Checked a D6N S/N AKM7** After it is warmed up and priority valve starts switching, it stops hard in first gear. Checked transmission solenoid pressure, they are not sticking. It does it when priority valve switches to low pressure, but second and third are fine. Clutch pressure on first gear clutch is good until it is decelerated and the pressure drops to about 130psi. Then when you switch low idle and priority valve switches pressure comes back up.
I have seen this before too. It shifts better at high rpm . It feels like the brakes come on during a shift. The later machines use an accumulator in place of the priority valve to get rid of the pressure drops. I have found that when you do a trans fill calibration you have to do it at as close to 1600 rpm as possible, higher rpm makes it worse. It is also affected by your clutch pressure calibrations. I would also recommend checking your priority valve pressure and setting in on low end of spec. I hope somebody has more answers for this too because I see it happen a lot even after setting everything .
I'll try that, thanks.
I have the same dozer with nearly the same serial number and it is having the same problem how did u fix it