bing tracking image
  1. Trailer Brakes
  2. Dexter
  3. Hydraulic Drum Brakes
  4. 2500 lbs Axle
  5. 7 x 1-3/4 Inch Drum
  6. 10 Inch Wheel
  7. 12 Inch Wheel
  8. 13 Inch Wheel
Dexter Hydraulic Trailer Brake Kit - Uni-Servo - 7" - Left and Right Hand Assemblies - 2.5K

Dexter Hydraulic Trailer Brake Kit - Uni-Servo - 7" - Left and Right Hand Assemblies - 2.5K

Item # 23-398-399
Our Price: $209.72
Trailer Brakes
This item qualifies for Free Shipping
Shipping Weight: 10 lbs
Dexter 2500 lbs Axle Trailer Brakes - 23-398-399
zoom in icon
slider vertical icon
zoom out icon
Comment field cannot be left empty.
Name field cannot be left empty.

Thank you! Your comment has been submitted successfully. You should be able to view your question/comment here within a few days.

Error submitting comment. Please try again momentarily.

Product Images

Need help with installation?
Locate installers near me
7" x 1-3/4" Driver's-side and passenger's-side hydraulic trailer brake assemblies feature a single-plunger design. Mounting flanges have a 4-bolt pattern. Fit 10" to 13" wheels. Great Prices for the best trailer brakes from Dexter. Dexter Hydraulic Trailer Brake Kit - Uni-Servo - 7" - Left and Right Hand Assemblies - 2.5K part number 23-398-399 can be ordered online at or call 1-800-496-5010 for expert service.
  • All Info
  • Reviews (31)
  • Q & A (0)
  • Videos (1)
  • Photos
  • Why etrailer?

Dexter Trailer Brakes - 23-398-399

  • Hydraulic Drum Brakes
  • 2500 lbs Axle
  • 7 x 1-3/4 Inch Drum
  • 10 Inch Wheel
  • 12 Inch Wheel
  • 13 Inch Wheel
  • Boat Trailer
  • Camper
  • Car Hauler
  • Snow Trailer
  • Utility Trailer
  • Single Servo
  • Dexter

7" x 1-3/4" Driver's-side and passenger's-side hydraulic trailer brake assemblies feature a single-plunger design. Mounting flanges have a 4-bolt pattern. Fit 10" to 13" wheels.


  • Hydraulic drum brake assemblies are designed for use with a surge-type trailer brake actuator
  • Periodic manual adjustment required
  • Adjuster plugs (included) cover access holes to keep dirt and grime out of the assemblies and off of the shoes
  • Left-hand (driver's-side) brake assembly, right-hand (passenger's-side) brake assembly, mounting bolts, and nuts included
  • Made in the USA


  • Dimensions: 7" diameter x 1-3/4" wide
  • Mounting flange bolt pattern: 4 bolt
  • Wheel size: 10", 12", and 13"
  • Axle rating: up to 2,500 lbs

23-398 Dexter 7" Single Servo Hydraulic Brake Assembly - LH - 2.5K

23-399 Dexter 7" Single Servo Hydraulic Brake Assembly - RH - 2.5K

Video of Dexter Hydraulic Trailer Brake Kit - Uni-Servo - 7" - Left and Right Hand Assemblies - 2.5K

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

Video Transcript for Dexter Axle Trailer Brakes - Hydraulic Drum Brakes - 23-398-399 Review

Male speaker: Today, we're gonna take a look at the Dexter 7-inch hydraulic trailer brake kit, with the left- and right-hand brake assemblies for 2500-pound axles. Now, hydraulic drum brake assemblies are designed to use with surge-type trailer brake actuators. These assemblies are manual adjustment brakes, so they do require a periodic manual adjustment. Right down here is your adjustment gear, where you'd adjust them. On the backing plate, there's an access hole at the bottom that you put your tool through to do your adjustment. What's nice on these brakes, if you notice, they have an adjuster plug that goes in there when you're not using it, so that hole's covered up.

It keeps any dirt and grime from getting into your brake assembly and off your brake shoes. This part number will include both the left-hand driver's side, right-hand passenger's side brake assemblies. You can notice all the mounting nuts are included to install it. The dimensions on these assemblies is 7-inch diameter by 1 3/4-inches wide, and the size on that, the 7 inches of diameter would be from this shoe all the way over to that shoe. So if we put the ruler on, there's your 7-inch diameter. The 1 3/4-inch width would be the width of the pad on the shoe.

There's the 1 3/4 inches. If you notice on the back, there's the four bolts. That's the mounting flange bolt pattern, is a four-bolt mounting flange, and again, there's your nuts that you'd install them with. Now, these assemblies do require the use of a 7-inch brake drum. The wheel size that'll fit on these is 10-inch, 12-inch, and 13-inch.

Again, these are designed for axles rated up to 2500 pounds. The last thing I wanted to show you is, how to tell the difference between the left-hand driver's side and right-hand passenger's side. On a new assembly of course, there'll be a sticker that'll tell you that, but if that sticker wasn't there, the easiest way to tell is you look at the length of the pad on the shoes. So this pad goes from here to here, this one's from here to here. This is a shorter pad, that's the longer pad. Shorter pad always faces the front of the trailer.

It tells you that this is the right-hand passenger's side assembly. If you go over to the other one, the pad goes from here to here. This one's from here to here. This is the shorter pad, this is the longer pad. Shorter one faces the front of the trailer. This is the left-hand driver's side assembly. That should do it for the review on the Dexter 7-inch hydraulic trailer brake kit with left- and right-hand brake assemblies for 2500-pound axles.

Customer Satisfaction Score:

Customer Reviews

Dexter Hydraulic Trailer Brake Kit - Uni-Servo - 7" - Left and Right Hand Assemblies - 2.5K - 23-398-399

Average Customer Rating:  4.7 out of 5 stars   (31 Customer Reviews)

7" x 1-3/4" Driver's-side and passenger's-side hydraulic trailer brake assemblies feature a single-plunger design. Mounting flanges have a 4-bolt pattern. Fit 10" to 13" wheels.


Their on time delivery was really Excellent ! I’m in gratitude to setup Hydraulic brakes to keep my load in order and safe from twisting. They exceeded the mark on ‘Prompt delivery’. However, I had to get the right spindle from another reseller; check that ‘a/16 is greater than road tolerance.

Seems like it was worth it. The installation took good care of providing an axle for the long distance.
Emanuel - 04/26/2022


I just received these breaks and have not had a chance to install them yet. etrailer was very helpful with returning of the wrong breaks and shipping the ones I need.The new order was very fast,looking forward to be installing them soon.


Perfect replacement for worn out parts.


Great job, it's exactly what I ordered & needed< Nick was great.


Fit perfectly arrived one day early anf the help from Terry was great


With what i have so far things look good


Everything works as it should, shoes move freely, nothing is binding, and it slid right into place of the old assembly. The brake line inlet is at a slight angle as opposed to straight in like my old one. Wasn’t a huge ordeal, but I did have reroute one of my lines to the other side of the axle.


Bought these for my snowmobile trailer. The studs lined up perfectly onto the brake plates. However, no lock washers were included, and the nuts were not locknuts. Further, when I added lockwashers the studs were too short and did not protrude beyond the tightened nut but instead were short by over 1/16 inch. Should work ok, but not ideal. Finally, the bleeder valves needed a 10mm socket or wrench, but the cap screw and the brake line were too close to allow access with either a socket or a wrench. Had to change them to bleeder valves with an 8 mm head.


The replacement brakes were used on a pontoon boat trailer. Installation was fairly simple. The only problem encountered was difficulty bleeding the brake lines due to tight spacing between the new brake bleeder and the existing flexible brake line. Brakes work great .


After trailing for a year, I have found real peace of mind. The brakes work perfect in the city and on long trips through the mountains. No more sliding through red lights. I am trailing a 21' pontoon boat.tandum axle. I highly recommend.


Really good quality, quick shipping,


parts fit as expected and are of a good visual quality. made installation of rebuilt trailers a breeze

Trailers are going strong no issues at all with the parts
Dave - 03/02/2020


Very Pleased

Quite happy
Brad - 09/29/2021
Very pleased. Good decision
Brad - 09/29/2021


Parts were exactly as I ordered, and came with good instructions. I will definitely use etrailer for any future towing needs.


Fast shipping and perfect fit!!


Seem well built bolted up nice. Would of liked some lock washers with the kit but I had some laying around. Installed quick.


perfect for me


Everything was delivered in 2 days during covid 19 lock down. I got exactly what I ordered and happy about the free shipping.
Customer service Was great and Alex went out of his way to find exactly what I need and also made other options that he thought would be best for my situation.


All parts fit great and delivered promptly . Hard to find 7” trailer brakes but they have a good selection of all sizes


Easy instal and great customer service


Excellent service


Great product, easy installation, no is sues.


Great servive



Show More Reviews

See what our Experts say about this Dexter Trailer Brakes

  • Is It Possible to Add Brakes to a Trailer that Never Had Them
    Sounds like you are looking to upgrade a trailer from having idler hubs to one that has brakes. There are several things to consider and determine to do this. If you check out the FAQ article I attached you will see exactly how to add brakes to a trailer that didn't have any. You will need to remove your hubs to either get the bearing numbers or spindle dimensions so that you can determine what hubs would fit your spindle. They aren't all the same.
    view full answer...
    Image 1 for
  • Replacement Hydraulic Brakes for Pop-Up Camper
    Brakes like the Dexter # 23-398-399 that are rated for 2,500 lbs have the capacity to work with 1,800 lb axles, but to get the right brakes you'll need to know your brake's mounting flange bolt pattern as well as your drum diameter. The aforementioned Dexter brakes will work if your trailer has a 4-bolt mounting flange and your drum is 7" diameter x 1-3/4" wide. I have added a link to a help article for you to check out what you need to know to add hydraulic drum brakes to your trailer...
    view full answer...
    Image 1 for
  • Can Replacement Parts Still Be Had for Atwood Hydraulic Braking Assemblies 84210
    The Atwood Hydraulic Braking Assemblies 84210 are no longer made so replacement parts for them are not easily found. If you wanted, you could scour the internet and you might have luck finding someone with replacement parts for these in stock. That said, I would have my doubts of this since they are very old and no longer produced so the best option would be to replace the assemblies for which we have the Dexter Hydraulic Trailer Brake Kit part # 23-398-399. If you were able to find the...
    view full answer...
  • New 7 Inch Brake Assemblies Leaking
    Where exactly is the leak? If it's on the back of the brake assembly, inboard of the wheel it's probably not the cylinder. The likelihood of two bad wheel cylinders right out of the box is pretty rare. A more likely cause would be bleeder screws that aren't completely tight, so that's where I'd start my search there. Also make sure that the brake line connection at the wheel cylinder is secure. If the leak is inside the brake drum, then it would indicate a faulty wheel cylinder which means...
    view full answer...
  • What Is The Bolt Pattern Of The Brake Mounting Bolts On Dexter Brake Kit 23-398-399?
    The 4 mounting bolts on the Dexter Hydraulic Trailer Brake Kit - Uni-Servo - 7" - Left and Right Hand Assemblies - 2.5K # 23-398-399 you were looking at are 2-3/4" apart on center or 4" apart when measured diagonally and will fit your brake mounting flange where the holes are 4" apart on center. Now I have not heard of an Atwood hub that has an I.D. of 6.810". Would you happen to be able to send me the part number on the hub so I can cross reference it and confirm which brakes it works...
    view full answer...
    Image 1 for
  • Correct Replacement for Atwood 7" x 1-3/4" Hydraulic Drum Brakes
    The correct replacement for Atwood 7" x 1-3/4" Hydraulic Drum Brakes is the Dexter Hydraulic Trailer Brake Kit part # 23-398-399. If you are having trouble removing the old brakes, I recommend applying heat but you can cut the nuts off worst case. Unfortunately, Atwood is no longer in business and there will be no replacement parts like the shoes etc. for this assembly.
    view full answer...
  • Can Brakes be Added to Trailer with Unknown Axle Capacity
    Since you have a torsion axle with an unknown capacity your best option is going to be to take off the hubs and get the bearing numbers out of them or get dimensions of the spindle where the bearings ride as that will tell us what components you'd need to pick out brake components. I also attached a help article that will walk you through the process as well.
    view full answer...
  • Uni-Servo Hydraulic Trailer Brakes For 7 Inch Drums
    There are hydraulic trailer brake kits for 7 inch drums; but there are no free-backing kits as those start at 10 inches and up. So you can get uni-servo hydraulic brakes, just not free-backing. The correct part for your 7 inch drums is the following: - Dexter Hydraulic Trailer Brake Kit - Uni-Servo - 7" - Left and Right Hand Assemblies # 23-398-399 The Dexter # 23-398-399 is rated for axles up to 2,500 lbs, and includes the mounting hardware for installation so you don't have to purchase...
    view full answer...
  • Availability of Replacement Wheel Cylinder for Atwood Hydraulic Brakes
    As you probably noticed Atwood is no longer in the actuator and brake assembly business so any spare parts are becoming extremely difficult to find. We do not currently have any replacement wheel cylinders that would work with your existing Atwood assemblies. The Dexter RH Wheel Cylinder # 54-80-4 that you referenced would unfortunately not be compatible. The only option I can offer, and really your best solution, is to replace the brake assemblies themselves. Even though your current...
    view full answer...
  • Recommended Dexter Brake Kit for 2500 lbs Dexter Axle
    For your 2500 lbs Dexter Axle you will want the Dexter Hydraulic Trailer Brake Kit # 23-398-399. These brake assemblies measure 7 inch x 1-3/4 inch, mount to a 4 bolt mounting flange, and are compatible with 10 inch, 12 inch, and 13 inch wheels. I have attached a review video that you can check out for more information. If your brakes are 10 inches x 2-1/4 inches, if you could let me know whether you have electric or hydraulic brakes I can look into those options as well. If you need...
    view full answer...
  • Replacement Brakes and Hubs for 1987 Moody Boat Trailer with 7 x 2-1/4 Hydraulic Brakes
    The 4-bolt mounting pattern of 7-inch brakes is the same as for 10-inch brakes; both use bolts/holes spaced apart by 2-7/8-inches on center. Moving to larger brakes will naturally require new hubs and these new hubs must use the same set of bearings and the same wheel bolt pattern as your current ones. Also note that larger brakes and drums will be compatible with different wheel diameters than your 7-inches brakes were. The free-backing 10-inch hydraulic brakes you referenced, kit # AKFBBRK-35-D...
    view full answer...
    Image 1 for
  • Bolt Spacing of Dexter 7 Inch Brake Drum/Brake Assembly
    If you're speaking of the wheel bolt pattern for the # 8-276-5 Dexter 2200 Brake Hub/Drum, it uses a 4 on 4 bolt pattern. If you're speaking of the # 23-398-399 brake assemblies you'd looked at, the wheel studs are 2-7/8 inches apart, center to center. I've provided a photo showing this.
    view full answer...
    Image 1 for
  • Dexter 7 x 1 3/4 Hydraulic Brake Assembly Kit
    The 7" x 1-3/4" Hydraulic Brake Shoe/Lining # bp04-050 is just the shoes for one wheel, however we do offer Dexter Hydraulic Trailer Brake Kit - Uni-Servo - 7" - Left and Right Hand Assemblies # 23-398-399 which is a complete left and right side kit that includes brake assembly, mounting bolts, and nuts. Unfortunately, we do not offer the hardware separately.
    view full answer...
  • Replacement Shoes for 7" Dexter Axle Hydraulic Drum Brakes
    The 7" x 1-3/4" Hydraulic Brake Shoe/Lining (One Wheel) # bp04-050 is designed to replace the shoes that come on the Uni-Servo Dexter Hydraulic Trailer Brake Kit # 23-398-399. This is the only 7" hydraulic brake assembly kit offered by Dexter Axle so if you have something that looks different then it may be an older brake assembly set - in which case I recommend replacing it altogether anyways to make sure everything is up to date and working properly. Another perk of updating your parts...
    view full answer...
  • Flexible Hydraulic Hose For Replacement Right-Hand Uni-Servo Wheel Cylinder 54-80-4
    The Dexter Replacement Right-Hand Uni-Servo Wheel Cylinder Assembly for 7" Brakes part # 54-80-4 is a replacement for Dexter Hydraulic Trailer Brake Kit - Uni-Servo - 7" - Left and Right Hand Assemblies part # 23-398-399. The Demco Hydraulic Brake Hose with Fittings has 1/8" fittings so they would not be compatible with the Dexter brakes. For the Dexter brakes you will need Dexter Hydraulic Flex Hose part # 18018-SF with a 3/8" fitting.
    view full answer...
  • How To Find the Correct Braking Assemblies and Hubs for a 1995 Jayco Eagle 10 ST
    Possibly, if there is an axle tag on your 1995 Jayco Eagle 10 ST then I can use this to determine the correct hubs and braking assemblies. If you know your axle capacity then that can be used as well but the axle tag is preferred. Based on the weight of your trailer, the Dexter Hydraulic Trailer Brake Kit part # 23-398-399 could work if your existing braking assemblies measure 7" x 1-3/4". The Dexter Trailer Hub and Drum Assembly part # 8-257-5UC3-EZ would then be a match for these and...
    view full answer...
  • Wheel Cylinder Assemblies for 7 Dexter Brakes
    The matching wheel cylinder for 7" brakes that pairs with the # 54-80-4 is the Wheel Cylinder Assembly Kit -LH # DA24FR. These are both of the parts you need to change both of the wheel cylinder assemblies on your 7" Dexter brakes. These cylinders will fit 7" brakes like the # 23-398-399.
    view full answer...
  • Trailer Brake Reverse Lockout Options Using 7" Hydraulic Trailer Brakes
    A reverse lockout will prevent the trailer brakes from activating when you reverse your trailer that has a surge brake style coupler. Certain surge couplers will allow you to use an electric Solenoid Valve like the # T4748800 that prevents hydraulic fluid from going to the brakes when you place your vehicle in reverse(Must have functioning 5-way or 7-way trailer connector). Other surge couplers will use a manual lockout like the Demco # DM5939 or Dexter # DX94FR. If you can let me know...
    view full answer...
  • Recommended Brake Kit For Fishing Holdings Single Axle Boat Trailer
    For your Fishing Holdings Trailer, I recommend the Dexter Hydraulic Trailer Brake Kit - Uni-Servo - 7" - Left and Right Hand Assemblies - 2.5K # 23-398-399. These can be used with the Dexter 4 on 4 Complete Hub-and-Drum Assembly - for Hydraulic Brakes - 2,200-lb Axles # 8-276-5UC3. This assembly is for spindles with measurements of 1.063 inches for the inner diameter of both the inner and outer bearing. I've attached an article to help you measure your spindles to confirm a bearing fit....
    view full answer...
    Image 1 for
  • Will 7 Inch Electric Brakes Replace 7 Inch Hydraulic Drum Brakes
    Yes, the Dexter Electric Trailer Brake Kit - 7" - Left and Right Hand Assemblies - 2,000 lbs # 23-47-48 will absolutely work as a replacement for the Dexter Hydraulic Trailer Brake Kit - 7" - Left and Right Hand Assemblies - 2,500 lbs # 23-398-399. The electric brakes measure 7" diameter x 1-1/4" wide so they are narrower than the 7" diameter x 1-3/4" wide hydraulic drum brakes, meaning they will fit in the drum; they also use the same 4-bolt mounting flange so you are set! Along with...
    view full answer...
  • Replacement Brakes for Unknown Dexter Axle on 1987 Fleetwood 5th Wheel Trailer
    For your braking assembly you will simply need to measure your hub diameter or the backing plate on your brake assembly and the thickness of your hubs. You will either need the Dexter Electric Trailer Brake Kit - 10" - Left and Right Hand Assemblies - 3,000 lbs # K23-472-473-00 that are 10 x 1-1/2 inches or the wider brake shoe assemblies # 23-468-469 that are 10 x 2-1/4 inches. If you have 7 inch assemblies, you will want # K23-103-104-00. If you have hydraulic brakes, you will either...
    view full answer...
  • Parts Needed to Add Hydraulic Brakes to Boat Trailer
    I may have a solution for you, but you would need to verify the bearings that are in the hubs that are currently on your trailer and the pattern of the brake mounting flange on your axle; if there is not a brake mounting flange present then you would either need to replace the axle completely or have a brake mounting flange welded on to the axle. You can purchase a brake mounting flange and have a qualified welder weld them to the axle. When a brake mounting flange is welded to an axle,...
    view full answer...
  • Correct Replacement Brakes and Hub/Drum Assembly for '97 Jayco Popup
    The difference between part # 8-276-5UC3 and part # 8-173-16UC3 is that the 5UC3 works with a 7" x 1-3/4" brake assembly while the 16UC3 works with a 7" x 1-1/4" brake assembly brake assembly. Other than that they use # L44649 inner and outer bearings and a 10-9 grease seal that has the 1.5" inner diameter. You definitely want to go with assemblies that match your bearings so if you're able to confirm that you have L44649 bearings then I'd use one of the options mentioned above. The GVWR...
    view full answer...
  • How to Determine Weight Rating of Dexter Trailer Axle
    The Dexter axle code P29 refers to the plant where it was made, plant 29, but this does not include capacity information. If you can find the complete serial number for the axle we can contact Dexter to find out more about it, particularly its weight rating. The 7 x 1-3/4-inch hydraulic brakes we offer, all shown on the linked page, are typically intended for axles rated for 2500-lbs, such as left- and right-hand brake kit # 23-398-399 from Dexter. For a new hub/drum we have 7 x 1-3/4-inch...
    view full answer...

< Previous

Do you have a question about this Trailer Brake?

  • Why

    At we guarantee:
  • Real product know-how.

    We make sure that the products we sell are what we say they are, and that they work the way they are supposed to work. Get real advice from a real person who has the knowledge and expertise needed to solve your problem.
  • Most detailed, accurate trailer brake information available.

    Because we take providing accurate product information seriously, we take our own detailed product photos, demo videos and installation videos, as well as verify measurements, instructions, and vehicle fit information.
  • Installations, made easy.

    We love helping people and have the most highly-trained customer service, hands-on experience, step by step videos and installation instructions.
  • Fast shipping.

    Your order is automatically routed to get out of our warehouse and to your door as quickly as possible. Receive free shipping on orders over $99.
  • Personalized service for life.

    We provide one-on-one, personalized service from the ordering process through the life of your product.
  • Trusted since 1946.

    We've been serving customers since our parts store first opened in 1946 and continue to be recognized by our customers, our vendors and third parties for exceptional service.
  • Returns Policy

    Need to return an item? No problem. Please read our Returns Policy for more information.

Info for this part was:

Employee Mike L
Expert Research:
Mike L
Employee Jameson C
Expert Research:
Jameson C
Employee Lindsey S
Edited by:
Lindsey S
Employee Jeff D
Installed by:
Jeff D
Employee Wilson B
Updated by:
Wilson B
Employee Alexander C
Written by:
Alexander C

At we provide the best information available about the products we sell. We take the quality of our information seriously so that you can get the right part the first time. Let us know if anything is missing or if you have any questions.