Rear Brakes, M375/400, 5 Lug Budd

[DaveVA78Chieftain]

Link to the picture below: http://i286.photobucket.com/albums/ll120/BaileyDave/M375LateFull_zps4f80489c.jpg

Need to look at the picture full size. Right click on the link and select new window.   Use Control + to zoom in on the picture in the new browser window so you can more easily trace the brake lines in the picture.

There are 2 "tees" shown.  The rear one (outboard the front booster) is actually a Brake Warning switch.  The Brake Warning switch is used to detect an imbalance between the front and rear brake systems.  Also, a leak in the front system will not result in a loss of braking in the rear system AND vice versa.    There is a wire attached to the Brake Warning switch which lights the brake light on the dash.  If your only problem is the dash light is lit, the problem is most likely adjustment rather than a defective switch.  You have to bleed the brakes (front vs rear circuit) in order to get the paddle inside the Brake Warning switch to center position.
Are you sure you are not looking for this? http://www.ebay.com/itm/Mopar-Chrysler-Brake-Proportioning-Valve-P-N-4131254-/281067960473?pt=Motors_Car_Truck_Parts_Accessories&vxp=mtr&hash=item4170f4b899






Dave

[bigoak54]

wow, are you Mr. Winnabago or some rv god?  i will get out to the winnabogo tomorrow morning and see if that is the right part.   i will let you know.  thanks again!!
Steve

[bigoak54]

Good morning Dave,

you were right, i have ordered the part.  with luck we will have it by spring break and we can get our for our first trip.  we will post some pictures once we get everything cleaned and put back together.  thanks again for your help.

[DaveVA78Chieftain]

A Brake Warning Light on the dash which is used to indicate when there is a loss of brake fluid pressure to the front or rear brake system.  When this loss of pressure occurs, the brake imbalance switch in the Brake Junction Block/Prop Valve (disc brake systems) will be pushed off-center within the valve and trigger the brake warning light on the dash to turn on.  This is a safety feature to let you know that there is a problem with your braking system that should be given immediate attention.  First, figure out the problem (leaky wheel cylinder, damaged brake line, new Power or Disc Brake Kit installation, etc.).  Once the problem has been fixed, the brake warning light can be reset by bleeding the front and rear brake systems.  If you have bled the front and rear brakes and the brake warning light is still on, you will need to bleed either the front or rear brake system additionally until the brake pressure valve has been reset to center.  To do this, follow these instructions:

1.  Check the Brake Master Cylinder and make sure the fluid in both reservoirs is within 1/4″ of the top of the reservoir.

2.  Turn the ignition switch to On so that the brake light switch is lighted up.
DO NOT START THE ENGINE!!!

3.  Have someone sit in the driver’s seat to control the brake pedal while bleeding and to keep an eye on the brake warning light.

4.  If the problem that caused the light to trip was in the front, start at the rear wheel cylinders.  If the problem was in the rear brake system, start at the front wheel cylinders.  Start by bleeding one of the wheel cylinders and attempt to bleed it until the brake pressure valve resets and the light goes off.  If the light turns off and then back on, you have bled too much and will need to bleed the opposite wheel cylinder to compensate (if you were bleeding the rear wheel cylinder, you will need to move to the front and vice versa).  If the light does turn off, have the person in the driver’s seat hold the pedal in that position and tighten the bleeder screw.  Once the bleeder is tight, release the pedal and pump it a few times to make sure the light stays off.  If the light stays off and the brake pedal is firm, the job is complete.  Make sure your master cylinder reservoirs are refilled after the bleeding.

5.  If the light does not turn off or has turned off and then back on, you will need to bleed the opposite side brake system (If you were bleeding the front, you will now bleed the rear and vice versa).  Follow Step 4 with the opposite wheel cylinder until the light turns off.  So long as the pedal is firm and the light is off, your brake fluid system should be good to go.  If the pedal is not firm, then there is likely air in the lines and you will need to continue to bleed the brakes until this air is completely removed from the brake fluid lines (it is also possible with drum brakes that the brake shoes are out of adjustment which can cause excessive pedal travel).

Dave

Courtesy: http://www.tomsbroncoparts.com/pages/schematics/bronco-schematics/drivetrain/h-blockprop-valve-brake-warning-switch-adjustment/

[DaveVA78Chieftain]

Full system:
Bleed MC at pedal
Bleed booster MC(s) [Early 375 one booster; Late 375 two boosters]
Bleed RR drum - If I recall correctly, the top feed bottom cylinder so bleed the bottom cylinder (always the last one in line)
Bleed LR
Bleed RF
Bleed LF

Many people do gravity bleed but a pressure bleed works just as well when you have an assistant.

Dave

[Jonbbrew]

Any place to get a new brake warning switch?

[DaveVA78Chieftain]

You will most likely have to search for NOS https://www.google.com/?gws_rd=ssl#q=mopar+4131254

These switches rarely go bad though.

[dkaven]

Hey All!


Thank you so much for sharing your work and thoughts! I'm starting on my 73 Indian M375 / 400..I'm still very green on this RV. I've done alot of working getting it ready. New Tires on the Budd Wheels, in refer, water heater plumbing etc. I was under the RV last Friday to jack it up to put on the new tires and notice the rear wheel Cylinders leaking on the LT. I did order some new wheel cylinders from a local Auto Parts Store. Some were I notice the parts numbers on Dave's web site. I do have a question the 2 parts numbers / parts have 2 different wheel cylinder bore sizes,   1 3/8" or 1 1/2"..could someone help me on the correct size?


Thanks you,
Danny

[dkaven]

Dave,


Thank you for your info / data on the brakes. I did order the correct kits.  1 3/8 are correct size.

[dkaven]

The Cylinders bore were to far gone.  So I had to open up the bores and install / machine SS sleeves.

[DaveVA78Chieftain]

So all is well now?

[dkaven]

Yes Yes! I well have the wheel Cyl's done this week and will reinstall bleed etc.


Thank you!