How's a stock 47RH suppose to shift?

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samiam44

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Sep 4, 2010
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I've purchased a used(recently rebuilt) diesel 47RH. I have questions on HOW the v/b is suppose to work.

I have the T/C engagement triggered with an adjustable pressure switch. It comes in by my speedo which is ~5% fast @ 32-34 mph. I'm not sure mph is a good judgement
as these trucks could have many different diff ratios? shift points are 1-2 is about 10-15 mph, and 2-3 is about 28-30. OD is 35 mph under extremely light throttle/ 40-45 moderate
throttle and 50-55 under heavier throttle. I'm just guessing that equates to highway gearing.. 3.07.

Does the T/C suppose to be always engaged in OD( ie coasting)? It seems like mine it stays engaged sometimes.. sometimes it doesn't
(at it's current 32 psi setting).

When I adjust the pressure switch up toward 40-45 psi, the T/C comes in and out with any off-throttle. And it's annoying- someone said stock it must engage
by 35 mph to stay engaged. SO I that's why I set the TC pressure switch <35 mph.

OD I'm planning on adjusting the TPS so it won't come in 35 mph- needs to be 40-45 mph min. Right now I just turn the OD off for acceleration and running on side
streets.

Does someone know if there is an easy way to modify the v/b(shift kit, hole drilling, etc) to make the T/C stay engaged when above 35 mph ???
 
no- I have replaced the 46RH trans with a 47RH in a 1991.5 truck. But I have no idea on how the valve body controls on the 47RH work w/TCC.

I've got it setup basically as has been suggested previously to me. If I can undertand how it should work.. I can get closer to the mark. I mean, the TCC behavoir in OD- not sure if it's correct or not.

That's why I was asking..

Thanks,

Michael
 
If you are running the signals off of pressure switch's then im not sure how you will keep lockup engaged when you are off the throttle. In a factory truck the TC unlocks whenever you let off the throttle or touch the brakes. I agree that its annoying and that is why i have a lockup switch in the cab.

TC lockup is controlled by the lockup solenoid. When you apply a ground it closes the solenoid and allows pressure to build up and shift the valve. THe only control you have over it is from the solenoid as far as i know.

OD needs to come on later like you said. Usually 45-50mph(3.55 gears) @ light throttle in the trucks i have driven. You just dont want it to bog the truck down too much when it shifts to OD.
 
mathews8pt said:
In a factory truck the TC unlocks whenever you let off the throttle or touch the brakes. I agree that its annoying and that is why i have a lockup switch in the cab.
Click to expand...

I just bought a 94 with the 47rh and hate how the lock up is designed, is there any way of changing it other then a toggle switch?
 
Toggle switch here....although I am willing to deal with more than most....considering one vehicle has a rollcage and the other has a manual valvebody.
 
Yes,

WHat's a kanuter valve? I was thinking of doing the 94+ where the OD switch is on the column lever. Then maybe use it for TC lockup od. I've also though of converting over to the OD with just a potentiometer. I think ~50 is ideal for OD. TC point higher rpm=quicker lock and less wear. So, I'll probably set the pressure switch higher and then have a second grounding point through the new switch.
 
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