Next step - brake lines...30 Tudor - Guidance?

[hammondite]

I have the front suspension assembled and brakes installed/adjusted on the estate Model A I've been working on (yay!)

Next step is plumbing the front brakes - they're 46-48 brakes and a Speedway under-floor master cylinder/clutch kit came mounted. I have the hoses for the front brakes, but need to run them back to the master cylinder.

Any recommendations on line size and routing? Do i go through the frame for the lines to the hoses or under it? Between the fenders and hood panels, I don't think over the frame will work. I plan on running the line inside the curve of the frame back to the master cylinder. Also think I'll T the lines either at the front end of that run or in the valley of the front crossmember.

I suspect I'll need check valves as well, since the wheel cylinders are above the master cylinder.

I've custom plumbed the brakes on my 40 Chevy before and those are still working fine. So i have some experience with it, and hopefully still have the flaring tool and bender as well.

Any feedback is appreciated. And if someone has a pre-bent kit...

Thanks
Paul

[Charlie Stephens]

I would use all 1/4 inch lines and original (or reproduction of original) fittings so you don't get involved with adapters. Look at the fittings and routing for a '39 Ford. Can you post a photo of your master cylinder mounted?

Charlie Stephens

[bruceincam]

I think Snyder's has a pre bent kit for the Model A. Don't hold me to that but I would go to them first.

[Charlie Stephens]

The pictures show the way I set up my '32. It involved a piece of angle iron and the original Ford fittings. First the left and then the right side.

Charlie Stephens

[Charlie Stephens]

Originally Posted by bruceincam

I think Snyder's has a pre bent kit for the Model A. Don't hold me to that but I would go to them first.

Be sure the kit is designed for the speedway master cylinder location.

Charlie Stephens

[desotoguy]

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NiCop (Nickle coper) is the easiest type of line to install, bends easily and is available in various lengths with fittings or on a roll for you to apply fitting and flare. It looks like like copper but is strong enough for brake line pressure.

[ModelA29]

Local parts stores carry various lengths of brake line - use 3/16". I like to start with the straight lengths - you only need to cut and flare one end (if any). The coiled stuff takes too much time to get really straight and looking good. You need a bracket (or just drill a hole in the frame) where the flex and hard line meet. Add a couple clips along the length to keep it from rattling. Be sure to do a double flare. Hand shaping is ok for a large radius but you'll want a good tubing bender for the smaller ones. Check (residual) valves are used in disc brake systems to keep the disc pads from retracting too far from the disc and not needed in a drum setup.

[hammondite]

Originally Posted by Charlie Stephens

I would use all 1/4 inch lines and original (or reproduction of original) fittings so you don't get involved with adapters. Look at the fittings and routing for a '39 Ford. Can you post a photo of your master cylinder mounted?

Charlie Stephens

As you requested, here's the mounted master cylinder.

[hammondite]

Originally Posted by hammondite

As you requested, here's the mounted master cylinder.

Well, this was weird, it didn't attach... trying again...

[hammondite]

Thanks. It appears there's no issue with the spring hitting the line. The soft lines that came with it aren't long enough to reach to that spot. I plan to run them to the top shock mount bolt at the bracket with a similar bracket to what you made.

Has there been any issue with running the lines below the frame to cross under? I'm not fond of doing that, but if that's what I need to do...

Here's a pic of that:

[40 Deluxe]

Originally Posted by ModelA29

Check (residual) valves are used in disc brake systems to keep the disc pads from retracting too far from the disc and not needed in a drum setup.

Oops! I think that you have it backwards. On a disc brake system the only thing that retracts the pads is the slight deflection in the square-cut 'O'-rings that seal the caliper pistons (there are no return springs). When the brake pedal is released, the 'O'-rings relax and pull the piston back just enough to prevent drag. If a residual pressure check valve is used (usually about 5 lbs.), the pads won't fully release and will drag.
On a drum system, the cups in the wheel cylinders will leak unless about 5 lbs. pressure is kept in the system. Thus a residual pressure valve is needed. The shoes will not drag because the shoe return springs easily overcome the 5 lbs. residual pressure.

[Jim Brierley]

Originally Posted by desotoguy

NiCop (Nickle coper) is the easiest type of line to install, bends easily and is available in various lengths with fittings or on a roll for you to apply fitting and flare. It looks like like copper but is strong enough for brake line pressure.

These are undoubtedly the best lines, but may be hard to find? Use 1/4" so the lines match the wheel cylinders, and a flex line at the m/cyl. and diff. Cut-to- length steel lines are available at most parts stores, do not use copper lines. All lines should be double-flared. Use a tubing bender of some type to avoid kinking the lines. Use care at the rear cylinders as they require a really tight bend. Good luck!

[Randy in ca]

What do you have (or are planning) on the rear?

[hammondite]

Originally Posted by Randy in ca

What do you have (or are planning) on the rear?

The car came with a 9 inch Ford rear end and all the brake parts for that. Though the line that came with it is 3/8 standard straight line. May need something else for that run...

[hammondite]

Follow up question - the car came with a Speedway brake/clutch combo. It's a power master cylinder. Will the flathead 8 have enough vacuum for the brakes?

[30Murray]

Make sure your brake lines and master cylinder are well clear of your exhaust pipes, or otherwise shielded. Heat will cause the fluid to expand and may cause the brakes to seize. Happened to me.

[40 Deluxe]

Originally Posted by 30Murray

Make sure your brake lines and master cylinder are well clear of your exhaust pipes, or otherwise shielded. Heat will cause the fluid to expand and may cause the brakes to seize. Happened to me.

Something else is wrong if your brakes seize from heat! Any pressure buildup from heat will vent into the master cylinder reservoir and out through the cap. Make sure there is about 1/16" free play between the master cyl. piston and the pushrod when the pedal is released.

[ModelA29]

Originally Posted by 40 Deluxe

Oops! I think that you have it backwards. On a disc brake system the only thing that retracts the pads is the slight deflection in the square-cut 'O'-rings that seal the caliper pistons (there are no return springs). When the brake pedal is released, the 'O'-rings relax and pull the piston back just enough to prevent drag. If a residual pressure check valve is used (usually about 5 lbs.), the pads won't fully release and will drag.
On a drum system, the cups in the wheel cylinders will leak unless about 5 lbs. pressure is kept in the system. Thus a residual pressure valve is needed. The shoes will not drag because the shoe return springs easily overcome the 5 lbs. residual pressure.

With disc runout the pads can just keep backing off (there is no positive stop and the runout forces the fluid back into the master cyl) needing you to pump the pedal to get them back into contact. Drum brake retraction is mechanical and they have a positive location when the springs retract them. If you need to keep pressure on the wheel cylinders the cups are worn. To check that idea just open a bleed valve on the wheel cylinder if there is pressure the fluid will squirt out. Some people will add a valve to the rears also but I've never encountered a situation that needed one.

[40 Deluxe]

Originally Posted by ModelA29

With disc runout the pads can just keep backing off (there is no positive stop and the runout forces the fluid back into the master cyl) needing you to pump the pedal to get them back into contact. Drum brake retraction is mechanical and they have a positive location when the springs retract them. If you need to keep pressure on the wheel cylinders the cups are worn. To check that idea just open a bleed valve on the wheel cylinder if there is pressure the fluid will squirt out. Some people will add a valve to the rears also but I've never encountered a situation that needed one.

Well, rotor runout will only push the pads back the same amount as the runout. I've test driven a lot of cars with rotors warped so bad that the steering wheel would shake violently when applying the brakes, yet I never needed to pump the brakes to extend the pads back to the rotor! Having to pump the pedal indicates some other problem.
I would suggest that you do an internet search for "Residual pressure brake valves".. You will find a lot of information on the need for residual pressure valves on drum systems (as well as some disc systems). The pressure maintained in the system is only 2 to 10 lbs. so you won't get much of a 'squirt'. Please note that the real experts mention several reasons why residual pressure is needed.