Honda B/D/K/L/R Transmission Differential Thrust Shim

Honda B/D/K/L/R Series Transmission Differential Thrust Shim

You're installing a Quaife, MFactory, or Wavetrac LSD in your transmission and someone told you about differential shims but you have no idea which one you need? Here's the deal, you won't know until the diff's installed and you've measured the gap with a feeler gauge. These OEM differential thrust shims sit on top of the oil seal in the transmission case under the final drive gear set. They control how much the differential can move up and down. Thicknesses range from 1.00mm to 1.80mm with part numbers from 41441-PL3-B00 to 41457-PL3-B00. Honda's spec is 0mm-0.10mm of clearance. If your gap's outside that range, you need a different shim or your transmission case is going to distort when you bolt it together.

Here's What Happens If You Skip This

The differential sits in bearings on both sides of the trans case. It's got to spin freely but it can't be flopping around. Too much play and the diff's bouncing around in there, the ring gear's not meshing cleanly with the pinion, and you're wearing everything out fast. Not enough clearance - shim's too thick - and the bearings bind up. Now the diff's not spinning smoothly and you're creating heat and friction. Worst case, the transmission case actually distorts when you torque the bolts down because the shim's forcing the bearings apart. That leads to leaks, binding gears, and premature bearing failure. The shim's cheap. The consequences of the wrong shim aren't.

Aftermarket LSDs Aren't the Same Size as Stock

Stock rebuild where you're reusing your factory open diff? You can probably reuse the shim that came out. But the second you're bolting in a Quaife, MFactory, Wavetrac, or even an OEM Type R diff, all bets are off. That aftermarket LSD's housing is a different thickness than stock. Maybe it's 0.03mm thicker, maybe it's 0.08mm. New bearings add more variance. Those tiny differences add up. You button up the trans with the old shim and either the diff's got too much slop or the bearings are binding. We've seen people install expensive LSDs and skip the shimming step. Six months later they're back with leaking transmission cases or the diff's making noise because the clearance was never set right. Same deal if you're swapping final drive gears. Different ring gear, different dimensions. Measure and shim it properly or you're doing the job twice.

How to Figure Out Which Shim You Need

Install the diff with the bearings and oil seal. Bolt the transmission case together. Use a soft mallet or driver handle to tap the diff down until it bottoms out in the bearing - you're making sure it's fully seated. Stick a feeler gauge in the gap between the shim and the bearing outer race. Honda says 0mm-0.10mm. Your gap's bigger than 0.10mm? Thicker shim. Can't get a feeler gauge in there? You might need a thinner shim or you're right at spec. You're aiming for as close to zero as possible without binding the diff. Some trans builders actually like to run 0.05mm-0.08mm of clearance with aftermarket LSDs because they've got looser tolerances than OEM diffs. As long as you can't feel any play when you grab the diff and try to move it, you're good.

What You Get

• One Honda OEM differential thrust shim (part number varies by thickness)
• Thicknesses from 1.00mm to 1.80mm in 0.05mm increments
• Sits on top of oil seal under final drive gear set
• Controls differential up-and-down movement (thrust)
• Critical when installing aftermarket LSDs or final drive gears

Fits These Transmissions

• 2013-2015 Acura ILX
• 1990-2001 Acura Integra
• 2017-2021 Acura NSX
• 2002-2006 Acura RSX Base/Type S
• 2004-2014 Acura TSX
• 2003-2012 Honda Accord (K24)
• 1992-1995 Honda Civic Si/EX
• 1996-2000 Honda Civic DX/EX/HX
• 1999-2000 Honda Civic Si
• 2001-2005 Honda Civic DX/EX/HX/LX
• 2002-2005 Honda Civic Si
• 2006-2011 Honda Civic DX/EX/LX
• 2006-2011 Honda Civic Si
• 2012-2015 Honda Civic DX/EX/LX
• 2012-2015 Honda Civic Si
• 2002-2006 Honda CR-V
• 2011-2016 Honda CR-Z
• 1988-1989 Honda CRX Si
• 1993-1997 Honda Del Sol S/Si/VTEC
• 2003-2010 Honda Element
• 2007-2020 Honda Fit

Note: Sold individually by thickness. Buy multiple shims when you're installing an LSD - three or four around 1.20mm-1.40mm - so you've got options when you measure. They're a few bucks each and cheaper than waiting for shipping while your trans is apart. Make sure the diff's fully seated before you measure or your measurement's garbage. This is separate from mainshaft thrust - if you're doing a full rebuild with an LSD, you're shimming both the diff and the mainshaft. Don't confuse the two.