Re: 42rh /a500 wont shift into third
[Re: ojcool]
#3272108
11/24/24 07:37 AM
11/24/24 07:37 AM
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ruderunner
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When it won't go into 3rd, does it stay in 2nd or go neutral?
Angry white pureblood male
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Re: 42rh /a500 wont shift into third
[Re: ojcool]
#3272200
11/24/24 04:19 PM
11/24/24 04:19 PM
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Joined: Jan 2003
Posts: 26,964 Rio Linda, CA
John_Kunkel
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Most likely a governor problem, only a gauge will tell. Could also be a weak front clutch problem...front clutch is also used in Reverse but at a much higher pressure
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Re: 42rh /a500 wont shift into third
[Re: ojcool]
#3272280
11/25/24 09:06 AM
11/25/24 09:06 AM
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Posts: 75,338 A gulag near you.
JohnRR
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Can you explain better not going into 3rd ??? Does it just wind up without making a shift staying in 2nd , or is the engine RPM racing up to limit ?? The way a 727 shifts is in all forward gears the rear clutch is always applied , this is first , 2nd the front band stops the front drum from spinning , 3rd is the front band releasing and the front clutch pack applying , if the front clutch pack doesn't apply the trans is back in 1st, the front band is not going to reapply until the vehicle slows enough for the governor circuit to make the front band reapply ... aka downshift.
I have never heard of the front band adjustment not allowing 3rd to happen , these shifts are hyd. controlled , if the valvebody sends fluid to the front clutch to apply and the band is so tight it's not releasing the vehicle is going to nose over like you stepped on the brakes.
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Re: 42rh /a500 wont shift into third
[Re: JohnRR]
#3272313
11/25/24 12:07 PM
11/25/24 12:07 PM
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Posts: 26,964 Rio Linda, CA
John_Kunkel
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if the front clutch pack doesn't apply the trans is back in 1st, Not necessarily...if there isn't enough governor pressure to move the 2-3 shift valve, it will stay in 2nd indefinitely. The only way it will drop back to 1st is if the 2-3 shift valve does move and releases the band but doesn't apply the clutch. Need to wait for OP's reply to see which it is. the front band is not going to reapply until the vehicle slows enough for the governor circuit to make the front band reapply ... aka downshift. Normally, when slowing to a stop, the trans drops from 3rd directly to 1st without applying the front band. Applying the front band on decel would cause an uncomfortable lurch.
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Re: 42rh /a500 wont shift into third
[Re: John_Kunkel]
#3272360
11/25/24 04:12 PM
11/25/24 04:12 PM
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JohnRR
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if the front clutch pack doesn't apply the trans is back in 1st, Not necessarily...if there isn't enough governor pressure to move the 2-3 shift valve, it will stay in 2nd indefinitely. The only way it will drop back to 1st is if the 2-3 shift valve does move and releases the band but doesn't apply the clutch. Need to wait for OP's reply to see which it is. the front band is not going to reapply until the vehicle slows enough for the governor circuit to make the front band reapply ... aka downshift. Normally, when slowing to a stop, the trans drops from 3rd directly to 1st without applying the front band. Applying the front band on decel would cause an uncomfortable lurch. Reason why we need more clarification. From my own experience with my Ram pickup with a slipping front clutch going back into 1st is what was I figured out was happening , it would shift , rpm drops for a second then right against the rev limiter , let off the throttle and it's back in third. I didn't realize that it skipped 2nd on the downshift , thanks for the clarification. The shift to 1st on decel happens when you pretty much come to a stop , otherwise you would probably get a lurch ???
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Re: 42rh /a500 wont shift into third
[Re: ruderunner]
#3272741
11/27/24 01:59 PM
11/27/24 01:59 PM
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Posts: 37 Stafford, VA
ojcool
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When it won't go into 3rd, does it stay in 2nd or go neutral? It just stays in 2nd. I tested the governor port on jackstands and it read 0 psi at idle. I ran it up to 30mph (it shifted into second) and it read 0 psi the whole time. I even switched out the gauge just to be sure. 0psi. No fluid came out the port either when I plumed it in which I thought was odd.
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Re: 42rh /a500 wont shift into third
[Re: John_Kunkel]
#3272742
11/27/24 02:00 PM
11/27/24 02:00 PM
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Posts: 37 Stafford, VA
ojcool
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Most likely a governor problem, only a gauge will tell. Could also be a weak front clutch problem...front clutch is also used in Reverse but at a much higher pressure
I tested the governor port on jackstands and it read 0 psi at idle. I ran it up to 30mph (it shifted into second) and it read 0 psi the whole time. I even switched out the gauge just to be sure. 0psi. No fluid came out the port either when I plumed it in which I thought was odd.
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Re: 42rh /a500 wont shift into third
[Re: ojcool]
#3272747
11/27/24 02:40 PM
11/27/24 02:40 PM
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Posts: 26,964 Rio Linda, CA
John_Kunkel
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A problem I have found when there's shift problems right after overhaul is the e-clips on the governor weight cross shaft will pop off if not seated firmly at the outer end of the groove like the one on the right below...this allows the shaft and valve to fall out of its bore. Another possibility is the governor pressure tubes were installed incorrectly.
Surprised it shifted to 2nd with no readable governor pressure
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Re: 42rh /a500 wont shift into third
[Re: ojcool]
#3272792
11/27/24 06:10 PM
11/27/24 06:10 PM
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A727Tflite
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When it won't go into 3rd, does it stay in 2nd or go neutral? It just stays in 2nd. I tested the governor port on jackstands and it read 0 psi at idle. I ran it up to 30mph (it shifted into second) and it read 0 psi the whole time. I even switched out the gauge just to be sure. 0psi. No fluid came out the port either when I plumed it in which I thought was odd. Which port did you test for gov. pressure.
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Re: 42rh /a500 wont shift into third
[Re: John_Kunkel]
#3272867
11/28/24 05:00 AM
11/28/24 05:00 AM
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Joined: Jan 2017
Posts: 37 Stafford, VA
ojcool
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A problem I have found when there's shift problems right after overhaul is the e-clips on the governor weight cross shaft will pop off if not seated firmly at the outer end of the groove like the one on the right below...this allows the shaft and valve to fall out of its bore. Another possibility is the governor pressure tubes were installed incorrectly.
Surprised it shifted to 2nd with no readable governor pressure Is there any point in running any other pressure checks? Is there any reason to pull off the pan and attempt anything or am I going to just have to remove the transmission completely? Thanks BTW for the help. It's very frustrating because I do basically everything else engine rebuilds etc, I've just never gotten into transmissions and I just didn't feel like learning a new skill so I paid "an expert". I called the guy and he was going to do research and call me back but of course, disappeared. I had the engine out doing the heads and cam and I figured I'd freshen up the trans.
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Re: 42rh /a500 wont shift into third
[Re: A727Tflite]
#3273054
11/28/24 11:20 PM
11/28/24 11:20 PM
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Joined: Jan 2017
Posts: 37 Stafford, VA
ojcool
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Approach I would take is pull the valve body and check the flat plates that are on the top of the shuttle valve and the plates on the sides that hold the governor valves and shaft valves in. Make sure the screws are tight. While there is a possibility that he misbuilt the valve body I would not take it apart unless you have a good reference doc. like a service manual.
Next would be to pull the overdrive assembly and remove the output and get to the governor assy. and see if there is anything wrong there.
If you built engines all this work is in easy reach for you. I have the ATSM book. It's, more the size of a magazine but hopefully that's because it's a simple trans.
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