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545RFE or 65RFE
#3094270
11/15/22 02:00 AM
11/15/22 02:00 AM
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Joined: Nov 2022
Posts: 215 Green Bay
Andyvh1959
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Posts: 215
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Is one better than the other? Meaning are there advantages to the 65REF versus the 545RFE transmission? This would be for an automatic tranny behind a 4.7HO engine.
x speed tranny. But the 545RFE tranny has the same 1 and 5th (6th) ratios. In fact, the 545RFE has all the same internal ratios IF you consider the 2nd gear kick down ratio the same as the 3rd gear in the 65RFE. So to connect to a 4.7HO V8 is there any reason to chose the 65RFE over the 545RFE tranny?
My 56 C3-B8 Dakota build
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Re: 545RFE or 65RFE
[Re: Andyvh1959]
#3094330
11/15/22 11:52 AM
11/15/22 11:52 AM
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Joined: Aug 2007
Posts: 1,819 Middle of A Field
OrangeProwler
top fuel
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top fuel
Joined: Aug 2007
Posts: 1,819
Middle of A Field
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Is one better than the other? Meaning are there advantages to the 65REF versus the 545RFE transmission? This would be for an automatic tranny behind a 4.7HO engine.
x speed tranny. But the 545RFE tranny has the same 1 and 5th (6th) ratios. In fact, the 545RFE has all the same internal ratios IF you consider the 2nd gear kick down ratio the same as the 3rd gear in the 65RFE. So to connect to a 4.7HO V8 is there any reason to chose the 65RFE over the 545RFE tranny? Going off memory and I'm not sure if this is 100% correct but, I believe the 45RFE, 545RFE, and 65RFE is the same transmission. The biggest difference between them is the programming of forward gears and computer modules. The 45RFE was a 4 speed automatic but, technically it had six forward gears. For example, on the WJs 2001 Jeep Grand Cherokees first used went to the 545rfe that year but, Dakota Dakota and Ram 1500s went to the 545rfe in 2003 but, was 45rfe prior. On 2004 Ram trucks I believe the computer for the transmission was integrated where 2003 trucks trucks had computer module separate. I'm not sure about the later trucks as the Dakota went to a new platform in 2005. Here's a YouTube video that gives a little more information. https://www.youtube.com/watch?v=0OYf2_MS4nA
Last edited by RustyMopar01; 11/15/22 11:55 AM.
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Re: 545RFE or 65RFE
[Re: moparx]
#3094528
11/15/22 11:09 PM
11/15/22 11:09 PM
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Joined: Nov 2022
Posts: 215 Green Bay
Andyvh1959
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Posts: 215
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Thanks for the tips. I did some more net digging and yes the 45RFE, 545RFE and 65RFE are essentially all the same transmission, different programming. In fact the 45RFE can be changed into a 545RFE just by changing the TCM. The "5th" gear is actually the 2nd-kickdown gear already in the 45RFE. The 545RFE and the 65RFE actually share all the same ratios except for the 2nd overdrive in the 6-speed 65RFE.
My 56 C3-B8 Dakota build
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Re: 545RFE or 65RFE
[Re: OrangeProwler]
#3101062
12/10/22 12:27 PM
12/10/22 12:27 PM
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Joined: Nov 2022
Posts: 215 Green Bay
Andyvh1959
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Dug a bit further into the tranny choices, and the new ZF8-HP would be a great choice, but it is a match to the 4.7. Biggest difference between the 65RFE and ZF8-HP is the lowest and highest ratios, and that the ratio changes in between gears is much closer. Yet the top gear ratios are comparable: 6th in the 65REF and 8th in the ZF8-HP are the same at 0.67. 1st in the 65RFE is 3.00 while 1st in the ZF8-HP is much higher at 4.71. So the ZF gives better off the line power and smoother power with less ratio change between gears. But for steady highway driving they're the same.
However, since the 545RFE and 65RFE are basically the same transmission gearsets wise, could a 545RFE be updated to a 65RFE with a TCM and torque converter change? Would an aftermarket convertor be a good upgrade into a 545RFE?
My 56 C3-B8 Dakota build
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