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03:53:17 - 12/24/2024
General Dakota Board
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Michigan Mike
Dodge Dakota
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3/28/2002
11:24:20
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 Subject: Take my 45RFE, please....!
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Message:
Okay, has anyone else had this happen with
THEIR 45RFE tranny?
I just bought a 2000 quadcab 4.7 4WD about 3
months ago, with about 50,000 miles on the
clock, and the auto tranny is starting to make
me question it already....
When I start the engine cold and hop
immediately on the expressway, it takes a
good ten minutes before the O.D. will engage.
That's right, I'm turning nearly 3000 rpm at
65-70 mph for a good while before the thing
finally agrees to do the "full shift" and get the
revs down.
Is this normal? The temp gauge shows the
engine fully warmed up WELL BEFORE (like 5
minutes before) the thing will finally do the
O.D. shift.
Another note: Pushing the "O/D off" button on
the shifter stalk makes the thing DROP DOWN
another gear! Or at least it feels like it. the
revs climb even more....
Could the tranny be not getting into 4th?
Maybe the O.D. IS engaging immediately, and
I'm stuck in 3rd gear for a while.
I'd heard of Chrysler putting something into
the system software of some trannies in the
past to prevent top gear shifting until the
engine was fully warmed up, but this is
ridiculous.
wondering if the truck should be going in to
the dealer for a look-see...I luckily DID buy the
3/36 extended warranty when I bought this
truck used off the dodge lot, so I should be
covered.....if I can get the dealer to admit
there's a problem, that is...
anyone?
thanks!!!!
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oldbird
Dodge Dakota
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3/28/2002
11:34:12
|  RE: Take my 45RFE, please....!
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Message:
I know that it is normal for the tranny to not shift into OD until fluid gets to a certain temp.
I did not notice this on my 2001 QC 4.7, 4x4 auto
until the cold weather set in. I bought it new in the summer and had read about it in my manual so I was expecting it. I never tried hitting the OD switch to see what will happen. Will have to try it while it is still cold out.
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chris
Dodge Dakota
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3/28/2002
11:55:46
| RE: Take my 45RFE, please....!
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Message:
It's actually the torque convertor that isn't locking up till you get to a certain temperature. You are in OD, so when you hit the button it drops you to 3rd.
This is basically how it's suppossed to work. Even though your engine temperature is warmed up, doesn't me the tranny is. Basically, by keeping the torque convertor from locking up, it's allowing the tranny to warm up properly.
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Dan Gruber
GenIII
3/28/2002
12:29:21
| RE: Take my 45RFE, please....!
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Message:
Chris is exactly right on this. And Michigan Mike, your transmission is behaving exactly as it is supposed to.
Couple of points...
1. Temp guage on the dash shows coolant temp only. Coolant will heat up quicker than the oil or the transmission fluid will because the thermostat blocks off the radiator until the coolant temp in the block is warm. Your oil and transmission fluid still flow through their respective coolers regardless of temperature. So while the coolant will reach normal operating temp fairly quickly, the oil and transmission fluid take longer. Hence the truck appearing to be warmed up after 5 minutes of driving but no torque converter lockup until 10 minutes into the trip.
2. The 45RFE is programmed to do a number of things, two of which are to not lock the torque converter until a preset transmission fluid temp is reached, and to slightly delay (but not prevent) the shift into OD during warm-up. So when you hit the road in the morning, you are using all the gears, but your converter won't lock up until it's warm.
3. Hitting the OD off button locks out 4th gear. So if your truck is not fully warmed up and you're cruising along in 4th gear with the converter unlocked, hitting that button will cause a downshift into 3rd, and your converter will still likely remain unlocked.
Again, your transmission sounds like it is behaving normally. Living in Florida, my torque converter will usually allow lockup inside of 2 minutes. But on a recent trip to Georgia during some REALLY cold weather, it took much longer to allow lockup. Watch what it does this summer during hot weather and you'll see what I mean.
Dan
2000 CC SLT 4.7 4X4 Auto 3.55 LSD
3 inch Performance Accesories lift & 32 inch BFG MT KM's
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YJ
Dodge Dakota
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3/28/2002
12:48:55
| RE: Take my 45RFE, please....!
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Message:
Michigan Mike,
I have a 2K Quad Cab 4x4 4.7 with the same tranny and just under 30K on it. The tranny is not doing so well. I'm going to have to take it in. So I wouldn't discount the possibility of your transmission not working perfectly. I've also heard of many others with close to my setup with the same problems in their transmissions. It bumps and jerks even at cruising speeds, and it will sometimes slam down when coming to a stop. Sometimes I don't know if the guy behind me hit me or whether it was my tranny. ;)
Just thought I'd share....
Good luck with your new truck. Even with the myriad of problems I've had, for some reason I still love this truck.
YJ
Black 2K QC 4x4 4.7 3.92 KVT910DVD
Black 91 YJ 4LHO Borla | Lifted
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nmdcommguy
Dodge Dakota
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3/28/2002
14:42:48
| RE: Take my 45RFE, please....!
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Message:
I agree that the torque converter is not locking up while cold - which is normal. But if the tachometer is reading 3000rpm at 70mph. There's a hell of a lot of slipping going on! Should only slip 200-300 rpm until the torque converter locks.
I would have the transmision fluid changed. And make sure when you (or somene else) changes the fluid that they change the torque converter's fluid along with it. If you just drop the pan, and change the filter/screen, then the torque converter doesn't get drained. Do it all!
Good Luck
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Michigan Mike
Dodge Dakota
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3/28/2002
17:27:41
| RE: Take my 45RFE, please....!
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Message:
I can't see how just changing the fluid would cure a slipping condition in the transmission...never in the history of automatic transmissions have I seen this work as a cure.
But what you guys said about the various coolants reaching operating temperatures at different times makes sense...
I just don't quite see why the Dodge engineers voted to make this trans operate in this manner, no other trannys from other manufacturers have I seen operate such that you had to wait ten minutes to be able to shift properly....
Oh well, its under warranty! For at least another 34,500 miles, anyway...
thanks
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Dan Gruber
GenIII
3/28/2002
19:29:28
| RE: Take my 45RFE, please....!
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Message:
It's all done for emissions. Consider the following...
The catalytic converters need to be hot to work efficiently. The quicker the cats get up to temp means more time at peak efficiency, which means less emissions produced for a given number of miles driven. There are two ways to get the cats hot quickly: position them as close as possible to the exhaust manifold, and get the engine to get up to operating temp as quickly as possible (i.e. producing hot exhaust). My CA version Dak has 2 small cats positioned just aft of the exhaust manifold and the main cat just after the Y pipe. That takes care of cat positioning. The engine warmup is helped by the torque converter not locking up...forces the engine to work a bit harder to maintain a given speed. An engine that is working harder will produce more heat. Gas mileage goes down during the warm-up phase, but emissions go down to a legal level quicker. And because the warm-up phase is relatively brief in anything but really cold weather, gas mileage isn't hurt too bad and most drivers in most circumstances won't notice anything unusual. Your situation is somewhat unusual...cold weather and getting up to highway speeds within a couple of minutes of starting the truck.
I think there are two basic reasons that this whole thing is more noticeable on the Dak. Reason number one: The unlocked torque converter in the 45RFE allows quite a bit of slip...more than in most modern transmissions. In that sense, it is almost reminiscent of the old 727's. Most automatic transmissions from the 80's and 90's went the route of really tight torque converters that lock up at the earliest possible moment in the name of gas mileage. Perhaps Dodge did this to help mask the relative "peakiness" of the 4.7's torque curve (as compared to the 5.2 or 5.9). Although if any of you have ever driven a Ram with the Cummins Diesel and automatic, that one slips a lot too, and the Cummins has BAGS of torque. And reason number 2: The 45RFE is heavily computer controlled. That computer control enables the transmission to help emissions when in the warm-up phase, and still help gas mileage for normal driving.
By the way, I'd really prefer a 5-speed. But overall I'm satisfied with the automatic.
Dan
2000 CC SLT 4.7 4X4 Auto 3.55 LSD
3 inch Performance Accesories lift & 32 inch BFG MT KM's
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kevster
Dodge Dakota
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3/28/2002
21:31:27
| RE: Take my 45RFE, please....!
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Message:
Has the trans been serviced?? it should have been at 30,000 miles. I know that after i had mine serviced,it shifted way better.
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