Brakes…brakes…brakes

[DrazJR]

So my brakes in the YJ always sucked….. I replaced the master cylinder with a little bit bigger one for the bigger brakes. they still suck…worst now. I put a full bottle through the master and every caliper shoots out full fluid. Any idea why the brake petal still goes to the floor.


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[YJScrounge]

Air in the proportioning valve or the valve isn’t centered?

 

[harryhood]

Did you bench bleed the mc?

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[DrazJR]

I use a wilwood proportioning valve. It is adjusted correctly.

Did bench bleed the MC


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[harryhood]

doa MC?

 

[redjeep]

I use a wilwood proportioning valve. It is adjusted correctly.

Did bench bleed the MC


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I have the same issue in the Red Jeep since I switched over to disc brakes in the front.  The pedal is plenty hard but there is no way I can lock up the brakes.  I always blamed the proportioning valve.  Rey gave me one of his old ones out of a YJ that was out of a disc front drum rear but when I went to install it there was too much crust to break the brake line free so I just lived with it. I've put in cheap soft pads and expensive ceramic pads in the front and it made no difference. I also bought a one ton master cylinder like in the BYS to try.  I'll probably do both when I re-do the frame.

Do you have the manual adjustable proportioning valve?
Can you set it all the way to the front or rear and see if one end works better than the other?

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[DrazJR]

I use a wilwood proportioning valve. It is adjusted correctly.

Did bench bleed the MC


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I have the same issue in the Red Jeep since I switched over to disc brakes in the front.  The pedal is plenty hard but there is no way I can lock up the brakes.  I always blamed the proportioning valve.  Rey gave me one of his old ones out of a YJ that was out of a disc front drum rear but when I went to install it there was too much crust to break the brake line free so I just lived with it. I've put in cheap soft pads and expensive ceramic pads in the front and it made no difference. I also bought a one ton master cylinder like in the BYS to try.  I'll probably do both when I re-do the frame.

Do you have the manual adjustable proportioning valve?
Can you set it all the way to the front or rear and see if one end works better than the other?

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I tried that also, it just sucks no matter what, I was talking to Jeremy and some other guys yesterday about it. Jeremy having a very similar problem in his YJ. They were saying it’s possible the booster has gone bad.


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[A new level]

I was going to say possibly booster. What are you using for rear brakes?

 

[DrazJR]

I was going to say possibly booster. What are you using for rear brakes?

It has an 8.8 with disks. 


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[A new level]

I was going to say possibly booster. What are you using for rear brakes?

It has an 8.8 with disks. 


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Stock calipers or eldorado?

 

[DrazJR]

I was going to say possibly booster. What are you using for rear brakes?

It has an 8.8 with disks. 


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Stock calipers or eldorado?

Stocks


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[redjeep]

I'm still running manual brakes. 

How about putting one of these in line at the wheel to test?

https://www.speedwaymotors.com/Speedway-Single-Brake-Pressure-Gauge,592.html

 

[DrazJR]

I'm still running manual brakes. 

How about putting one of these in line at the wheel to test?

https://www.speedwaymotors.com/Speedway-Single-Brake-Pressure-Gauge,592.html

I’ll have to look into this


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[clarkie]

Would a bad booster cause the pedal to go to the floor or would it make the pedal hard?

 

[DrazJR]

Would a bad booster cause the pedal to go to the floor or would it make the pedal hard?

I was told it could possibly do both


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[clarkie]

Seeing that you tried two different masters and bled the air out with the same symptoms. Probably not the master or trapped air.

Sounds like trying a booster may be in order?

Is it possible the calipers on it now require more fluid volume to move the pistons than the master cylinder can deliver? I know you said you went larger on the new master, I’m not familiar with changing caliper sizes and the results.
Something else to note is when you increase the size of the master, you are increasing the volume of fluid, but actually decreasing the applied pressure to the caliper.

 

[DrazJR]

Seeing that you tried two different masters and bled the air out with the same symptoms. Probably not the master or trapped air.

Sounds like trying a booster may be in order?

Is it possible the calipers on it now require more fluid volume to move the pistons than the master cylinder can deliver? I know you said you went larger on the new master, I’m not familiar with changing caliper sizes and the results.
Something else to note is when you increase the size of the master, you are increasing the volume of fluid, but actually decreasing the applied pressure to the caliper.

I ordered a booster this morning, should be in tomorrow. I ordered a 2000 dodge 2500 master, I was reading some forums and seemed like people were having great success with that one.


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[redjeep]

Good Luck!

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[clarkie]

Please keep us updated.
Good luck!

 

[A new level]

I was going to say possibly booster. What are you using for rear brakes?

It has an 8.8 with disks. 


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Stock calipers or eldorado?

Stocks


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Damn was hoping for the easy out that eldorados need the e-brake hooked up or it this will happen.