What Brake Fluid & Lock For Demco Hydraulic Drum Brake Actuator
Updated 01/05/2026 | Published 09/26/2024
Products Featured in This Question
Question:
4 Questions What brake fluid should I use? I replaced the complete brake set, and the actuator. I blew the lines out before I installed everything to make sure they were not restricted so the brake lines are empty. Can I use a vacuum bleeder on this to bleed the brakes? Do you know how much fluid I will need? What do I need for a lock to lock this hitch?
asked by: Mike K
Expert Reply:
Hi Mike,
For the Demco Hydraulic Brake Actuator - Drum # DM72VR, Demco just recommend using any DOT 3 or 4 brake fluid, and a 12 oz. bottle will be fine, which you can find at any type of auto parts or big chain store. As for bleeding the brakes, you won't be able to use a vacuum bleeder, you'll need to follow the directions that come with the actuator and do that by hand.
Then for a lock, you can either use a pin lock like # e98888 or surround lock like # FA86-0015-316.
Product Page this Question was Asked From
Demco Hydraulic Brake Actuator - Drum - Zinc - 2" Ball - 7,000 lbs
- Brake Actuator
- Surge Brake Actuator
- Farm Trailer
- Boat Trailer
- Construction Trailer
- Travel Trailer
- Utility Trailer
- Bolt-On
- 7000 lbs GTW
- 2 Inch Ball Coupler
- 3 Inch Channel Tongue
- Drum Brakes
- No Lockout
- Demco
more information >
Featured Help Information
Instructions
Continue Researching
- Q&A: Replacement for Atwood 61101 Brake Actuator
- Q&A: Recommended Replacement for Atwood Surge Brake Actuator 85778
- Article: How to Bleed Your Trailer Surge Brakes
- Q&A: Surge Brakes for Demco KK260 Tow Dolly
- Q&A: Replacement Actuator for an Older Atwood 85736
- Q&A: New Brake Assemblies, Hub/Drums, Brake Lines, and Bearing Buddy for Trailer with 3,500 lb Axle
- Q&A: Replacement 10" Drum Hydraulic Trailer Brakes for Converting 3,500 lbs Axles to Hydraulic Brakes
- Q&A: Is There Manual Lockout Available for Demco Surge Actuator part # DM72VR
- Article: Trailer Wiring Diagrams
- Article: Trailer Drum Brakes vs. Disc Brakes: Making the Decision
- Article: Hydraulic Trailer Brakes: How They Work & What to Buy
- Article: Trailer Brakes Not Working? Troubleshooting Guide
- Article: Most Popular Wheel Bearings
- Article: Wiring Trailer Lights with a 4-Way Plug (It's Easier Than You Think)
Jerred H.
1/5/2026
Hey Mike, how did things go with bleeding the brakes on your Demco actuator using the hand method? It’d be great to hear if the DOT 3 or 4 fluid and the 12 oz. amount worked out as expected. Your update could make it easier for others working on the same setup.