Granada swap problem

[Hack]

Well, I have everything in the car. The thing is, I can't get the pedal to firm up. I have '77 Monarch calipers and a '77 Monarch non-power master cylinder. I'm using the proportioning valve from a '77 Monarch as well.

I installed an adjustable brake pushrod. I set the installed stick-out to be the same as the original pushrod on my Mustang non-power master cylinder (about 4 1/2 inches to the center of the pedal mount). The first time I pushed the brake pedal I heard a clicking sound. I don't know if I damaged something with too much brake travel?

I bench-bled the MC prior to installation, and it got quite firm. The instructions said to install plugs in the ports and slowly pump until it got firm. I could barely move it by hand. I vacuum bled the brakes, and it seems like the system has unlimited air in it. I double checked all my fittings, and I'm fairly certain none are leaking..any more.

So then I removed the MC and rechecked it. It was still firm on the bench.

I've bled the system much more than I expected to, even with all new lines to fill. The pedal goes right to the floor. If I pump it for a while, it starts to firm up a little, but it's a momentary thing.

Please help! What should I do now? I'm ready to give up.

 

[D.Hearne]

Sounds to me like you've damaged something inside the master cylinder. And the fluid's bypassing inside it. When I did a 4 wheel drum to 4 wheel disc swap back in the 80's, I used a non-power master cylinder for a 71 Full size Ford. Had a 1 1/16 bore and used the pushrod that came with the Stang. Also used the Stang's proportioning valve. Wroked great.

 

[Hack]

Sounds to me like you've damaged something inside the master cylinder. And the fluid's bypassing inside it. When I did a 4 wheel drum to 4 wheel disc swap back in the 80's, I used a non-power master cylinder for a 71 Full size Ford. Had a 1 1/16 bore and used the pushrod that came with the Stang. Also used the Stang's proportioning valve. Wroked great.

Thanks for answering, D.Hearne. I have seen your posts and can tell you know your stuff. I have some more questions I hope you or someone can answer.

If the fluid was bypassing inside, would it still be really firm with the ports plugged? I pulled it out of the car, and I could only move the pushrod about 1/8 to 1/4 inch by hand - pushing very hard - with the ports plugged. When I started bleeding, it easily moved about 3/4 of an inch. I just want to be sure before I move on, even though it's only $20 or something. I'm cheap.

What year Mustang was yours that you did the swap on? Mine is a '70. Are there any differences between the brake pushrod travel in Mustangs from year to year, or do you think it will work just like yours did? What if I put in a '70 Mustang non-power MC for front disc/rear drum (is there even such a thing?)? Is it a smaller bore diameter, so the pedal effort would be higher? I don't really mind a higher pedal effort I guess, so I'll probably do that unless I feel really really confident that my next path will work.

I'm really willing to swap out the MC for a '71 full size Ford unit. I just don't want to spend half a day working on it and find out that there's something else going on.

 

[D.Hearne]

Thanks for answering, D.Hearne. I have seen your posts and can tell you know your stuff. I have some more questions I hope you or someone can answer.

If the fluid was bypassing inside, would it still be really firm with the ports plugged? I pulled it out of the car, and I could only move the pushrod about 1/8 to 1/4 inch by hand - pushing very hard - with the ports plugged. When I started bleeding, it easily moved about 3/4 of an inch. I just want to be sure before I move on, even though it's only $20 or something. I'm cheap.

What year Mustang was yours that you did the swap on? Mine is a '70. Are there any differences between the brake pushrod travel in Mustangs from year to year, or do you think it will work just like yours did? What if I put in a '70 Mustang non-power MC for front disc/rear drum (is there even such a thing?)? Is it a smaller bore diameter, so the pedal effort would be higher? I don't really mind a higher pedal effort I guess, so I'll probably do that unless I feel really really confident that my next path will work.

I'm really willing to swap out the MC for a '71 full size Ford unit. I just don't want to spend half a day working on it and find out that there's something else going on.

Yes, it's possible for it to be firm with the ports plugged and bypassing inside. You might try setting it in the vice and pulling the piston out and checking to see what , if any parts ( O rings ) have broken. You might have just split an O ring.I don't know if the pushrod length changed from year to year, but there's a difference in length from power to manual brakes. You don't want a smaller diameter piston, you want a larger one to reduce the pedal effort. I'd also go over the system again just ot make sure there's no leaks, also inspect the rubber hoses to see if they're swelling when you apply the brakes, that would also give you a spongy pedal.

 

[Hack]

Yes, it's possible for it to be firm with the ports plugged and bypassing inside. You might try setting it in the vice and pulling the piston out and checking to see what , if any parts ( O rings ) have broken. You might have just split an O ring.I don't know if the pushrod length changed from year to year, but there's a difference in length from power to manual brakes. You don't want a smaller diameter piston, you want a larger one to reduce the pedal effort. I'd also go over the system again just ot make sure there's no leaks, also inspect the rubber hoses to see if they're swelling when you apply the brakes, that would also give you a spongy pedal.

The rubber hoses are good. Since it can be firm with the ports plugged and bypassing inside, I think your first answer must be hitting the nail on the head.

I'm thinking I should just try the '71 full size MC. Thanks!

 

[SandSprite]

I'm pretty sure the larger diameter bore of the MC will increase pedal effort. You will notice that the non-power MC's are usually 15/16" and the power MC's are 1"-1 1/8". You will get less pedal travel with the larger bore.

 

[Hack]

I'm pretty sure the larger diameter bore of the MC will increase pedal effort. You will notice that the non-power MC's are usually 15/16" and the power MC's are 1"-1 1/8". You will get less pedal travel with the larger bore.

Oh, duh you're right. The ratio of the size of the bores in the wheel cylinder and master cylinder will be equal to the ratio of force applied, brakes to brake pedal. So, bigger MC bore means less travel to displace the amount of fluid needed to move the brakes, but more pedal force required.

Thanks for the FYI.

 

[68GEETEE]

just a thought: when you installed the front calipers, did you make sure that the bleeders are at the top , 12 noon position? My car had the calipers on the wrong wheels with the bleeders at 4 o clock, and as a result I could never get the trapped air out of the system.

 

[D.Hearne]

Oh, duh you're right. The ratio of the size of the bores in the wheel cylinder and master cylinder will be equal to the ratio of force applied, brakes to brake pedal. So, bigger MC bore means less travel to displace the amount of fluid needed to move the brakes, but more pedal force required.

Thanks for the FYI.

Well just the opposite was true on my 67, pedal effort was less with the 1 1/16 bore M/C and 4 wheel discs than it was with the smaller M/C and the 4 drums.

 

[64coupe]

Bench bleeding

I bench-bled the MC prior to installation, and it got quite firm. The instructions said to install plugs in the ports and slowly pump until it got firm. I could barely move it by hand. I vacuum bled the brakes, and it seems like the system has unlimited air in it. I double checked all my fittings, and I'm fairly certain none are leaking..any more.

When I have bench bled a master cylinder, I did not use plugs. Instead, I ran lines from the port back into the resevoirs and pumped it until the air was gone. Done.

Give it a try.

 

[Hack]

just a thought: when you installed the front calipers, did you make sure that the bleeders are at the top , 12 noon position? My car had the calipers on the wrong wheels with the bleeders at 4 o clock, and as a result I could never get the trapped air out of the system.

I think that I have them on the correct sides. The bleeders are at the top of the caliper, and the bleeder opening points toward the rear of the car. Does that sound right to you?

 

[Hack]

When I have bench bled a master cylinder, I did not use plugs. Instead, I ran lines from the port back into the resevoirs and pumped it until the air was gone. Done.

Give it a try.

It would be easy enough to do, I have a bleeder kit. I might just do that. I was prepared to do it that way, but then I thought I should follow the instructions that came with the MC. If the MC wasn't so firm, I'd think that the bleeding didn't work.

I'm thinking that I should measure the travel of the push rod while everything is still in the car. Since I have an adjustable push rod, I can shorten it so that the travel is correct. The instructions for bleeding the MC said to avoid pushing the piston farther than 1 inch. If it looks to me that the current setup has more than 1" travel, I'll guess that too much travel is my current problem. So, if I set the adjustable pushrod so that I get about 3/4" or slightly more travel, that should prevent over-compressing the MC piston.

If that all goes that way, I'll probably just buy a rebuild kit for the MC and replace the split o-ring. I have a few household projects in the way, but I'll post again here once I've tried to tackle this.. maybe Saturday or so.

 

[Hack]

Well just the opposite was true on my 67, pedal effort was less with the 1 1/16 bore M/C and 4 wheel discs than it was with the smaller M/C and the 4 drums.

Well, I'm not sure whether the discs apply more stopping force with less hydraulic pressure in the system or not when compared to drums. I'll use an example below of my logic regarding the MC piston diameter and its relationship to pedal effort.

Lets say you need 100 psi hydraulic pressure for a panic stop (I have no idea what the real number is, just using a number for doing calcs). If your piston is 1 inch in diameter, the area of the piston is 0.78 square inches and the force that must be applied to the piston is 78 pounds to get that 100 psi.

If your piston is 3/4 of an inch in diameter, the area of the piston is 0.44 square inches and you must apply 44 pounds to get 100 psi in the system. However, your piston must stroke almost twice as far to move the same amount of fluid through the lines.

So, you end up with a compromise between the effort required and the amount of fluid you must move with the travel available. On the brake caliper end, you want the pistons to be larger, so they'll apply more force. However, larger pistons require more fluid to move.

Too much info?

 

[D.Hearne]

I'd have to be drinking something else to comprehend all that at this time Seems to me that with a larger M/C piston , you're moving more fluid with the same distance stroke, so in effect it would require less effort.

 

[6T6coupe]

It's the other way around. Smaller bore MC = less pedal pressure, but at the expense of pedal travel.

 

[TOM B]

Monarch parts for the Granada swap are different. I found both these cars in my cousins yard and some parts are different. I found the spindle to be different and the tie rods. Even though some sites say they are the same, watch out. Stay with the Granada. If your running styled steel wheels you will have to cut the outer nose of the hub down a little to clear. I have the manual brake system on mine and it works great. I bought a adjustable proportioning valve but dont think I will need it.

 

[SandSprite]

Monarch parts for the Granada swap are different. I found both these cars in my cousins yard and some parts are different. I found the spindle to be different and the tie rods. Even though some sites say they are the same, watch out. Stay with the Granada. If your running styled steel wheels you will have to cut the outer nose of the hub down a little to clear. I have the manual brake system on mine and it works great. I bought a adjustable proportioning valve but dont think I will need it.

They are the same car. You may have been looking at different years. In '80 or '81 they went with a different front suspension (fox chassis?).

 

[6T6coupe]

Or you may have run across a Lincoln Versailles which has different ball joints.

 

[Hack]

Ok, the '77 Mercury Monarch non-power front disc rear drum master works fine in my '70 that originally had non-power 4 wheel drums. I checked the brake travel and it's about 0.75". I don't think the clicking sound I heard with the first MC was it destroying itself.

However, I do believe there was a problem with that MC. I bought a second rebuilt unit for $18. I spent 2 hours trying to bench bleed it before I took it back. The third one bled in about a minute and works great!

So, live and learn. Next time I get a rebuilt MC, I'll expect it to bleed really fast or I'll just take it back.

 

[castrol69coupe]

So that master cylinder works... good news. I have a non power brake,
69 coupe going from 4 wheel drum to front discs. The guy at the parts
house couldn't find a master cylinder for non power, disc front. He ended
up giving me a Power M/C and told me to see if it would work. If the one
you bought works, I am going that route.

~castrol