M/T Mainshaft Thrust Clearance Adjustment

Special Tools Required
Mainshaft holder (  07GAJ-PG20110)

Mainshaft base (  07GAJ-PG20130)


1.Remove the 82 mm shim (A) from the transmission housing (B).


2.Install the ball bearing (A), 3rd/4th synchro hub (B), distance collar (C), 5th/6th synchro hub (D), distance collar (E), and ball bearing (F) on the mainshaft (G), then install the assembled mainshaft in the transmission housing (H).


3.Measure distance (1) between the end of the transmission housing and ball bearing with a straight edge and a depth gauge. Measure at three locations, and average the reading.

4.Measure distance (2) (the depth of the clutch housing) with a straight edge and a depth gauge. Measure at three locations, and average the reading.


Shim Selection Formula

5.Select the proper 82 mm shim from the chart. Follow the example below, and use the measurements you made in 3 and 4.

(Basic Formula)
(2) - (1) - (0.85 + 0.14) = shim thickness (maximum) 
(2) - (1) - (0.85 + 0.21) = shim thickness (minimum) 

  • Subtract distance (2) ( 4) from distance (1) ( 3).
  • 0.85 mm (0.033 in.): Spring washer, a dimension in the installation.
  • 0.14 mm (0.006 in.): Minimum thrust clearance.
  • 0.21 mm (0.008 in.): Maximum thrust clearance.

(For example)
21.04 - 17.97 - (0.85 + 0.14) = 2.08 mm (0.082 in.) 
21.04 - 17.97 - (0.85 + 0.21) = 2.01 mm (0.079 in.) 

Take the middle value 2.04 mm (0.080 in.) of the minimum value and the maximum value, and select the 0.93 mm (0.037 in.) and 1.11 mm ( 0.044 in.) shims.

NOTE: You may need to select two thicknesses of the 82 mm shim from the chart.

82 mm Shim
 Part Number Thickness 
23931-PR8-F00 0.60 mm (0.024 in.) 
23932-PR8-F00 0.63 mm (0.025 in.) 
23933-PR8-F00 0.66 mm (0.026 in.) 
23934-PR8-F00 0.69 mm (0.027 in.) 
23935-PR8-F00 0.72 mm (0.028 in.) 
23936-PR8-F00 0.75 mm (0.030 in.) 
23937-PR8-F00 0.78 mm (0.031 in.) 
23938-PR8-F00 0.81 mm (0.032 in.) 
23939-PR8-F00 0.84 mm (0.033 in.) 
23940-PR8-F00 0.87 mm (0.034 in.) 
23941-PR8-F00 0.90 mm (0.035 in.) 
23942-PR8-F00 0.93 mm (0.037 in.) 
23943-PR8-F00 0.96 mm (0.038 in.) 
23944-PR8-F00 0.99 mm (0.039 in.) 
23945-PR8-F00 1.02 mm (0.040 in.) 
23946-PR8-F00 1.05 mm (0.041 in.) 
23947-PR8-F00 1.08 mm (0.043 in.) 
23948-PR8-F00 1.11 mm (0.044 in.) 
23949-PR8-F00 1.14 mm (0.045 in.) 
23950-PR8-F00 1.17 mm (0.046 in.) 
23951-PR8-F00 1.20 mm (0.047 in.) 
23952-RAT-000 1.23 mm (0.048 in.) 
23953-RAT-000 1.26 mm (0.049 in.) 
23954-RAT-000 1.29 mm (0.050 in.) 
23955-RAT-000 1.32 mm (0.051 in.) 
23956-RAT-000 1.35 mm (0.052 in.) 
AA 23957-RAT-000 1.38 mm (0.053 in.) 
AB 23958-RAT-000 1.41 mm (0.054 in.) 
AC 23959-RAT-000 1.44 mm (0.055 in.) 

6.Install the 82 mm shim (A) selected in the transmission housing (B).


7.Throughly clean the spring washer (A) before installing it on the clutch housing (B). Note the installation direction of the spring washer.

8.Install the mainshaft in the clutch housing.

9.Place the transmission housing over the mainshaft and onto the clutch housing.

10.Tighten the clutch and transmission housings with several 10 mm bolts.

NOTE: It is not necessary to use sealing agent between the housings.

11.Lightly tap on the mainshaft with a plastic hammer.

12.Attach the special tools to the mainshaft as follows:

  • Back-out the mainshaft holder bolt (A), and loosen the two hex bolts (B).
  • Fit the holder over the mainshaft so its lip is towards the transmission.
  • Align the mainshaft holder lip around the groove at the inside of the mainshaft splines, then tighten the hex bolts.


13.Fully seat the mainshaft by tapping on its end with a plastic hammer.

14.Thread in the mainshaft holder bolt until it just contacts the wide surface of the mainshaft base.

15.Zero a dial gauge (A) on the end of the mainshaft.


16.Turn the mainshaft holder bolt (B) clockwise; stop turning when the dial gauge has reached its maximum movement. The reading on the dial gauge is the amount of mainshaft end play.

NOTE: Do not turn the mainshaft holder bolt more than 60 degrees after the needle of the dial gauge stops moving. Applying more pressure with the mainshaft holder bolt may damage the transmission.

17.If the reading is within the standard, the clearance is correct. If the reading is not within the standard, recheck the shim thickness.

Standard: 0.14-0.21 mm (0.006-0.008 in.)