U240E U241E Piston Kit

The U240E U241E Piston Kit is a bonded piston set used during overhaul and internal clutch repair of Toyota/Aisin U240E and U241E four-speed automatic transmissions. Alto’s piston catalog lists kit 145670 for U240E and U241E applications from 2000-on and identifies it as a six-piston set. The six pistons cover direct, forward and underdrive clutch apply and balance functions inside the transmission. Because some aftermarket suppliers also sell five-piece versions, customers should compare the actual kit contents and original transmission components before ordering.

This product is intended for professional transmission workshops, gearbox rebuilders, distributors and wholesalers. The U240E and U241E share many internal components, but production differences and supplier kit configurations can affect what is included. Clear photos of the original pistons or previous kit are useful when confirming the correct package.

U240E U241E Piston Kit Components

The U240E U241E Piston Kit commonly contains six molded or bonded piston components. Alto identifies the set as 145670 and lists the individual piston references 136300, 136301, 136304, 136305, 145300 and 145301.

These correspond to:

• 136300 – Direct Apply Piston
• 136301 – Direct Balance Piston
• 136304 – Forward Balance Piston
• 136305 – Forward Apply Piston
• 145300 – Underdrive Apply Piston
• 145301 – Underdrive Balance Piston

These numbers are aftermarket manufacturer references rather than one Toyota OE number for the complete kit. For that reason, a generic replacement piston set should not be advertised as Toyota genuine simply because it fits U240E or U241E transmissions.

Some transmission-parts catalogs also list five-piece bonded piston kits for U240E/U241E. This difference is important. The exact number of pistons can depend on the supplier, kit design and whether a particular piston is included separately. Stellar catalogs even show both five- and six-piston aftermarket configurations for this transmission family.

If your physical product contains six pistons, the Alto 145670 six-piece configuration is the better reference for the product page.

Bonded Piston Function

A bonded transmission piston combines a rigid piston body with an integrated sealing material. Hydraulic pressure acts on the piston and moves it against the corresponding clutch pack or balance chamber. The sealing surface must hold pressure while moving smoothly inside the clutch drum or bore.

The U240E U241E Piston Kit supports several internal hydraulic circuits. Direct, forward and underdrive clutch pistons help apply the clutch elements required for different operating ranges. Balance pistons help manage hydraulic forces and piston return behavior.

Heat, age, contaminated ATF and repeated pressure cycles can harden or damage the bonded sealing surfaces.

Possible symptoms related to piston sealing problems may include delayed engagement, slipping, flare during shifts, burnt clutch material or inconsistent shift quality. These symptoms do not automatically confirm piston failure. Valve-body wear, solenoid problems, damaged friction plates, worn drums or low hydraulic pressure can create similar symptoms.

U240E U241E Transmission Rebuild Inspection

During a U240E or U241E rebuild, technicians should inspect each piston for hardened rubber, cracks, torn sealing lips, deformation or damage. The clutch drums and piston bores should also be checked for scoring, wear and contamination.

Related components such as friction plates, steel plates, return springs, sealing rings, bushings and bearings should be inspected at the same time. If the transmission contains burnt friction material or metal debris, the cause of the failure should be corrected before installing a replacement piston kit.

Clean assembly conditions are important. Piston contact surfaces should be free from dirt and burrs, and suitable ATF or assembly lubricant should be used according to professional rebuilding procedures. Care should be taken not to cut or roll the bonded sealing lip during installation.

U240E and U241E Application Matching

The U240E and U241E are Toyota/Aisin four-speed automatic transmissions used in a range of Toyota, Scion and related applications. Alto catalogs list the U240E/U241E piston kit for 2000-on transmissions.

For accurate matching, customers can provide the transmission code, original piston photos, previous kit reference, vehicle information and required quantity. Physical comparison is recommended when the transmission has previously been rebuilt or contains mixed replacement parts.

Related U240E U241E Transmission Parts

We supply additional U240E and U241E transmission repair components, including overhaul kits, friction plate kits, steel plate kits, filters, solenoids, seals, gaskets, bearings and other automatic transmission parts.

Customers rebuilding a complete transmission can combine the piston kit with related overhaul and friction components in one order. Sending a parts list and clear original-product photos helps us confirm the required specification.

U240E U241E Piston Kit Wholesale Supply

We supply U240E U241E Piston Kit products to professional transmission workshops, rebuilders, distributors and wholesalers worldwide.

Contact us with the transmission model, original piston photos, kit quantity and required order volume for product matching, current availability and wholesale quotation.