Engine/Transmission (1994 - 1998) '98 47RE abnormal operations

[fest3er]

Been a long time since I posted a question. I'm still driving my '98 that I got in October, '97.

Last month as I was leaving my sister's house in NW Wisconsin, reverse all but vanished. I drove back to Virginia being careful about not needing to back up; forward gears were OK (except for the problem below which has become 'normal'). A local shop (familiar with ATS products) rebuilt it (new reverse drum and band, new gov. solenoids and sensor, OD bearing and seal, new clutches, flushed everything) and I have reverse again. But it is still misbehaving the way it did before.

Details: original 47RE rebuilt 68k miles ago when the input shaft lost its splines. ATS TripleLock TC and valve body (since around 2005). Apparently that rebuild included a 'beefier' input shaft, even though I didn't want to pay for a billet shaft. Original TPS (I flushed it out with contact cleaner years ago which cleared its 'dropout' for years; I need to do it again), TV cable, PCM. 215HP injectors, stock plate slid all forward, then back about 1/8" for smoke control. Rarely loaded or towed with it. Biggest load was a bout 4k# of horse dung (once, a slow, local drive in Ill. before 2000). Heaviest trailer might've been 10k# (once, from Virg. to Mich. about 5 years ago.) I have a TruSpeed speedo/odo corrector installed (from when I was running 19.5 tires).

Problem(s):

• Often the trans works as expected, though the 1-2 shift has a little too much overlap and the 2-3 shift has even more overlap). It goes up through the gears nicely, and goes down to first around 8MPH when stopping.
• Almost as often, it doesn't drop to first properly. It half-shifts to first around 18MPH but without any deceleration ability. When taking off, it stays in first until around 2800 RPM, and then shifts to 2nd (and immediately to 3rd if in D).
• Sometimes it only drops to 2nd when stopping. Takes a little extra throttle to get going.
• Sometimes it stays in D when stopping. Takes a lot of throttle to get going, but does move fairly smartly.
• The problems seems to happen faster when I lock out OD. (Fast enough to make me think they might be related.)
• Often, flicking the key off and on a few times clears the problem.

I thought the rebuild would correct these problems, but clearly I hoped in vain. At least I can back up again.

So, what might cause the transmission to behave like this? Does the TPS have much to do with it? Would the ancient TV cable be too elastic now? Might the PCM have passed its geriatric stage? Could it be bad ground(s) or bad +12VDC supplies? Corroded wires or connections? Broken wires that make intermittent contact (like the rear diff. speed sensor wire that was broken some years back, causing intermittent speedo operation)? Might the VB have aged out? Does the FSM cover/describe this sort of mal-operation?

Despite its geriatric condition (cancer, wear, failing interior, needs a new steering gear, etc.), I still like driving the truck. And I'll quit now before I type another 2000 words.

Thanks!
Neal

 

[Timd32]

Lots of other more experienced folks will hopefully jump in and take a look at this one for you.

Something super simple just to cover the basics of basics. Did they use ATF+4, is it at the proper level when warmed up and unless you have the modified VB, stock is checked in N.

ATF+4 anything is good stuff, nothing fancy needed it's all very good stuff.

Some custom trans do use DEX3 as per the builder, VB, and the sort. But if a stock build start there.

The TV cable for sure you want that adjusted properly prior to running this too long after a rebuild. Can be the stock adjustment in the book, some folks use a manual gauge to check the gov pressure set up.

From what I recall 1-2, 2-3 then back down is all pressure related so the TPS is not part of that.

 

[Ozymandias]

How does it shift driving in low range?

 

[fest3er]

Low range shifting is the same with the 1-2 and 2-3 shift overlaps much more noticeable. I assume levels are checked in neutral.

During the rebuild, there was also a broken spring replaced, and the backup light switch was broken and replaced.

I'm finding that if I simply start the engine, trans operation is usually abnormal (starts in 2 or D, downshifts to 1 way too soon, etc.) But if I flick the key on and off a few times before starting, the trans seems to behave properly. Methinks the ignition [sic] switch is feeling a mite poorly; it's likely beyond its 15 000 on/off spec. Perhaps the switch is one of the electrical gremlins.