A different way to hook up 911 e-brakes, Another way to do the 911 parkbrake -merged threads Options

[Wes V]

I think I've come up with a totaly new way to hook up 911 parking brakes. It involves making up longer hybrid cables.

It's not complex, doesn't cost tons, and is about as straight forward as possible.

It functions exactly as intended in the 911.

Here is a teaser photo;

(IMG:http://www.performanceforum.com/wesvann/914a/my-rear-brake/b-mrb1.jpg)

Here is a link to my write-up on how I did it (it's a preliminary write-up).

hybrid cables

Wes

(can somebody please find me the photo that I've seen on this site where somebody used a cable end block at the parking brake lever that had set screws)

[craig downs]

Mocking up a shoe stop I'll make them up this weekend. The stop will have to have support blocks welded on to reach the rear of the spreaders.

[Wes V]

The stop will have to have support blocks welded on to reach the rear of the spreaders.

This comment has me confused!!

As I read it, you are saying that there is a "stop" that limits how far to the side the spreader can move. (in addition to rubbing on the "backing plate")

I can't see the need due to the fact that the shoe will only move outward a certain amount and that would limit the side to side movement.

(as you pull on the cable, it would pull the spreader and shoe assembly off to that side and stop once that shoe is in contact with the drum. Then continuing to pull would spread the other shoe outward)

It may have somthing to do with the fact that there will always be a certain amount of tension on the cable??

Maybe I'm just reading your comment wrong!!!

If you could add an arrow to the photo showing the wear pattern on the spreader, it may make it clear.


That brings up another subject!

Are you planning on installing a "return" spring (as shown on that sub-cable)? I haven't seen anybody show consern about it, even in bell-crank versions.

In most versions, everybody is counting on the shoe return spring (the one near the spreader) on pulling the cable back!!!!!

In the original 911, there isn't an additional return spring, but that's a straight pull.

What was there in the original BMW installation?? (wish I had a black E30 to look under!)

Wes

[Richard Casto]

The stop will have to have support blocks welded on to reach the rear of the spreaders.

This comment has me confused!!

Wes, you are a good sport for allowing the thread hijack. (IMG:style_emoticons/default/smile.gif) And Craig stop me if I am way off base here.

So, I "think" that what Craig is saying when he says the "rear of the spreaders" is the part that would be next to the backing plate. And that in addition to pushing against the shoes, the spreaders also need to push against something along the other axis to prevent from putting an un-needed side load on the shoes.

The image below is without a plate for the spreader to push against. The green arrow is the force from the cable. The red arrows is the force from the spreader on the shoes. So you see in addition to the force that pushes the shoes against the drum, you also have an un-needed side force.




In the image below, the blue is a plate for the spreader to push against. The green arrow is the force from the cable. The red arrows is the force from the spreader on the shoes. The purple arrows is the force from the spreader on the blue plate. So here the only force on the shoes is the ones pushing them against the drum.



Also in the above photos you can see how the two pivot points on the spreader are offset away from what would be the backing plate. So if I understand Craig correctly, I think he is saying that in addition to just bending a flat section of metal 90 degree to create the “stopping block” that he may also need to weld in something extra (what I show in blue above) onto that to take into account that offset.

In the image below, you can see the bent "stopping block" but with two extra sections welded on to account for the offset and meet up with the spreader.