79 LeBaron Medallion - currently front brakes re-do.

[69-]

I _assume_ that the original buyer had it already, mabe it was needed for registration in europe at that time in the netherlands.
Reason is because it was in very decent shape and the seller (2nd owner) didn't know anything about was it was, but luckily kept it with the car.

As the seller was neither into the details of the car nor did he mess/work on it, I think he would probably just have tossed it as junk if he would have found it.

But thats only my weird thinking . There was nothing below the rear bench when I removed it (usual location for the earlier Mopars). I did not lift the carpet, yet.

Oh, and many thanks to BudW for the insight.
I'll later post the build sheet for the car.

 

[BudW]

I'll later post the build sheet for the car

Thumbs up.

Our cars used build sheets on the assembly line, but because of potential fire hazard, they were removed from car as car was built.
I found a couple of taped-on corners in my '77, but the paper was ripped at the tape line.

 

[69-]

So, here it is:

Couple notes:
Sales Code D55 (Axle) says on the backside 2.45/2.47 (D81 is 7.25 axle). So, I obviously have the 2.47 (the faint 7 you mentioned).
Special: Delete Cat Conv option - European Export.

And here's the backside of the build sheet.

 

[BudW]

In great condition, no less!

 

[69-]

To get back to the brakes - one question I had on my mind.

While bench bleeding the new master cylinder I noticed, that the first approx. 1/2 inch of the stroke only triggered the secondary chamber (i.e. rear brakes).

That would then translate to 2 inch of pedal travel (approx 4:1 pedal-ratio) before the front brakes engage??
I read through the service manual. It states, that the combined warning/hold off/proportioning-valve should do exactly that (first engage rear brakes with light brake pressure, and to overcome rear brakes inertia/springs etc.) should do this "rear first", instead of the master cylinder?

Just trying to understand it technically .

 

[Mikes5thAve]

It is neat that you have it and that it was purposely built as European export.

 

[BudW]

I'm not understanding the question exactly.
The proportioning valve slows down pressure to front wheels until rear brakes feed back (make contact with drums) sense it takes more fluid to get the rear brakes initialized.

when bench bleeding a master cylinder, it does take a bit of time to get air out. Once air is out, the front and rear brake fluid output from master cylinder will be the same. What differs is what comes from the proportioning valve.

When bleeding the brakes, you always go from wheel farthest from master cylinder and work way to wheel closest to master cylinder - but for a different reason.
BudW

 

[69-]

Of course I followed the required procedures for bench bleeding (no air bubbles [plus a couple more strokes to ensure]) as well as system bleeding (farthest to closest).
And, of course, when bench bleeding succeded one can hardly tell which chamber comes through first (if so). At least, I noticed disturbance in the secondary chamber half an inch of stroke before noticing same in the primary chamber. Together with stronger stroke force required after the first half inch. That made me think that different springs inside the master cylinder are somehow responsible for this. Looking at the service manual (Fig. 1, page 5-16), it at least looks like the piston return spring is weaker than the spring in the primary piston assembly.

Anyway.
I haven't test driven, yet, because of the rear end. I will let the sealant cure for another day before refilling. And of course, report back.

 

[Ele115]

I have had issues with aftermarket bleeder screws before with not sealing. I try to get new mopar ones if they are available.

The red box stores and/or Ho chi-minium drama. Stick with MOPAR

 

[69-]

Diff filled with 2 pints of proper GL5 hypoid oil (I use the same on my Camper with a Dana 70, so it should suffice for the 7.25 ). At least now, nothing leaking - trust it'll keep dry...

On a side note, I just bench-stroked the old master cylinder, see the result. Fail. Good I replaced that one as well... Test drive still outstanding....
I wouldn't have noticed this leak until the master would have been empty. Brake fluid would be sucked right into the engine via the vacuum booster, I guess.

 

[BudW]

The brake booster has seals at both ends to prevent fluid from getting sucked into engine. Even that, the booster will need to be full enough for fluid to be at level of the vacuum check valve to get sucked into engine. It can happen, but not a common thing.

The booster diaphragm can also leak vacuum. It is most noticeable when pushing and releasing the brake petal via abnormal noise under the dash.
Brake boosters are designed to keep about 1-1/2 brake applies worth of vacuum in the event your moving and need to apply the brakes - and should have this capability no matter how long the car has been parked.
If you hop into any FMJ and apply the brakes (car not turned on) you should have one good power assisted brake, one half-ish apply of power brakes - then full on hard brake petal apply - so if you are still traveling and apply brakes the third time, you will get some full-on personalized rear pucker power going on and/or might have to change your britches after you come to a stop (from puckering . . . or not).

One nice thing about aluminum vs. cast iron master cylinders is aluminum can't rust. Rust is very abrasive and eats away at rubber seals like sand paper.
The bad thing about aluminum is it will corrode in time. Your master cylinder was anodized, which is the blue colored coating - which prevents corrosion.
Note: the anodization (spelling?) color can be just about any color. Some racers have a lock on certain colors - which aids knowing who's parts are whose (aluminum wheels, and so forth).

The anodization can wear off and can be removed chemically or mechanically - then corrosion can then eat away at rubber seals, but not to the extent that rust does. Also, rubber can just simply wear out over time, as well.
in this case, the steel snap ring is rusty - which makes me wonder.
BudW

 

[69-]

Test drive done. I am quiet happy with the brakes now. Bleeder are tight, axle seems tight as well.

And, as if I had asked for some idiots on the street, some woman just pulled out of a side street right in front of me. Brakes hold it just in time...

 

[69-]

Front brakes do fine, but while changing to winter tires a week ago (additionally, I had a nail in one of my new summer tires... *sigh*) I briefly took of the brake drums. Driver side was really wet - assuming the rear cylinder broke.

Today I changed the cylinder. Took me 4h !! Why? Well, former "service technicians" actually put strong lube on the whole back plate. It was a PITA to remove the lube (I guess you can see some of the remains in the picture)...

Anyway, in the end, I replaced the cylinder hoping it'll stay dry . This change itself took probably like an hour, at most. And my newly acquired small hoist helps a lot to do the job in a more comfortable and safe position.

 

[69-]

Ahh, I just learned that I cannot change the topic to reflect the current things I'm doing on the car, so, sorry for that

 

[69-]

OK, other side today. Not finished.

No lube inside (good), but some idiot torqued one of the rear cylinder screws that strong, that it did not move. Then it was round. I had to grind it apart... *sigh*
Ready then to remove the brake line - aaaand: BROKE. It just basically fell apart. I could not see, that it was mounted "twisted" and with the other direction it just basically fell off. Fortunately, I was able to close the gate of my garage (which is pretty tight) to just let it sit.
Reminder for others: have the brake pedal fixed in a part-depressed position and your brake fluid won't just run through. But also remember to disconnect the battery (re: brake lights).

WIll probably re-do the whole brake line from the rear axle tee....

Not very sharp, but you'll see the problem of the twisted brake line.

Somehow, flaring still works. Will get some new brake line, as this one was sitting outside the last 4 years...

 

[69-]

Replaced the brake line, new rear brake hose (of course), stainless steel protection and properly connected to the diff cover (not in picture), bleeding, take off.
While waiting for bleeding, I used the time to check on play in the steering linkages. Next project identified - the idler arm is kind of loose... But that should be easy and with less hassle than the rear brakes.

And the LeBaron proofed his daily usability - carrying an e-bike -> no problem.

 

[Aspen500]

The lube on the backing plate looks like it could be axle fluid. Take a look at the axle seal, just to be sure. Of course I'm looking at a photo and could be wrong.

 

[69-]

I was suspecting that as well, but no, it didn't have the typical hypoid-smell and the viewable parts of the seal had no sign of axle fluid.