A750E Overhaul Kit 2002-2009

Rebuilding the five-speed automatic out of a two-wheel-drive 4Runner, Tacoma PreRunner, Tundra or Sequoia? This is the sealing kit that goes in every A750E teardown: a complete gasket set with sealing rings and seals, reference K86900CA, made in the United States and listed for the 2002 through 2009 model run. It is the right buy when the hard parts are healthy but the unit leaks, engages slowly when cold, or has lost pressure to tired rubber after years of towing and heat.

What the overhaul kit does in an A750E

The A750E is Aisin's electronically controlled five-speed for rear-wheel-drive Toyota trucks, with ratios of 3.52, 2.042, 1.40, 1.00 and 0.716 plus a 3.224 reverse. Every one of those gears is selected by hydraulic pressure that the ECM meters through solenoids in the valve body, then routes through the case, across rotating sealing rings and into clutch and brake pistons. This kit renews the parts that keep that oil where it belongs: the pan and case gaskets, the Teflon and metal sealing rings on the shafts, the lip seals on each piston and the O-rings at the pump and passages. It does not include friction plates, steels or a filter, so it is the correct kit for a reseal or for a rebuild where you are sourcing clutches separately.

Symptoms that point to worn seals

• A slow, soft engagement into Drive or Reverse on a cold start that sharpens up after a few miles
• Drips at the oil pan, the rear extension housing or the front pump area after the truck sits overnight
• Slipping or flare on upshifts with clean red fluid and no friction debris in the pan
• Fluid level that drops between checks with no visible external leak
• Shift or gear ratio codes that keep returning after the solenoids have already been replaced

How to confirm the seals are the cause

Drop the pan before you order anything. Red fluid with fine gray paste on the magnet is normal wear; black fluid, a burnt smell and loose friction material mean the clutches are finished too, and you should step up to a full kit. Then rule out the valve body. TransGo reports that 2003-and-newer A750 units commonly wear the line pressure boost valve and bushing, which leaves the transmission short on line rise under load and produces the same soft, slipping shifts and codes such as P0751, P0756 and P0894 that a leaking piston seal would. A line pressure test with a gauge separates the two. Our guide to Aisin slipping under load walks through that order of testing.

Fitment

The listing covers the A750E for 2002 to 2009. The E suffix is the two-wheel-drive version; four-wheel-drive trucks carry the A750F, which we stock as its own listing. In the United States the A750E arrived in the 2003 4Runner V8, joined the Sequoia for 2004, and spread to the V6 4Runner, V6 Tacoma and Tundra for 2005, so a 2002 date on the box reflects the catalog range rather than a 2002 truck. Toyota made running changes across those years, so lay each new gasket over the original during teardown, and if you want fit checked before you order, send us the year and VIN. Browse the rest of our A750 hard and soft parts on the Aisin transmission page.

Install notes

• Let the rubber piston seals soak in Toyota WS fluid while you clean the case, and use a smear of assembly gel to hold sealing rings centered as shafts slide into their bores.
• Air-check each clutch and brake circuit before the valve body goes back on; a steady hiss instead of a firm thump usually means a rolled lip seal.
• If the frictions are glazed, the A750E master rebuild kit adds clutches and steels to the seals.
• The valve body is already on the bench, so this is the time to address bore wear with the A750E shift kit for 2003-2007.
• Refill with Toyota WS only, set level at the overflow plug at operating temperature, and read our Toyota transmission service guide for why WS fluid matters on these trucks. Reset adaptives after the first drive.

What is in the K86900CA kit?

It is a gasket set with sealing rings and seals for the A750E and A750F. It does not include friction plates, steel plates or a filter, so buy those separately if the clutches are worn.

Will this fit my 2007 two-wheel-drive Tacoma V6?

The 2005-2015 V6 Tacoma 4x2 uses the A750E, and this kit is listed for 2002-2009. Compare the gaskets with your originals, or send your VIN and we will confirm before you order.

Does it also fit my 4x4?

Four-wheel-drive trucks use the A750F. The same seal set is catalogued for both versions, but we list the A750F kit separately so you can buy the one that matches your transmission tag.

Do I need a new filter with it?

Yes. A rebuild or reseal should always get a new filter, because debris from the old unit will otherwise circulate through the fresh seals and valve body.

Do I have to do a relearn after resealing?

Toyota stores shift adaptives in the ECM. Clearing them with a scan tool and driving through every gear gently lets the computer relearn fill times on the fresh seals.

• Aisin Slipping Under Load: Root Causes and Fixes
• Toyota Camry and Tacoma Transmission Service: What the Dealer Won't Tell You
• Adaptive Relearn After a Valve Body Swap or Rebuild
• Rebuild vs. Replace vs. Reman Transmission: How to Make the Right Call