73 travco M375 rear brake

[DivinylRecords]

long difficult first year since we bought the 73 dodge Travco, I had no previous mechanical experience and we didn't realize how much work needed to be done and how difficult it is to live in and work on along with the extremely strict difficult laws in San Diego. No rv is allowed in any city street or property between 2_6am.  Or receive $112.00 ticket.  None the less we are still here but face a serious brake issue, the rear brakes lock up after driving well essentially after pressing the brakes I can goo under the car and release some fluid from the bleeder on the hydrovac and then they let go until usually further down the road.  We have taken off the back wheels and it lookedike almost the brake springs and parts were almost brand new well newer than anything else on the rig since we bought it. Could it be the hydrovacs failing? We've bled the system multiple times and now this is causing a lot of stress to drive anywhere.  The star wheel adjuster looked like they had no teeth left of them and everything I read is these parts are near impossible to find we had a new master cylinder put on by a friend/mechanic which Is not like the previous Chrysler /Lockheed one as it has a larger plastic reservoir(s)  on top  anyways I couldn't be more grateful for all the advice on this forum especially from Dave and Rick I want to express my sincere gratitude.

[DaveVA78Chieftain]

Assuming you have the Bendix Twinplex Brake system




While I am not 100% sure, parts for this system may be shown here starting on page 421:

http://truckpartsetc.com/sales/PDFs/Leland/Leland_WedgeBrakeParts_418-422.pdf


My M375 Brake web page: http://dave78chieftain.com/M375Late.html

[Rickf1985]

If the brakes only release after releasing fluid then it is probably because the rod is too long on the master cylinder and not allowing the return port to clear. Can you space the master cylinder away from the rod just a hair with a couple washers to see if that alleviates the problem? If it does then you can work on a more permanent solution.

[turbinebronze]

I would agree with Rick, with the master cylinder not being stock.
   I also wonder...Some master cylinders had a pressure holding valve (residual check valve) build into them for drum brakes...and some of the wheel cylinders had the same residual check valve build into them also. Is it possible to have both with the mix of parts, and have them holding the drum brakes on to much?
The only reason I ask is that I had to install residual check valves in my braking system to get a good brake pedal. (I mixed my parts...)
  More than likely, Rick made the right call...
  Just a thought, Craig
 

[DaveVA78Chieftain]

I agree with the master cylinder comments.  Here is what information I have about the M375 MC:

TRAVCO Website Thread
Rockauto listing for that MC
MC39013 Specs

CENTRIC says the P/N is 130.83006

The Flare nut sizes are different between these

[RANGERRICK]

On some GM chassis the rod is adjustable,not sure on the Dodge chassis.

[DivinylRecords]

Hey guys sorry for late response I had to hop a plane to Florida to donate bone marrow for my twin sister with leukemia the travco got impounded the day before I left for 6 unpaid parking citations from the SDMC code no parking between 2-6am any city property of street, so my lady is fundraising to get our home out of impound lot in national city. I'll get back to ya'll on updates but I had made some adjustments on the linkage that seemed to help I noticed that the pushrod can be lengthened and shortened but I couldn't get enough room I haven't tried the washers I wasn't sure where I should exactly put them but I thin I. Understand now what Rick is saying. Right now helping my sister is my main plan and hopefully our financial situation will help my girl get the rig out and then we gotta leave San Diego. Again I can't say how. Much this forum has helped me out and Daves website. I'll keep ya posted thanks again

[Rickf1985]

Best of luck on all fronts and yes, you have GOT to get out of there. It would have to be cheaper to find a cheap campground than try to move constantly.