Demco Hydraulic Drum Brake Assembly - Free Backing - Galvanized - 12" - Left Hand - 7,000 lbs

Demco Hydraulic Drum Brake Assembly - Free Backing - Galvanized - 12" - Left Hand - 7,000 lbs

Item # 42029

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Demco Trailer Brakes - 42029
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  • Trailer Brakes
  • Hydraulic Drum Brakes
  • Brake Assembly
  • Demco
  • 12 x 2 Inch Drum
  • LH
  • Free Backing
  • 7000 lbs
Free-backing, driver's-side trailer brake assembly won't engage when you reverse, even if your hydraulic actuator is activated. Galvanized steel resists rust, making the assembly great for boat trailers. Mounting flange has 5-bolt pattern. Call 800-298-8924 to order Demco accessories and parts part number 42029 or order online at etrailer.com. Free expert support on all Demco products. Guaranteed Lowest Price and Fastest Shipping for Demco Hydraulic Drum Brake Assembly - Free Backing - Galvanized - 12" - Left Hand - 7,000 lbs. Accessories and Parts reviews from real customers.


  • All Info
  • Reviews (17)
  • Q & A (3)
  • Videos (1)
  • Photos
  • Why etrailer?

Demco Accessories and Parts - 42029

Free-backing, driver's-side trailer brake assembly won't engage when you reverse, even if your hydraulic actuator is activated. Galvanized steel resists rust, making the assembly great for boat trailers. Mounting flange has 5-bolt pattern.


Features:

  • Marine-grade hydraulic drum brake assembly is great for boat trailers
    • Designed for use with surge-type trailer brake actuators
  • Sturdy, corrosion-resistant steel construction
    • Galvanized backing plate
    • Stainless steel spring hardware
    • Zinc-plated wheel cylinder
  • Free-backing design lets you back up without engaging the trailer brake, even if the actuator is activated
    • Riveted, fall-away brake shoe only anchors on drum when brakes are engaged as trailer is moving forward
  • Periodic manual adjustment required
  • Mounting bolts sold separately


Specs:

  • Configuration: left hand (driver's side)
  • Dimensions: 12" diameter x 2" thick
  • Mounting flange bolt pattern: 5 on 3-7/8"
  • Wheel size: 14-1/2", 15", and 16"
  • Axle rating: up to 7,000 lbs
  • 1-Year warranty


Note: Because free-backing brakes are designed to eliminate nearly all friction between the brake shoes and the drum when you are driving in reverse, a trailer breakaway kit will not be effective should your trailer disconnect from your tow vehicle while you are backing up.


Free-backing brakes let your trailer move in reverse without the brakes being activated by your surge actuator. These brakes are needed if your actuator does not have a reverse lockout, which is a mechanism that ensures that the actuator does not activate when your rig moves in reverse.


Demco Free-Backing Brake with Fall-Away Shoe

This Demco free-backing brake assembly has a fall-away shoe that is designed to provide full braking action when your trailer is moving forward and to supply only limited friction when the trailer is moving in reverse. This is largely due to the incorporated dual springs at the shoe's pivot point. (One spring sits on either side of the shoe lever, so only a single spring is visible when looking at the brake assembly.)


Demco Free Backing Brake Labeled Diagram - Left Hand Assembly

When your rig is moving forward and you engage the trailer brakes, the fall-away shoe expands normally, with the leading edge of the shoe catching the drum. This occurs because the plunger on the hydraulic cylinder pushes on the shoe lever, forcing the leading edge of the brake shoe into the drum. Once that edge catches, the dual springs at the shoe's pivot point facilitate braking by forcing the rest of the shoe to pivot into the drum. The action of the shoe against the drum provides the friction required for braking.


When you are driving in reverse, however, the hydraulic cylinder and the springs work against one another. Even though the plunger pushes on the shoe lever, the dual springs of the fall-away shoe overcome the pressure from the brake cylinder, keeping the leading edge from catching on the drum and ensuring that the shoe does not fully pivot into the drum. Because the shoe makes only slight contact with the drum, just enough friction is generated so that only a minimal amount of braking occurs when you are in reverse.



SB42029M Demco Galvanized 12" Marine Trailer Brake Assembly - Freebacking - Left Hand







Video of Demco Hydraulic Drum Brake Assembly - Free Backing - Galvanized - 12" - Left Hand - 7,000 lbs


Videos are provided as a guide only. Refer to manufacturer installation instructions and specs for complete information.




Video Transcript for Demco Trailer Brakes 42029 Review

Today were going to review part number 42029. This is the Demco Free Backing 12 inch galvanized left hand side brake assembly. This brake assembly is designed for a marine application, does have the galvanized backing plate as you can see right here. Does used the stainless steel spring hardware, does have the plated wheel cylinder. This is a single survey design wheel cylinder, does have the riveted marine brake shoe as you can see that is recommended to you be use on marine application but it will work fine on a non-marine application also. This is the left hand assembly and that mean it will sit on the drivers side and the easiest to tell that is that this one happens to be marked but a lot of them will not be marked right or left.

The best way to tell if you look at the shoe, smaller shoe, and the primary shoe will always face the front of the trailer. The larger secondary shoe will face the rear of the trailer so this one will be in a left hand side, driver side assembly. This assembly does have a 3500 pound weight capacity so when you used with the right hand passenger side assembly. The pair will give you a 7000 pound capacity. When they say this is a 12-inch by 2-inch brake assembly what they are saying is the 12-inch measurement will be measured from the edge of the shoes directly across.

The diameter is going to be 12-inches and then width of the shoe as you can see will be 2 inches so that means its 12 by 2 brake assembly. Now, this thus use the 12 inch hub and drum and it does require a wheel size of 14 inches up to 16 inch wheel. You do want to make sure you use a five bolt, this is five bolt mounting pattern so you want to make sure you actually have use the five bolt mounting pattern. The mounting bolt we do sell separately. It does require periodic manual adjusting and the way you will do that is that if you look on the back here you will see this rubber plug at the bottom and the two adjustment hole.

You can pull out the rubber plug and then use a screwdriver or a brake adjustment tool to reach the star wheel at the bottom here and you can turn the star wheel whichever way it needs to go to its either let the shoes out or bring them in. You just have to do that periodically. This is a free backing design of brake assembly and a free backing design brake would need to be use anytime your trailer has a surge coupler that does not have a reverse lock out feature so when your trailer is attached to your tow vehicle and youre backing up the brakes should be applied you wont be able backed up much. You do need to have a trailer that the brakes will be released on. For your surge coupler does not have a lock reverse lockout feature we do recommend using the free backing brakes.

The free backing brake assembly will work and the way you could tell this is a free backing assembly is if you look at the front primary shoe it would be sort of D-shape to it as supposed to regular brake assembly that will have the crescent shape to it. Free backing would have the D-design and this would be in the front and this is the primary shoe so what happens is the front primary brake shoe when youre backing up will back away from the drum and let the trailer roll free when youre backing up. It will reduce the braking power or give you a minimal braking power in reverse. Youll just have to remember that when you do that to your tow vehicles brake will be carrying more of the load when backing up but the way the free backing works, this is mounted on the driver side or the left side and when youre going forward the tire wheel will be rotating this way. When your brakes you spread or applied and spread out to stop the drum the spring is actually compressed the shoes will operate normally. When youre going in reverse which means the tire wheel will be rotating this way this primary shoe would go out to apply the brake and it be pulled around by the wheel and tire rotating when it pulled at this way is going to pull on the spring and theres actually I can try to show you theres a spring here and theres actually one back here, there are two springs.Well, those two springs will have more tension on them that will overcome the pressure of the cylinder when youre applying the brake. Those two springs will actually pull that shoe away from your hub, your brake drum. That way the brakes wont be fully applied very minimal pressure, thats the way of free backing brake assembly would work on your trailer. And that should do it for the review on part number 42029 the Demco Free Backing 12 inch galvanized left hand side brake assembly. .


Customer Reviews

Demco Hydraulic Drum Brake Assembly - Free Backing - Galvanized - 12" - Left Hand - 7,000 lbs - 42029

Average Customer Rating:  4.8 out of 5 stars   (17 Customer Reviews)

Free-backing, driver's-side trailer brake assembly won't engage when you reverse, even if your hydraulic actuator is activated. Galvanized steel resists rust, making the assembly great for boat trailers. Mounting flange has 5-bolt pattern.

- 42029
by:

Fit great. Nice quality. No issues at a ll. 641062



- 42029
by:

No problems, the brakes came in on time and were as described. 564397



- 42029
by:

Good experience all around. Product shipped quickly and bolted right up. Problem solved. 521990



- 42029
by:

One year of service on boat trailer and no problems. Very satisfied with quality and technical help. 342309



- 42029
by:

Good comunication. Great products at a very reasonable price. Very helpful and pleasant to deal with. Thx Jim 300074



- 42029
by:

Product looks great, fit like a glove. Haven't tried with boat on the trailer, but everything worked perfectly with trailer empty. Wont take boat out of water till September, may know more then. 245865



- 42029
by:

Installed easy. No problems. 208750



- 42029
by:

I ordered the assemblies on Thursday expecting their delivery on Monday or Tursday but to my great surprise UPS delivered them on Friday. The salesperson I worked with, Karen was knowledgeable and courteous, simply fantastic. The new assemblies fit perfectly as simply as changing a pair of shoes. Thank you eTrailer. 189070



- 42028
by:

Review from a similar Demco Demco FreeBack 12 Inch in Accessories and Parts


Quality parts. Fit great! Received shipment on time. I am buying more trailer parts from etrailer right now. 641061



- 42028
by:

Review from a similar Demco Demco FreeBack 12 Inch in Accessories and Parts


No problems, the brakes came in on time and were as described. 564504



- 42028
by:

Review from a similar Demco Demco FreeBack 12 Inch in Accessories and Parts


Good experience all around. Product shipped quickly and bolted right up. Problem solved. 522156



- 42028
by:

Review from a similar Demco Demco FreeBack 12 Inch in Accessories and Parts


One year of service on boat trailer and no problems. Very satisfied with quality and technical help. 340103



- 42028
by:

Review from a similar Demco Demco FreeBack 12 Inch in Accessories and Parts


Good product fit perfectly. Trailer stops great again 315257



- 42028
by:

Review from a similar Demco Demco FreeBack 12 Inch in Accessories and Parts


Good comunication. Great products at a very reasonable price. Very helpful and pleasant to deal with. Thx Jim 300072



- 42028
by:

Review from a similar Demco Demco FreeBack 12 Inch in Accessories and Parts


They are holding up pretty well. Rust on the star adjusters have rendered them useless. The hubs only show a little rust on the exterior, but substantial rust on the interior. I believe I purchased a set of submersible trailer lights from you a few years ago. The lasted about a year and the LED lights started burning out. About half of them are now functioning. I would rate them as poor. Thank you. 242504



- 42028
by:

Review from a similar Demco Demco FreeBack 12 Inch in Accessories and Parts


Great product, price. Easy to install complete backing plate vs. brakes and new hardware. 202345



- 42028
by:

Review from a similar Demco Demco FreeBack 12 Inch in Accessories and Parts


I replaced the complete brake system on my trailer. I watched the video for install and proper adjustment. I completed my first trip to Florida and back to Maryland trouble free. 2263 miles The brakes adjust easily, and stop well. They are well made and easy to install. 159952


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Ask the Experts about this Demco Accessories and Parts

Do you have a question about this Accessories and Part?


  • Availability of Corrosion Resistant Brake Assemblies for Boat Trailer
  • Because electric brake assemblies like the etrailer.com self adjusting brake assembly part # AKEBRK-7L-SA are not typically used for boat trailers, the assemblies are not specially coated for saltwater corrosion resistance. Boat trailers usually use hydraulic brakes, and would use a hydraulic brake assembly like part # 42029 and # 42028. These assemblies are galvanized for corrosion resistance. To convert to hydraulic brakes, you would need a hydraulic coupler/actuator like part...
    view full answer...

  • Comparing Demco and Titan 12 x 2 Inch Hydraulic Drum Trailer Brakes
  • The difference in price, besides being from two different manufacturers, is the materials. Demco assembly # 42028 is galvanized steel. Titan assembly # T4489600 is Galphorite plated steel. So you could say that a galvanized material is superior to a plated one though the Galphorite is certainly a fantastic product. It also has a better warranty. The matching Titan right hand side assembly is # T4489500. Other than that there isn't a reason why you couldn't use either one provided they...
    view full answer...

  • Demco Hydraulic Brake Line Kit # DM5426 for Use on 1993 Calkins Trailer in a Marine Environment
  • I have confirmed with my contacts at Demco, that the Demco Hydraulic Brake Line Kit # DM5426 is coated with a galvanized finish. With the additional galvanized finish, it provides the additional corrosion resistance that you are looking for compared to steel brake lines. This brake line kit is also 3/16 of an inch in diameter, and is designed for use on single axle trailers. This kit includes lines and fittings needed to run brake fluid from your surge brake actuator to the trailer...
    view full answer...


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Info for this part was:

Updated by:
Laura H

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