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code2e · 04-01-2023, 10:44 PM

Just an idea crossed my mind. You mentioned the 9/16 line nut was difficult to access when swapping out the bleeder tubes. Is there any chance some rust or other debris slipped in there and may be blocking the port?

gandl2123 · 04-02-2023, 08:38 AM

Threaded 2-1/4"

gandl2123 · 04-03-2023, 06:17 AM

Well, that's a great mystery. I will have you an answer tomorrow, Tuesday April 4th. I plan to work on her for some hours.

First thing I'm doing... Remove cap from master... Verify fluid full removing both lines from master .. reach up and pull on brake arm to visually see fluid ejected from ports.

If positive outcome will disconnect 9/16 line at proportioning (pv). Then going to blow air through that line to verify clear.

Then connect to mast at top, press brake to push fluid (w one way bottle hooked to bottom) to pv. Going to try some other things to see if I can get both input to and output from the pv.

gandl2123 · 04-04-2023, 08:10 PM

Great discoveries today. I spent most of the day on her and was able to force brake fluid past the proportioning valve and down the line to the rear brakes and up to the front brakes. But....

The fluid bled fine to and in all of the metal lines but not one single rubber hose brake line could I get fluid past.

In the rear...fluid exited the proportioning valve and then I bled again where the fluid entered the rubber hose that let to the brass junction bolted to the rear axle where one line shoots over to right rear and one line shoots over to left wheel. Not a drop of fluid would come out "south" of that last metal line. The rubber brake line must be totally blocked as I could not bleed either line across the back axle fed by that rubber hose.

Moved to the front right and metal line leaves the proportioning valve and goes to each front wheel where it enters into the rubber hoses on each side. Brake fluid was bleeding from the metal line as it was burped as it entered the rubber line running to the wheel cylinders. Bleed the wheel cylinders and dry as a bone, not a drop reaching them.

So, now I'm going to order all new rubber brake lines front and rear and then see if we can get some brake fluid to the wheel cylinders.

Also of note...the fluid was not your typical clean light colored fluid...it was more of a medium brown. I think I may just gravity feed new fluid to the exit sides of the proportioning valve and then blow out the rear and front brake lines of all of their old fluid as I install the new lines. Then connect the lines up and gravity feed new brake fluid through all of the lines starting with the rear right and working my way around. Sounds like a good plan. Yes? Thanks again.

code2e · 04-04-2023, 08:30 PM

Yes, good plans. Not surprised about rubber hose blockage. Hoses are made with an inner hose, wrapped with belting and covered with outer rubber hose. They always live with a bend in them and flex a lot while driving. At some point of older age, the inner will form a crack that becomes a rubber flap. Flap folds over and plugs hose. Many times flap can act as a one way check valve and cause brakes to drag keeping pressure applied. Good luck.

gandl2123 · 04-05-2023, 07:48 AM

Moving on to break hose is now there's some confusion. Parts houses are showing of course the two front brake lines but they're also showing two back brake lines. The only rubber brake line on the back is a longer one coming from the main single brake line going back and allowing for connection into the block that feeds the left and right rear. In other words, there's only one hose in the back and that feeds the brake line to the rear axle which are metal.

Anyone got any idea as to parts and the best place to get these lines and make sure they fit?? Thanks for all your support guys.

gandl2123 · 04-05-2023, 10:12 AM

Quote:

Originally Posted by code2e

Yes, good plans. Not surprised about rubber hose blockage. Hoses are made with an inner hose, wrapped with belting and covered with outer rubber hose. They always live with a bend in them and flex a lot while driving. At some point of older age, the inner will form a crack that becomes a rubber flap. Flap folds over and plugs hose. Many times flap can act as a one way check valve and cause brakes to drag keeping pressure applied. Good luck.

Ordered some good Raybestos lines this morning from Amazon. I'm hoping, going to check again, that there are only 3. Two in the front and one in the back as it transfers from metal line to diff. I don't remember seeing a left and a right rear as some parts places are saying. Maybe for a 1 Ton application of sorts but not on this RV.

Some pics from yesterday's work. Got my father who drove one of these int he 70's helping me. 82 yrs young.

code2e · 04-05-2023, 01:43 PM

Quote:

Originally Posted by gandl2123

Moving on to break hose is now there's some confusion. Parts houses are showing of course the two front brake lines but they're also showing two back brake lines. The only rubber brake line on the back is a longer one coming from the main single brake line going back and allowing for connection into the block that feeds the left and right rear. In other words, there's only one hose in the back and that feeds the brake line to the rear axle which are metal.

Anyone got any idea as to parts and the best place to get these lines and make sure they fit?? Thanks for all your support guys.

Could you clean up the rear brake hose fitting? Is there any chance the brass tee is a separate part and the hose actually threads into it?

If not, a clear picture might help find the part. I found plenty of listings for a single center rear hose with threaded end.

gandl2123 · 04-05-2023, 10:28 PM

You are correct. The rear hose is driver side frame. Connects to metal brake line bringing fluid to rear axle.

24" rubber brake line then attaches to that brass block and two metal lines run to rear L&R wheel cylinders.
It almost looks as if there is a vent of sorts on that brass part. Can't imagine why.

code2e · 04-06-2023, 08:14 PM

Quote:

Originally Posted by gandl2123

You are correct. The rear hose is driver side frame. Connects to metal brake line bringing fluid to rear axle.

24" rubber brake line then attaches to that brass block and two metal lines run to rear L&R wheel cylinders.
It almost looks as if there is a vent of sorts on that brass part. Can't imagine why.

Good. The rear hose is a Raybestos BH4960. RockAuto.com has one only for $22 plus shipping. Amazon has sellers who have it for $34 including shipping.

The "vent hole" you see is likely a mounting hole for the brass tee. 24" is correct length.

gandl2123 · 04-26-2023, 11:28 AM

Hey guys, not sure if I closed this up but was able to get new rubber brake lines 2 in front and 1 in back replaced and bled out. The brakes will toss you through the windshield.

Thanks to everyone for all their help.

Now I'm off to replace the 7.50 x 16 LT Super Hwy tires as they are flat spotted and make for a horrible ride. Some are saying 235/80R/16 is close. Wonder what others have used.

Also ponder what the GVW is of this 24' vintage motor home. From what I can tell and have learned the front axle is 4500lbs and rear 6500lbs. Not sure if that means the campers gvw is 11k. Going to look at some data plates and see if I can get some answers. Tks

code2e · 04-27-2023, 07:13 PM

Quote:

Originally Posted by gandl2123

Hey guys, not sure if I closed this up but was able to get new rubber brake lines 2 in front and 1 in back replaced and bled out. The brakes will toss you through the windshield.

Thanks to everyone for all their help.

Now I'm off to replace the 7.50 x 16 LT Super Hwy tires as they are flat spotted and make for a horrible ride. Some are saying 235/80R/16 is close. Wonder what others have used.

Also ponder what the GVW is of this 24' vintage motor home. From what I can tell and have learned the front axle is 4500lbs and rear 6500lbs. Not sure if that means the campers gvw is 11k. Going to look at some data plates and see if I can get some answers. Tks

I found that a 235/85R-16 is even closer to the 7.50 X 16 LT. Will need to be sure of clearance between tires on the rear duals. Radials tend to squat a bit. You don't want any contact between the duals.

I couldn't find any GVWR ratings. Hopefully, you may still have a label somewhere. Usually by the entrance door or on inside wall near driver. I did find a model numbering list. In 1972 Dodge made 2 models, the M-300 and the M-375. Later years there were M-400, M-500 and M-600 models.

gandl2123 · 04-28-2023, 07:37 AM

Brakes are working well... 3 of the 4. The brake farthest from the Master (rear right) will not bleed...I've bled it all the way to the brass block that allows for the fluid to come into the rear lines. Removing the line in and bleeding fluid out, removing the left rear line and fluid bleeding out there and the left wheel cylinder.

Remove the right rear line at that block and fluid bleeds out...move over to the wheel cylinder and nothing after several attempts. Remove the line entering into the wheel cylinder and still nothing.

So.... next step when I get time is to remove that rear line and or blow it out independent of the block or wheel cylinder to see if it has trash in it. Then blow out the wheel cylinder, then try and back fill with fluid as much as possible then reinstall and attempt a final bleed.

That's the plan for now. Going to do it after I get the new tires installed or during installation of the tires. Then we should have a camper that cruises smoothly down the road at 55 instead of a camper that shakes the dishes out of the cupboards at 40mph. lol

thanks for your help.

code2e · 04-28-2023, 07:29 PM

Quote:

Originally Posted by gandl2123

Brakes are working well... 3 of the 4. The brake farthest from the Master (rear right) will not bleed...I've bled it all the way to the brass block that allows for the fluid to come into the rear lines. Removing the line in and bleeding fluid out, removing the left rear line and fluid bleeding out there and the left wheel cylinder.

Remove the right rear line at that block and fluid bleeds out...move over to the wheel cylinder and nothing after several attempts. Remove the line entering into the wheel cylinder and still nothing.

So.... next step when I get time is to remove that rear line and or blow it out independent of the block or wheel cylinder to see if it has trash in it. Then blow out the wheel cylinder, then try and back fill with fluid as much as possible then reinstall and attempt a final bleed.

That's the plan for now. Going to do it after I get the new tires installed or during installation of the tires. Then we should have a camper that cruises smoothly down the road at 55 instead of a camper that shakes the dishes out of the cupboards at 40mph. lol

thanks for your help.

Good plan. Very likely a chunk of rubber from that rear flex hose found its way into the metal line. Interior wall of metal line may have some corrosion that keeps rubber chunk stuck. I'd try removing the metal line and blowing it out backwards onto a clean paper towel. Get to see what comes out. Would also blow it out forwards. You could remove the bleeder screw from that wheel cylinder and blow it out, if you wanted. Then you can be certain it will bleed when all back together.