Installing ZF Posi Carrier Swap

[Mopar440]

I'm swapping out my rear differential carrier in my 2017 Ram. It has a 9.25 ZF diff. Currently it has an open differential and I am swapping it out with a LSD (Posi). I am having a huge issue finding the proper specs and tightening references for the ZF diff. I have the specs and all for the older 9 1/4 but as the ring gear bolt sizes are different, they should have a different torque spec.

Looking for:

Ring Gear Bolt Torque specs.
Carrier Bearing Cap torque specs.
Bearing adjuster torque specs.
Gear Back Lash tolerance.

For older units, it's 65 ft/lbs for Ring Gear Bolts, 75 ft/lbs for Bearing Cap Bolts, 75 ft/lbs for adjuster and .006" - .010" for back lash.

Also curious on the gear oil to use. My manual recommends 75W140 with friction additive for LDS.

Any help would be appreciated.

Thanks in advance.

 

[GTyankee]

First of all, both the AAM & ZF, Ram 1500 9.25" & 234.5 MM are the same size, as far as the Ring & Pinion goes

The bolts may have a different torque
The SAE may be Course or Fine Thread, i don't recall which

side note;
Limited Slip Differential is not the same as a Posi-Traction
LSD slips a little
Posi does not slip

 

[DILLIGAF]

Its the same

Pdf service manual

Has anyone found a 4th generation service manual in a PDF format? If so can you please share the link? I can't get the McFall one to work on my phone. Thanks!

www.ramforum.com

 

[Mopar440]

First of all, both the AAM & ZF, Ram 1500 9.25" & 234.5 MM are the same size, as far as the Ring & Pinion goes

The bolts may have a different torque
The SAE may be Course or Fine Thread, i don't recall which

side note;
Limited Slip Differential is not the same as a Posi-Traction
LSD slips a little
Posi does not slip

I just finally found out the proper specs for the ZF. I sure hope this helps other folks out there who are doing the same swap out.

I am aware the two ring gears are the same size (both 9 1/4" or 234.5mm) but the bolt spacing is a larger spread pattern on the ZF and uses a larger metric bolt (14mm which is close to 9/16" in comparison) than the older NP carrier (7/16 Fine Thread).

Apparently the bolts have a different torque, so I have just found out.

The older unit has the torque specs as follows:

Ring Gear: 65 ft/lbs.
Brg. Cap Bolt: 75 ft/lbs.
Back Lash: .006" - .010"

ZF specs apparently are:

Ring Gear: 166 ft/lbs.
Brg. Cap Bolt: 100 ft/lbs.
Back Lash: .005" - .008"

I hope others find this info of help.

Side note:

A Posi is a type of LDS. It was a name given to the LDS system by GM. Chrysler used Sure Grip. Modern day OEM LDS's offer more slippage than the Posi-Traction or Sure Grip. Yes, it is true the "Posi" has far less slippage than the modern LDS but it still slips. If a posi didn't slip, you would be hopping and chirping around corners. The only differentials that don't slip are Spools and Lockers (when locked). Lockers however, can break as can clutch type LDS's/Posi's/Sure Grips/Anti Spins/Anti Slips and all the other names given to LDS differentials by manufacturers.

 

[Mopar440]

Its the same

Pdf service manual

Has anyone found a 4th generation service manual in a PDF format? If so can you please share the link? I can't get the McFall one to work on my phone. Thanks!

www.ramforum.com

I found some specs online showing the same for the older 9 1/4" as for the ZF but in some service procedures, they use different specs. I finally found some for the ZF and they are a little different than the older unit.

I'll let you know if I find anything on a PDF Service Manual.

 

[DILLIGAF]

This is the printout I used for my ZF axle 2 years ago when I did my gear swap. Close enough for me ... lol...

 

[Mopar440]

Thanks. The 115 ft/lbs. sounds more realistic than the 166 ft/lbs.
What did viscosity oil did you use? 75W-140 or 80W-90?

 

[DILLIGAF]

Amsoil severe gear 75w140

 

[Mopar440]

Great! Thanks!!

 

[Mopar440]

UPDATE: Installed JEGS Posi (LSD) into my ZF 9.25 to replace the open carrier. Replaced the parking brake shoes at the same time. All went smooth and am very happy with the results. A special thanks to DILLIGAF for help with the proper specs for the ZF diff. I also replaced the OEM diff. cover with an aluminum B&M cover. Perfect fit. Fits both New Process and ZF 9 1/4" diff housings. Clears the sway bar and panhard arm.

 

[DC Tradesman]

Thanks for the info. I am looking at doing the same thing. I was going go with a Spartan Locker or similar for ease of install. I can't find one for a ZF model. So LSD here I come.