repairing a suitcase

Due to my work I'm traveling a lot.
Once I got a huge suitcase but it did not survive the first trip.
They had used a thin tin-tube as an axle.
So I replaced it with a massive M8 one and secured everything with bolts, locking bolts and large washers.
I did not replace the already worn down wheels yet but will do so in the future (and add wheels with ball bearings in the process.).