63 Galaxie Disc Brake issues

[Smokinjoe3]

I acquired a 63 Galaxie recently. Previous owner did a front disc brake conversion (booster with dual master cylinder that looks like it is from an early 70s mustang, drilled slotted discs with braided lines). My test drive of the car went well and the brakes were solid. Now that I've owned the car for a little bit it felt like the brakes were dragging. Sure enough, I jacked the front and the wheels turned, but there was significant drag. I unbolted the master from the booster thinking that the rod was adjusted too far, but that didn't release the brakes. I cracked the bleeder at one of the calipers and they released. Thinking it might be the master cylinder, I picked another one up at the local parts store from a 72 mustang with front disc brakes. Changed it out and bleed the system well, but still holds pressure. Interestingly, the car does not have a proportioning valve, but stopped well without locking up the rear. Any ideas on what to do? Why is it not releasing the pressure?

 

[fordor41]

have a RPV (residual pressure valve) in the system to the front? disc uses a 2# valve but drums take a 10 # valve, or correct valve and plumbed backwards? with new M/C, will the pressure bleed off when M/C is removed from the booster?

 

[KULTULZ]

Previous owner did a front disc brake conversion (booster with dual master cylinder that looks like it is from an early 70s mustang, drilled slotted discs with braided lines).

Can you ID the front disc type (sliding caliper/four piston caliper/GM)?

No valving of any type (no RPV used in DISC unless MC is below caliper hose line), front metering or rear proportioning valve?

 

[cadillac512]

If you loosen the line to the front wheels at the master cyl does it release the brakes? If so, it's the master. (Is the line to the front connected to the correct port?) If not, it's downstream and is probably either a valve in the system or a brake hose (although it'd have to be both hoses if both wheels drag...unlikely).



Terry

 

[Smokinjoe3]

Can you ID the front disc type (sliding caliper/four piston caliper/GM)?

No valving of any type (no RPV used in DISC unless MC is below caliper hose line), front metering or rear proportioning valve?

Front disc, rear drum. They are single piston calipers with no markings on them to ID. How do you know if they are Ford calipers or GM? No valving of any type installed (no residual valve, no proportioning valve no metering valve). I've crawled under the car and found nothing all the way back to the rear. One brake line goes from the large reservoir on the rear of the MC down to the four way block as previously described and straight to the steel braided flex hoses to the calipers. The other brake line goes from the small reservoir on the MC straight to the rear brake hose.

I honestly don't know why it does so well stopping the way it is set up (no valving), but it does. Other than the front calipers holding pressure. I don't think there is anything wrong with the calipers being that they release when you crack the bleeder. Still puzzling why the front system is holding pressure. And when I pulled the MC away from the booster, the piston was fully seated on the snap ring.

 

[KULTULZ]

How do you know if they are Ford calipers or GM? No valving of any type installed (no residual valve, no proportioning valve no metering valve).

I honestly don't know why it does so well stopping the way it is set up (no valving), but it does. Other than the front calipers holding pressure. I don't think there is anything wrong with the calipers being that they release when you crack the bleeder. Still puzzling why the front system is holding pressure. And when I pulled the MC away from the booster, the piston was fully seated on the snap ring.

Well, here's the thing. These so-called DISC BRAKE KIT CONVERSION SELLERS either do not understand brake dynamics or don't give a crap. Most of it is CHI-COM.

If you have replaced the MC (with quality) and the calipers still hang, I would suspect the hoses. I guarantee you they are crapola to make things look racy along with the cheese grater rotors.

The MC push-rod may also be mis-adjusted or just the wrong style not allowing the MC pistons to fully return.. There is also an air-gap adjustment between the MC and booster.

I would start with the adjustments first. Do you have a source of theory and service manual(s)?

Once you get the calipers freed, we can talk about valving if you like.

 

[KULTULZ]

DAMN! ...

Photos are either too small or too large ...

 

[fordor41]

Well, here's the thing. These so-called DISC BRAKE KIT CONVERSION SELLERS either do not understand brake dynamics or don't give a crap. Most of it is CHI-COM.

If you have replaced the MC (with quality) and the calipers still hang, I would suspect the hoses. I guarantee you they are crapola to make things look racy along with the cheese grater rotors.

The MC push-rod may also be mis-adjusted or just the wrong style not allowing the MC pistons to fully return.. There is also an air-gap adjustment between the MC and booster.

I would start with the adjustments first. Do you have a source of theory and service manual(s)?

Once you get the calipers freed, we can talk about valving if you
like.

He said he separated the M/C from the booster and the piston was fully retracted so that should take any booster/ M/C adj. out of the equation. My guess is bad front hoses.

 

[KULTULZ]

He said he separated the M/C from the booster and the piston was fully retracted so that should take any booster/ M/C adj. out of the equation. My guess is bad front hoses.

Ah the DOUBTER ...

Of course it was bottomed when removed, there is no push-rod actuation when the MC is removed. All that showed is that the MC is probably not frozen.

The MC is actuated by the booster push-rod. That adjustment has to be correct as if not, there can be either a delayed MC actuation or a constant actuation of the MC leading to dragging brakes on whichever circuit.

Usually, when the BOOSTER-MC is sold as an assembly, that adjustment has been made. Who knows? The brake pedal to booster rod length/type may be incorrect also. It could also be a bad METERING VALVE (if equipped) or a bad COMBINATION VALVE (if equipped). When those adjustment(s) are verified, then you would suspect hose(s).

 

[Smokinjoe3]

Thanks for all of your responses. Residual valve found and removed from the rear port of the MC (larger reservoir). Brakes bleed. Success! Brakes work good!

 

[KULTULZ]

Residual valve found and removed from the rear port of the MC (larger reservoir).

If there was a RPV in the rear reservoir outlet, it was not a DISC/DRUM MC or was rebuilt incorrectly (or CHI-COM).

Did the take-off MC have an RPV in the rear circuit?

I saw your install photo at H.A.M.B. and the BRAKE LAMP SWITCH is installed incorrectly. It is on a separate line and that line will hold a large air pocket (no way to bleed).

 

[Gene F]

DAMN! ...

Photos are either too small or too large ...

Where did you buy that handy little jig to measure?

 

[KULTULZ]

Where did you buy that handy little jig to measure?

PIXEL-POINT MANUFACTURING AND FORTUNE-COOKIE SALES -

- ONE HUNG LO, CHINA

Nah, the first photo I entered took up two pages. I entered another and surprisingly it showed as the correct size. I didn't delete that 2nd post.

 

[KULTULZ]

Did the take-off MC have an RPV in the rear circuit?

I've seen this malady before.

Someone will say they want to go to DUALING RESERVOIR MC but want to keep the car DRUM/DRUM for present ($$$) thinking maybe going to front disc later. The kit vendor will then sale them a DRUM/DRUM application.

They do not realize a DRUM/DRUM MC is much different that a DISC/DRUM MC and then make this mistake of not upgrading the MC with a front disc conversion or the next owner doesn't realize the differences and is caught up in a predicament.

ADDENDUM - (Similar To Corundum) - Fr. For More Info ...

- TO WIT -

This is A 1954-1956 ford and mercury power brake booster and master cylinder, It is A dual reservoir master cylinder. This is designed to work with with drum brakes or with disc brakes. You will have to modify your brake lines to install this unit.

If you are using disc brakes we sell the correct proportioning valve for your ford It is in another listing.

... ... there is no correct PPV for an early FORD disc conversion.

The above is a general adv for booster kits. Read these very closely or one can hurt you.

 

[KULTULZ]

REFERRING TO POST #11​

Where did you buy that handy little jig to measure?

​

Gene,

I am sorry as hell. I thought you were referring to the pixel size of my photos. I hope that didn't come across as a SMART-A$$ REPLY (which I seem to be noted for).

The actual gauge you referred to is available from many sources.

Search MASTER POWER BRAKE - AC 2003

I was held over in the third grade due to my failure in READING COMPREHENSION FOR DUMMIES 101.

... you can dress them up ...

 

[poolplayer1]

Kultulz, at least you got to the third grade before you were held over, I was held back in the second grade and stayed there tooooo long. Dang it.
All kidding aside, this is a very good discussion on brakes. Good to know all this for future reference.