@a-slice-of-pizza, Check to be sure the orientation of the axle bone is correct. It looks like it's switched. Select the bone, then hit the 'Select and Rotate' button and make sure they are all zeros. The bone should NOT be rotated at all and will cause problems if it is.
that will mean I will have to re-skin the whole suspension correct?
No. Just select the axle that is skinned and look into the 'Advanced Parameters' section of the Skin modifier and un-check 'Always Deform'. Then you can move the bone and/or rotate it without it effecting the skinned model. Just remember, after you move/rotate the bone you have to re-check 'Always Deform' before exporting the model.
edit: I think it'll be ok if you forget to re-check it tho.