GaryM2 wrote: Also, the parts book list bolt 4082 for both the front and the rear tank bolts on all K and early large tank Sportsters. The colony hardware has 4082 and 4072 bolts which are different lengths.
Regarding the spacers: The parts manual list 2 spacers for the rear bolt and that's all that shows up in the picture. There is no mention of spacers for the front bolt.
What is correct? Seems like the bolts, washers, and spacers, need to be confirmed for correct application on each bike.
I’m quite certain that for the K Model and early large tank XLs that the bolts were all the same length – 3-1/16” length. The front mounting boss that the tank attaches to is ~ 2.5” wide. The rear mounting boss is considerably narrower, but with the 2 required rear spacers present (~ 0.70” total additional width), it too has a total width of ~ 2.5”. This is also the distance between the tank mounting tabs. In conclusion, the 2 bolts have to be the same length in this application.
That said, I’ve seen several of the subject bikes that employed narrower spacers or no spacers at all, resulting in the rear tank mount tabs being crushed/narrowed significantly, and therefore one shorter bolt could be employed in such damaged applications.