ping GG tranny questions

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wrote:


well, as I said, it's a lube issue
consider this:
the Cummins has low-end torque out the wazoo
that means it will lug down before it shifts out of OD; my expereince with this unit is that it takes a sharp jab on the pedal to force a kick-down, if you gradually apply pressure, you can have the pedal to the floor and still not shift down
now, consider the factors here:
1) bogged down, if the converter unlocks, that means gobs of heat, even if it doesn't unlock, the factors below come into play
2) pedal to the floor, pressures to clutch packs to the max, less flow to converter
3) lower ground speed, less air flow thru cooler
4) lugging engine, radiator temp is up (cooler flow is first thru air cooler, then thru radiator cooler, at least on the ones I've seen)
5) lower engine speed means lower pump output, less overall flow
now, one or two of these factors won't do in the OD, but add 'em all up and you have an OD section that is being lubed by an insufficient flow of very hot fluid, under extreme strain as the engine speed drops and individual pulses of power become more pronounced, and the reuslts cannot be good.
G
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Quick question Gary and not to dispute your points, more for my education. Under full throttle and as slower speeds or RPM's, wouldn't the computer force both an unlock of the converter and a shift out of overdrive?
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"TranSurgeon" < snipped-for-privacy@mchsi.dotcom> wrote in message
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the 46/47/48 RE uses an electronically-controlled hydraulic 'governor' (shift control) in the first three gears and electronics for 4th and OD
it's a hybrid system that seems to me to have too much 'hysterysis' (lag between input sugnal and output switching), for lack of a better word
if you are in 4th and gradually apply full throttle, it will not kick down until about 30 mph
you have to drive one, loaded down, to get the full feel of what it does and doesn't do
I've tried messing with governor pressures vs throttle pressure to get an earlier k/d, just won't happen
the Transgo kit has a resistor that is added to the governor pressure sensor to get it to 'lag' the GP solenoid a bit, which helps, but not enough IMO
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No, it would not. Unloaded, and with some light loading, my truck is able to climb hills without a thought at 1500RPM in OD. When I discovered this, I started manually killing OD.
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if youre unloaded or loaded lightly, why the concern?
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Cummins lists lugging as more pedal but not more RPM. Since the truck weighs in at 7000+lbs, going up a hill in OD is not only pulling the RPM down, its creating more EGT, more strain, etc. All of that is unnecessary, since I have a direct ratio, so why not use it, and avoid all bad effects? My MPG rarely suffers with such a move. With no adverse effect, and a bunch of good things happening, its not worth the constant bragging rights.
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at what point (assuming flat ground)? i mean, towing a 400 pound atv on a 400 pound trailer obviously wouldnt hurt a toyota tranny in overdrive, much less one built for the cummins. is 1000 pounds the shift point (taking it out of overdrive)? 2000? 5000?

......sure wish i had gotten the 6 speed now. had i forseen just how much towing i would be doing (getting ready to purchase a slide in camper and will be pulling the 7x18 loaded with the toys every chance i get) i wouldnt have got the automatic in the .04.5.
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Nate, the 48RE isn't the concern here... the concern is the 47RE in your '01. The 48RE has better fluid flow to the OD unit, more clutches in the OD pack, and MANY more clutches in the direct pack. Put a temp gauge in it, don't let it go over 180-190F or so, and don't lug it in OD (below 1500-1600RPMs), just like you wouldn't do with a manual.
Dry your eyes, blow your nose, and cheer up... your automatic will handle your towing needs just fine... yep, even in the mighty mountains of the great northwest :)
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sweet. do you feel that an automatic would also do "fine" in the '02 dually im searching for?
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....and just out of curiosity, how difficult would it be to retrofit a 48re into an '02?
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I'm a little less optimistic with the 47RE towing >8,000lbs. in OD, unless it's on flat ground - just because of the issues with the OD unit we've talked about previously.
As for retro-fitting a 48RE, it's not that difficult at all. Physically, they're identical. Electrically, I'm pretty sure the valve body connector and underlying electronics are the same. The only thing you'd have to work on would be adapting the wiring from the 47RE's park/neutral switch to the 48RE's transmission range sensor. Fortunately, the TRS has a separate output that mimics the P/N switch behavior, so that should just be a matter of obtaining the proper connector and splicing a wire.
If you can get a good-condition 48RE for cheap, then that would be the way to go. Otherwise, I'd just look at having the 47RE upgraded by a good transmission shop - one that's familiar with the Mopar trannies, and who can address the shortcomings when it comes to towing heavy.
Remember that most of the heat comes from the torque converter, and until very recently ('05 and up), Dodge still had a very anti-tow-friendly lockup strategy, and a barely adequate converter to boot. I can tell you that my beefed-up 48RE, with a better torque converter and electronic controller for improved lock-up, has pulled a 10K load effortlessly, up several 4-5% grades (one about 2 miles - the other about 6 miles), and I never saw over 160F on the temp gauge - that was only when I hammered it from a stop to "see what she'd do", and the converter was slipping until 3rd gear. Any other time, and the needle never came off the 140F peg.
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can the 47re be upgraded to the same durability as the 48re?

does this include the '04.5?
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Nate, these folks build as close to bullet proof as you can get. www.dieseltrans.com
Roy
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And, of course, the obligatory counter-point to that: http://www.atsdiesel.com
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DTT was fantastic, never had a ats.
Roy
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wrote:

"IS the transmission built for the Cummins?"... Or, it is a standard transmission that is the best that they have for the Cummins..
Sort of off topic.. we tow with a 5.9 gasser and our TT is only about 6,000 pounds or so, but we are very rarely in OD... 2 reasons for this: Unless we're on flat ground and at pretty good speed, (65+), it takes a lot more pedal pressure to maintain speed that it does in OD.. my guess is that more pedal pressure means less MPG, and more heat generated..
I sort of think of it like I would a 5 speed manual.. you can run it all day in 4th without hurting it, but sometimes being in 5th CAN hurt it..
We've played around with OD on trips and it seems like we get the same 8-9 MPG either way, so I'd rather be driving with OD locked out and not having to worry about the tranny.. YMMV
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assuming youre talking about both the 48re and the 47re, SWEET!
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I'm talking about the Cummins, the trannies will hold up to 6000 RPM no problem. Drive smart, and you'll be fine. Downshift when ya would if it was a stick, and the ECM hasn't done it yet.
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ouch. i just hate winding my cummins (either one) that tight. i dont like getting anywhere near redline.

cool, i can handle that. does it hurt to run in o/d so long as the tranny isnt hunting?

sweet, will have to get back to you when i know a little more about what im doing.
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the cruise control on at about 80 MPH on the open road. Toad it all the way from Churchville NY to Dallas and it only downshifted on the steepest of hills and quickly made the speed up and upshifted to overdrive again.
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