Transmission rebuild: Gen4 JB74 Jimny M/T

I actually have yet to undertake this myself, so at this point it is simply so I can add in relevant useful details for those who need to rebuild a gen4 Jimny manual transmission. They are not the most complicated gearboxes to rebuild, but it’s worth having all of the various service limits on parts published.

Specifications

Sealant

Between case parts, Suzuki Bond 1217G (99000–31260) is to be used. See fluid cross referencing for suggestions, but this is essentially rebranded Threebond 1217G.

Shift fork specifications

All shift fork bushings that drive the synchronisers need to have shift pads between 7.7 and 7.9 mm thick

Synchroniser specifications

Key slot width for 1st gear synchro is 8.1 to 8.3 mm

Key slot width for 2nd gear synchro is 8.7 to 8.9 mm

Key slot width for 3rd/4th synchro is 9.5 to 9.7 mm

Key slot width for 5th gear synchro and reverse brake is 8.7 to 8.9 mm

Slots in the all of the synchro sleeves are to be 8.0 to 8.2 mm thick

Countershaft bearing clearance

The countershaft in the Jimny’s gearbox needs to maintain a degree of end clearance between it and the end case of the gearbox. Shims are available in 0.1 mm increments from 1.00 to 1.80 mm. The relevant clearance is between the bearing and where the shim sits on the countershaft. Shim sizing is as follows:

• 1.25 to 1.34 mm clearance: 1.00 mm shim
• 1.35 to 1.44 mm clearance: 1.10 mm shim
• 1.45 to 1.54 mm clearance: 1.20 mm shim
• 1.55 to 1.64 mm clearance: 1.30 mm shim
• 1.65 to 1.74 mm clearance: 1.40 mm shim
• 1.75 to 1.84 mm clearance: 1.50 mm shim
• 1.85 to 1.94 mm clearance: 1.60 mm shim
• 1.95 to 2.04 mm clearance: 1.70 mm shim
• 2.05 to 2.14 mm clearance: 1.80 mm shim