Correct Brake Pedal Feel

If it's mechanical, electrical or just downright confusing, this is the place to find and share answers.
SoCal Cougar
Registered Member
Posts: 97
Joined: 04 Sep 2020, 20:04

Correct Brake Pedal Feel

#1

Post by SoCal Cougar »

Hey all, now that I've got my engine and trans running together better and got rid of a shifting stumble, I'm hoping to figure out if I've got an issue with my brakes or if I am just to used to newer vehicles.

I haven't driven my Cougar very much, not daily, and I've driven newer vehicles for a while so I may just need to get used to the older brakes, however I had some concerns. I've also got an odd setup, courtesy of the previous owner. From the spindle out, everything I have is 67 or 68, it all matches and meshes correctly, seems like good clearances, no binding or loose spots. I've got a 70 Master Cylinder, 70 lines, 70 rear brakes, adjustable proportioning valve, and then a Bendix booster since It seems I have a 69 pedal. The booster I pulled out and sent to WCCC had the curved tear drop style linkage, and it lined up perfectly with my pedal. It's a 70 car, that must have been converted at some point.

My issue is that there is a bit of travel before anything really happens. With the car off, my pedal has a half inch of travel before I get any real resistance, which feels like some kinda travel inside the booster, then it hits the master cylinder, and I can push another half inch before it's too hard to push anymore, so with the car off, it has an inch before it's too hard to push, about 3 inches off the floor. With the car running, I have brakes, but it seems like I can only stop, or do medium to hard braking, not really any light braking or just slowing down. The first half of the pedal doesn't really seem to do much at all.

I'm wondering if I need to get a master cylinder with a different bore size, or perhaps swap around parts again since I replaced everything with parts that looked identical to what came off the car when I got it, but perhaps it was the wrong combination in the first place.
1970 Standard Cougar 351C-2V, PB, PS, A/C, AOD Swap
Pastel Blue, Blue Interior
Cougar Bill
Registered Member
Posts: 1003
Joined: 19 Jan 2011, 08:39
Location: Golden, Colorado

Re: Correct Brake Pedal Feel

#2

Post by Cougar Bill »

So, we have a bit of a mixture.
The 1st I suggest it to take the cap off the master cyl.
With someone you trust, have them slowly VERY slowly press pedal..
you get to watch the bottom of master cyl, looking for the piston to move (its shiny aluminum. maybe a light will help)
Once the piston starts to move you have contact between the rod of the booster & the piston.
This is most likely you 1st issue.

The basic idea is to stick w/ year. You don't say if you have 67 or 8 front disc, not that it should matter.
The pedal year possible miss match. This can easily be wrong.

Lastly. The booster you pulled, was it a midland or Bendix?

The both have a spacer, but are NOT interchangeable, nor can they be used together.

Keep us posted on the results.
1970 XR-7 428 Ramair 4 speed (now under restoration)
1970 Eliminator Boss 302 -sold
1969 XR-7 428 R-code 4 speed- Project for sale
1969 Std. 428 R-code C-6- Project for sale
1969 XR-7 Convertible 351 AOD
1969 XR-7 Convertible 428 C6
1969 XR-7 351 5 speed "RestoMod" New 525Hp "pacemaker"
http://www.cougarbill.com/videos/2017/8 ... -the-track
https://www.youtube.com/watch?v=SBkOzr7N13Y
1968 XR-7 302-4v 4 Speed (J-code) For Sale
1967 XR-7 302 & AOD Green- Wife's Cat
www.cougarbill.com
SoCal Cougar
Registered Member
Posts: 97
Joined: 04 Sep 2020, 20:04

Re: Correct Brake Pedal Feel

#3

Post by SoCal Cougar »

I checked when the piston moves compared to the pedal, and it's after that half inch of pedal travel. I adjusted it to there because the rod coming out of the booster is now the length of the hole for the piston, if I lengthen the rod out of the booster any further, it compresses the piston just by installing the master cylinder. I once had it too long and when I was installing it in there it pressed the piston enough to squirt some fluid out. I figured you wouldn't want to compress the piston without the pedal being pressed on, so that half inch of pedal travel that I mentioned seems to be in the booster, since I looked at the pedal and rod under the dash and they move 1:1 as well.

Even if I was able to eliminate that half inch of free play in the pedal, with the car running, the pedal goes more than an inch, perhaps even 2 inches without feeling like the brakes are really doing anything.

I believe the calipers are 67, the rotors I believe I had to order 68, as 67 didn't fit on my spindle. From what I can tell, the pedal is 69, It fits the tear drop shape perfectly, if I used a 70 booster the rod would be very crooked.

The booster I pulled was a Midland, I talked to some people at WCCC a while ago when I sent them my core, and they sent me back a Bendix, which is what they said I should use. I believe I did have a front spacer, however I'm not sure where it's at, and the booster I got from WCCC came with a rear spacer/bracket to mount onto the firewall.

Thanks.
1970 Standard Cougar 351C-2V, PB, PS, A/C, AOD Swap
Pastel Blue, Blue Interior
Cougar Bill
Registered Member
Posts: 1003
Joined: 19 Jan 2011, 08:39
Location: Golden, Colorado

Re: Correct Brake Pedal Feel

#4

Post by Cougar Bill »

The rod tip of the booster is adjustable (as you know), and is supposed to be set as spec by a gauge. This can be found in the shop manuals.
I suggest checking this.

"Even if I was able to eliminate that half inch of free play in the pedal, with the car running, the pedal goes more than an inch, perhaps even 2 inches without feeling like the brakes are really doing anything."

If you have the calipers on the wrong side the bleeders won't work properly (Bendix 68 and later)

Confirm when the wheels slow/stop w/ pedal application. Jack up & test fronts & rears.

The Bendix spacer is stamped metal at the rear of the booster & held to the booster by 1 flange lock nut.
The Midland spacer is aluminum and is between the front of the booster & the master cyl, w/ a plastic baffle & sponge filter.

Lastly, rear brakes. The incorrect preset, and possible adjuster issues ( frozen threads, adjuster arm not adjusting )
They should just go on & drag by hand a bit.
The rear brakes can have issue after 50 years. The rear backing plates get grooved by the shoes. Welding & grinding them is a solution.

The adjustable valve. We'll cover that a bit later, but wonder why not use the original ?

If you suspect the car is not the problem, find a friend w/ a Cougar or like car & test drive it.

You really should be able to lock the front tires.
1970 XR-7 428 Ramair 4 speed (now under restoration)
1970 Eliminator Boss 302 -sold
1969 XR-7 428 R-code 4 speed- Project for sale
1969 Std. 428 R-code C-6- Project for sale
1969 XR-7 Convertible 351 AOD
1969 XR-7 Convertible 428 C6
1969 XR-7 351 5 speed "RestoMod" New 525Hp "pacemaker"
http://www.cougarbill.com/videos/2017/8 ... -the-track
https://www.youtube.com/watch?v=SBkOzr7N13Y
1968 XR-7 302-4v 4 Speed (J-code) For Sale
1967 XR-7 302 & AOD Green- Wife's Cat
www.cougarbill.com
SoCal Cougar
Registered Member
Posts: 97
Joined: 04 Sep 2020, 20:04

Re: Correct Brake Pedal Feel

#5

Post by SoCal Cougar »

From a previous thread I had I saw that the spec was just under an inch, something like .995. I don't have a caliper to measure that, but I set it to 1" and figured that .005 won't be too crucial, especially since I've had it shorter than that, and longer than that, and neither made any difference.

I've got the 4 piston 67 calipers, they are at the top left of the rotor, with bleeders pointed upward.

The Front wheels do stop with the pedal, right about where it gets some resistance with the car turned off, they slow down and stop from me hand turning them with someone else pusing the pedal. I'll check the rear, but I believe it was the same a while ago.

My Bendix booster does have the stamped metal spacer at the back, and I remember the Midland spacer, I sent it in with the booster to WCCC.

I've set the shoes so that they have a small amount of drag on the drums, the E-brake pedal only has to go halfway down before it is able to hold the car on a slant so I know they don't have too far to move within the drum, the adjusters on both sides work pretty well, easily spun by hand when the arm is not on the gear.

The adjustable valve was on the car when I got it, I assume if the previous owner went through enough trouble to swap in a 69 pedal, booster, and adjustable prop valve, they probably replaced the prop block with just a distribution block. My brother has a 66 mustang, and a 71 Ranchero, and he said that they feel similar, I'll have to drive those to see but from what I remember, his brakes are more responsive to light pedal movement, more than mine are.

While watching the piston yesterday, I did notice that the fluid in the front brake reservoir is darker than the rear brake reservoir, but they were filled at the same time. I also have been told to look for a small geyser of fluid when you press the brakes, and I can get a small spurt from the rear brake reservoir, but not from the front brake reservoir, however I wasn't able to get the pedal all the way down since the car was off.

Another thing I noticed was that my adjustable prop valve normally is quite adjustable, I can turn the knob freely and set it whenever, however currently it's set fully open, and I can't turn the knob more than half a turn without it just stopping. would this be due to the pressure in the line or another issue?
1970 Standard Cougar 351C-2V, PB, PS, A/C, AOD Swap
Pastel Blue, Blue Interior
User avatar
PacificaXR7GT
Registered Member
Posts: 586
Joined: 23 Aug 2018, 20:40
Location: Pacifica, CA

Re: Correct Brake Pedal Feel

#6

Post by PacificaXR7GT »

I used this tool to adjust the booster rod. Worked great, super simple. https://www.ecklerscorvette.com/1968-19 ... gLxPfD_BwE
Steve
CCOA #9998
1968 XR7 GT 4 speed - Augusta Green / Dark Ivy Gold
blue68cat
Registered Member
Posts: 275
Joined: 24 Jun 2012, 20:40

Re: Correct Brake Pedal Feel

#7

Post by blue68cat »

How much vacuum is your car making?
SoCal Cougar
Registered Member
Posts: 97
Joined: 04 Sep 2020, 20:04

Re: Correct Brake Pedal Feel

#8

Post by SoCal Cougar »

I thought about getting the tool to adjust it but I feel like the problem is elsewhere, since I've had it longer than the manual says, and shorter, and obviously shorter was worse, but longer didn't change anything, and I was risking pressure building up since fluid might not be able to return properly. I may try it out, I just can't imagine that they would want the rod to compress the piston at all when installing, and since the rod I have is already adjusted to around 1" and fits well in the piston, I think the rod is not the main issue.

I've got 14-15" in park, around 10" in gear, I've never had a hard pedal feel or any problems with the booster so far. While the car is running the pedal is pretty easy, it just doesn't do much for the first half of it's travel.
1970 Standard Cougar 351C-2V, PB, PS, A/C, AOD Swap
Pastel Blue, Blue Interior
blue68cat
Registered Member
Posts: 275
Joined: 24 Jun 2012, 20:40

Re: Correct Brake Pedal Feel

#9

Post by blue68cat »

Does your pedal pump up?
SoCal Cougar
Registered Member
Posts: 97
Joined: 04 Sep 2020, 20:04

Re: Correct Brake Pedal Feel

#10

Post by SoCal Cougar »

How do you mean pump up? I don't have to pump it to get a hard pedal, with the car off it has about a half inch of moving fluid before its too hard to press.
1970 Standard Cougar 351C-2V, PB, PS, A/C, AOD Swap
Pastel Blue, Blue Interior
Post Reply

Return to “Classic Cougar Maintenance Restoration and Repair”