I've read elsewhere that the 4-speed 45RFE gearbox can be upgraded to a 5-speed 545RFE with just a change of softwear. I know that the 45RFE is sometimes thought of as a 5-speed due to its choice of two 2nd gears but the 545RFE get an additional overdrive gear. Does anyone know if this is true and if so, how can I get it done?
I would love to fit some 4.10 gears but don't realy want to loose the relaxed cruising that the 3.55 currently give. Getting the extra top gear would help offset the 4.10 extra revs on the highway whilst getting the advantege of the extra acceleration they'll give.

Thanks,
Paul.

 

you dont get any extra forward gear, the 545rfe's extra second gear is used only when downshifting (slowing down). and your 45rfe already has 4 gears plus overdrive

 

I know that the although the 45RFE is sometimes thought of as a 5-speed box, as it has two 2nd gears (one ratio for the upshift and a slightly lower ratio for the downshift to give better kick-down performance), it should still be thought of as just the gear between 1st and 3rd rather than two seperate gears. Thats why the 45 is classed as a 4-speed box, in fact Mopar blurr the definition by calling it Multispeed. The 545 still has the duel speed 2nd gear but gains an extra, high (numericly lower) overdrive on top of the existing one, making it 5-speed or 6-speed if you still count the two 2nd gears.
This is all explained in Wikipedia in further detail (including ALL the ratios) so I won't go into it here. It says that the 45 and 545 are mechanicly identical and its just the software that changes a 4-speed to a 5-speed. All I want to know is if its possible to get the software upgraded and if so how?

Regards,

Paul.

 

I believe I have read something similar to this on another site... let me find a link for ya.


EDIT- Heres the link...http://www.dakota-durango.com/forum/...ghlight=545RFE

 

Thanks for finding that link. Unfortunatly, I don't think I'll be able to do this mod as mine is a 2000 model, although one of the last posts on that link thought that a dealer might be able to do it if you were willing to pay their prices. my local Jeep dealer has been pretty helpful, considering the Dakota was never officilaly imported over here but this might be stretching things a bit to expect them to to be able to things this time!

Thanks again,

Paul.