65 F-85 brakes
Thread Starter
Registered User
Joined: Feb 2008
Posts: 38
65 F-85 brakes
Hey-
I'm having some problems with my 65 F-85's brakes and would like to know if anyone on the list has ideas as to what might be the problem with them.
Basically, the car had it's original single master cylinder, non-power, 4 wheel drum brakes, which originally worked just fine and did a good job stopping the car.
For safety reasons, I decided to convert the car over to a dual reservoir master cylinder. I found that using the master cylinder out of a 67 Cutlass would work since it has the same bore size, but there were some differences in how the master cylinder would bolt up to the firewall and also differences in the depth the pushrod would go into the plunger (don't know what else to call it) in the back of the master cylinder.
I eventually found that a Year One dual reservoir master cylinder would have the right bore size, plunger depth, and would bolt up correctly to the firewall, so I went that route.
Since that time, although the brakes DO work, I've never been very satisfied with the car's braking performance. For one thing, pedal effort is higher and the brakes seem to engage more slowly than they did with the single res. m/c. When I remove my foot from the pedal, the brakes also seem to disengage more slowly.
I have found that I have problems when taking the car on long trips, as pedal effort gets VERY hard and stopping the car becomes extremely difficult. It seems to me that the brakes are dragging somehow. For whatever reason this is not much of a problem on short around town trips.
I don't fully understand what the problem is here. My one guess is this. With the old setup, there was a 5/16" line going from the m/c down to the junction block, with three 3/16" lines going to the left front, right front, and rear of the car.
With the new setup, I have 3/16" lines leading from one reservoir of the m/c to the junction block (now used for the front brakes only) or from the other reservoir of the m/c directly to the rear of the car.
I made no changes to the wheel cylinders or anything like that.
I'm wondering if it's possible that the 3/16" lines from the m/c to the junction block are too restrictive? Perhaps I need to use 1/4" lines? But if I do that, the fitting size will be wrong and I won't be able to screw the fitting into the m/c and the junction block.
Am I on the right track? Or is it something else I've overlooked?
Any brake experts here?
Thanks,
Scott
I'm having some problems with my 65 F-85's brakes and would like to know if anyone on the list has ideas as to what might be the problem with them.
Basically, the car had it's original single master cylinder, non-power, 4 wheel drum brakes, which originally worked just fine and did a good job stopping the car.
For safety reasons, I decided to convert the car over to a dual reservoir master cylinder. I found that using the master cylinder out of a 67 Cutlass would work since it has the same bore size, but there were some differences in how the master cylinder would bolt up to the firewall and also differences in the depth the pushrod would go into the plunger (don't know what else to call it) in the back of the master cylinder.
I eventually found that a Year One dual reservoir master cylinder would have the right bore size, plunger depth, and would bolt up correctly to the firewall, so I went that route.
Since that time, although the brakes DO work, I've never been very satisfied with the car's braking performance. For one thing, pedal effort is higher and the brakes seem to engage more slowly than they did with the single res. m/c. When I remove my foot from the pedal, the brakes also seem to disengage more slowly.
I have found that I have problems when taking the car on long trips, as pedal effort gets VERY hard and stopping the car becomes extremely difficult. It seems to me that the brakes are dragging somehow. For whatever reason this is not much of a problem on short around town trips.
I don't fully understand what the problem is here. My one guess is this. With the old setup, there was a 5/16" line going from the m/c down to the junction block, with three 3/16" lines going to the left front, right front, and rear of the car.
With the new setup, I have 3/16" lines leading from one reservoir of the m/c to the junction block (now used for the front brakes only) or from the other reservoir of the m/c directly to the rear of the car.
I made no changes to the wheel cylinders or anything like that.
I'm wondering if it's possible that the 3/16" lines from the m/c to the junction block are too restrictive? Perhaps I need to use 1/4" lines? But if I do that, the fitting size will be wrong and I won't be able to screw the fitting into the m/c and the junction block.
Am I on the right track? Or is it something else I've overlooked?
Any brake experts here?
Thanks,
Scott
Old(s) Fart
Joined: Mar 2007
Posts: 50,841
From: Northern VA
Yes he did, since drum brake cars do not use a proportioning valve.
It sounds like you did not use the 67 distribution block. This should not be a problem, as all it does is provide the differential pressure valve.
What is the condition of the rubber hoses to the wheels? The inner liner can deteriorate and act like a one-way valve. The other problem is that if the M/C and pushrod are not adjusted properly, the pedal will not allow the M/C piston to travel to the full rearward position. This can prevent fluid in the lines from returning to the M/C when you release the brakes. I don't know anything about the Year One M/C. Personally I would have used a 1967 non-power M/C with the matching manual brake pushrod. I assume you have the pushrod installed in the correct (upper) hole in the pedal arm.
It sounds like you did not use the 67 distribution block. This should not be a problem, as all it does is provide the differential pressure valve.
What is the condition of the rubber hoses to the wheels? The inner liner can deteriorate and act like a one-way valve. The other problem is that if the M/C and pushrod are not adjusted properly, the pedal will not allow the M/C piston to travel to the full rearward position. This can prevent fluid in the lines from returning to the M/C when you release the brakes. I don't know anything about the Year One M/C. Personally I would have used a 1967 non-power M/C with the matching manual brake pushrod. I assume you have the pushrod installed in the correct (upper) hole in the pedal arm.
Thread Starter
Registered User
Joined: Feb 2008
Posts: 38
>>>It sounds like you did not use the 67 distribution block. This should not be a problem, as all it does is provide the differential pressure valve.
What is the condition of the rubber hoses to the wheels? The inner liner can deteriorate and act like a one-way valve. The other problem is that if the M/C and pushrod are not adjusted properly, the pedal will not allow the M/C piston to travel to the full rearward position. This can prevent fluid in the lines from returning to the M/C when you release the brakes. I don't know anything about the Year One M/C. Personally I would have used a 1967 non-power M/C with the matching manual brake pushrod. I assume you have the pushrod installed in the correct (upper) hole in the pedal arm.>>>
Joe, thanks for your thoughts.
No, I did not use a 67 distribution block, I used the junction block that was original to the car.
All of the rubber brake hoses have been replaced.
You may be right about the m/c and pushrod not being adjusted properly, perhaps the m/c piston does not go rearward enough as you said.
I couldn't use a nonpower 67 Cutlass m/c and pushrod because the pushrod for a 67 will not bolt up to the brake pedal on the 65. The 65 pushrod will not work with a 67 m/c because the plunger on the 67 m/c is deeper, and the pushrod could not pivot properly in the back of the m/c as the brake pedal is depressed and released. My only option might have been to convert the car to power brakes to avoid all of this.
The only thing I can tell you is that this was NOT easyto figure out how to get the whole setup to work to begin with, since the brake systems on the 65 and 67 cars are more different than you would expect.
What is the condition of the rubber hoses to the wheels? The inner liner can deteriorate and act like a one-way valve. The other problem is that if the M/C and pushrod are not adjusted properly, the pedal will not allow the M/C piston to travel to the full rearward position. This can prevent fluid in the lines from returning to the M/C when you release the brakes. I don't know anything about the Year One M/C. Personally I would have used a 1967 non-power M/C with the matching manual brake pushrod. I assume you have the pushrod installed in the correct (upper) hole in the pedal arm.>>>
Joe, thanks for your thoughts.
No, I did not use a 67 distribution block, I used the junction block that was original to the car.
All of the rubber brake hoses have been replaced.
You may be right about the m/c and pushrod not being adjusted properly, perhaps the m/c piston does not go rearward enough as you said.
I couldn't use a nonpower 67 Cutlass m/c and pushrod because the pushrod for a 67 will not bolt up to the brake pedal on the 65. The 65 pushrod will not work with a 67 m/c because the plunger on the 67 m/c is deeper, and the pushrod could not pivot properly in the back of the m/c as the brake pedal is depressed and released. My only option might have been to convert the car to power brakes to avoid all of this.
The only thing I can tell you is that this was NOT easyto figure out how to get the whole setup to work to begin with, since the brake systems on the 65 and 67 cars are more different than you would expect.
Old(s) Fart
Joined: Mar 2007
Posts: 50,841
From: Northern VA
I couldn't use a nonpower 67 Cutlass m/c and pushrod because the pushrod for a 67 will not bolt up to the brake pedal on the 65. The 65 pushrod will not work with a 67 m/c because the plunger on the 67 m/c is deeper, and the pushrod could not pivot properly in the back of the m/c as the brake pedal is depressed and released. My only option might have been to convert the car to power brakes to avoid all of this.
The only thing I can tell you is that this was NOT easyto figure out how to get the whole setup to work to begin with, since the brake systems on the 65 and 67 cars are more different than you would expect.
The only thing I can tell you is that this was NOT easyto figure out how to get the whole setup to work to begin with, since the brake systems on the 65 and 67 cars are more different than you would expect.
Thread Starter
Registered User
Joined: Feb 2008
Posts: 38
Joe, I think it CAN be done if you have a power brake setup.
If it's manual, though (which is what I have), there is some problem with the pushrod hookup at the pedal...
I forget now what exactly the problem is because I did this over a year ago. I think there's also some issue with how the pushrod goes into the back of the m/c.
I haven't driven the car a whole lot since that time, but I'm getting back to working on it now.
Despite all of that, I did get the brakes to work, it's just that they don't work as well as they should (i.e. see above for details).
If it's manual, though (which is what I have), there is some problem with the pushrod hookup at the pedal...
I forget now what exactly the problem is because I did this over a year ago. I think there's also some issue with how the pushrod goes into the back of the m/c.
I haven't driven the car a whole lot since that time, but I'm getting back to working on it now.
Despite all of that, I did get the brakes to work, it's just that they don't work as well as they should (i.e. see above for details).
Thread Starter
Registered User
Joined: Feb 2008
Posts: 38
It appears that I may have found my problem with the brakes on the
'65.
As far as I can tell, it was simply that the left rear brake shoes
were adjusted too tight. So tight, in fact, that I couldn't even get
the drum off without backing the adustment way off.
What I don't understand is how the adjustment got so tight to begin
with. I drove the car around all last summer without a problem, so
I'm not sure why they would have been so tight when I never touched
the brakes since that time.
The tight shoes were rubbing on the drum just from driving the car
around normally, making that one wheel very hot. Eventually pressure
built up in the lines, causing the brake pedal to become very hard to
push down. It was like how it would be if you rode around with your
foot resting on the brake pedal all the time.
It seems I've gotten it solved, except as I said, I don't know how the
adjustment got so tight to begin with. I thought that the star wheel
couldn't over-adjust on its own.
'65.
As far as I can tell, it was simply that the left rear brake shoes
were adjusted too tight. So tight, in fact, that I couldn't even get
the drum off without backing the adustment way off.
What I don't understand is how the adjustment got so tight to begin
with. I drove the car around all last summer without a problem, so
I'm not sure why they would have been so tight when I never touched
the brakes since that time.
The tight shoes were rubbing on the drum just from driving the car
around normally, making that one wheel very hot. Eventually pressure
built up in the lines, causing the brake pedal to become very hard to
push down. It was like how it would be if you rode around with your
foot resting on the brake pedal all the time.
It seems I've gotten it solved, except as I said, I don't know how the
adjustment got so tight to begin with. I thought that the star wheel
couldn't over-adjust on its own.
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