Trailer Disc Brake Conversion with DeeMaxx: Which Kit Fits Your Axle

Converting a trailer from drum brakes to hydraulic disc brakes starts with one question: which kit matches the axle under your trailer? DeeMaxx builds its conversions for axles rated 3,500 to 8,000 lb and sells them three ways, from a complete master kit for a tandem or triple-axle trailer down to a single wheel end. This guide covers each kit type, what comes in the box, and the axle details to confirm before you order. The full range is in our DeeMaxx collection.

Three ways to buy a DeeMaxx conversion

Master kits: MK-TA (tandem) and MK-TR (triple)

A master kit is the whole conversion in one order. Each tandem kit (MK-TA) includes an EOHA1600 actuator, the DOT-TA20K tandem brake line kit and 4 single-wheel 1/DBI kits, one for every wheel. Each triple kit (MK-TR) steps up to the larger EOHA1600XL actuator, the DOT-TR20K triple brake line kit and 6 single-wheel kits. All master kits are MAXX coated.

Weights are DeeMaxx’s listed figures for the complete kit. There is no 8KA (Al-Ko/Quality) master kit in our DeeMaxx range, so for those axles you build the set from single-wheel kits.

One-axle kits (DBI)

A DBI kit covers both wheels of one axle. DeeMaxx lists each set as the integral rotor/hub, caliper and caliper bracket: DBI-3.5K-MAXX, for example, pairs the RTR/HUB-102-MAXX rotor/hub with the CALP-3-6K-MAXX caliper and the DBB-3.5KI-MAXX bracket. One-axle kits come in 3.5K and 6K, in MAXX, MAXX-SS (MAXX rotor/hub and bracket with a stainless steel caliper and stainless pads) and MECH/MAXX versions. MECH/MAXX uses mechanical/hydraulic calipers with a parking-brake lever, such as DBI-6K-MECH/MAXX. If you want bearings, seal, cap, lug nuts and bracket hardware itemized in the box, the single-wheel kits list all of them. The actuator and brake lines are separate with a DBI kit.

Single-wheel kits (1/DBI-…-KIT)

A 1/DBI kit is one complete wheel end, so you order 2 per axle. It is the only format offered at every axle rating, including 8K Al-Ko/Quality. Every 1/DBI kit includes the rotor or rotor/hub, caliper, caliper mounting bracket, inner and outer bearings, grease seal, dust cap (or a screw-in hub cap on threaded hubs), bracket bolts and nuts, lug nuts and a rubber plug. Here is what is in 1/DBI-7K-MAXX-KIT, which weighs 58 lb:

• RTR/HUB-131-7K-MAXX: 13.1" integral rotor/hub, 8 lug, 1/2" wheel studs
• CALP-7-8K-MAXX caliper and DBB-7K-MAXX bracket
• 25580 inner and 14125A outer bearings, 2250DL grease seal, TRP-DC-275L dust cap
• 5 bracket bolts with nuts, 8 lug nuts and the rubber plug

Choosing by axle rating and bolt pattern

The axle rating sets the rotor size, caliper and bracket. The lug count and stud size have to match your wheels. This is how the MAXX single-wheel kits line up:

For bolt pattern, DeeMaxx’s galvanized hubs and stainless slip-over rotors list 5 on 4.5" at 3.5K, 6 on 5.5" at 6K and 8 on 6.5" at 7K and 8K. The integral MAXX rotor/hub listings give the lug count only, so measure your wheels before ordering.

Check the brake flange too. The DBB-7K-MAXX bracket is for a 7K axle with a 5-bolt brake flange. At 6K, DeeMaxx makes an open-style bracket (DBB-6K-MAXX, used in the 6K MAXX kits) and a closed 5-bolt bracket (DBB-6KC-MAXX); both mount to a 5-hole brake flange.

Stud size and oil-bath vs grease hubs

At 7K and 8K, the part number tells you the stud size and hub type:

• No stud code (7K): 1/2" studs on a non-threaded rotor/hub, closed with a dust cap.
• 9T: 9/16" studs on a threaded rotor/hub, as in 1/DBI-7K-9T-MAXX-KIT.
• 10T: 5/8" studs on a threaded rotor/hub.

The threaded rotor/hubs have a 2-7/8"-12 oil thread and take the AT-6-8K-LC Lexan screw-in cap with a Viton O-ring, which DeeMaxx lists for oil bath or grease. Every 9T and 10T kit includes one in place of a dust cap. On DeeMaxx hub part numbers, T means threaded and NT means non-threaded: the RTR/HUB-131-8KNT rotor/hubs are the non-threaded grease versions, sold as separate parts rather than in kits. One detail worth knowing: the 7K-9T kit uses the same 8K threaded rotor/hub as the 8K 9T kits, paired with the 7K bracket.

Dexter/Lippert (8KD) vs Al-Ko/Quality (8KA)

At 8K, the bracket has to suit the axle brand. 8KD kits are for Dexter/Lippert 8K axles and use the DBB-8KD-MAXX bracket, listed for Dexter hub numbers 008-399-05 to 08. 8KA kits are for Al-Ko/Quality 8K axles and use the DBB-8KA-MAXX bracket. Beyond the bracket, the two share the same rotor/hub, CALP-7-8K caliper, bearings and hardware. Both come in 9T and 10T, in MAXX or MAXX-SS: see 1/DBI-8KD-10T-MAXX-KIT and 1/DBI-8KA-10T-MAXX-KIT.

The 8KDD kits (1/DBI-8KDD-9T-SS-KIT and 1/DBI-8KDD-10T-SS-KIT) are the full stainless option for Dexter 8K axles: a stainless slip-over rotor on a galvanized threaded hub, with the DBB-8KDD-SS bracket.

MAXX coating vs stainless

• MAXX: DeeMaxx’s MAXX corrosion-resistant coating on the rotor/hub, caliper and bracket. The rotor and hub are one integral part.
• MAXX-SS (written MAXX/SS on the 3.5K and 6K single-wheel kits): the MAXX rotor/hub and bracket with a stainless steel caliper and stainless steel pads.
• SS: full stainless for marine and salt exposure. SS kits use a stainless slip-over rotor (10.9" at 3.5K, 12" at 6K, 13.1" at 7K and 8K) on a separate galvanized hub, with a stainless caliper and bracket.

Stainless adds weight. Single-wheel kits weigh 32 lb (MAXX) vs 37 lb (SS) at 3.5K, 38 lb vs 45 lb at 6K, and 58 lb vs 62 lb at 7K, as with 1/DBI-7K-SS-KIT. SS single-wheel kits are offered at 3.5K, 6K, 7K, 7K-9T and 8K Dexter (8KDD). Master kits are MAXX only.

What else you need

A master kit already includes the actuator and brake lines. With DBI or 1/DBI kits, add them yourself:

• EOH actuator. Disc brakes use the 1,600 psi models: EOHA1600 for single or tandem axles, or EOHA1600XL with 28.7 fl oz of fluid capacity for triple axles or more. The 1,000 psi EOHA1000 is designed for hydraulic drum brakes.
• Brake line kit. DOT-SA18K (18' single axle), DOT-TA20K (20' tandem) or DOT-TR20K (20' triple), each with flex lines, brass fittings, clamps and axle tie straps.
• Service parts. Replacement pad sets come in ceramic, semi-metallic and stainless steel for both the 3-6K and 7-8K calipers, and CALP-GREASE-10 is DeeMaxx’s MAXX Glide silicone caliper grease.

DeeMaxx galvanized hubs, hub caps and lug nuts are also sold separately. For the wider range, browse brakes and suspension.

How to read a DeeMaxx part number

• MK-TA / MK-TR: master kit for a tandem or triple-axle trailer.
• DBI: one-axle set. 1/DBI-…-KIT: one wheel end.
• 3.5K, 6K, 7K, 8K: axle rating, 3,500 to 8,000 lb.
• 8KD / 8KA / 8KDD: Dexter/Lippert, Al-Ko/Quality, or Dexter with a slip-over rotor (the stainless 8K Dexter kits).
• 9T / 10T: 9/16" or 5/8" wheel studs on a threaded (oil-bath) hub.
• MAXX, MAXX-SS, SS: finish. MECH: mechanical/hydraulic caliper with parking-brake lever. 6KC: closed bracket.
• RTR slip-over rotor, RTR/HUB integral rotor/hub, CALP caliper, DBB disc brake bracket, EOHA EOH Alpha actuator.

So 1/DBI-8KD-10T-MAXX-KIT reads as: one wheel end, 8K Dexter/Lippert axle, 5/8" studs on a threaded hub, MAXX coating.

Fitment checklist

1. Axle rating: 3.5K, 6K, 7K or 8K.
2. Number of axles: 1 (two 1/DBI kits, or one DBI at 3.5K and 6K), 2 (MK-TA) or 3 (MK-TR).
3. Lug count and bolt pattern: 5, 6 or 8 lug.
4. Wheel stud size: 1/2", 9/16" or 5/8".
5. Hub type at 7K and 8K: non-threaded with a dust cap, or threaded for the 2-7/8"-12 screw-in cap.
6. Brake flange, and at 8K the axle brand: Dexter/Lippert or Al-Ko/Quality.
7. Bearings: compare yours with the kit’s, for example 25580 inner with 14125A outer at 7K, or 25580 with 02475 at 7K-9T and 8K.
8. Finish: MAXX, MAXX-SS or full stainless.
9. Actuator and brake line kit, if you are not buying a master kit.

Not sure about any of these? Contact us with your axle rating, bolt pattern and a photo of the brake flange, and we’ll help match the kit.

Specifications are DeeMaxx’s published figures. Confirm your axle rating, bolt pattern and brake flange before ordering.