- The Gear Box

* CWVRV News

HOT!  69-73 Dodge Service Manual - Better quality text and schematics.
Three volume set and FREE, one-year Full Membership upgrade!
 
GET YOURS!

Author Topic: No rear brakes  (Read 1429 times)

Offline horbre

  • *
  • Posts: 10
  • Member since: 2013
  • Year: 1975
  • Make: Winnebago
  • Model: Chieftain D25CL
  • Chassis: Dodge
  • Engine: 440
No rear brakes
« on: May 12, 2013, 09:05 AM »
Cannot figure out why I have no rear brakes! shoes and cylinders and hardware are good, lots of fluid, bled them, but nothing, I am however hearing a hissing coming from the cruise box behind master cylinder. ANYONE HAVE ANY IDEAS? ???

Offline Froggy1936

  • *
  • Posts: 1026
  • Member since: 2004
  • I own: a Motor Home
  • Year: 1977
  • Make: Winnebago
  • Model: Minnie Winnie
  • Chassis: Chevy G30
  • Engine: 5.7 1995
Re: No rear brakes
« Reply #1 on: May 12, 2013, 12:36 PM »
Horbre. Check that the safty lockout has not been activated (shuts off 95% of fluid to either frt or rear brakes in case of a rusted or broken line) This may have happened before any repairs were made or it can happen wile bleeding brakes . It is supposed to also activate the brake warning light but a wireing prob could eliminate the light . If you have a ground connection at the lockout switch it has activated You will have to consult a hydraulic layout for your veh to determine the location ! Frank
The Journey is the REWARD !

Offline DaveVA78Chieftain

  • Tech Support Specialist
  • *
  • Posts: 2673
  • Member since: 2003
  • I own: a Motor Home
  • Year: 1978
  • Make: Winnebago
  • Model: Chieftain
  • Chassis: Dodge M400
  • Engine: 440-3
Re: No rear brakes
« Reply #2 on: May 12, 2013, 03:29 PM »
Since you are hearing a hissing sound:
 
Do you have an M300 chassis: http://dave78chieftain.zxq.net/M300_74.html
 
or
 
Do you have a M400 chassis: http://dave78chieftain.zxq.net/M400_73-75-RM350.html
 
Dave
 

Offline horbre

  • *
  • Posts: 10
  • Member since: 2013
  • Year: 1975
  • Make: Winnebago
  • Model: Chieftain D25CL
  • Chassis: Dodge
  • Engine: 440
Re: No rear brakes
« Reply #3 on: May 19, 2013, 09:18 AM »
Yup the warning light is on and where would the safety lock out be and how do I fix it? Hm?
 
it is a rm400
 

Offline Froggy1936

  • *
  • Posts: 1026
  • Member since: 2004
  • I own: a Motor Home
  • Year: 1977
  • Make: Winnebago
  • Model: Minnie Winnie
  • Chassis: Chevy G30
  • Engine: 5.7 1995
Re: No rear brakes
« Reply #4 on: May 19, 2013, 06:27 PM »
Horbre The post above shows location for your model Since you have no rear brakes it must be upset to shut off the rears, So wile someone holds the brake pedal down open a bleeder on either frt wheel and it will reset to shut off frt brakes But just as the light goes out ease up on the brake pedal to catch the valve in the center if it goes all the way to shut off frt then you have to do the same procedure but open a rear bleeder and ease up as the light goes out Have Fun !! Frank W%
The Journey is the REWARD !

Offline DaveVA78Chieftain

  • Tech Support Specialist
  • *
  • Posts: 2673
  • Member since: 2003
  • I own: a Motor Home
  • Year: 1978
  • Make: Winnebago
  • Model: Chieftain
  • Chassis: Dodge M400
  • Engine: 440-3
Re: No rear brakes
« Reply #5 on: May 19, 2013, 06:28 PM »
1. The warning light just means there is an imbalance between the front and rear circuit.  That could be a actual problem or it could mean the brakes need to be bleed in order to center the warning switch (which is what Froggy was explaining).

2.  I have never heard of a Dodge product of this era having any form of safety lock unless you talking manual emergency brake..  The front rear valve is combination warning light switch proportion valve.  The warning light section only indicates there is a front to rear imbalance.  The proportion valve section only reduces the pressure to the rear brakes because disk brakes require more pressure.  This prevents the rear drum brakes from locking up before the front disk breaks.

3.  RM400 - Look under the rig to see if you have two big boosters just forward of the rear axle like this:



if not, then you should have a hydroboost unit just inboard of the front drivers side wheel  like this



I have to know what system you have to continue further.

Dave

Offline horbre

  • *
  • Posts: 10
  • Member since: 2013
  • Year: 1975
  • Make: Winnebago
  • Model: Chieftain D25CL
  • Chassis: Dodge
  • Engine: 440
Re: No rear brakes
« Reply #6 on: May 20, 2013, 10:09 AM »
Well now im stumped cuz it has the brake warning metering velve and the big lines coming off the pots like in the very top picture. I took some pics ill put them up also the second pic is that speedostat that the hissing is coming from

Offline horbre

  • *
  • Posts: 10
  • Member since: 2013
  • Year: 1975
  • Make: Winnebago
  • Model: Chieftain D25CL
  • Chassis: Dodge
  • Engine: 440
Re: No rear brakes
« Reply #7 on: May 20, 2013, 10:12 AM »
here is the rest of the pics the brake pads are 4x15 if that means anything

Offline horbre

  • *
  • Posts: 10
  • Member since: 2013
  • Year: 1975
  • Make: Winnebago
  • Model: Chieftain D25CL
  • Chassis: Dodge
  • Engine: 440
Re: No rear brakes
« Reply #8 on: May 20, 2013, 10:18 AM »
Thank you ill give it a whirl :)ThmbUp  I did post some pics of my brake system in the forum

Offline horbre

  • *
  • Posts: 10
  • Member since: 2013
  • Year: 1975
  • Make: Winnebago
  • Model: Chieftain D25CL
  • Chassis: Dodge
  • Engine: 440
Re: No rear brakes
« Reply #9 on: May 21, 2013, 06:51 AM »
well I tried that with one front brake but I could not with the other as it is stripped and the rear ones have no bleed valve, that was odd so it didn't work

Offline DaveVA78Chieftain

  • Tech Support Specialist
  • *
  • Posts: 2673
  • Member since: 2003
  • I own: a Motor Home
  • Year: 1978
  • Make: Winnebago
  • Model: Chieftain
  • Chassis: Dodge M400
  • Engine: 440-3
Re: No rear brakes
« Reply #10 on: May 21, 2013, 01:09 PM »
Quote
here is the rest of the pics the brake pads are 4x15 if that means anything

Yep means a WHOLE LOT!   You have what is normally refferred to as a M500 chassis.  Dodge created a lot of confusion in the 73-75 time frame by redefining the chassis nomenclature.  RM400 = M500  Winnebago normally did not place a 25ft rig on a M500 chassis (14,000 GVW) so that can also throw people of the trail.  My 1978 27ft ft is on a M400 chassis (12,000 GVW).  You can see how this can get to be a bit confusing at times which is why I ask questions before I answer.

http://dave78chieftain.zxq.net/M500_73-75-RM400.html

Note : I forgot to update the pic on my website to reflect the larger shoe size however the basic information is good

You have:
Bendix Dual Master Cylinder: http://dave78chieftain.zxq.net/MCBendixDual.html
Twin Hydro-Vac Boosters: http://dave78chieftain.zxq.net/HydroVac_brakes.html
Front Brakes - Dual piston Disc: http://dave78chieftain.zxq.net/DiscBrake.html
Rear Brakes - Bendix twinplex: http://dave78chieftain.zxq.net/TwinplexBrakes.html

There should be a hose connected to a air filter that is most likely either behind or under the drivers seat inside the RV.  It is the air supply to the one side of the diaphram in the brake boosters.  Engine vacuum is applied to the other side of the diaphram.

The brake boosters slave cylinders have to be bleed before the wheel cylinders / calipers are bleed. http://www.classicwinnebagos.com/forum/index.php/topic,993.msg1009.html#msg1009

Rear brake bleeder valves should be on the bottom cylinder of each wheel (point farthest away from Master cylinder). 

If the hissing sound is coming from the Speedostat then that is just a vacuum leak that is not directly related to the brakes.  The Speedostat is part of the vacuum operated cruise control system.  There should be a vacuum line going from that unit to a large vacuum chamber on the left rear of the intake manifold.  Linkage from the vacuum chamber attaches to the throttle linkage at the carb.  The Speedostat varies the amount of vacuum to the chamber based on the speed setting.  Thats why the Speedometer cable is also connected to that box.


Dave

Offline horbre

  • *
  • Posts: 10
  • Member since: 2013
  • Year: 1975
  • Make: Winnebago
  • Model: Chieftain D25CL
  • Chassis: Dodge
  • Engine: 440
Re: No rear brakes
« Reply #11 on: May 24, 2013, 09:47 AM »
Thank you very much Dave this is all valuable info it is greatly appreciated :)ThmbUp :)ThmbUp

Offline horbre

  • *
  • Posts: 10
  • Member since: 2013
  • Year: 1975
  • Make: Winnebago
  • Model: Chieftain D25CL
  • Chassis: Dodge
  • Engine: 440
Re: No rear brakes
« Reply #12 on: May 29, 2013, 02:02 PM »
Dave do you also know what size hub seal that is on my unit? Hm?

Offline DaveVA78Chieftain

  • Tech Support Specialist
  • *
  • Posts: 2673
  • Member since: 2003
  • I own: a Motor Home
  • Year: 1978
  • Make: Winnebago
  • Model: Chieftain
  • Chassis: Dodge M400
  • Engine: 440-3
Re: No rear brakes
« Reply #13 on: May 29, 2013, 04:09 PM »
Rear wheel seal on inside of drum:
Dodge P/N 2914518
NAPA P/N 33136
Timken P/N 456648

Offline horbre

  • *
  • Posts: 10
  • Member since: 2013
  • Year: 1975
  • Make: Winnebago
  • Model: Chieftain D25CL
  • Chassis: Dodge
  • Engine: 440
Re: No rear brakes
« Reply #14 on: May 30, 2013, 07:24 AM »
Thanks Dave! your a life saver! :)ThmbUp :)ThmbUp

 

* Salvage Yards

RV Salvage Yards
By STATE
.

* Need a Manual?

Dodge,  Ford
John Deere
Service & Parts Manuals

&
Coach Manuals Too!
.

* Dave's Place

All the critical info you need for:
Dodge brake systems
Converters
Charging systems
Belts & Hoses

And more!

Dodge VIN Decoder

Want to know what your Dodge VIN means?

Dodge VIN Decoder

* Model Brochures

View Brochures for all
Winnebago, Itasca,
LeSharo & Phasar
from:
1969-present


Layouts, features,
options & more

* Resources

Need parts and information?
View the Resource List
.