[deandeib]

Inspected my rear brakes and saw a small, spring-loaded plunger on the inside of the rear wheel backing plate at about 7 o'clock position looking at the back surface of the plate. After pulling the drums I saw that when pushed in (from the back side) moves about 1/2" to contact a tang on a lever arm (for the parking brake?). Doesn't seem to be doing anything other than that. Anybody know what this little plunger is for ??????

Also, after doing front brake job, getting a very light brushing or scraping sound at low speed. Last time something like this happened after a wheel bearing job, I found a length (18-24" +/- ???) of small tubing that looked like hard brake line running transverse near the frame close to the front axles. It had become disconnected from a rubber tube and was rubbing against an axle. After reattaching it, the light brushing sound went away. Anybody know what that is? Can't find any info on this item either.

I can take photos if necessary. Thanks.

 

[rambleon84]

The rear brake soudns like the parking brake line...

Here is a disassembled drum, the hand/parking brake cable is the silver thing at around 4 o'clock. Does that correspond with what you are describing? If yes, then that is its sole job...just uses tension from that line to lock in the rear drums

The hard line up front sounds like the hard brake line but if it was detached, it would be leaking brake fluid and your brakes wouldnt be working correctly (as in very noticeable lack of pedal.) You should also be able to follow the brake line off the caliper and it would go straight to the hard line. Posting a picture would help us tell you what it is

 

[deandeib]

The rear brake soudns like the parking brake line...

Here is a disassembled drum, the hand/parking brake cable is the silver thing at around 4 o'clock. Does that correspond with what you are describing? If yes, then that is its sole job...just uses tension from that line to lock in the rear drums

The hard line up front sounds like the hard brake line but if it was detached, it would be leaking brake fluid and your brakes wouldnt be working correctly (as in very noticeable lack of pedal.) You should also be able to follow the brake line off the caliper and it would go straight to the hard line. Posting a picture would help us tell you what it is

Thanks for the reply but Nope and NOPE

The plunger is just that, a little ~ 1/2 dia cylinder coming into the shoe-side of the backing plate from the back side of the backing plate. In your pic it would be at around 7 o'clock. It just pushes in and makes contact with a tang. I'll try a photo. Sorry for the poor description.

The line is not a brake line. No liquid in it and the brakes are fine. Is there a pressure equalization line running across the width of the underside near the front axles? Again, I'll try a photo but thanks for the reply.

Dean

 

[deandeib]

OK, here are some pics. The tubing shown had popped out of its fitting during some dog bone work last summer. The tubing runs just over the dog bone but not sure what it attaches to on the passenger side. The plunger is just some very curious item I noticed while checking rear brake lining and wondering what it does. On the inside view of the brake backing plate, the other end of the plunger would be located around the location indicated.
Thanks to anyone who can identify these parts.

 

[sailor]

First one is easy, transfer tube for air in the boots of the steering rack.

Second one's kinda got me puzzled, added to newer version. Unless they moved the adjuster so that could trip it I'm left guessing.

 

[deandeib]

Thanks Sailor. Can you tell me any more about the what exactly the air transfer tube does?

And the plunger...???? Doesn't seem to do anything but butt up against part of possibly a tang on the lower end of the parking brake actuator arm (I'm making some of this up since I didn't take a photo when I had the drum off) when pressed in from the back side.

AND...I don't even see an adjustment device in these brakes. Do they still make the star wheel/ratchet mechanism that I've been screwing with since the 60's???

 

[emsvitil]

I think I know.......

The brake adjuster bar self adjusts to the correct length when you apply the parking brake.

I think it pushes against the parking brake arm and moves it just enough so that the brakes self adjust after you've put on the shoes and drums.

 

[sailor]

And the air transfer tube does the obvious (once you think about it a bit) and transfers air from one bellows to the other as the steering moves.

Otherwise the bellows would spew air when moving in one direction & collapse when moving the other way as it tries to draw air back in - combine it with the one for the other side and the air just moves from one to the other. All to help keep the rack & the inner tie rod ends protected from crud & water by enclosing them.

Star adjust = none on these, just a ratchet mechanism to take up slack & no way to release it.

 

[deandeib]

Thanks, guys, still don't know what the plunger is for, but thanks for your input.

 

[deandeib]

I think I know.......

The brake adjuster bar self adjusts to the correct length when you apply the parking brake.

I think it pushes against the parking brake arm and moves it just enough so that the brakes self adjust after you've put on the shoes and drums.

Yea Ed, something like that, I guess. But the plunger is already all the way out and pushing on it from the inside can't move it. It only moves in toward the shoes when pushed from the back side of the backing plate. I just asked the guy who inspected my car about it and he must be one of these guys who just can't seem to say the words, "I don't know" so his answer, twice, was, "Oh, it's part of the e-brake system", which is just one click above the total BS reply of "Oh, it's part of the brake system". No shit?!?! But you're right about the totally self-adjusting part but how do you retract the shoes if you ever have to in order to pull off a tight drum? In the old days you just accessed the adjuster wheel thru a slot in the backing plate and cranked the bottom of the shoes in until the drum would just about fall off. I'm on a mission boys and I'll let anybody interested know what I find out about this.

 

[emsvitil]

Put everything together except for the drum, and


PUSH IT............


And tell us what happened

 

[deandeib]

Put everything together except for the drum, and


PUSH IT............


And tell us what happened

10-4. But from what I saw the last time, the inside end of the plunger just touched a bent tang on the bottom of what might have been an actuator arm for the e-brake. I'll take a video and see if I can figure out how to post it.

 

[shortbusno27]

i think the "plunger" is a bump stop for the emergency brake mechanism. its hard to say without it assembled.

 

[deandeib]

OK boys. If this works - first time trying to post video clips. Seems like it worked...so. ANYBODY know what this plunger is supposed to do? For the life of me, I see absolutely no effect of this thing on anything.

http://http://s1274.photobucket.com/user/deandeib/media/plunger%20e-brake%20ON_zpsijc6doiu.mp4.html?sort=3&o=1

http://s1274.photobucket.com/user/deandeib/media/plunger%20e-brake%20OFF_zpsf5o4ievz.mp4.html?sort=3&o=0

 

[emsvitil]

It looks like if you push the plunger hard enough, it will move the emergency brake lever a little.

 

[iminhell]

It's a reset for the adjuster.

Lets say you go through the adjustment procedure and you set them too tight. The plunger will be all the way out. Push it and you will reset the adjuster.


Or that's how I recall it working. Been a little while though.

 

[deandeib]

It's a reset for the adjuster.

Lets say you go through the adjustment procedure and you set them too tight. The plunger will be all the way out. Push it and you will reset the adjuster.


Or that's how I recall it working. Been a little while though.

[thumb]That's the most likely function I've heard so far. Most of the replies (NOT from FF) have been, "Oh, that's part of the brake system", !!!!!!!!!! Oh, OK, that explains everything---NOT! You're probably right though since I don't see any other possible way to retract the shoes with the the drum still on. Maybe after the weather gets better I might open it up again and try to test your theory. For the time being, I'm gonna let it rest - I'm tired of messing with it for now.

Q. Is it possible to "set them too tight" buy their normal automatic adjustment process of just applying the brakes while driving in reverse?? I can see them wearing into the drum so far that you can't pull the drum off unless you retract the shows. Done that a hundred times over the years but with a brake system I could understand! [?|]

It might be analogous to the "forward assist" on the right side of the AR-15 receiver that allows you to manually try to close the bolt by pushing on a "spring loaded plunger".