We'e Back To Working On The 8670 And 8770

You can look up the past threads where I'm trying to repair the 8670. The 8770 will be discussed also.
8670: Tractor has 13000 hours on it. valve stack on back rebuilt. Hydraulic couplings, repacked. Brake seals in both rear axles. At that time, we cleaned the filter in the bottom of the axle housing. It was clean. Both control modules sent off along with dash and gear shift circuit board. The control modules were bad. Yesterday my tech came and we pressure checked the reverse port. It was only 80#. The values of the C1 was 11, Rev was 63. Didn't record C2. But it was in the ranges per the service manual. All the screens in the valves were clean. Tractor has all gears, the shift smoothly. Its jerky in all forward and reverse gears. Makes no difference if the inching pedal is used or not. Clutch pedal, potentiometer. checks good. Also, no remote pressure and pto won't work. I welcome any and all input on this tractor.
The 8770 has 5700 hours on it. It has no reverse. It tries to back up but "slips". pressure on the reverse port was 120. It never changes with the position of the clutch pedal. C1 was 75, C2 was 44, Rev was 26. All screens in were clean. It does have remote pressure. Also, the dash will not show what gear you're in. It shows code F018 and FO 24. I plan on sending the control modules, gear shift circuit board and dash to AgExpress next week. As stated, I welcome any and all input on this tractor.
 
You can look up the past threads where I'm trying to repair the 8670. The 8770 will be discussed also.
8670: Tractor has 13000 hours on it. valve stack on back rebuilt. Hydraulic couplings, repacked. Brake seals in both rear axles. At that time, we cleaned the filter in the bottom of the axle housing. It was clean. Both control modules sent off along with dash and gear shift circuit board. The control modules were bad. Yesterday my tech came and we pressure checked the reverse port. It was only 80#. The values of the C1 was 11, Rev was 63. Didn't record C2. But it was in the ranges per the service manual. All the screens in the valves were clean. Tractor has all gears, the shift smoothly. Its jerky in all forward and reverse gears. Makes no difference if the inching pedal is used or not. Clutch pedal, potentiometer. checks good. Also, no remote pressure and pto won't work. I welcome any and all input on this tractor.
The 8770 has 5700 hours on it. It has no reverse. It tries to back up but "slips". pressure on the reverse port was 120. It never changes with the position of the clutch pedal. C1 was 75, C2 was 44, Rev was 26. All screens in were clean. It does have remote pressure. Also, the dash will not show what gear you're in. It shows code F018 and FO 24. I plan on sending the control modules, gear shift circuit board and dash to AgExpress next week. As stated, I welcome any and all input on this tractor.
On the 8670 I would suggest some very thorough pressure testing be done on the low pressure hydraulic system. You only have 80 PSI in reverse, that's way low. The same pump that serves the transmission also provides pressure for the PTO, diff lock, and transfer case circuits. If you only have 80 PSI at the trans and the PTO does not work, you either have a serious internal leak somewhere or else a problem with the pump or regulating valve.

I think on the 8770 I would not jump to any conclusions until you get the modules looked at and reinstalled.
 
When I had an 8240 it had some transmission problems. My recollection is that low readings meant leaking seals on a given clutch pack.
 
On the 8670 I would suggest some very thorough pressure testing be done on the low pressure hydraulic system. You only have 80 PSI in reverse, that's way low. The same pump that serves the transmission also provides pressure for the PTO, diff lock, and transfer case circuits. If you only have 80 PSI at the trans and the PTO does not work, you either have a serious internal leak somewhere or else a problem with the pump or regulating valve.

I think on the 8770 I would not jump to any conclusions until you get the modules looked at and reinstalled.
I got the 8770 modules back and put them in. We tried calibrating the transmission today. F1 was 62, F2 was 88, reverse would not calibrate. It would go to 99 and EL code would pop up. We're thinking the reverse clutch pack is bad. We'll be testing the 8670 tomorrow. We have pressure gauges hooked up.
 
Man!! I'm glad I left the AG tractor field in 1976. Power company equipment didn't get serious with electronics until the late 90s. Electra/mechanical, or hydraulic, were much easier to troubleshoot.
 

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