Rear end swap

[Mark Wood]

Thinking about swapping in a rear end with 3.92 gears . What yrs will work? Are 4x4 rear ends posi?
Any other generations swap with out modification?
Thanks in advance.

 

[chrisp2493]

You mean swapping the entire axle out or just changing the gears? Do you have a 4wd or 2wd?


I Bleed Ram Trucks

 

[Mark Wood]

You mean swapping the entire axle out or just changing the gears? Do you have a 4wd or 2wd?


I Bleed Ram Trucks

Swapping the complete rear end

 

[chrisp2493]

It should work without issue. I’m assuming you have a 2wd truck?


I Bleed Ram Trucks

 

[HemiLonestar]

Posi (Positraction) is a GM trademark. It is random whether 4x4 or 4x2 have LSD. You can swap the whole rear axle, but if you have a 4x4 you have to front AND rear (hence why that question was asked that you didn't answer).

 

[Mark Wood]

Sorry..yes it is a 2wd.
What yrs or other gens will swap?

 

[chrisp2493]

All 02-08 9.25” rear axles should be a direct fit. 2nd gen truck’s have drum brakes I believe so it probably wouldn’t be worth getting one from there


I Bleed Ram Trucks

 

[HemiLonestar]

All 02-08 9.25” rear axles should be a direct fit. 2nd gen truck’s have drum brakes I believe so it probably wouldn’t be worth getting one from there


I Bleed Ram Trucks

^^That. Then you just need to adjust the pinion factor in the TCM. It will run (no limp mode) but things will be off.

 

[chrisp2493]

^^That. Then you just need to adjust the pinion factor in the TCM. It will run (no limp mode) but things will be off.

No need to adjust the computers for gear changes, only tire size


I Bleed Ram Trucks

 

[HemiLonestar]

No need to adjust the computers for gear changes, only tire size


I Bleed Ram Trucks

Gotta be a reason it's a DRB option

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[Mark Wood]

Gotta be a reason it's a DRB option

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What is this you all are talking about .
I'm new to Ram...kust want a little more pep..figured it would be just easier to swap whole rear end.

 

[HemiLonestar]

No need to adjust the computers for gear changes, only tire size


I Bleed Ram Trucks

No he's right, had to go back to the manual and check myself. Pinion factor setting is for tire height. If you swap in an unaltered factory rear, the tone ring will be the same diameter regardless of what ring gear it's attached to and read the same. Just don't change your tire height.

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[Wahrsuul]

That doesn't make sense. Changing tire size changes the effective gear ratio. Changing the rear would be the same thing. Just having done it on some older cars, it definitely threw off the speedo.

 

[chrisp2493]

That doesn't make sense. Changing tire size changes the effective gear ratio. Changing the rear would be the same thing. Just having done it on some older cars, it definitely threw off the speedo.

I’m pretty sure rams have the abs/speed sensor in the rear differential or the front hub bearings. The rear diff has a tone ring behind the ring gear that has a sensor in the top of the diff. So it’s just calculating how fast the driveshaft/axles spin and the computer adjusts that to the tire size that’s programmed in. It doesn’t matter if it’s turning at a 3.55, 3.92 or 4.56 ratio, it’s reading the tone ring at whatever speed it’s rotating at. That’s why you reprogram for tire size and not gears. In this pic you can see the tone ring behind the teeth or the ring gear. That got swapped from my old oem diff to the new TruTrac unit I put in


I Bleed Ram Trucks

 

[HemiLonestar]

I’m pretty sure rams have the abs/speed sensor in the rear differential or the front hub bearings. The rear diff has a tone ring behind the ring gear that has a sensor in the top of the diff. So it’s just calculating how fast the driveshaft/axles spin and the computer adjusts that to the tire size that’s programmed in. It doesn’t matter if it’s turning at a 3.55, 3.92 or 4.56 ratio, it’s reading the tone ring at whatever speed it’s rotating at. That’s why you reprogram for tire size and not gears. In this pic you can see the tone ring behind the teeth or the ring gear. That got swapped from my old oem diff to the new TruTrac unit I put in

Both, depending on if 2 or 4 wheel ABS. The tone ring is the same size on all the 9.25's regardless of ratio; even the Dana 60 in the SRT trucks has the same size tone ring.

That doesn't make sense. Changing tire size changes the effective gear ratio. Changing the rear would be the same thing. Just having done it on some older cars, it definitely threw off the speedo.

As long as the tire height stays constant it doesn't affect how the electronic speedo reads. Changing gear ratio in an old car will because speedo input is taken from the transmission. Changing the gear ratio changes how fast the output shaft (where most of them read or are gear driven if it's old enough) of the transmission spins.

 

[Wahrsuul]

gotcha, didn't realize they were pulling from the diff and not the trans. Makes sense now.

 

[Simpsj2]

I'm also interested in gear swap. I have an 2012 express with the 3.55 gears and anti spin differential. Also swapped to 22 in wheels. Was thinking I'd like the 4.10 gears like the rt model. Whats best option? Buy parts or swap axle?

 

[HemiLonestar]

I'm also interested in gear swap. I have an 2012 express with the 3.55 gears and anti spin differential. Also swapped to 22 in wheels. Was thinking I'd like the 4.10 gears like the rt model. Whats best option? Buy parts or swap axle?

Easiest is swap axle as a unit (as long as you have a 2wd like an R/T).

 

[Simpsj2]

HemiLonestar Thanks for advice. Gears are 699 w install kit. Then I gotta pay to have put in so I'm going to start searching today. Hopefully not to difficult to find.

 

[hilby17]

Just throwing it out there I have carrier with lsd if you are in need


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