Mercury Cougar Owners banner

1 - 11 of 11 Posts

·
Registered
Joined
·
166 Posts
Discussion Starter #1
:1zhelp: :1zhelp: :1zhelp:
Okay, i've got a problem with my brakes on the 67 coug that I havent been able to figure out. It has 4 power drums all the way around, and the problem is not that they do not work well enough, but that they work *too* well...very touchy, they have a tendency to grab. I replaced my front drums, front shoes, and the rear ones appear fine. however, I have noticed that the brake fluid resivoir on the master cyllinder seems to be one from a front disc brake system, because one of the fluid spots is larger than the other. Could this be the cause of the problem? Have any of you guys experienced the same problem, or are the old cars just plain supposed to behave that way?

Also, it bleeds quite peculiarly. starting from the back, it bleeds fine. however, when you get to the front....bleeding the passenger side is fine, you can get it nice and firm. the problem comes with bleeding the drivers side. doing that seems to let air into the system, for the brakes seem to get mushier with every pump. by bleeding the passenger side after that though, i seem to be able to get all the air back out. any idea whats going on?

Any answers or ideas would be greatly appreciated, for this has been troubling me ever since i purchased the car a few months ago. Thanks a lot, guys (and gals).
 

·
Moderator
Joined
·
11,000 Posts
I hate the power drums on a Cougar. They are as you say too touchy. Plus in a panic stop at 90 MPH they fade out before you get stopped (been there). I recommend you save up for a front disc conversion.
 

·
Registered
Joined
·
889 Posts
I have one for sale off a 69
 

·
Registered
Joined
·
2 Posts
I have a few suggestions for you:

Try getting a new porportioning valve. 70% of your cars braking ability is in the front. The porportioning valve distributes the power from the front to the rear. If the porportioning valve is going out, which they do over time, the braking load gradually shifts to the front causing severe front-end dip and undesireable "grabbing" characteristics in some instances. This could also account for accelerated wearing in the front brakes. You can find an OEM valve from most parts vendors and special adjustible porportioning valves as well. Since you are using drums all round I would go with the OEM valve.

The rubber brake hose from the chasis to the front driverside drum might need to be replaced. Over time they have a tendency to crack and wear out do to dryrot. I recently replaced all three rubber lines on my cougar ( 1 from the chasis to the rear axel housing for the rear drums and 1 from either side of the chasis to each of the drums in the front) and noticed improved pedal feel (firmer) and quiker response. I have manual drum brakes all round on my car.

As far as the loss of braking ability is concerned when doing hard stops from 70+ mph, you'll just have to cope. Brakes convert kinetic energy into heat energy. Drum brakes cannot disipate heat nearly as efficiently as disc brakes can. The drums don't have time to disipate all of the heat generated by sudden and prolonged "hard" braking, thus their effectiveness is highly compromised. The only way to hadle this situation is by installing disc brakes or by changing your driving and braking habits to cope with a 35+ yr old car.

Tom Arnold

________________________________________
68 Cougar
68 Cougar XR7G
 

·
Registered
Joined
·
175 Posts
Can anybody tell me if a manual brake (drum) system has a proportioning valve?
 

·
Moderator
Joined
·
11,000 Posts
It has a distribution block but no proportioning valve.
 

·
Registered
Joined
·
4 Posts
The other potential cause of "touchy" drum brakes is that the shoes may be installed backwards. I have always had front discs on all of my old Fords, so I don't know if they even have non-symmetric shoes, but I had this problem on an old MG, and swapping the shoes around cured it.
 

·
Registered
Joined
·
3,141 Posts
Small goes toward the front. Long goes to the back.
 

·
Banned
Joined
·
4,754 Posts
Another problem with the midland booster I have found is that if one of the two rubber diaphragms gets a hole in it a very touchy pedal is the result. Its different than the later style which when it goes bad pedal goes very hard. While a hard pedal can be experienced in a midland booster a very touchy pedal is not a problem experienced by Bendix boosters. For $100 you can buy a Midland booster and master ready to bolt on from many sources.
 

·
Banned
Joined
·
4,754 Posts
No prop valve in drum brake cars. I have a set of 67 spindles and one caliper I believe still. Rotors and seals etc readily available at local parts store . The shoes are called primary(frt) and secondary (rear)
 
1 - 11 of 11 Posts
Top