Hi,

One of my friends has a Freightliner Columbia. The question I have is I noticed when I was helping him replace some air springs on the third axle that when the bags are fully deflated when the trailer is hooked up and landing gear up, his rear u bolts from the axles had a slight gap in them. There are no chafing marks or anything. After we finished the repair and put air back in the suspension, the gaps were long gone. They were probably no more than 1/8". Does anybody know if that's normal when all the air is out of the suspension? I checked and the bolts were tight, no noticeable damage was found. Any help would be appreciated! :)

The "U-bolts" (#6 in the attached link) are to always be tight to the axle, inflated or not. Are those the one's in question?

http://www.truckcomponentsonline.com/assets/images/Suspension/Freightliner/fas2rs.gif

http://www.truckcomponentsonline.com/FAS-II-AIRLINER-REAR-Current-Production_c_380.html

The "U-bolts" (#6 in the attached link) are to always be tight to the axle, inflated or not. Are those the one's in question?

http://www.truckcomponentsonline.com/assets/images/Suspension/Freightliner/fas2rs.gif

http://www.truckcomponentsonline.com/FAS-II-AIRLINER-REAR-Current-Production_c_380.html

Yes they are. Do you know the torque specs on them by chance? In fact, he recently had a 3 axle alignment done. Is it possible that the U-bolts weren't tightened down enough after that alignment? I'm not sure which pieces are moved during a realignment procedure on the big rigs.

Here's a generic chart

http://www.autoandtrucksprings.com/pages/U-Bolt_Torque.html

Thanks for the info Heymccall. I'm hoping the shop covers it for him. 8K miles ago, he had a three axle alignment. Do you think this could be related to that? I'm not sure how the big rigs have their axles aligned in the back and what they loosen, etc.

See item #5. Shims are added or removed at that point to "align" the axles.

See item #5. Shims are added or removed at that point to "align" the axles.

I just learned that as you typed it. Haha. Ok, I will help him with his U-bolts and he will be on his way. Might need the oxy-acetylene torch for getting the old ones off, but that's what the toys in the shop are for. :)