Hi 12g sn3wco1360 This grader has 20k on the trans never been apart serviced 200hrs ago very clean ,pushing a heavy load started shuddering barely turning the wheels in 3hrd gear ,went to Cat checked pressures all in spec ,filter clean ,could it be just a case of old o rings cracking/failing leaking under load all other gears are fine
Possibly... clutches slip due to low hydraulic pressure or too much wear/damage from contaminants, or a combination of both. In theory 6th speed should have similar symptoms... What grade oil are you using?
With 20k on the trans the condition of the piston seals is probably something like glass.
TDTO 30 Cat
It sounds like all the bases have been covered, good oil, good pressures, clean filters. No clutch or torque converter to complicate anything. Sounds like a tranny-out fix to me. Looking at the table above, that #3 clutch is working it's butt off even when the machine's doing nothing.
The story grader went to Cat they checked the pressures screens ,filter ,suggested a rebuild . I asked if they checked the modulator cable was told it wont be that ,well got it floated home checked the modulator cable out of adjustment and streched fitted a new one adjusted ,went back to work no more problem
Thanks for the feedback Pedro. Sounds very strange if it was only faulting in 3rd gear.
3rd gears what we use so it was the most we experienced it at
My 74 12G has suddenly been losing 4th, after you get working it a couple hours. About 28K on it. makes me wonder if it's the same issue. Thanks for the post, I will have a look.