M/T Mainshaft Thrust Clearance Adjustment (5MT)

M/T Mainshaft Thrust Clearance Adjustment

Special Tools Required
Mainshaft base (  07GAJ-PG20130)

Mainshaft collar (  07GAJ-PG20120)
Mainshaft holder (  07GAJ-PG20110)

1.Remove the 72 mm shim (A) and oil guide plate M (B) from the transmission housing (C).


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


3.Install the washer (H) on the mainshaft.

4.Measure distance (1) between the end of the transmission housing and washer with a straight edge and vernier caliper. Measure at three locations and average the reading.

5.Measure distance (2) between the end of the clutch housing (A) and bearing inner race (B) with a straight edge and depth gauge. Measure at three locations and average the readings.


Shim Selection Formula:

6.Select the proper 72 mm shim from the chart. Follow the example below, and use the measurements you made in steps 4 and 5:

(Basic Formula)
(1) + (2) - (0.75 + 0.11) = shim thickness (maximum) 
(1) + (2) - (0.75 + 0.18) = shim thickness (minimum) 

  • Add distance (1) (step 4) to distance (2) (step 5).
  • 0.75 mm (0.029 in): Spring washer, a dimension in the installation.
  • 0.11 mm (0.004 in): Minimum thrust clearance.
  • 0.18 mm (0.007 in): Maximum thrust clearance.

(For example)
2.41 + 0.22 - (0.75 + 0.11) = 1.77 mm (0.070 in.) 
2.41 + 0.22 - (0.75 + 0.18) = 1.70 mm (0.067 in.) 

7.Take the middle value of the minimum value and the maximum value, and select shim of 1.74 mm (0.069 in).

72 mm Shim
 Part Number Thickness 
23931-P21-000 0.60 mm (0.0236 in.) 
23932-P21-000 0.63 mm (0.0248 in.) 
23933-P21-000 0.66 mm (0.0260 in.) 
23934-P21-000 0.69 mm (0.0271 in.) 
23935-P21-000 0.72 mm (0.0283 in.) 
23936-P21-000 0.75 mm (0.0295 in.) 
23937-P21-000 0.78 mm (0.0307 in.) 
23938-P21-000 0.81 mm (0.0319 in.) 
23939-P21-000 0.84 mm (0.0331 in.) 
23940-P21-000 0.87 mm (0.0343 in.) 
23941-P21-000 0.90 mm (0.0354 in.) 
23942-P21-000 0.93 mm (0.0366 in.) 
23943-P21-000 0.96 mm (0.0378 in.) 
23944-P21-000 0.99 mm (0.0390 in.) 
23945-P21-000 1.02 mm (0.0402 in.) 
23946-P21-000 1.05 mm (0.0413 in.) 
23947-P21-000 1.08 mm (0.0425 in.) 
23948-P21-000 1.11 mm (0.0437 in.) 
23949-P21-000 1.14 mm (0.0449 in.) 
23950-P21-000 1.17 mm (0.0461 in.) 
23951-P21-000 1.20 mm (0.0472 in.) 
23952-P21-000 1.23 mm (0.0484 in.) 
23953-P21-000 1.26 mm (0.0496 in.) 
23954-P21-000 1.29 mm (0.0508 in.) 
23955-P21-000 1.32 mm (0.0520 in.) 
23956-P21-000 1.35 mm (0.0531 in.) 
AA 23957-P21-000 1.38 mm (0.0543 in.) 
AB 23958-P21-000 1.41 mm (0.0555 in.) 
AC 23959-P21-000 1.44 mm (0.0567 in.) 
AD 23960-P21-000 1.47 mm (0.0579 in.) 
AE 23961-P21-000 1.50 mm (0.0591 in.) 
AF 23962-P21-000 1.53 mm (0.0602 in.) 
AG 23963-P21-000 1.56 mm (0.0614 in.) 
AH 23964-P21-000 1.59 mm (0.0626 in.) 
AI 23965-P21-000 1.62 mm (0.0638 in.) 
AJ 23966-P21-000 1.65 mm (0.0650 in.) 
AK 23967-P21-000 1.68 mm (0.0661 in.) 
AL 23968-P21-000 1.71 mm (0.0673 in.) 
AM 23969-P21-000 1.74 mm (0.0685 in.) 
AN 23970-P21-000 1.77 mm (0.0697 in.) 
AO 23971-P21-000 1.80 mm (0.0709 in.) 

8.Install the 72 mm shim (A) selected and oil guide plate M (B) in the transmission housing (C).


9.Throughly clean the spring washer (A) and washer (B) before installing them on the clutch housing side ball bearing (C). Note the installation direction of the spring washer.


10.Install the mainshaft in the clutch housing.

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

12.Tighten the clutch and transmission housings with several 8 mm bolts.

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

13.Tap the mainshaft with a plastic hammer.

14.Slide the special tools over the mainshaft (A).


15.Attach the special tool 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¢s lip around the groove at the inside of the mainshaft splines, then tighten the hex bolts.


16.Seat the mainshaft fully by tapping its end with a plastic hammer.

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

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


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

Do not turn the mainshaft holder bolt more than 60 degrees after the needle of the dial gauge stops moving, this may damage the transmission.

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

Standard: 0.11-0.18 mm (0.004-0.007 in.)