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2006 Ram CTD 4x4 with 48RE, 167,xxx miles. Brought it home with a blown #4 injector line. I know it would pull on the gooseneck with a lot of throttle, and reverse seemed alright, but didn't drive it much. Fixed the fuel line, and on to the trans. Park would hang so bad we thought we would break the column shifter. Previous owner installed Derale pan. Dropped pan, found glittery fluid, pulled valve body, installed Georend bullet detent kit. Reinstalled valve body, and filled with new ATF4, and there's a weak reverse or 1st with engine braking. Put a transducer on the rear servo port, and I'm seeing 180-190 in reverse at 1500 rpm, but the truck still won't pull in 4 low. 1st has no engine braking, pressure ranges from 65 at idle to 70-72 at 1800 rpm. Removed the TTVA, ran the throttle lever around by hand, and pressures go up to 285-290.

 

Drove it around the block, and I have this shudder in forward at really low rpms, and the same shudder in reverse, and it won't back up a slight incline. 

I turned in the screw under the throttle valve a few rounds, because as my wife would step on the throttle, it wouldn't push the throttle valve in all the way. Pressures came up some, but it still doesn't feel right. 

 

Didn't take anything else on the valve body apart except the manual valve to put in the bullet detent, so I'm stumped here. I also made a mistake and didn't gauge the pressures before, since it was only a park detent issue. Anyone have some really good ideas, or is it toast? 

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1st won't have much engine braking due to the torque converter not being locked. 

 

Any tuning on the truck?

 

The few stock 48RE's I've driven are pretty weak in 1st and R due to tuning. 

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Thanks Mopar. Saw Dynamic on here a bunch, seems real knowledgeable. 

 

Truck is stock. No tunes. Minor upgrades like Derale deep pan, but best I can tell, no major updates.

Old man I bought it from just drove it a little. His son owned it before, and can't remember any major upgrades, mostly just the deep pan for towing his travel trailer.

 

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Next update. Got back under truck to do pressure testing, reverse will build up to about 190 or so, and the trans quits pulling backwards. When you let off, and it gets back under 190, it will surge backwards.

 

Also, did a forward gear pressure test after that, and hooked to a heavy load. Went about 5 feet, and lost all pressure in forward and reverse. Fluid level looks ok, not burnt. No vehicle motion at all now. Any ideas?

 

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Your pressures, while somewhat on the low side, should work. It sounds like you could have a broken rear band or something broken in the servo. It would be tough to give an exact diagnosis without actually looking at it, but either way, you're looking for a problem with the rear band/servo in my opinion.

 

FWIW, there are no electronics involved in either Reverse or Manual Low. Both are 100% hydraulic in function.

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@Dynamic

Took the trans out, rear band had ground up the rear drum. Also found gasoline clutch packs in the overdrive sections (5 disk instead of 6 per ATSG manual). Got it all rebuilt, and set upright on the workbench, and applied air to the rear servo port through the 1/8 NPT, and I have air leaking between the valve body and the separator plate? Is this probably what caused my issues? Have you seen similiar before?

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You can't apply the band by blowing air into the pressure port. The air will simply exhaust out of the valve body, as you are seeing.

 

BTW, 5 discs in the OD brake is stock on a 48RE.

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