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unusual brake / parking brake question

delbertinie

New member
I had an idea to eliminate the e brake cables wonder if it will work

As I said in a earlier post I want remove the hand brake and add a foot brake.
Here's where the strange engineering comes in I want to add a second master cylinder to control the foot e brake. Has this ever been done and will the back pressure harm the master cylinder not in use?

Somebody tell me the folly of my ways*hee-hee-hee*

I thought it would work because I have seen sand buggies with multiple masters so they could lock up one wheel and make really hard turns. I believe dukes of hazard charger had a foot brake for all four and four individual hand brakes to do stunts. Not talking about the jump cars however many thousand of them there were. The chase car is what I was talking about the only real general that survived.

I digress, anyways is there any special valves in a rail buggy to keep the master cylinders from destroying each other.
 

letterman7

Honorary Admin
I'm not sure how the rail buggies are run. The turning brake setup in a traditional dune buggy simply locked the parking brake caliper on one side of the vehicle at the rear. All parking/emergency brakes should be a separate caliper anyway, I've never seen a production vehicle that uses the same brake caliper as a parking brake. It's against DOT code anyway.. (if the main brakes fail you have no safety net).
On one of my projects I plan to use a simple single hydraulic cylinder handbrake to the rear parking caliper. No cables, and a single thin tube to the rear. I'd imagine you would be able to do the same thing if you could figure out how to set the slave cylinder to pull the levers on the parking brakes at the rear of the car.
 

Brett Proctor

Active member
Are you planning to incorporate this into your existing system?? If so what do you have now?

Do you have some kind of an idea or design of how your going to hook it up??

The main reason of using a cable as Rick may have mention is if the system fails it bypasses the hydraulic braking system.

There are electric parking brake systems out there that you maybe able to use. No lever or peddle just a button. Something else to think about. *hmmm*

Brett
 

vpogv

Member
Something to inquire about though (if doing away with the cable entirely) is if hydraulic parking brakes are legal. Typically they are not.
 

letterman7

Honorary Admin
Oh? I thought (probably wrongly) that if the parking/emergency brake system was completely separate from the main system it wouldn't matter if it were mechanical or hydraulic. You just couldn't use something like a line-lock on the main. Any other info on that, Pog? If that's the case, I need to re-think my one project.
 

farfegnubbin

Site Owner
Staff member
This is an interesting topic. My interpretation of the law in PA is that there just has to be a system that is separate from the main system in which case, Rick, I think you'd still be fine. I'm trying to think how they worded it, though. They MIGHT have made a distinction between hydraulic and mechanical (requiring the parking brake to be mechanical in nature). And I know there was some definition of what holding strength was sufficient...something like "as would hold the car indefinitely in neutral on a 15% grade" or some such operational definition.

I know that they specifically forbid line locks as a parking brake, so those are out. And you're right, Delbertinie, that you could definitely rig a second master. But I know that in PA, if they looked at it and understood what you did, they would reject it on the basis that, if a line failed, you'd loose both systems.

That said...they seem to focus on certain things but not others. Thus if you had two separate actuators that both made a wheel stop turning, they MIGHT lazily miss the fact that some components were in common to both systems.

It's funny though; I never had a desire to cut corners on my E-brake. I want it to be a separate system. I can see having two systems that go to the same pads. But I wouldn't want any part of the hydraulics to be shared.

Rick, I like the idea of a secondary hydraulic system that eventually actuates an otherwise standard E-brake caliper. Cool. ...And basically, if the inspector can see that you've created a safe and truly isolated/redundant system, I think they would be fairly likely to look past any more strict details of whether they are both hydraulic, etc.
*****
Hey, related to this...

I've often wanted to have power brakes, not because a car this light needs them but simply because I like the way they feel. We're all spoiled by the feel of modern power brakes, and so when I get into my Sterling, it always makes me FEEL like there is something wrong with my brakes.

Well, there is essentially no space to put a vacuum assist in front of a brake pedal in a Sterling. It just can't be done without seriously cutting up the firewall or floor or interfering with the steering shaft, etc. Been there. Tried that.

BUT...

I always wondered if you could use the stock master cylinder to hydraulically push the "pedal" of a remotely located vacuum assist. In other words, there would be a simple 1:1 link between the two with just a simple brake line, but the second (in series) master cylinder would have vacuum assist which would give the overall system the same mechanical advantage (pneumatic advantage) as if you were directly pushing on the input of the second master cyclinder...the advantage being that you could then stick that big vacuum assist ANYWHERE in the car and then just run the appropriate brake lines to it.

I had kind of scuttled the idea (or at least put it on a back burner) until, thanks to a link to a kit car parts catalog posted by Yaughn, I saw just that product -- a specialty, vacuum assisted master cylinder that had a HYDRAULIC line as an input rather than a mechanical push rod.

What a great product! I don't know whether they'd ship one across the pond or if we could find a domestic source. I hate using things that are ultra-rare. It kind of defeats some of the unique advantages of having a kit car.

But I sure would love some extra bite to my brakes. Don't get me wrong: I have four wheel disc brakes that will stop the car as if you threw out an anchor. But yet, they just kinda FEEL like they're too hard to push.

Perhaps I'm just a wuss. :D
 

delbertinie

New member
Are you planning to incorporate this into your existing system?? If so what do you have now?

Do you have some kind of an idea or design of how your going to hook it up??

The main reason of using a cable as Rick may have mention is if the system fails it bypasses the hydraulic braking system.

There are electric parking brake systems out there that you maybe able to use. No lever or peddle just a button. Something else to think about. *hmmm*

Brett

thats great until the battery runs down
sounds like a line lock to me.
 
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delbertinie

New member
Something to inquire about though (if doing away with the cable entirely) is if hydraulic parking brakes are legal. Typically they are not.

on the yearly inspection in missouri all they do is push the brake ( if they even bother ) beside I can inspect my own vehicles*thumbs up* doubt if they would even question the source of the brakes.
i usually don't fail my own vehicles*ah ha*
 
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delbertinie

New member
Are you planning to incorporate this into your existing system?? If so what do you have now?

Do you have some kind of an idea or design of how your going to hook it up??

The main reason of using a cable as Rick may have mention is if the system fails it bypasses the hydraulic braking system.

There are electric parking brake systems out there that you maybe able to use. No lever or peddle just a button. Something else to think about. *hmmm*

Brett

Just split the lines and add t blocks how easy is that
 

delbertinie

New member
This is an interesting topic. My interpretation of the law in PA is that there just has to be a system that is separate from the main system in which case, Rick, I think you'd still be fine. I'm trying to think how they worded it, though. They MIGHT have made a distinction between hydraulic and mechanical (requiring the parking brake to be mechanical in nature). And I know there was some definition of what holding strength was sufficient...something like "as would hold the car indefinitely in neutral on a 15% grade" or some such operational definition.

I know that they specifically forbid line locks as a parking brake, so those are out. And you're right, Delbertinie, that you could definitely rig a second master. But I know that in PA, if they looked at it and understood what you did, they would reject it on the basis that, if a line failed, you'd loose both systems.

That said...they seem to focus on certain things but not others. Thus if you had two separate actuators that both made a wheel stop turning, they MIGHT lazily miss the fact that some components were in common to both systems.

It's funny though; I never had a desire to cut corners on my E-brake. I want it to be a separate system. I can see having two systems that go to the same pads. But I wouldn't want any part of the hydraulics to be shared.

Rick, I like the idea of a secondary hydraulic system that eventually actuates an otherwise standard E-brake caliper. Cool. ...And basically, if the inspector can see that you've created a safe and truly isolated/redundant system, I think they would be fairly likely to look past any more strict details of whether they are both hydraulic, etc.
*****
Hey, related to this...

I've often wanted to have power brakes, not because a car this light needs them but simply because I like the way they feel. We're all spoiled by the feel of modern power brakes, and so when I get into my Sterling, it always makes me FEEL like there is something wrong with my brakes.

Well, there is essentially no space to put a vacuum assist in front of a brake pedal in a Sterling. It just can't be done without seriously cutting up the firewall or floor or interfering with the steering shaft, etc. Been there. Tried that.

BUT...

I always wondered if you could use the stock master cylinder to hydraulically push the "pedal" of a remotely located vacuum assist. In other words, there would be a simple 1:1 link between the two with just a simple brake line, but the second (in series) master cylinder would have vacuum assist which would give the overall system the same mechanical advantage (pneumatic advantage) as if you were directly pushing on the input of the second master cyclinder...the advantage being that you could then stick that big vacuum assist ANYWHERE in the car and then just run the appropriate brake lines to it.

I had kind of scuttled the idea (or at least put it on a back burner) until, thanks to a link to a kit car parts catalog posted by Yaughn, I saw just that product -- a specialty, vacuum assisted master cylinder that had a HYDRAULIC line as an input rather than a mechanical push rod.

What a great product! I don't know whether they'd ship one across the pond or if we could find a domestic source. I hate using things that are ultra-rare. It kind of defeats some of the unique advantages of having a kit car.

But I sure would love some extra bite to my brakes. Don't get me wrong: I have four wheel disc brakes that will stop the car as if you threw out an anchor. But yet, they just kinda FEEL like they're too hard to push.

Perhaps I'm just a wuss. :D

on the vacuum assist with scca race cars we add a separate dc vacuum pump just to run the brake booster, seriously. reason being they think robbing vacuum from the engine robs horses. I REALLY don't believe thats for real. These aircooled engines don't have enough vacuum to run a booster properly( I think ) . I reason that because an a/c compressor drags the engine from what I have been told.

What we have done in the past (for scca cars) is use a hydraulic slave/clutch cylinder to push a master cylinder if it can not be placed in where it usually placed.
 
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letterman7

Honorary Admin
But you're missing a critical issue: VW parking brakes rely on a pull lever to actuate. You'll still need to figure out a slave cylinder to pull or push those levers... I really wouldn't plumb into the main master circuit. If for some reason it fails (and they do) you're screwed if you try to stop.
 

farfegnubbin

Site Owner
Staff member
Rick, thanks for that link to the electrically assisted master cylinders! Very cool. I wish they had one either specialized for a VW already or one with a remote booster that you could add to essentially any master. If I were building from scratch, I would seriously entertain one of those electrical units.

Delbertinie, thanks for that info on using a remote master on the SCCA cars. That gives me confidence that the idea isn't nuts. As for vacuum... That's an interesting twist. I never really considered whether a VW engine would make a usable vacuum without upsetting anything. I don't think it would be radically power-robbing, but it would suck if it messed with the tuning of the carbs in general. Interesting point. (The car I was considering this for is my red Sterling, which has a Mazda rotary engine in it. I'm sure it would power a typical vacuum assist because the donor car had one.)

Regarding hydraulics to an E-brake...

I know that a lot of sport airplanes use hydraulic line locks as parking brakes. They seems to work adequately. With any hydraulic system, one of the things you have to worry about is slight creep/subtle leaks past the seals even if the seals are good. We all know that you never leave a car up on a hydraulic jack for days on end because it's likely to drift back down and may or may not cause your seals to crap out more quickly. I can see using a redundant hydraulic system as an emergency brake -- ie, if both sides of your main system freakishly crap out at once. And I can see using a hydraulic system/line lock as a short term parking brake. I personally wouldn't want to stomp on a pedal, make 2000 psi, lock it, and expect it to hold for three weeks in any sort of situation where it mattered. But...you can control and plan for that. Who out there routinely parks their Sterling unattended on a giant hill for days at a time?

I guess a lot of this boils down to what functionality you actually want from the emergency brake/parking brake system. If you want a truly safe back up system, do NOT share any of the same hydraulic lines or cylinders. If you want a safe system with a temporary parking brake, I think any of the above will work. If you want a long acting, virtually fail safe parking brake, the only good way to do it is with cables (which is why most states technically require that).

I still like the compromise of a truly redundant system but one that uses hydraulics to somehow actuate the otherwise stock E-brakes. I don't have this on any of my cars, but two of my cars do have "pull" type slave cylinders that actuate the VW Bug clutch. I love them. Very good pedal feel and never gave any problems. I can easily picture how one could use those same pull-cylinders to yank on E-brake cables.
 

delbertinie

New member
But you're missing a critical issue: VW parking brakes rely on a pull lever to actuate. You'll still need to figure out a slave cylinder to pull or push those levers... I really wouldn't plumb into the main master circuit. If for some reason it fails (and they do) you're screwed if you try to stop.

what usually fails first on a hydraulic system wheel cylinders or the master? In my experience its been the master....... no real data jsut what I've seen*insane*. if ya got a second master then......
I will just relocate the damn cables and beeeeeee done with it*humpf**laugh**laugh*. I just wanted to take the easy way out. On vw's I would just get some steel tube and bend it to the shape and the length desired and run new cables inside the tubes rite? They just hid the tubes in the tunnel rite?
thankx Dale
 

farfegnubbin

Site Owner
Staff member
what usually fails first on a hydraulic system wheel cylinders or the master? In my experience its been the master....... no real data jsut what I've seen*insane*. if ya got a second master then......
I will just relocate the damn cables and beeeeeee done with it*humpf**laugh**laugh*. I just wanted to take the easy way out. On vw's I would just get some steel tube and bend it to the shape and the length desired and run new cables inside the tubes rite? They just hid the tubes in the tunnel rite?
thankx Dale


Yep, the tubes are in the tunnel. They end immediately under/slightly behind the e-brake lever. Relocating them is possible, but the problem I had when I mocked that up is that there wasn't really any other way to route the tubes that didn't require a fairly substantial bend in the tube at some point (or multiple shallow curves) and thus by the time the cables got to where I wanted them, the friction in the tube was so high that the cables either bound in the tube or actually started to cut it.

What would be really cool is to leave the cables and tubes EXACTLY where they are but find a clever way to hide a pull-type slave cylinder right there in the tunnel, right under where the lever used to be. That way you wouldn't even have to figure out new cable ends, etc. Threaded ends would be right there. You could make a little access panel to get in to service it, but otherwise it would be out of site and out of mind. You could then put a remote foot pedal or hand lever just about wherever you want.

Or you can do like most of the rest of us and cut the e-brake lever a little shorter and just live with it. :D

*IF* you try to relocate the tubes and cables, I found a really nice cable guide -- go to Lowe's and get some underground armored flexible conduit. It's rubberized on the outside, stainless (and rather low friction) on the inside, about 1/2 inch in diameter, and it's flexible yet can't be bent into a radius too small for the cable to function. I like it.

On my blue car, I'm using the E-brake lever out of the Nissan 300zx donor car, mounted on the SIDE of the tunnel right next to the passengers left thigh. It uses a cable, and I routed the cable through that underground conduit.

(On my car, after the conduit, the cable splits. To get the cable to the brake on the driver's side, I had to run it 90 degrees around a garage door pulley then over to the brake. The single cable to the lever was stock Nissan. The dual cables to the brakes were stock Bug. I joined them with a little fabricated yoke after the single cable emerged from the floorboards.)
 

letterman7

Honorary Admin
:D Yep... relocate the cables. Put in a footbrake and have it pull the cables.. got it on my car and seems to work, but I haven't really eyeballed it to see how they managed to put everything together... and I'm not sure I want to know!
 

delbertinie

New member
:D Yep... relocate the cables. Put in a footbrake and have it pull the cables.. got it on my car and seems to work, but I haven't really eyeballed it to see how they managed to put everything together... and I'm not sure I want to know!

as long as it works*thumbs up*
 

Brett Proctor

Active member
:D Yep... relocate the cables. Put in a footbrake and have it pull the cables

Easier said than done.

thats great until the battery runs down
I haven't researched the topic since I don't have it in my car and don't need it but Nissan, subaru, BMW just to mention a few use the system so they must have some kind of a fail safe to it so it passes DOT specs. I wouldn't have mentioned it if it wasn't already in use and the bugs weren't worked out of it.


Brett
 

delbertinie

New member
Easier said than done.


I haven't researched the topic since I don't have it in my car and don't need it but Nissan, subaru, BMW just to mention a few use the system so they must have some kind of a fail safe to it so it passes DOT specs. I wouldn't have mentioned it if it wasn't already in use and the bugs weren't worked out of it.


Brett
I'm sorry my comment was not meant as a put down, just an observation. If anything can go wrong it WILL for me. I would end up leaving my lights on running my battery down and finding my car in a ditch or worse. This is the first I have heard of this,....... just popped off *eek!*:worried:*nothing to see*sorry
 

farfegnubbin

Site Owner
Staff member
Brett, that's really interesting. I didn't know there were any production cars that were using an electrically actuated E-brake. (I've heard of it on some commercial trucks).

It must have some cam or ratchet mechanism to passively hold tight until you electrically trigger it back off as well. That's how I'd engineer it at any rate.

But hey, if it's being used on production cars then that means, absolutely, we could pilfer it for our own sh*ts and giggles!
 
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