What makes Allison high flow transmission coolers
so different from regular transmission coolers?
In the case of Allison transmission coolers, Size matters!


Most automotive duty transmission coolers use 5/16" & 3/8" cooler lines, tubes, fittings and barbs.
Those automotive coolers are designed for most cars & light duty pick-up truck transmissions applications.
But many commercial trucks, diesel motor homes and new GM Duramax diesel pick-up trucks use heavier duty Allison transmissions which require larger coolers and cooling lines to carry a much higher volume of transmission fluid.
Installing a lower volume transmission cooler on a Allison transmission can lead to back pressure, loss of lubrication, and transmission failure.

Our DB Series high flow coolers are designed to allow transmission fluid to enter by large (3/4" & 1" NPT) inlets,
flow slower through larger cooling tubes, and exit without major pressure drops.


TDI High Flow transmission coolers
  • Designed for rugged heavy duty use
  • Use with transmission, engine and hydraulic oils.
  • Working pressures up to 300 psi.
  • High flow Allison transmission cooler applications
  • Very conservative BTU rating system!
  • Flow ratings listed for normal transmission cooler psi.
  • BTU ratings at 1000FPM air speed @ 100 ITD temp.

  • If the Outside diameter (O.D.) of your Steel Cooling line is:
  • 5/8" O.D. or 3/4" O.D. use 3/4" fitting coolers with 5/8" I.D. TOC hose.
  • 7/8" O.D. & up to 1 1/8" O.D. use 1" fitting coolers with 7/8" I.D. TOC hose.
  • TOC (transmission oil cooler) hose is different than hydraulic hose!
    - Most hydraulic hose is rated for 212 degree
    - TOC hose is rated to 300 degree
    - Build your own hose assemblies with our Gates C5C field installable fittings.


  • Click on any link below for current prices and availability.
    High flow transmission coolers - 3/4" fittings
    Allison A1000, A2000, AT 540 & AT 640 series transmissions

    # DB-1268 High flow cooler - 3/4" fitting, 18.0 x 13.0 x 1.5 Overall size
    Flow range 4 - 20 GPM
    Heat rejection range 16,500 - 21,500 BTU/Hr

    # DB-1260 High flow cooler - 3/4" fitting, 24.0 x 13.0 x 1.5 Overall size
    Flow range 4 - 20 GPM
    Heat rejection range 22,000 - 31,000 BTU/Hr
    Includes (2) DB-515-B mounting kits

    # DB-1290 High flow cooler - 3/4" fitting, 24.0 x 19.0 x 1.5 Overall size
    Flow range 5 - 20 GPM
    Heat rejection range 31,500 - 42,500 BTU/Hr
    Includes (3) DB-515-B mounting kits

    # DB-1299 High flow cooler - 3/4" fitting, 24.0 x 22.4 x 1.5 Overall size
    Flow range 2 - 12 GPM
    Heat rejection range 26,500 - 45,000 BTU/Hr
    2 pass type cooler, lines are on opposite sides.
    Includes (3) DB-515-B mounting kits

    Allison transmission cooler

    # DB-515-B
    Mounting kit for High Flow Tube cooler


    Installs like this on each side of cooler.



    High flow transmission coolers - 1" fittings
    Allison AT 540, MT 640, HT 740 series transmissions

    # DB-1292 High flow cooler - 1" fitting, 24.0 x 25.4 x 1.5 Overall size
    Flow range 5 - 30 GPM
    Heat rejection range 39,000 - 56,500 BTU/Hr
    Includes (4) DB-515-B mounting kits

    # DB-2305 High flow cooler - 1" fitting, 24.0 x 31.4 x 1.5 Overall size
    Flow range 12 - 30 GPM
    Heat rejection range 47,000 - 68,000 BTU/Hr
    Includes (4) DB-515-B mounting kits

    # DB-515-B Mounting kit for High Flow Tube cooler (1 kit = 2 mounts)
    Order as many needed!
    2 rubber mounts, 2 brackets & 2 bolts.
    Isolates cooler from vibration and offers a secure mount. Special elastomer block installs in header holes (side tubes) and expands when tightened, for a secure hold.




    Allison transmission cooler

    # DB-515-B
    Mounting kit for High Flow Tube cooler




    High flow transmission coolers with Fans
    # DB-343DC-12 High flow - Fan cooler 3/4" fitting, 18 x 12.75 x 6.75 overall size
    Flow range 4 - 20 GPM
    Heat rejection range 15,100 - 19,700 BTU/Hr
    12 volt fan
    Hoses, couplers & thermostat sold separately.

    # DB-345DC-12 High flow - Fan cooler 3/4" fitting, 24 x 19 x 6.75 overall size
    Flow range 5 - 21 GPM
    Heat rejection range 22,900 - 31,100 BTU/Hr
    12 volt fan
    Hoses, couplers & thermostat sold separately.

    # DB-341DC-12 High flow - Fan cooler 1" fitting, 24 x 19 x 6.75 overall size
    Flow range 5 - 30 GPM
    Heat rejection range 22,700 - 33,000 BTU/Hr
    12 volt fan
    Hoses, couplers & thermostat sold separately.


    # DB-TCF180 In-line fan thermostat
    Screws in to a "T fitting" (customer supplied) in the Inlet side of the Fan Cooler.
    1/2" pipe thread on unit, activates at 180 +-
    Allison Fan coolers





    TOC hose = Transmission oil cooler hose

    A lot of hydraulic hose is being sold for use as Transmission Cooler Hose.
    But transmissions run hot, and using a inexpensive hose not rated for HOT transmission fluid use is asking for a premature failure.

    Gates C5C fleet / commercial duty hose 5/8" & 7/8" I.D.
  • Meets or exceeds all requirements of J1402 Type II applications
  • Fleet use Temperature range: Hot oil -40 to 300 F
  • Use with these C5 Field Attachable Couplings - No Special tools needed!
  • These Field Attachable - Reusable Couplings are DOT FMVSS 106-74 Type AII approved!
  • Reinforcement: One braid of high tensile carbon steel wire over one braid of polyester.
  • Cover: Black, oil and mildew resistant polyester braid.
  • Inner tube: black, oil resistant Nitrile - Type C

    # 16C5C-hose Transmission Oil Cooler hose, 7/8" id Commercial duty
    Sold by the foot! Order lengths as needed- Qty 3 = 3 ft., Qty 6 = 6 ft.
    Use with 16C5 Field Attachable Couplings
    7/8" hose ID, 1.23" OD, 800 psi Max working pressure



    12C5C-hose Transmission Oil Cooler hose, 5/8" id Commercial duty
    Sold by the foot! Order lengths as needed- Qty 3 = 3 ft., Qty 6 = 6 ft.
    Use with 12C5 Field Attachable Couplings 5/8" hose ID, 1.08" OD,
    1,500 psi Max working pressure


    We carry assorted fittings and hose couplings for the most common hose to cooler installations.
    Hose coupler, Female JIC 37 Flare Swivel
    Hose coupling, Female JIC 37 Flare 90 Swivel
    Hose coupling, Male 1" NPTF straight
    Hose coupling, Male 3/4" NPTF straight
  • Gates TOC Hose

    TOC hose fittings







    Installing Gates C5C Field Attachable Coupling in 5 easy steps.
    Be sure to start with the correct transmission Oil Cooler Hose and matching fitings.
    Gates 16C5 series fittings are designed to fit the 16C5C hose.
    Gates 12C5 series fittings are designed to fit the 12C5C hose.

    Gates hose fittings


    Water cooled - Transmission Oil Cooler assembly.

    This is totally different from all the other transmission coolers that use Air to cool the fluid.
    Water from the radiator flows around the sealed inner transmission cooler.
    This is a great low cost choice when you have an original external "water cooled" transmission cooler that is leaking.
    This is a aftermarket cooler designed to replace many original type coolers that are no longer being made.
    Designed to REPLACE existing water cooled coolers, NOT intended to be installed as a retro fit!

    Part # TDI-13680 - Transmission oil cooler ports are 3/4" npt
    Water cooling ports are 2.25"
    Heat duty ~up to 360,000 BTU/hr at 10 to 20 GPM flow rate
    Aftermarket replacement oil to water heat exchanger for many motor homes & large trucks.
    Overall length = 22.70" +-
    Cooler body width = 3.36" +- (excludes brackets)
    Overall height = 5.3" +-
    Mount bracket bolt holes = 9.75" +- / 5 3/4" +-
    oil to water heat exchanger for many motor homes & large trucks
    oil to water heat exchanger for many motor homes & large trucks

    Makco Distributing, Inc. - 101-B Business Centre Dr., Miramar Beach, FL 32550
    Phone 850-837-9800 - FAX 850-837-9801
    e-mail at sales@bulkpart.com