinder was bench bled. We could not get the rear wheel cylinders to bleed. The front calipers bled just fine. We undid the rear line at the combo valve, and found we were not getting any fluid there. I took the master cylinder off to rebleed it, and found a big blurp of air. I think it sucked this out of the empty rear lines. After this, we were able to bleed the rear cylinders.

I might try that 1 more time. I initially got fluid. But now I don't have any. The system worked before. I replaced the 2 steel lines from the master cyl, 2 front brake hoses, and the left front steel line. Then went to bleed and can't get the rear to bleed. I see the rear brake reservoir shoots brake fluid up when I hit the brake. Is that indicator of a bubble in the master cyl?

I also took the proportion valve off last night and made sure to have the plunger centered then tried to gravity bleed. Nothing. Then vacuum bled. Also nothing

 

[threewood]

Take it apart if the fittings allow. You can buy a rebuild kit for it. It's most likely gunked up.