Parking brake

[Alex]

Incase somebody needs an idea for a parking brake - I gave up on cables a long time ago. Too much effort to route and make functional (in any of my builds, heh) so I use a manual line lock - it's basically a ball valve plumbed into the rear brakes...manual so it doesn't rely upon any power.

Press the brakes, turn the handle, and it's basically like you're sitting there on the brake. Release handle, get brakes back.

It's 2 Swagelok compression fittings and one of their high pressure ball valves. That was the cheapest/easiest way I ever found to convert 3/16'' brake line to their fittings.

 

[Mark Maybury]

Alex,
Just remember that is not a legal emergency brake and when your brakes cool down and the rotors shrink your valuable car could roll.
Also, this has been discussed before and many members have given the pros and cons.
Mark

 

[Alex]

Legal smeagle

I have that concept on my cobra; it's been 2yrs and I've never once encountered an issue with it.

 

[Lynn Erickson]

This system is great for a parking brake, it is also use on many aircraft. it is not a emergency brake, would not be legal in most US states for street use.

 

[Ian Anderson]

I thought this was how most Mercs now have their "parking brakes"

Foot on brake - press button - brakes locked on

If Merc can do it and get away they why not a "homebuilt" car?

Ian

 

[David Morton]

The control with the red lever is my parking brake.

 

[Alex]

I thought this was how most Mercs now have their "parking brakes"

Foot on brake - press button - brakes locked on

If Merc can do it and get away they why not a "homebuilt" car?

Ian

(not at all familiar with MBs, but) if they have that setup there has to be something involving cables, or similar. The reason most states won't allow my idea is because if you loose rear brakes, you loose your parking brake .... with a mechanical seutp you still have a backup.

 

[Dave]

The control with the red lever is my parking brake.

Could you describe what it is and how it works in greater detail please?

 

[Mark Maybury]

Alex,
There is something like your set up used in the towing industry called a micro lock this can be a single brake line (1 axle) or dual line (2 axle) lock up. Mine was from A and W Direct from Connecticut.
These worked great when I had my tow truck for holding it still while loading but I never trusted it beyond that.
Mark

 

[Rick Muck- Mark IV]

Alex,
There is something like your set up used in the towing industry called a micro lock this can be a single brake line (1 axle) or dual line (2 axle) lock up. Mine was from A and W Direct from Connecticut.
These worked great when I had my tow truck for holding it still while loading but I never trusted it beyond that.
Mark

Actually, it is a "MICO" brake lock. Had on on our 73 F350 tow truck. I wouldn't be happy with just that as a park brake, for short time, yes....long term, not so much.

 

[Doc Kaler]

I ran across these mechanical parking brake calipers today so I don't have any additional information. I have a set of Brembo parking brake calipers from my Viper that I was considering for use, but these may be lighter weight and simpler to install:

Mechanical Parking Brake Calipers

 

[Randy V]

Alex,
Just remember that is not a legal emergency brake and when your brakes cool down and the rotors shrink your valuable car could roll.
Also, this has been discussed before and many members have given the pros and cons.
Mark

This system is great for a parking brake, it is also use on many aircraft. it is not a emergency brake, would not be legal in most US states for street use.

Too many red flags for me.... It may pass inspection in Canada, but it won't (as said above) in most states in the USA.

Also - Even if it did pass, it does not address a secondary means to help slow/stop the car should their be a failure in the brake hydraulic systems..

There are many mechanical solutions that should be acceptable.

 

[Alex]

Actually, it is a "MICO" brake lock. Had on on our 73 F350 tow truck. I wouldn't be happy with just that as a park brake, for short time, yes....long term, not so much.

Worked fine on my cobra when it was parked on the lift for 6mths.

It's a Swaglok shut-off valve ..... if it failed I'd be highly surprised.

Too many red flags for me.... It may pass inspection in Canada, but it won't (as said above) in most states in the USA.

Also - Even if it did pass, it does not address a secondary means to help slow/stop the car should their be a failure in the brake hydraulic systems..

There are many mechanical solutions that should be acceptable.

Won't pass here, but like i said, I don't bother with inspections so it's not a big deal :laugh:

I thought about the secondary stopping issue when I did it in the cobra, but for 99% of people (including me) if the brakes fail I think the response will be - 'oh shit oh shit oh shit oh shit oh shit oh shit oh shit', so it's a moot issue.

 

[Kevin L]

Worked fine on my cobra when it was parked on the lift for 6mths.

I am sure it did, your lift is level right...

Probably okay leaving the car in gear and using your linelock but if I was to park it on a slight incline (or more) I would want a mechanical brake.

With that said, your car, not mine so whatever you want to do

 

[Alex]

I figured you meant that over-time it might bleed out pressure (or something) ..... I can't imagine anybody parking their car on an incline for months on end....

but let me re-phrase that - i've had my cobra parked on a steep incline for 9 or 10hrs with it set and it held just fine.

Perhaps somebody could explain to me why they think it would fail over time. You press the brakes down, brake fluid goes to the rear, you turn the ball valve and it traps the fluid back there. It can't escape (baring any leaks) and it can't return forward to the master cylinder. It can't evaporate. So I can't see how it would fail.

 

[Terry Oxandale]

I think if the seals and all other components are well maintained and have no losses, then this line-lock method should work indefinitely. BUT, I've seen too many situations of MC seals deteriorate, or leak (not leak out of the system to a visible area, but instead to the back-side of the bore) that under normal short term or intermittent braking, never indicate any softness or issue. Brake fluid for all practical purposes is incompressible, so even a single drop lost out of a pressurized system (and brake systems don't have a lot of volume, so that exacerbates the situation) can have a fairly large impact on pressure. I'm sure the seals have some "give" that will soften the impact of the loss of a minute amount of fluid, but when it's all said and done, I'd like to rely on a back-up system (emergency brake or parking brake, whichever is preferred) that has a minimal amount of overlapping parts. The mechanical back-up in essence overlaps only at the rotor, the line-lock overlaps with rotor, PLUS the caliper, plus the lines and connections, plus...the fluid. To me this is risk management, and not putting all your eggs in a single basket.

I wished I could practice what I preach though. On my Z, with Outlaw calipers front and rear, I had no emergency brake system, and I ran like that for 15 years. This new project though will have some kind of mechanical back-up.

 

[Will Campbell]

Perhaps somebody could explain to me why they think it would fail over time. You press the brakes down, brake fluid goes to the rear, you turn the ball valve and it traps the fluid back there. It can't escape (baring any leaks) and it can't return forward to the master cylinder. It can't evaporate. So I can't see how it would fail.

I think the theory is that clamping force on a hot rotor will be reduced as the rotor cools and shrink, so if you had just the amount of force needed to hold the car, when the rotor cooled and shrank, the remaining clamping force might not hold the car on an incline.

That's why my approach of a separate hydraulic circuit on a dedicated rotor and hydraulic caliper that is only used for parking won't be susceptible to this. Since the rotor is never hot (it isn't used for slowing the car, just parking) the clamping force should stay constant, assuming the hydraulics don't leak. This is arguably better than cable-actuated brakes as the cables do stretch.

My SLC has a dedicated Wilwood rotor that will be mounted on the axle bell, and clamped by a small Wilwood caliper than is actuated by a small linear actuator pushing on a small master cylinder. The linac and MC will be mounted between the body and the chassis.

 

[Alex]

You make some good points.

My theory - it's Swagelok; it's built for industrial uses so it should be fine - does lack the risk management aspect. But it's sooo much simpler

And honestly, i'd 110% trust my life to a Swagelok product before I'd trust it to a master cylinder made by GM or Ford or whomever makes them for them.

 

[Dave]

Parking on an incline is a big part of daily life in San Francisco. That said, I had no e-brake in several of my Mazda's over the years. Just curb the wheel, problem solved. Actually you better curb the wheel anyways as you are likely to get a hefty parking ticket in a matter of seconds for not doing so.

 

[Howard Jones]

I might use one of these at some point. I wouldn't use it to leave the car on a hill while I went into a resturant to eat dinner but it might be useful to hold the car while you tie it down on a trailer for example.

Park-Lok Hydraulic Brake