i want to build my own 47RH ??? - Page 2

K204DR · 06-28-2008, 08:27 PM

theres three terminals coming out of the transmission. one is 12v in to power the solenoids, and the other two are ground connections for the overdrive and lockup solenoids. if you put a pressure switch in the 3rd gear port, you can have it disconnect the connection between the ground and the computer under a certain speed to automatically kick off the overdrive and lockup. I have a 35psi on mine but a 40 would be better.
the switch on the shifter jusdt interupts the ground connection.

__________________
88 Chevy airforce crewcab 1ton 6bt nv4500 valair clutch modified 4K GSK
72 Scout 4bt 1tons http://4btswaps.com/forum/showthread.php?t=1667

Joe G. · 06-28-2008, 08:31 PM

Just making sure we were on the same page.

The PCM determines when to ground the OD or the TC lockup solenoids depending on inputs from the TPS, speedo, and tach. The governor port does indicate vehicle speed, but is not used by the PCM. It is only used by the 47RH VB for shifts 1-2 and 2-3. The solenoids control OD and lockup. Of course there has to be certain pressures before OD and lockup will happen if the solenoids are energized.

Actually, the OD gear set is always engaged. And so are the direct drive clutches. It took me some time to figure out how the OD unit works. The OD clutches send power to the sun gear so the output shaft rotates faster than the direct drive clutches because the overrunning clutch lets go when that happens.

You can use a pressure switch the break the connection between the PCM and the OD solenoid to control minimum OD engagement speed. There is a kit to convert a non-OD 727 to OD that has pressure switches to control OD and lock up that way.

__________________
KDP tab fix info and fuel system article jgeorge1@suddenlink.net '95 2500 CC auto 4X4, 3.54, EGT, boost, fuel pressure, trans temp guages, PacBrake, TST #5, DTT VB, DTT triple disk TC, DTT billet flex plate, Cummins chrome kit.

1970 300 SEL · 06-28-2008, 10:58 PM

JoeG, i am going to assume you are referring to PATC's swap kit?

wasnt sure if their gasser designed kit would cooperate with the 47RH even though the design seems to be very similar.

ok so it sounds like i can prevent OD with a pressure switch if i find the right one.

this will be good since it seems to have a lot of slip when i decel down to 25 and then get back onto the pedal since it has the delayed down shift. i suppose i should take a look at the TPS too.

my thought is other people with minimal experience may be operating this truck and i dont need to give them a 1 hour lecture on specific driving techniques.

Joe G. · 06-29-2008, 11:46 AM

I'm not sure where I saw the pressure switch set up. I was checking the prices of repair kits when I saw it. It was part of a kit to convert the older type of 727 that does not have OD or lockup to have those features. All of the 727 type transmissions are about the same. Some of them are built stronger than others because of the intended application. For example, you would not want to use a 42RH with a Cummins diesel. The frustrating part of looking for repair kits is finding out exactly what is in them. I think my front clutches are getting ready to give up so I'm going to replace all the wear parts in mine.

There is an old thread on the TDR that goes into the TPS problem in great detail and has a discussion about how to set up the transmission so you can dial in OD and lockup points at just about any speed you want without fooling around with pressure switches.

__________________
KDP tab fix info and fuel system article jgeorge1@suddenlink.net '95 2500 CC auto 4X4, 3.54, EGT, boost, fuel pressure, trans temp guages, PacBrake, TST #5, DTT VB, DTT triple disk TC, DTT billet flex plate, Cummins chrome kit.

1970 300 SEL · 06-30-2008, 12:54 AM

yeah i read the TDR thread about the guy driving w/o a working TPS for several thousand miles.

Quote:

Actually, the OD gear set is always engaged. And so are the direct drive clutches. It took me some time to figure out how the OD unit works. The OD clutches send power to the sun gear so the output shaft rotates faster than the direct drive clutches because the overrunning clutch lets go when that happens

ok to clarify? does this mean that any time i dont push the button, the overdrive is active and providing a .69 reduction on the other 3 gears? like a gear splitter?

Joe G. · 06-30-2008, 01:00 AM

Quote:

Originally Posted by 1970 300 SEL

yeah i read the TDR thread about the guy driving w/o a working TPS for several thousand miles.

I don't think you read the article I'm talking about. It went into how the TPS works, how to modify the wiring so it can be adjusted better, and how to eliminate it with a pot. The latter option was discussed in detail about how the effects of the modification works and how to adjust it for optimum performance. The drawback were also discussed. Must too long to paste in here.

__________________
KDP tab fix info and fuel system article jgeorge1@suddenlink.net '95 2500 CC auto 4X4, 3.54, EGT, boost, fuel pressure, trans temp guages, PacBrake, TST #5, DTT VB, DTT triple disk TC, DTT billet flex plate, Cummins chrome kit.

1970 300 SEL · 06-30-2008, 02:40 AM

this one TPS myth buster or this one ? TPS adjustment

Joe G. · 06-30-2008, 10:23 AM

The myth buster. A non-member may not be able to access it because the thread is pretty old.

__________________
KDP tab fix info and fuel system article jgeorge1@suddenlink.net '95 2500 CC auto 4X4, 3.54, EGT, boost, fuel pressure, trans temp guages, PacBrake, TST #5, DTT VB, DTT triple disk TC, DTT billet flex plate, Cummins chrome kit.

1970 300 SEL · 06-30-2008, 07:17 PM

i ve been reading and re-reading all 4 pages of that article.

it seems to be 2 different schemes. seems as if some people use a potentiometer to boost tps signal while others use the pot as a replacement for the tps.

it seems there is not any automatic kickdown with either scheme.

i cant have that because of the possibility of less intelligent people piloting this truck and may not understand or remember to turn the pot or dimmer switch to kick down.

so it seems that a pot allows a lot more tunability for my exact issue, but i think the psi switch may still have its place as a automatic kick down, lets say around 35-40mph.

when oil pressure drops in the tranny, it cuts ground signal and forces a down shift at the 35-40mph range.

on upshifts, the switch still closes at 35-40 but since it would be wired in series with the pcm wires, upshift would occur until the pot and pcm tells it to.

thats my thoughts on the issue

the pot works great if you re the only one driving your truck, but put a gf, wife, or a friend who is semi clueless behind the wheel and best case scenario is they are mad and blame the truck, worst case scenario is mechanical damage.

Joe G. · 06-30-2008, 08:16 PM

Not quite. If the TPS is left in the system and a pot added to the ground leg to make it easier to adjust the TPS voltage value, the system will still kick down. If you remove the TPS from the circuit and only use a pot, then the PCM does not know what the throttle condition is and kick down will not work.

In other words, if the pot is added for adjustment purposes, the system works just like stock. That method only helps to adjust the TPS.

__________________
KDP tab fix info and fuel system article jgeorge1@suddenlink.net '95 2500 CC auto 4X4, 3.54, EGT, boost, fuel pressure, trans temp guages, PacBrake, TST #5, DTT VB, DTT triple disk TC, DTT billet flex plate, Cummins chrome kit.

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

06-28-2008, 08:27 PM	#13 (permalink)
K204DR Cummins Fanatic Join Date: Nov 2007 Location: Chatt TN Posts: 190 Thanks: 0 Thanked 0 Times in 0 Posts K204DR's Truck Pics	theres three terminals coming out of the transmission. one is 12v in to power the solenoids, and the other two are ground connections for the overdrive and lockup solenoids. if you put a pressure switch in the 3rd gear port, you can have it disconnect the connection between the ground and the computer under a certain speed to automatically kick off the overdrive and lockup. I have a 35psi on mine but a 40 would be better. the switch on the shifter jusdt interupts the ground connection. __________________ 88 Chevy airforce crewcab 1ton 6bt nv4500 valair clutch modified 4K GSK 72 Scout 4bt 1tons http://4btswaps.com/forum/showthread.php?t=1667

Remove Advertisements Sponsored Links
Dodge Cummins Diesel Forum Advertisement

06-28-2008, 08:31 PM	#14 (permalink)
Joe G. Diesel Head Join Date: Apr 2007 Location: Eureka, CA Posts: 1,644 Thanks: 2 Thanked 38 Times in 35 Posts Joe G.'s Truck Pics	Just making sure we were on the same page. The PCM determines when to ground the OD or the TC lockup solenoids depending on inputs from the TPS, speedo, and tach. The governor port does indicate vehicle speed, but is not used by the PCM. It is only used by the 47RH VB for shifts 1-2 and 2-3. The solenoids control OD and lockup. Of course there has to be certain pressures before OD and lockup will happen if the solenoids are energized. Actually, the OD gear set is always engaged. And so are the direct drive clutches. It took me some time to figure out how the OD unit works. The OD clutches send power to the sun gear so the output shaft rotates faster than the direct drive clutches because the overrunning clutch lets go when that happens. You can use a pressure switch the break the connection between the PCM and the OD solenoid to control minimum OD engagement speed. There is a kit to convert a non-OD 727 to OD that has pressure switches to control OD and lock up that way. __________________ KDP tab fix info and fuel system article jgeorge1@suddenlink.net '95 2500 CC auto 4X4, 3.54, EGT, boost, fuel pressure, trans temp guages, PacBrake, TST #5, DTT VB, DTT triple disk TC, DTT billet flex plate, Cummins chrome kit.

06-28-2008, 10:58 PM	#15 (permalink)
1970 300 SEL Cummins Fan Join Date: Jun 2008 Posts: 46 Thanks: 0 Thanked 0 Times in 0 Posts 1970 300 SEL's Truck Pics	JoeG, i am going to assume you are referring to PATC's swap kit? wasnt sure if their gasser designed kit would cooperate with the 47RH even though the design seems to be very similar. ok so it sounds like i can prevent OD with a pressure switch if i find the right one. this will be good since it seems to have a lot of slip when i decel down to 25 and then get back onto the pedal since it has the delayed down shift. i suppose i should take a look at the TPS too. my thought is other people with minimal experience may be operating this truck and i dont need to give them a 1 hour lecture on specific driving techniques.

06-29-2008, 11:46 AM	#16 (permalink)
Joe G. Diesel Head Join Date: Apr 2007 Location: Eureka, CA Posts: 1,644 Thanks: 2 Thanked 38 Times in 35 Posts Joe G.'s Truck Pics	I'm not sure where I saw the pressure switch set up. I was checking the prices of repair kits when I saw it. It was part of a kit to convert the older type of 727 that does not have OD or lockup to have those features. All of the 727 type transmissions are about the same. Some of them are built stronger than others because of the intended application. For example, you would not want to use a 42RH with a Cummins diesel. The frustrating part of looking for repair kits is finding out exactly what is in them. I think my front clutches are getting ready to give up so I'm going to replace all the wear parts in mine. There is an old thread on the TDR that goes into the TPS problem in great detail and has a discussion about how to set up the transmission so you can dial in OD and lockup points at just about any speed you want without fooling around with pressure switches. __________________ KDP tab fix info and fuel system article jgeorge1@suddenlink.net '95 2500 CC auto 4X4, 3.54, EGT, boost, fuel pressure, trans temp guages, PacBrake, TST #5, DTT VB, DTT triple disk TC, DTT billet flex plate, Cummins chrome kit.

06-30-2008, 02:40 AM	#19 (permalink)
1970 300 SEL Cummins Fan Join Date: Jun 2008 Posts: 46 Thanks: 0 Thanked 0 Times in 0 Posts 1970 300 SEL's Truck Pics	this one TPS myth buster or this one ? TPS adjustment

06-30-2008, 10:23 AM	#20 (permalink)
Joe G. Diesel Head Join Date: Apr 2007 Location: Eureka, CA Posts: 1,644 Thanks: 2 Thanked 38 Times in 35 Posts Joe G.'s Truck Pics	The myth buster. A non-member may not be able to access it because the thread is pretty old. __________________ KDP tab fix info and fuel system article jgeorge1@suddenlink.net '95 2500 CC auto 4X4, 3.54, EGT, boost, fuel pressure, trans temp guages, PacBrake, TST #5, DTT VB, DTT triple disk TC, DTT billet flex plate, Cummins chrome kit.

06-30-2008, 07:17 PM	#21 (permalink)
1970 300 SEL Cummins Fan Join Date: Jun 2008 Posts: 46 Thanks: 0 Thanked 0 Times in 0 Posts 1970 300 SEL's Truck Pics	i ve been reading and re-reading all 4 pages of that article. it seems to be 2 different schemes. seems as if some people use a potentiometer to boost tps signal while others use the pot as a replacement for the tps. it seems there is not any automatic kickdown with either scheme. i cant have that because of the possibility of less intelligent people piloting this truck and may not understand or remember to turn the pot or dimmer switch to kick down. so it seems that a pot allows a lot more tunability for my exact issue, but i think the psi switch may still have its place as a automatic kick down, lets say around 35-40mph. when oil pressure drops in the tranny, it cuts ground signal and forces a down shift at the 35-40mph range. on upshifts, the switch still closes at 35-40 but since it would be wired in series with the pcm wires, upshift would occur until the pot and pcm tells it to. thats my thoughts on the issue the pot works great if you re the only one driving your truck, but put a gf, wife, or a friend who is semi clueless behind the wheel and best case scenario is they are mad and blame the truck, worst case scenario is mechanical damage.

06-30-2008, 08:16 PM	#22 (permalink)
Joe G. Diesel Head Join Date: Apr 2007 Location: Eureka, CA Posts: 1,644 Thanks: 2 Thanked 38 Times in 35 Posts Joe G.'s Truck Pics	Not quite. If the TPS is left in the system and a pot added to the ground leg to make it easier to adjust the TPS voltage value, the system will still kick down. If you remove the TPS from the circuit and only use a pot, then the PCM does not know what the throttle condition is and kick down will not work. In other words, if the pot is added for adjustment purposes, the system works just like stock. That method only helps to adjust the TPS. __________________ KDP tab fix info and fuel system article jgeorge1@suddenlink.net '95 2500 CC auto 4X4, 3.54, EGT, boost, fuel pressure, trans temp guages, PacBrake, TST #5, DTT VB, DTT triple disk TC, DTT billet flex plate, Cummins chrome kit.