47rh trans issues

1977IHLoadstar

1977IHLoadstar

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Nov 4, 2011
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47rh trans issues- stall in reverse

Background- i bought an engine and transmission for a swap- iits a 94 or 95 160 ppump with 47rh trnasmission. When i went to look at it its out of vehicle and the guy said the engine works great but he doesnt know about the trans-so i buy it for a good price assuming the trans needs work.

When i get it home i pulled the pan to find shavings, not too surprised. After tear down i find the front pinion has walked on of the pins out but doesnt seem to have done other damage. Also had torn overdrive piston seal and couple others.

I have since put all front and rear performance servos as well as an aftermarket acculator, as well as billet stru and anchor.
I also installed a transgo TFOD-HD2 shift kit, as well as a DPC billet single disc with a slightly lower stall. Line pressures are 100 psi at idle/ 140 psi at idle with TV maxed.

I am running tractor fluid (10 liters/ 2.5 gals?) and the remainder dex 3. my engine came without the coolant to trans cooler so i am using an air conditioning condenser as a cooler- i am trying to find an original cooler setup.

Now for the issues- when the transmission is warrmed up ( and only when warm) when i shift to reverse the truck will stall very much like the convereter clutch is locked on. In drive it feels like it is pulling the motor down abit but not nearly as bad- probably wouldnt notice if i wasnt paying attention for it. It seemed to run a bit warm on the highway as well- but main concern is the stalling.

Thanks for reading.
Sorry for the long post just trying to be thorough in my explanation.
 
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Od and lockup are controlled by factory computer only, no manual switches (yet)
Cooler lines are 8an. I Plan to try bypass the cooler- is it possible for back pressure in the cooler to lock the converter? or something similar?
I have been looking through the hydraulic power flows to see if there could be any "cross contamination" of fluid pressure. In reverse pressures are higher, and as parts warm up they expand/ fluid gets thinner- but i havent yet found a possible place for cross leak.

The truck moves fine in reverse if i give throttle and can keep it alive but when i try to come to a stop it tries to stall again.
 
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1977IHLoadstar said:
Od and lockup are controlled by factory computer only, no manual switches (yet)
Cooler lines are 8an. I Plan to try bypass the cooler- is it possible for back pressure in the cooler to lock the converter? or something similar?
I have been looking through the hydraulic power flows to see if there could be any "cross contamination" of fluid pressure. In reverse pressures are higher, and as parts warm up they expand/ fluid gets thinner- but i havent yet found a possible place for cross leak.

The truck moves fine in reverse if i give throttle and can keep it alive but when i try to come to a stop it tries to stall again.
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Yes, try bypassing the cooler and see if it gets better.

Also, a common problem people experience with a low stall converter is it stalls the motor in reverse when the motor is cold. Try raising the idle just a little and see if that helps out since a tight converter and hydraulic fluid on a cold morning could load the motor enough to cause it to stall if your idle is 800-850 rpm range.
 
Big Blue24 said:
Yes, try bypassing the cooler and see if it gets better.

Also, a common problem people experience with a low stall converter is it stalls the motor in reverse when the motor is cold. Try raising the idle just a little and see if that helps out since a tight converter and hydraulic fluid on a cold morning could load the motor enough to cause it to stall if your idle is 800-850 rpm range.
Click to expand...

It does not do it cold. It works flawlessly then. I think I will bypass the cooler this weekend, after checking flow rate out of it. And also check all my pressures hot and cold.
On older gm cars they use to stick the lockup solenoid on after they heated up so I am going to look into that as well.
 
There is definitely a cooler flow issue. Flows about 1/4 out the cooler as it does before the cooler, so thats where i will start.
With transgo hd2 shift kit what line pressures should i see- cant find any good info. I have 95 psi idle and about 125 idle with TV maxed, reasonable or turn it up?
I have the pan off and there are aluminum (non magnetic) 'shavings' in it they are thin and longer than they are wide, any possible source. Overdrive planetary? Havent had the OD section apart yet.
 
With the cooler bypassed i no longer have reverse issues, should have known better then to take a chance with a non factory setup- but it seemed to work well on my old IDI/E4OD setup.
Any thoughts on line prsssure? with cooler bypassed it is 90 idle 110idle with TV maxed, and around 120 in OD (no load, raised rear wheels)
I still have some messing with shift points etc, but im hoping to get most chassis bugs worked out before pulling trans for overhaul this winter- so i need to get it driveable for a bit at least.

Truck i'm playing with,

DSC_0777.jpg
 
Nice truck!!!

As far as line pressure, stock hits 95-100 psi in overdrive. Transgo kit with "4" turns on the pressure screw, "wild" per their instructions netted 140 psi max in overdrive on my 47re transmission. With upgraded internals including increased clutch count in direct (3rd gear) and overdrive brake clutches, I feel that 140 psi is barely sufficient for 450 rwhp and good for long term 350-400 HP.

In my opinion, stock internals with 120 psi is good for 300 rwhp long term. It probably wouldn't slip till about 350-375 HP but it wouldn't last long at that power level. If you max out the pressure screw about 10-12 turns with the transgo spring setup, you'll end up around 150-155 psi. This is too much for stock high mileage seals and the stock band strut and anchor but since you upgraded them, you shouldn't have a problem with that much pressure.


Another example, my 47rh in the Junker Drag Truck runs 200-215 psi in overdrive and seems to be holding up fine as far as clutch/band wear with 700 HP and 1475 ft/lbs.
 
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Thanks for your input. Mine is setup around 4 turns in, i didnt feel my setup was more than "wild" lol. I will turn it up a bit more if i have the pan off again. I dont plan to run more than stock hp for a while till i am entirely happy with the way everything is working, then i will see where it goes from there- lots of room in the engine bay for twins ;)

BTW i have enjoyed reading through a lot of your trans info on here, and it has been very helpful.
 
1977IHLoadstar said:
Thanks for your input. Mine is setup around 4 turns in, i didnt feel my setup was more than "wild" lol. I will turn it up a bit more if i have the pan off again. I dont plan to run more than stock hp for a while till i am entirely happy with the way everything is working, then i will see where it goes from there- lots of room in the engine bay for twins ;)

BTW i have enjoyed reading through a lot of your trans info on here, and it has been very helpful.
Click to expand...



For stock 160 HP, 130 to the wheels or so, you'd be just fine with 100 psi so where the pressure is currently set gives you plenty of room for moderate power upgrades.
 
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