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Brake bleeding questions


JoeR

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So I am replacing the front brake hoses on my truck and will need to bleed the system. Where are the bleed valves on the rear drums? Also, I read somewhere that the brake proportioning valve also needs to be bled, am I correct in assuming that there is a bleed valve on it somewhere? Thanks.

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So I am replacing the front brake hoses on my truck and will need to bleed the system. Where are the bleed valves on the rear drums? Also, I read somewhere that the brake proportioning valve also needs to be bled, am I correct in assuming that there is a bleed valve on it somewhere? Thanks.

 

 

To find the rear bleeders follow the brake line on the axle housing up to the top of the brake backing plate where it is connected to the wheel cylinder. Look on the brake cylinder just above where the line connects. The bleeder will always be positioned high to allow air to collect.

 

There is no proportioning valve on the 720. Front rear bias is achieved during the design by varying the rear wheel cylinder size. Who ever told you this is probably thinking of the NLSV (Nissan Load Sensing Valve). It's located on the inside of the frame under the passenger side seat. It does have a bleeder nipple.

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It is only if there is a load in the back. Increased weight = more traction so more braking force can be added. The NLSV is mounted tilted up slightly at the front. There is a heavy steel ball inside that will roll up hill under hard braking and shut off the brake pressure to the back to prevent locking. As the weight on the back increases the back llowers and the tilt angle of the NLSV increases making the tilt angle increase, which makes it harder for the ball to roll up and shut off the brake pressure and more gets through to the back wheels.

 

I suppose it regulates the bias but it's subject to the load in the back.

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