Do I Need Different Master Cylinder When Upgrading To Disc Brakes? Demco DA75 Brake Actuator

Question

Question:

I’m switching from drum to disc brakes. do I need a different master cylinder or is this ready to go?

asked by: Audrey

0

Expert Reply:

Audrey, this unit # DM33CV is factory-set up for disc brakes with the higher-pressure master cylinder already installed. So you’re good to go, no upgrades needed. Just make sure your lines are in good shape and you have some spare Dot 3 or Dot 4 fluid handy!
You'll love the disc brake upgrade; you'll wonder why you didn't do it sooner!

Did you have a reverse lockout kit on your old one?

expert reply by: Andrew N

0

Andrew N.

8/15/2025

Hey Audrey, how did the switch to disc brakes go? Did you find that everything was set up as expected with the master cylinder? I'm asking because I want to make sure others can benefit from your experience!

Answer 1

If you are only getting 1.5 volts at your brakes then there is an issue, but there is not a fuse that controls the brakes. There are a number of possible issues so you will need to find out if the issue is on the brake controller, truck, or trailer.…

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Answer 2

It does sound like there is a short to the brake controller through the wiring or in the internal circuitry of the brake controller. Since your brake controller shows no red light this indicates a short to the brake line (blue wire). If you are using…

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Answer 3

Hey Matt, thanks for bringing this to our attention. Yes the mounting hole dimensions of the Demco DA75 Trailer Brake Actuator for Drum Brakes #DM33CV that you referenced are separated by 3 inches horizontally and 2.5 inches vertically. Do you have a…

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Answer 4

Hey there Lorna. Yes, the Demco Drum Brake Actuator #DM28CV or Demco Brake Actuator Disc #DM33CV will 100% fit your 3" wide 4" tall trailer tongue. Even though the actuator says 3" wide and 2-1/2" tall, it will work because it…

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Answer 5

Good question, Carla. This version is zinc-plated only, without a secondary powder coat layer. That zinc finish is strong on its own and helps prevent corrosion, especially in freshwater or light salt environments. Most brake actuators are either raw…

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Answer 6

There sure is! You'll be needing the Lockout Key #DX94FR for your Brake Actuator #T4606520. Do you use the key much? Or are you using the electric solenoid?

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Answer 7

The Demco Hydraulic Trailer Brake Actuator part #DM72VR should be a direct replacement for the Atwood 61101 Brake Actuator that you have now. This newest updated it rated at 7K instead of 6K. This is a bolt on option that mounts on 3" centers.…

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Answer 8

Great question, Hannah, and welcome to the world of boating and trailering! Since the Demco Disc Brake Actuator #DM33CV doesn’t include a lockout, you’ll want to add Demco Manual Lock Out Kit #DM93CV if you want to prevent the brakes from engaging…

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Answer 9

Dan, you’ll want to use 1/2" x 4-1/2" Grade-5 or higher for a secure mount. They aren't included, but you can find them at any hardware store. The mounting holes on the Demco DA75 Brake Actuator #DM33CV are standard size for bolt-on…

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Answer 10

Hey Edd, thanks for reaching out. Yes, the Demco DA75 Trailer Brake Actuator for Disc Brakes #DM33CV does indeed have an electric lockout. The solenoid has two wires coming off it which are the reverse lockout wires mean to hook up to the vehicles…

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Do I Need Different Master Cylinder When Upgrading To Disc Brakes? Demco DA75 Brake Actuator

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