J Replace Rear Main Seal KA24DE RB20/ RB25 / RB26 / RB30

Oil dripping from the bellhousing after a clutch install is almost always the rear main seal. This J Replace rear main seal fits the Nissan KA24DE as well as the RB20, RB25, RB26 and RB30 engine family, and it is the part to have on the bench any time the transmission is separated from the engine, whether for a clutch, a flywheel or a full rebuild.

Engine Coverage

• Nissan KA24DE (S13 and S14 240SX)
• Nissan RB20DET and RB20DE
• Nissan RB25DET and RB25DE
• Nissan RB26DETT
• Nissan RB30

Why Replace It Preemptively

The rear main seal is cheap and the labor to reach it is not. Once the gearbox and flywheel are off, the seal takes minutes to replace; leaving an original seal in place and discovering a leak a month later means doing the whole job again. Most experienced builders replace it on principle during any clutch service on a KA or RB.

Installation Tips

Pry the old seal out without scoring the crankshaft flange or the seal bore. Clean the flange, lightly oil the new seal lip, and press it in square using a seal driver or a flat block so it seats evenly. Check the crank for a wear groove where the old lip ran; a sleeve may be needed if it is deep.

With limited availability and frequently increasing prices on new OEM parts, J Replace offers a quality alternative at a steady price.

Note: Legal only for use in competition vehicles which may never be registered, licensed, and/or used on public streets or highways, and also for use in other exempted vehicles.