E brake cable question

[upnsmoke]

I put this in general discussions because it is a matter of curiosity for me more so than an attempt to diagnose a particular issue. I was adjusting my E brake cables today and can't help wondering how they work. It looks to me like the front cable actuated by the pedal pulls only on the driver side rear cable. The only force applied to the passenger side cable is through the equalizer, and the only force applied to the equalizer, it would seem, is created by the effect of the sheath of the driver side cable trying to straighten as tension is put on its inner cable. Wouldn't it seem that the driver side cable would get pulled on harder? Is this compensated for in the brake mechanism inside the drums? I rebuilt my drum brakes a while back but did not pay enough attention to notice any differences between the two sides. I do remember them looking similar at a glance though.

My E brake works fine as it is. I just can't help being curious. This is a link -click here- to an Autozone page with some pictures of the setup, just in case I haven't made any sense. I'm curious to hear what some others think about this.

 

[adsm08]

The sheath is just a sheath. It is there to help hold the cable itself in place and protect it from the elements. The pedal arm pulls on the forward cable itself, which then pull on the driver's side cable (except in my truck where it pulls on the crap on the floor behind the front seat). The driver's side cable drags the equalizer along with it, which in turn pulls on the passenger side cable.

The equalizer does just that, it equalized the force applied. There are no differences in the internals of the brake setup except for the adjusters. The adjusting pawls are bent differently, being backwards from each other so that the both face forward when hooked into the outside of the shoe, and the adjuster screws are likewise backwards, the RH one having a left-handed threading so that is unscrews when the adjuster pawl turns it to the right (outside).

Also worth noting is that the shoes are not the same front to rear. The rear shoe is longer and thinner than the forward shoe and putting them in backwards will allow the auto-adjusting assembly to fall out upon application of the brakes.

 

[upnsmoke]

That all makes sense, except I still don't know how the driver's side cable drags the equalizer along with it. The equalizer is only attached to the sheath, not the actual cable, right?

 

[PanamaExpat]

I studied that off the wall engineering idea for a while when I put all that back in the chassis... Near as I can tell you are correct in the fact that the driver's side shoes would contact the drum first then the passenger side would cinch up. Once the cable tensioned though I would suspect that the pressure on both rear drums is fairly equal.

 

[upnsmoke]

At least it's not just me that thinks this rig is a little weird. I expected to see an equalizer connected to each cable, like on every other vehicle I have seen, as far as I can remember. I had considered rerouting the cable to a hand lever for use while driving. With this system it might be a little weird though. I have a good posi, which I guess could help. Then again, it's not broken, so maybe I'll just leave it alone for now.

 

[cvar]

Adsm08, I'm curious & confused. How does "The driver's side cable drags the equalizer along with it" ?

When I pull the lever, it pulls the driver's side cable (not sheath), which pulls on driver's side brake shoe, but it doesn't seem to pull on the equalizer. So what pulls/pushes the equalizer itself, or the driver's side sheath which is clamped to the equalizer?

Also, what does the 1" dia. equalizer spring do? Some trucks (eg, mine) have one, others don't. Is it just to prevent sagging of the longest cable?

 

[doorgunner]

FYI.......squirt some internal lubricant inside the cable "housing" to keep the steel cable sliding easily...(dust/rust can get inside the black cable liner & cause stuff to bind or not grab properly or even grab----- but it won't release all the way)

 

[adsm08]

I have a theoretical understanding of how they work. I don't have a full mechanical understanding, nor do I currently have a working unit to play with to figure it out. I don't really get it enough to explain it.

Also, I have no idea what that spring is for.