Torque Rod Tightness Against Frame?

Put it back the way it was before. The frame shims are to be added or taken away for alignment purposes to center the axle to the frame for proper tracking. Make sure the new arm measure the same as the old ones and the spacers/ washers are in the same position on the axle bracket.

 

Your suspicions may be correct. As a rough guide drive the truck a bit to let everything settle and measure the gaps from inside dual to frame to see if the gaps are equal at all 4 drives.

Either way a 3 axle should be completed to ensure everything is in line.

The other thing that works is a straight edge on the outside of duals to see if all four sidewalls touch.

 

If all was well beforehand, it should go back same way. What’s happened is the axle shifted when you took old one off.Once new one is installed, everything should be lined up exactly as before. It will be doing its job. If you add shims now, it will definitely be off center. Your lucky you don’t need a jack between tire and frame to get bolts to reach. I broke one once. rear axle shifted a good 6” or more. Took a lot of persuading to get it back in line. Dealers Shop Service adviser, wanted to drop the whole axle, new u bolts etc. Luckily the young mechanic, did what I suggested, using a couple jacks. Before the adviser knew. Saved Me hundreds.

 

Release the driver brakes , after blocking the front wheels ,helped me a lot, let us know what you find Out

 

This caused by front springs weakness or wrong tires size. Steer or drives.
Truck frame should be parallel to the ground, distance from the frame to the ground in point where front drive axle and in point where rear drive axle should be exactly same. Keep in mind truck has only one leveling valve located on the front drive axle or on the rear. If front steer spring flattens truck has some incline to the front and tandems get out of cpecs. In case leveling valve located on the front drive axle the rear axle get higher and offset to the side.

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I don't think a dealer could tell you which size it came with, when built they use what ever it takes to line it up, it is normal to not have the same size shims. If it was lined up good before, then just put it back like you found it. If you don't remember how they came out, it would be best to just put it back together and get a 3 axle alignment done.

 

Connect it how it was. Measure distance between wheel rim and frame on all four wheels. Adjust if needed with shims.