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Parking Brake Question

 
Old 10-13-2016, 08:54 AM
  #1  
leadfoot4
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Default Parking Brake Question

I was never very impressed with the holding ability of my parking brake, so like many "week-end wrenches', I decided to fix it. This, of course, ended up with the brake working in an even less effective manner.

Earlier this week, I bought the proper sized drum brake measuring tool, as illustrated in the FSM, and two days ago, I set about re-adjusting the brake shoes. Initially, I found that I had way too much clearance between the p-brake shoes and the inside of the rotor, so I adjusted it to the specified 0.015" clearance. I then put everything back together, happily thinking I was good to go.

Not so fast.....as the p-brake will now at least hold the car from rolling down the driveway, if I put the car in gear, and give it even a little bit of gas, the engine will still overcome the p-brake's holding ability.

Is this right?
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Old 10-13-2016, 09:14 AM
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Yes, common on all vehicles I've own, I can move all cars I have against parking brake, it's made only for parking not driving.
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Old 10-13-2016, 10:33 AM
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Yes. It's right. As mentioned, it's just so your car doesn't roll away when parked, not for stopping your car vs. movement or engine power.
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Old 10-14-2016, 12:20 PM
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craig-o
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There's a reason these are now called "Parking Brakes" and not "Emergency Brakes" like they were in decades past. Back when cars had drums on all 4 wheels and a master cylinder that had a single circuit, if any part of the hydraulic system was compromised, NONE of your brakes worked (that was changed in the late-'50s, early-'60s when dual circuit M/Cs were installed which isolated the fronts and rears). If you had a hydraulic failure, the "Emergency Brake" used a cable system to activate the rear drums. Although you only had rear brakes, it was activating the same brake shoes that the hydraulic system activated, and would stop the car, albeit a bit slower. It also doubled as a Parking Brake.

Most passenger cars into the early-'90s still used drum brakes on the rear, and the "Parking Brake" still activated the rear drums that are used to stop the car.

On cars with 4 discs, the most common form of parking brake is a small drum with correspondingly small shoes inside the rear disc. This is the case for the C5. Since the drums and shoes are so small, they don't have a lot of stopping power - but they can keep a parked car from rolling away. It also means they should NEVER wear out, as they should only be activated when the vehicle is completely stopped.
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Old 10-16-2016, 03:06 PM
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Any one have a right up on this? Mine has no tension whatsoever.
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Old 10-16-2016, 10:50 PM
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Old 10-16-2016, 11:03 PM
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To the Op, mine just got a bunch of work in the past weeks. Mine holds the car fine on any hill if I reef on the handle well. No way I could overcome it with as much cam as I've got now. I just don't have the idle torque now.

Originally Posted by Chicago1 View Post
Any one have a right up on this? Mine has no tension whatsoever.
THere are writeups on how to adjust them here on the forum. Iirc, it's a post by Evil Twin.

That said, I tried several fixes on mine to no avail. Getting to the cables under the tunnel is about impossible. I didn't bother trying to replace cables when all the how-tos didn't work. I figured I'd get it when I did my engine/trans replacement, and I did. However, I found mine to be the handle itself. I don't know if someone tried to spray some 'grease' on it to lube it or what, but the stuff basically turned to tar and the adjustment pawl would no longer engage the cam it was supposed to adjust. I had access to a new handle so I installed that and found that I had already adjusted the brakes to perfection long before.

If you're getting no brake action at all, take a look at that handle and see if everything actually works. It's a lot easier than replacing cables. Be sure to look at the pawl that drops into place immediately after you start to pull the handle. If that never engages, it never pulls on the cable and there's no brake at all.
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Old 10-16-2016, 11:06 PM
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Originally Posted by K-Spaz View Post
To the Op, mine just got a bunch of work in the past weeks. Mine holds the car fine on any hill if I reef on the handle well. No way I could overcome it with as much cam as I've got now. I just don't have the idle torque now.

THere are writeups on how to adjust them here on the forum. Iirc, it's a post by Evil Twin.

That said, I tried several fixes on mine to no avail. Getting to the cables under the tunnel is about impossible. I didn't bother trying to replace cables when all the how-tos didn't work. I figured I'd get it when I did my engine/trans replacement, and I did. However, I found mine to be the handle itself. I don't know if someone tried to spray some 'grease' on it to lube it or what, but the stuff basically turned to tar and the adjustment pawl would no longer engage the cam it was supposed to adjust. I had access to a new handle so I installed that and found that I had already adjusted the brakes to perfection long before.

If you're getting no brake action at all, take a look at that handle and see if everything actually works. It's a lot easier than replacing cables. Be sure to look at the pawl that drops into place immediately after you start to pull the handle. If that never engages, it never pulls on the cable and there's no brake at all.
Ill check into that then. Ill look for ET post yeah mine isnt doing anything just clicks but no tension on it
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Old 10-17-2016, 11:25 AM
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Originally Posted by Chicago1 View Post
Any one have a right up on this? Mine has no tension whatsoever.
http://bfy.tw/8EIi
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Old 10-17-2016, 01:58 PM
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Originally Posted by huesmann View Post
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Old 10-17-2016, 03:53 PM
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Everything revolves around pivot pin/bolt D
The idea is to tighten the brake with ratcheting cam C
In an ideal world, you pull the handle, Pawl A moves away from stop-pin B and engages cam C thus pulling the brake cable.

What happened to me was pawl A was so mucked up with sticky goo that when you pulled the handle and it rotates away from stop-pin B, pawl A never moved into cam C. It just sat there glued in place and never engaged the cam which pulls the cable. No amount of helping seemed to matter either. It was really stuck.

If you have pawl A not falling into place freely, you will have no parking brake. And you certainly can't adjust it. Furthermore, if someone put grease on any parts of it and it's dried and sticky, it will never self adjust. Cam C is what does all the self adjusting up at the handle anyway. Again, if it doesn't move smoothly, forget it.

I tried cleaning mine with varsol, brake clean, 2+2 gum cutter... It was improving, but I said f it and bought another one. Life is too short for that.



Last edited by K-Spaz; 10-17-2016 at 03:58 PM.
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Old 10-17-2016, 06:25 PM
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Originally Posted by K-Spaz View Post
Everything revolves around pivot pin/bolt D
The idea is to tighten the brake with ratcheting cam C
In an ideal world, you pull the handle, Pawl A moves away from stop-pin B and engages cam C thus pulling the brake cable.

What happened to me was pawl A was so mucked up with sticky goo that when you pulled the handle and it rotates away from stop-pin B, pawl A never moved into cam C. It just sat there glued in place and never engaged the cam which pulls the cable. No amount of helping seemed to matter either. It was really stuck.

If you have pawl A not falling into place freely, you will have no parking brake. And you certainly can't adjust it. Furthermore, if someone put grease on any parts of it and it's dried and sticky, it will never self adjust. Cam C is what does all the self adjusting up at the handle anyway. Again, if it doesn't move smoothly, forget it.

I tried cleaning mine with varsol, brake clean, 2+2 gum cutter... It was improving, but I said f it and bought another one. Life is too short for that.


Good stuff thanks. How much was the new one?
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Old 10-17-2016, 07:09 PM
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Originally Posted by Chicago1 View Post
Good stuff thanks. How much was the new one?
I bought so much crap for that car during the rebuild I don't recall. It wasn't much. I gave back the boot. Turns out that is in much higher demand than the handles. They'll just about give them away. Let me know if you need one. They've got more.
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Old 10-17-2016, 11:33 PM
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Ill check into mine this weekend and let you know. Finally working on getting it back on the road after a year sitting.
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Old 10-19-2016, 09:56 AM
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Parking brake on mine has been poor from brand new. It's only ever really grabbed at the top of the range. I have had the rear brakes apart and manually adjusted the shoes the old fashioned way - to a slight "rub". Worked for a while after that. You SHOULD be able to hold the car on almost any grade with the brake - in fact if you need to do a hill start on a severe slope (M6) without rolling back at all, you need an effective parking brake.

In contrast, the parking brake on my wife's 86k mile Subaru is incredibly effective - try to move with it on, and the tail just "squats" and you don't get far.
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Old 10-20-2016, 11:05 AM
  #16  
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Maybe Subaru just has a better design for the hardware inside the drum.
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Old 10-20-2016, 03:38 PM
  #17  
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Originally Posted by craig-o View Post


There's a reason these are now called "Parking Brakes" and not "Emergency Brakes" like they were in decades past. Back when cars had drums on all 4 wheels and a master cylinder that had a single circuit, if any part of the hydraulic system was compromised, NONE of your brakes worked (that was changed in the late-'50s, early-'60s when dual circuit M/Cs were installed which isolated the fronts and rears). If you had a hydraulic failure, the "Emergency Brake" used a cable system to activate the rear drums. Although you only had rear brakes, it was activating the same brake shoes that the hydraulic system activated, and would stop the car, albeit a bit slower. It also doubled as a Parking Brake.

Most passenger cars into the early-'90s still used drum brakes on the rear, and the "Parking Brake" still activated the rear drums that are used to stop the car.

On cars with 4 discs, the most common form of parking brake is a small drum with correspondingly small shoes inside the rear disc. This is the case for the C5. Since the drums and shoes are so small, they don't have a lot of stopping power - but they can keep a parked car from rolling away. It also means they should NEVER wear out, as they should only be activated when the vehicle is completely stopped.
Thanks for the insight, I never put any thought into parking brake evolution , although I find the knowledge interesting. I now need to get the driver to evolve and release the brake before blastoff, so parking brake problems and repairs will not be so compelling.
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Old 10-20-2016, 04:42 PM
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Originally Posted by huesmann View Post
Maybe Subaru just has a better design for the hardware inside the drum.
Looks similar - I think it's just that their self adjusting system works well. Was driving it yesterday and at low (parking lot speed) the handbrake stops the car quite effectively. In fact it will lock the rear wheels up if you give it a good tug.
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Old 10-20-2016, 06:28 PM
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Since, as I stated in post #1, my p-brake shoes are adjusted correctly, it looks like I'm going to find some time to remove the passenger's seat, console, and e-brake boot, and take a look-see......
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Old 10-21-2016, 09:12 AM
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Originally Posted by craig-o View Post
On cars with 4 discs, the most common form of parking brake is a small drum with correspondingly small shoes inside the rear disc.
Actually I wouldn't say that's the most common at all. I'd say it's 50/50. Certainly I see no reason for the drum parking brake to still be in use when manufacturers have been able to design and build disc-only parking brake systems for many years. The disc parking brake on my 1995 Miata works amazingly well.
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