Thanks for all the excellent information. It is interesting to know that the frame rails are the same on the non FG model other than the "S" frame. I may find one from an wrecked FE and cut it down. John, When you mention the extension to put in between my current rear frame and the "S" frame, is the extension put on the inside of the current frame and another "U" channel put on the outside? Should they be riveted back on the same way or can it be bolted on? I would imagine the 45 deg end has to be welded on the inside of the current frame? You are an expert at this but I do want to ask something as I have heard that welding onto a frame is not allowed since it can weaken it. Does that mean anywhere along the frame and would not mean at the end? By the way, I have the shortest frame rails on my truck.
Thanks,
Darcy
Hi Darcy,
Have seen it done plenty of different ways......about two years ago Fuso ran completely out FG84's due to the mining boom. To escape going to Euro 5 on time, they built an extra large batch of Euro 4 trucks plated as 2010 models and kept them for sale until the 2012 FGB71model was released mid that year. Most of the trucks sold at the end were actually SWB's with local chassis extensions and we got to see plenty of variations on how to strech them.
I didn't realize you had a SWB....that makes it a little harder as you will need to find a shafting service that can build you a two piece tailshaft with centre bearing that will need to be mounted on a crossmember. As for the extension, this is how I have done the MWB's out longer ( I am sure you will find plenty of variations of what is considerred correct but this works) .....take some measurements first and make some reference marks. Pull the rear rails out of the "S". Cut them back and up at 45deg on the end. Weld in the new section. Exactly the same profile as chassis....vertical up welds. No porosity. I presume you know how to weld ...if not get someone who knows what theyre doing for this part. Then clean up the welds on the outside of the rails with a sander. Then add the outside section . It should be a neat or slightly tight fit over the outside of the chassis rail (and the new section) and it should overlap the 45deg join evenly by a distance of 2x the height of chassis rail so the outside "cover" should end up around 800mm or 900 mm long in total. For a neat finish, replicate the scalloped shape of the "S" onto each end of the "cover" and only weld around the inside of the scallop. This is the bit where you can come unstuck and there may be debate but I used to weld a short 12mm long weld top and bottome at each end of the cover right in the middle of the flange....like a big spot weld just to help hold the cover tight. Either way you need to be careful and never put excessive heat into the chassis rail flanges. So NEVER weld across the flange when you are fitting the cover.
Mate, If those other guys can make you those new chassis rails and crossmembers at any length you like, then I'd go that way.....pending price of course. We don't have anyone like that here.
