Gear Change How To....??

[ronwest]

Anyone have or know of a step by step with pics on doing a gear change?
Going from 3.23 to 3.73 or 3.91.

I've got a 2004 ram truck Hemi/Trans in it now. The shift points are off because of the gears.

Thanks

[Rolling_Thunder]

the factory gear in the trucks are a 3.92 gear i believe - but remember the difference in tire height     

there is a step by step guide to swapping gears in the latest Car Craft...   it actually uses a Mopar 489 case as the model     

[elacruze]

http://www.pirate4x4.com/tech/billavista/Gear_Setup/

If you need more than that one article and a factory service manual specific to your axle, you need a shop to do it for you.

Good hunting!

[flyinlow]

I have a 2004 Hemi Ram has 3.92 axle due to 20 inch wheels and trailer towing package. I think 3,54 was standard for 17 inch wheels.

If the truck is a 4x4 you have to change both axle sets.

You will need special tools to set up the gears.

[mauve66]

is this a old Charger or .............
do you have the wiring for changing the trans programing under the dash
leave the gears in it and re-calibrate it with a diablo or Superchips tuner

[ronwest]

is this a old Charger or .............
do you have the wiring for changing the trans programing under the dash
leave the gears in it and re-calibrate it with a diablo or Superchips tuner

I have both and neither currently support that feature. I've worked very closely with them for months but they are not there yet.

The trans is the 5 speed overdrive unit, and it has 15" rims with 255's or 265's (hhhmmmm) in the back. I was just at the Mopar Spring Fling here in L.A. and some guys told me 3.91's were great. Others told me I could go all the way up to 4.56's. I just want a street car, that at 70 mph is hitting around 2200-2300rpm. Right now the shift points are super sloppy.

[TylerCharger69]

2200 to 3000 rpm at 70 mph?     I would say a 3:23 if available....anything more and you will be out of the ballpark of what you are looking for.....I put a 3:91 in mine at one time....i hated it....it was revving high at 70 mph....I have a 3:00 (ford) rear in mine now....and that's about where i am....about 2800 rpm  at 70

[Rolling_Thunder]

friend of mine is having similar problems with his 5.7 hemi in his 69 barracuda...     We swapped in the whole harness and drivetrain out of a 05 Ram - his only complaint is erratic shift points  -  I am attempting to diagnose his problem -  he is running 4.56 gears with no avail -  in all likelihood it is NOT the gear ratio but rather a sensor giving false input to the computer....

[ronwest]

friend of mine is having similar problems with his 5.7 hemi in his 69 barracuda...     We swapped in the whole harness and drivetrain out of a 05 Ram - his only complaint is erratic shift points  -  I am attempting to diagnose his problem -  he is running 4.56 gears with no avail -  in all likelihood it is NOT the gear ratio but rather a sensor giving false input to the computer....

Yep, I think you're onto it. Keep us in the loop of your findings please.

It's not all that bad with the 3.23's it just could be much better. I spent many, many months trying to get it to take special tunes from Superchips and it just wouldn't.
The programming and wiring is very tricky.

[ronwest]

Here's what Chris said at hotwire auto:

There is NO programming change needed for shift points with an axle change.  The 545RFE has both an input and an output speed sensor, it uses these in combination with the throttle position to determine when to shift.

Unhook the green wire labeled "Speedo Signal" if you are using it to run your gauge.  See if that fixes it.  If not then you'll need to get a scanner on it that can scan the transmission module.

[Rolling_Thunder]

well that sounds pretty simple...    I have to still work on my harness for my 6.1 then send the PCM out for a flash...        I'm glad the 6.1 uses a separate TCM but the downside is the PCM needs a flash or else it'll run in limp mode...    while its there say bye bye to downstream O2s and some more RPMs...     

The only thing i dont like about the modern trans is the torque sensing BS -  it works but I still don't like it...     

[ronwest]

I'm still a bit lost on the whole thing 

[mauve66]

tire diameter will effect what the sensor "thinks" its reading from the rearend which in turn will effect when it "thinks" it needs to shift
a handheld tuner can change the tire diameter (not rim diameter)so the trans knows whats going on

[ronwest]

tire diameter will effect what the sensor "thinks" its reading from the rearend which in turn will effect when it "thinks" it needs to shift
a handheld tuner can change the tire diameter (not rim diameter)so the trans knows whats going on

Yeah... I thought so too... but those functions didn't work on superchips or diablo Predator tuners. Custom wiring harness and electronics hell!

[mauve66]

the SC i had on my 05 would let me change tire diameter........