209 

 

Fill up accordingly 

Tighten the torque 

accordingly 

Buzz sound during driving at high speed 

Transmission oil viscosity, quantity 

Tightening torque at connection of 

transmission lever 

Meshing mark of differential gear ring 
and output shaft, and differential 
bearing abrasion 

Transmission cone bearing adjustment 

Transmission synchronizer, hub, cover, 

slide block 

Adjust according to 

standard gap 

Adjust or repair 

Repaiar or replace 

Normal 

Abnormal 

Abnormal 

Abnormal 

Abnormal 

Abnormal 

Normal 

Normal 

Normal 

 
 

 

 

210 

 

No.156 Transmission with abnormal sound while shifting   

Malfunction  

Causes 

Solution  

Clutch tie-line malfunction 

Clutch tie-line (improved version) having too small bending; while 
shifting, clutch sound introduced to cab via tie-line; replace old 
version of clutch tie-line;   

Check tightening torque at connections 
of gear shifting lever and transmission is 
too tightening, and rubber cover is not 
isolating vibration, making sound 
introduced to cab; 

Tighten connections of gear shifting lever and transmission 
according to standard torque;   

Synchronizer gear ring, hub, cover 
excessively worn or clearance 
incorrectly  

 Toothed ring of synchronizer is excessively worn. Clearance on 

①
the gear pressed by synchronizer ring is no less than 0.5mm. 
Specified value is between 0.85-1.45. Area of joint face of fifth-gear 
synchronizing ring and gear shall be larger than 80%; if lower, 
replace synchronizing ring;   

 

②

Check fit clearance of hub, cover, which shall be no obvious 

clearance while shaking from left to right. Hub shall be assembled 
within the cover freely. Joint part of cover and gear shall be 
triangular. Replace synchronizer assembly if damaged, worn, or its 
edge angle turning round; 

 Check height of slide block of synchronizer; if less than 5mm, 

③
replace slide block;   
 

Transmission 
with abnormal 
sound while 
shifting 

Transmission inner malfunction 

Transmission input, output shaft bearing, gear severely worn, or 
long-term impact causing burr at meshing of gear; replace damaged 
parts; 

 

 
 

 

 

211 

 

No. 157 Transmission gear disorder   

Malfunction Causes 

Solution 

Lock frame, pin of interlocks deformed or 
severely worn. 

Replace interlock ball, pin and spring of 
transmission  

Lower end of gear lever (automotive) is not 
sufficient in length, and working face of 
lower end greatly worn or fork, guide block 
greatly deformed, worn.   

Replace shift operation mechanism   

When clutch not fully separated, put 
into gear at start or shifting during 
driving; not switched to the gear 
needed; unable to return to neutral 
position after put into gear; put into 
two gears while vehicle is static.   

Location pin of gear lever ball head worn, 
loosening broken, or ball head, hole greatly 
worn. 

Replace gear lever assembly   

 

Transmission with abnormal sound while 

shifting 

Check clutch tie-line 

Check tightening torque at connection of 

transmission lever 

Check transmission synchronizer gear ring, hub, cover, slide block 

Check transmission gear, shaft and bearing, etc. 

Tighten 

accordingly 

Replace tie-line 

Replace damaged 

parts 

Replace 

Abnormal 

Normal 

Normal 

Normal 

Abnormal 

Abnormal 

Abnormal 

 
 

 

 

212 

Gear disorder 

 

Try to put into gear but 

cannot or try to shift down 

but cannot? 

Put into two gears at 
the same time? 

 

No 

Malfunction caused 
as shifting swing 
lever falls out from 
fork groove, such as 
severely worn lever 
or groove 

Malfunction caused by 
damaged locking 
device, such as 
severely deformed, 
worn lock pin, frame 

Interlocjing 

Put into different gear. Hold gear lever 
with hands and shake around. Check 
swing angle of gear lever (automotive) 

Swing or not 

But swinging angle of 
gear lever exceeds 
normal range 

Malfunction caused by 
broken or leaked 
location pin 

Malfunction caused by 
loosening mating of location 
pin and slot or severe abrasion 
of ball head and seat 

End 

Yes 

No

No 

Yes 

Yes 

No