Brake master cylinder replacement 73 D18

[ralis]

WOW Guys, thanks!

I will attempt to at least pull the booster and Master Cylinder off.

If all goes well I will attempt to put the new ones on. If not, just have it towed as planned I have over a week at nights to try.

Thanks Dave I have the single booster with master cylinder

[LJ-TJ]

Since yours is a 1973 I'm assuming it's just the Master and single boost. Hm?

[DaveVA78Chieftain]

I suspect you have this configuration: 1972-73 Dodge Class A M300 (Late) Motorhome Brakes
Has 4 wheel drum brakes

[CapnDirk]

Wow Dave:  Just looking at that multi booster setup stood up the hairs on my arms.


Ralis:  We think you'll be fine.  If we were there to help it would cost some amount of beer (we sit in lawn chairs and watch/advise, AKA the good old boys club), but we are available most anytime during the day here.

[Oz]

Hi!  I found the manual for 73 Chieftain but not the 73 D18 Brave

The store manual covers the Brave as well as the Chieftain, and the Indian as well.  It goes by chassis designation, not model name.

[SR66]

I just purchased a 1974 Brave and have a leaking master cylinder. As well I should replace the booster too.


The start of this thread showed images of the replacements from ebay. I have tried to find the part numbers on here and elsewhere but not sure they are the right ones.


Does anyone have the link to the ebay items or actual part numbers to other retailers?


Thanks!

[DaveVA78Chieftain]

Assuming you have this configuration: 1973-74 Dodge Class A RM300 Motorhome Brakes

You want to use the M300/RM300 1973-78 (Front 12.82" Disc; 12" x 3" Rear Drum) section on this page: Dodge MH Brake Parts

Dave

[ralis]

Hi Guys!

So work got in the way again.The wife and I got to spend some on the Winnie. I crawled under and sprayed some of the BG Enforcer penetrating oil that LJ recommended on the two nuts holding the the master cylinder to the booster and the nuts hold the brake lines in. In the mourning I will attempt to open the top of the master cylinder and suck out the braked fluid with a squeeze bottle and tube. I am thinking of cutting a trap door for easier access.

[SR66]

After some more research I found both the master cylinder and booster on Rock Auto.


Removing the old ones was fairly easy and the replacements went in without any issues. Nice to have properly working brakes that don't leak.


Here are links to the parts -

MC -http://www.rockauto.com/en/moreinfo.php?pk=309140&cc=573&jsn=9


Booster -http://www.rockauto.com/en/moreinfo.php?pk=259078&cc=555&jsn=8

[LJ-TJ]

Here's one of two examples how chaps have solved there access problems

[LJ-TJ]

Here's one of two examples how chaps have solved there access problems

[LJ-TJ]

Here's number two of two examples how chaps have solved there access problems

[Rickf1985]

#1 looks factory right down to the perfectly radiused cutout and the recessed nutserts.

[Wilhelm7]

I have to do the same on my '71 D22. Are there bleeders on the frame-mounted boosters? The instructions with the new master cylinder say I have to bleed it on the bench before installation and never pump it more than 1 inch. Any comments?

[Rickf1985]

That is the bench bleeding procedure. You need to make lines to go from the ports back into the reservoir. short strokes over and over til you see no more air bubbles. You will have to clamp the master cylinder in a vice, be sure to grab it by the bolting flange and not the body.

[DaveVA78Chieftain]

As far as the two frame mounted hydrovac boosters (one for front circuit; one for rear circuit), I believe there is a bleeding port on each hydraulic cylinder as shown in this picture.  You have to bleed them before you bleed the front calipers or rear wheel cylinders.




THat was a Hydrovac system.  71 should have the Midland booster.  Here is you system to that also has a link to the Midland booster page.
http://dave78chieftain.com/M300_69-Early.html

[Wilhelm7]

Excellent information, gentlemen. Thanks. So, after bench bleeding and mounting the new master cylinder, I want to bleed the boosters, then the RR, LR, RF, and lastly the LF?
re: 1971 D22

[legomybago]

Sounds about right

[Rickf1985]

I don't think you have to do the bench bleed since you have bleeders on that master cylinder. That is a generic instruction that is put in with every master cylinder since that is the procedure for a normal master cylinder. Normal, more modern cylinders do not have bleeders.

[DaveVA78Chieftain]

Just to be clear 

The Master cylinder that the brake peddle is attached to I would bench bled if replaced or disconnected (no bleeder screw at that assembly)

The slave/master cylinders attached to each booster typically do have bleeder screws so they have to be bled.

Finally the caliper and/or wheel cylinders (depends on configuration) RR. LR, RF, LF.

Requires lots of brake fluid because the main Master Cylinder also supplies the slave/master cylinders at the boosters as well as the remainder of the system.

[k94536]

I have a hydroboost system had to get it rebuilt toon of $150.00 best $ spent so far but then again my RV has all the addons I'm finding out like copper water lines...