Fuselage - Drums to Disc Brake Conversion

[Big_John]

I'm not understanding this at all.

Why are you making new lines? Are the old ones bad?

You should just be able to screw the old brake lines into the new master cylinder and add one small piece of new line for your proportioning valve. No need to make new lines or cut and flare.

 

[70_NPORT]

I'm not understanding this at all.

Why are you making new lines? Are the old ones bad?

You should just be able to screw the old brake lines into the new master cylinder and add one small piece of new line for your proportioning valve. No need to make new lines or cut and flare.

I had originally set out to do that; make new lines. Would have looked nicer than the old ones; but even though they are old, they are still secure and intact. So they can stay where they are. I just want to keep this simple and get it done. I just checked to make sure the old lines/fittings that went into the old MC (front/rear) would fit properly into the brand new MC; they do.

 

[SF-66TC]

I had originally set out to do that; make new lines. Would have looked nicer than the old ones; but even though they are old, they are still secure and intact. So they can stay where they are. I just want to keep this simple and get it done. I just checked to make sure the old lines/fittings that went into the old MC (front/rear) would fit properly into the brand new MC; they do.

Gary, I just wanted to make sure you didn't feel my suggestions were mis-leading you. Your old lines and fittings may or may not have lined up and fit correctly thus I was providing you with the resolve to make up new lines and the tool to do so. If the old lines work, then proceed with them as Big_John has been saying and just plumb in a short line in between the DB to the PV then to existing rear brake line.

I don't recall, but I believe the two nipple that came with your PV are to receive the brake line fittings. The nipples screw into the INLET & OUTLET of the PV and the brake line fittings screw into those nipples. The reason for the nipples is because the threads are different. TEST before installing so you don't cross thread your fittings.

 

[Big_John]

I looked at the Allstar valve on line and it looks like those are female inverted flare fittings with 1/8 NPT male to screw into the valve. Pretty simple, but don't use teflon tape on the NPT part.

A 3/16 brake line should screw in there and seat without an issue.

 

[70_NPORT]

Gary, I just wanted to make sure you didn't feel my suggestions were mis-leading you

Nope, not at all Steve...I just think I'm in over my head at this point. I'd love to have everything brand new and shiny but I don't know what the heck I'm doing. ..it isn't very reassuring when you don't know what you don't know. So I just want to button it up and be done. I wanted pwr disc brakes and I have them now; that was my main goal. I appreciate all the guidance from everyone though.

 

[70_NPORT]

so m

I looked at the Allstar valve on line and it looks like those are female inverted flare fittings with 1/8 NPT male to screw into the valve. Pretty simple, but don't use teflon tape on the NPT part.

A 3/16 brake line should screw in there and seat without an issue.

So here's the Allstar PV along with one of the fittings it came with (loose fitting). Ok...are you saying the tube is meant to fit into the fitting on the bottom?....it has a "cone" shape inside of it...the tube does not seem to seat properly. Those two fittings already on each end of the tube will fit into the PV....but that tube itself is still kind of loose...it can be pulled in and out of its fitting slightly while its screwed into the PV.

 

[Big_John]

The fittings are screwed into the valve and tightened. They are pipe threads.

The tube is then screwed into the fitting.

The tube has to "seat" against the inverted "cone" inside the fitting. That's what they call an inverted flare.

 

[Big_John]

 

[70_NPORT]

Ahhh, got it. Never seen something like that before.

 

[SF-66TC]

Just as Big_John said.

You're in the home stretch....
Obviously the brake line shown will be too long for the short piece you need from the DB to the PV, so you will need to cut the tubing.

1. Measure how much you need and cut it to the desired length and put that piece aside.
2. With the left over piece of tubing you can then try out your flaring skills using the Eastwood tool - I'm sure you'll get it on the first shot!
3. Once you're happy with the results, recut the tubing and remove the fitting.
4. Place the just removed fitting on the other tubing (one you put aside) - make sure you put the fitting on facing the correct direction.
5. Flare the cut end of the tubing
6. Connect the new tubing between the DB & PV
7. DONE

Don't forget to Bench Prime the MC BEFORE installing it onto the booster.

Also, don't forget to adjust the end of the booster rod (adjustable screw end) that fits into the master before you bolt the master to the booster? Insufficient play and the brakes will drag, too much play and you won't have sufficient braking power.

 

[70_NPORT]

Just as Big_John said.

You're in the home stretch....
Obviously the brake line shown will be too long for the short piece you need from the DB to the PV, so you will need to cut the tubing.

1. Measure how much you need and cut it to the desired length and put that piece aside.
2. With the left over piece of tubing you can then try out your flaring skills using the Eastwood tool - I'm sure you'll get it on the first shot!
3. Once you're happy with the results, cut the tubing and remove the fitting.
4. Place the just removed fitting on the other tubing (one you put aside) - make sure you put the fitting on facing the correct direction.
5. Flare the cut end of the tubing
6. Connect the new tubing between the DB & PV
7. DONE

Don't forget to Bench Prime the MC BEFORE installing it onto the booster.

Also, don't forget to adjust the end of the booster rod (adjustable screw end) that fits into the master before you bolt the master to the booster? Insufficient play and the brakes will drag, too much play and you won't have sufficient braking power.

oK got it. What is the best way to cut this tubing? I don't want to crush it while trying to cut it. OR can it be bend into a coil?

 

[SF-66TC]

oK got it. What is the best way to cut this tubing? I don't want to crush it while trying to cut it. OR can it be bend into a coil?

You should really use a tubing cutter to get a straight cut. Have you done any plumbing work and had to cut copper pipes etc..
If not you can get one at Home Depot or Lowe's or anywhere. Get a mini - any brand will do since you just need to do a couple cuts anyway.

 

[70_NPORT]

You should really use a tubing cutter to get a straight cut. Have you done any plumbing work and had to cut copper pipes etc..
If not you can get one at Home Depot or Lowe's or anywhere. Get a mini - any brand will do since you just need to do a couple cuts anyway.

no, can't say I've ever done any real plumbing before...glad you have a pic. Looks like I'll be at HD saturday, thx.

 

[Big_John]

Another way is where you don't need to cut anything... Get a short piece of tubing from NAPA etc. Put a coil in it and the old tube to take up the excess if you have to (good idea anyway) and call it a day.

 

[Big_John]

Better yet, why even screw with the proportioning valve?

My 70 has disc brakes with no proportioning valve. This is a C-body, not a race car where you are trying to achieve balance.

If this was an A body where you are bolting some giant brakes on it, I'd say to do it. This is pretty balanced the way it is.

You could try it... See if it works and add the valve at a later date if you think you may need it.

 

[70_NPORT]

Better yet, why even screw with the proportioning valve?

My 70 has disc brakes with no proportioning valve. This is a C-body, not a race car where you are trying to achieve balance.

If this was an A body where you are bolting some giant brakes on it, I'd say to do it. This is pretty balanced the way it is.

You could try it... See if it works and add the valve at a later date if you think you may need it.

The prop valve was in Steve's plans along with the calipers and other related parts.

 

[Big_John]

The prop valve was in Steve's plans along with the calipers and other related parts.

If Steve told you to jump off a bridge, would you? (Channeling my Mom)

Seriously, I think Steve has said that here... That these cars didn't have proportioning valves.

 

[70_NPORT]

If Steve told you to jump off a bridge, would you? (Channeling my Mom)

Seriously, I think Steve has said that here... That these cars didn't have proportioning valves.

Uh.. hello, it was in the parts list that he was good enough to make up and post for those who wanted to convert drum brakes; which is the very same one Ive been diligently following from day one. I figured there are folks here with more experience than myself when it comes to drum to disc brake conversions. As far as I can see he has mad skillz with this stuff. So im just trying to follow the steps outlined in the info. Youll have to forgive me if I dont have 40 or 50 years worth of knowledge and or experience of the subject. I havent even been walking upright long enough to even come close to that.

 

[Big_John]

That was meant as a joke. I apologize if it wasn't taken that way.

Steve has given you a lot of options and has outlined them in this thread. One option, as I read it, was not to run the valve.

 

[Big_John]

Correcting myself .... Steve has mentioned that there was no proportioning valve on early C bodies. He recommended using a proportioning valve.
I read through most of this thread until I found what he said.

But... as he said, there wasn't a proportioning valve on many c bodies. There isn't on my 70 and it stops fine.

Steve has given you some very sound advice on everything here and I do not mean for you not to follow it. My intention is to help you and help you make things as simple as possible. I'd also like to see you think this stuff through and understand what you are doing.

Again, I apologize for the wise crack. No disrespect to anyone intended.