Valve adjustment question on sbf 302

[signorc 31]

Thanks for your input dcm.

I'd buy a new one but it's not as straight forward as I thought.  I have a front disk (Granada conversion kit with 1 piston calipers) & rear drum set up.  I don't know if I have a 15/16" or 1" bore.

I was gonna buy a new or refurbished m/c but not all sites are clear in regards to the setup it can be used for.

Any input or words of advice are appreciated

[aslanefe 342]

2 hours ago, signorc said:

Thanks for your input dcm.

I'd buy a new one but it's not as straight forward as I thought.  I have a front disk (Granada conversion kit with 1 piston calipers) & rear drum set up.  I don't know if I have a 15/16" or 1" bore.

I was gonna buy a new or refurbished m/c but not all sites are clear in regards to the setup it can be used for.

Any input or words of advice are appreciated

Remove the two nuts attaching the master to booster and pull it forward (without removing the brake lines from the master) and see if it is leaking in to the booster. If it is, you will have fluid inside the booster. May be you just need a new lid and lid seal.

[signorc 31]

Removed m/c from booster and found the booster nice and dry.

So i removed the m/c and found a broken push rod (see pic).  So i made a new one.....don't forget i live in Italy and we're on lockdown so you gotta make stuff  :)

Also saw that the rod made 2 signs where it was pushing the cylinder (see pic). I'll be putting a washer at the end so it is always centered.

Any thoughts?

[aslanefe 342]

Well, you do not need a new MC after all. Make sure you have the rod length adjusted correctly, there are dimensions on the net on how much gap you need between the rod and the piston.

[aslanefe 342]

I don't think you need a washer to center the rod.

[aslanefe 342]

While you are working on brakes, I would replace the fluid (the whole system, lines MC etc) if it has been over a few years since last replacement.

[signorc 31]

Hi aslanefe,

I bench bled the mc tinight and I'll bleed the entire system tomorrow and pray that it won't leak anymore.  The bore was entirely clean except by the front where the lock ring is.

 

[aslanefe 342]

12 minutes ago, signorc said:

Hi aslanefe,

I bench bled the mc tinight and I'll bleed the entire system tomorrow and pray that it won't leak anymore.  The bore was entirely clean except by the front where the lock ring is.

 

Where is it leaking from? Looking at the picture, there was some flow through the bowl on the front side.

[signorc 31]

These are 2 pics I took today when I took the mc off.  The inside of the boostwr was dry.  The outermost rubber seal on the external piston of the mc had some grudge on it.  I cleaned up all the rubber seals and outrmost part of the bore hopeing that will stop the leak

[aslanefe 342]

I think you will be fine, if there was a leak your fluid level would drop real quick.

[signorc 31]

Hello everyone,

I reinstalled the 1" bore m/c and bled the brakes and took it for a drive.......and so far no leaks :)

 In a "panic stop" situation the car does NOT stop quickly enough.  I cannot lock the front brakes no matter how hard I push on the pedal.

 I have a Granada conversion kit installed with 1 piston calipers in the front and drums in the rear.  The proportioning valve is turned counterclockwise all the way (to give the front 100% hydraulic pressure) .... I cannot lock the front wheels for the life of me!

Tomorrow I'll check that the rear have a little drag when spun by hand, I'll also make the booster push rod a smudge longer.

Also, the brake pedal is spongy.....it doesn't have that solid feeling of "I'm stopping NOW!"..... I slam on the brakes and the car says "......I'll stop in a few seconds"

Stay safe & thanks for any suggestions or input......... and remember please stay home..... it's still a crapshow here in Italy.

[barnett468 418]

4 hours ago, signorc said:

Hello everyone,

I reinstalled the 1" bore m/c and bled the brakes and took it for a drive.......and so far no leaks :)

 In a "panic stop" situation the car does NOT stop quickly enough.  I cannot lock the front brakes no matter how hard I push on the pedal.

 I have a Granada conversion kit installed with 1 piston calipers in the front and drums in the rear.  The proportioning valve is turned counterclockwise all the way (to give the front 100% hydraulic pressure) .... I cannot lock the front wheels for the life of me!

Tomorrow I'll check that the rear have a little drag when spun by hand, I'll also make the booster push rod a smudge longer.

Also, the brake pedal is spongy.....it doesn't have that solid feeling of "I'm stopping NOW!"..... I slam on the brakes and the car says "......I'll stop in a few seconds"

Stay safe & thanks for any suggestions or input......... and remember please stay home..... it's still a crapshow here in Italy.

a stock proportioning valve works best. if the rears lock easily but the fronts don't, you can install a different size rear wheel cylinder, but others here will have some ideas.

[signorc 31]

i cant get either to lock

[barnett468 418]

2 hours ago, signorc said:

i cant get either to lock

and this is power brakes right?

do you have the original proportioning valve?

[dcm0123 15]

On 3/30/2020 at 5:27 AM, signorc said:

Thanks for your input dcm.

I'd buy a new one but it's not as straight forward as I thought.  I have a front disk (Granada conversion kit with 1 piston calipers) & rear drum set up.  I don't know if I have a 15/16" or 1" bore.

I was gonna buy a new or refurbished m/c but not all sites are clear in regards to the setup it can be used for.

Any input or words of advice are appreciated

Not sure if you are past this problem but have some thoughts.

 Is the bore you are looking for the bore of the master or or the disc caliper cylinder? If the master, you can measure the hole with a tape measure to find out.

If you click on the "info" tab at the RockAuto site next to the "Cardone" brand master cylinders called for under a 1969 Mustang, it tells you the bore of the cylinder. The bore of a manual brake cylinder is 1" while a power brake cylinder is .937" (15/16").

Looking up the same for a 1975 Granada I see both manual and power master cylinders use 15/16" bore and the cylinders are different..

They also state the size of the threads on the ports (brake lines) going into the cylinder. The Granada threads are smaller than the Mustang. This may help you figure out which one you have.

Pump the brake pedal with the engine off to bleed off all the vacuum. Then apply pressure lightly to the pedal and see if it quickly comes to a hard  stop or slowly sinks. The pedal should come to a firm stop. If it slowly sinks, you may have a leak between the drum and disc sections inside the cylinder which will cause loss of brake power but not an external fluid leak. The reason I say under light force is because sometimes if you apply a lot of force, it causes the bad seal to work properly.

If the pedal does not sink but is spongy when you run the above test, you likely have air in the system.

You will send more pressure to the wheels using the smaller 15/16" master cylinder. Not sure if it is enough to make a difference.

How much vacuum is there going to the vacuum booster? If the vacuum level is low, it may not produce enough power to lock the brakes up.

https://www.speedwaymotors.com/the-toolbox/braking-components-selection-and-design/28678

[signorc 31]

Hey everyone, 

I re-bled the brakes today. the calipers are on correctly with bleeder facing the rear.....and still could not lock up either front or rear by standing on the brake pedal with BOTH feet from about 60mph.

Tomorrow I'll check how much vacuum I'm getting to the booster and I'll make the booster push rod a bit longer (again).

....don't know if this matters but I can't get the brake pedal to the floor.  it has a short and hard travel.

I could buy new flex hoses but I live in Italy and I gotta wait till my next trip to the US to see my kids......no time soon thanks to Covid 19.

I believe I have the Raybestos RRD14 riveted pads on them now (see picture).

[dcm0123 15]

Do not think hoses will help.

When I previously experienced short and hard travel while driving it was due to either a failing power booster or an adjustment problem with the push rod you replaced. When you pump the brakes without the engine running you will get short hard travel as the vacuum is used up.

If this happens with the engine running, you may have installed a master cylinder designed for manual brakes on a power brake booster so it does not interface to the push rod the same. If you have both master cylinders measure the distance from the power booster mating surface to the bottom on the piston in the master cylinder where the push rod hits. If one is longer than the other it could be part of your problem. If this is the case, try making a push rob about 1/8" shorter and see if it helps. If not, try another 1/8" shorter.

Based upon what I wrote earlier, the 1" diameter piston is for manual brakes, not power so using a 1" with a power booster maybe your problem.

Do you here air leaking inside the car when the brakes are applied? This is a sign of a bad power booster.

 

[signorc 31]

I bought the entire brake set up from SSBC in 2003.  When I set it up the original booster was bad so they replaced it.  They supplied me the current set up (not to say that they couldn't have made a mistake).

No, I don't hear any air leaking when the brakes are applied.

What is the difference between a manual mc and a power mc?  besides one having a booster and the other not

[aslanefe 342]

11 minutes ago, signorc said:

I bought the entire brake set up from SSBC in 2003.  When I set it up the original booster was bad so they replaced it.  They supplied me the current set up (not to say that they couldn't have made a mistake).

No, I don't hear any air leaking when the brakes are applied.

What is the difference between a manual mc and a power mc?  besides one having a booster and the other not

As far as I know, for the same vehicle and calipers, manual mc will have a smaller bore than power mc. It is harder to push a larger bore mc without the help of the booster.

[barnett468 418]

4 hours ago, signorc said:

I re-bled the brakes today. the calipers are on correctly with bleeder facing the rear.....and still could not lock up either front or rear by standing on the brake pedal with BOTH feet from about 60mph. Tomorrow I'll check how much vacuum I'm getting to the booster and I'll make the booster push rod a bit longer (again).....

don't know if this matters but I can't get the brake pedal to the floor.

 

ok, you should have around .015" clearance between the end of the push rod and the hole in piston in the master in which it pushes on but this can be hard to measure.

the brake pedal should never go to the floor, however, it will travel noticeably farther with the power booster working than it will with the booster not working.

 

[signorc 31]

Could i test the booster by removing the vacuum line to it and see how the pedal travels differently?

[dcm0123 15]

All master cylinders which should be used with power boosters made for a 1969 mustang and a Ford Granada have a 15/16" bore which is the hole the piston goes in. If yours measures 1", it is not designed for use with a power brake booster. There could be other differences internally to the cylinder or possibly externally which is why I suggested you measure the depth of the hole in the piston.and compare them.

If you put a power booster from a Granada in a Mustang and did not confirm the length of the rod with the eye in it which is attached to the brake pedal is the same as the Mustang one, it could also be your problem.

Power brake boosters from a 69 Mustang have dual diaphragms. A power booster from a 1975 Ford Granada has a single diaphragm. A single diaphragm can not develop as much power as a dual diaphragm but this does not sound like you problem. Concentrate on checking the clearance noted below.

If there is not enough clearance when your foot is off the brake petal, between the rod you made and the bottom of the hole in the piston which it contacts, the brake system will not work properly. This is why I suggested trying a shorter length rod. I read several articles on line and it says the clearance between the end of the rod and the bottom of the hole should be between 1/16 and 1/4 of an inch. It also suggested using clay to determine the clearance. Assemble then remove and measure the thickness of the clay. I did this before and it fixed the no power assist problem.

If you pull the vacuum hose off including the check valve which is pressed into the rubber grommet on it, it will release all the vacuum. The pedal should travel much less and come to a firm stop than when you have full vacuum. The same will happen if you stop the engine and repeatably step on the break pedal because this will drain all the vacuum. If you do not notice a difference, either your power booster is bad, you have the wrong master cylinder or you have the wrong length rod.

You need a minimum of 17" of vacuum to have full power as stated in the link below. Please read it since it also explains why a MC for power brakes has a smaller bore than one for manual brakes and states a single diaphragm has less power than a dual..

The rod you used does not look like a hardened steel bolt. If it was not, please look for a grade 8 or higher steel bolt which typically will have 8 dash lines on the hex head. If you use a soft bolt, it may break just like your original one and cause you to loose all your brakes. I would buy a hardened hex head bolt and grind the head into the shape of the head on the original rod.  To small a contact area with the piston in the cylinder may cause excessive wear or damage. Looking at the 2'nd picture from the top I see damage already in the bottom of the hole.

https://www.speedwaymotors.com/the-toolbox/braking-components-selection-and-design/28678

 

 

[signorc 31]

Hello,

I can't compare the piston depth cause I only have 1 mc.

As I removed the mc to check the clearance....the bolt I made was bent.  I made a new one of 8.8 steel grade.  adjusted the pushrod to .015 clearance but it still takes too long to come to a complete stop.

I have a single diaphragm.  this is what they sent with the kit.

I have 17,5 to 18" Hg of vacuum to the booster.

the 2 pivot points that you see in the second picture was done by my first rod. when I saw the rod was broken in half I crapped in my pants knowing I could have lost all braking!

Tomorrow I'll compare the brake pedal feel with and without the vacuumed booster.  This sucks cause it was a kit that was sold by SSBC and I took for granted they would have sent me a compatible kit :(

[barnett468 418]

1 hour ago, signorc said:

This sucks cause it was a kit that was sold by SSBC and I took for granted they would have sent me a compatible kit :(

The booster may very well be correct for their brake system.

What was wrong with the rod in the booster they sent to you?

[signorc 31]

Nothing. I just found ot broken a few days ago.