Bike as it was rolled off the ute...
I was flat out with Duk working on his Shovel, so gave Phil directions and minimal assistance on the Saturday. First job was getting it up on the truing stand. He had to make up a one small frame to hold the left side of the frame, so the GSX could be firmly mounted on the stand...
Once it was bolted up he removed the front end. The headstem bearings were so dry we assume they have never been regreased a lesson to all to keep your bearings greased at least every 5 years if not more often.
At this point we discussed what was to be done. He wanted the bike lowered 2" and the front end raked. That meant removing the rear shockers and setting the rear wheel up on a wooden block to raise the wheel the 2"...
Next the GSX was levelled. Level can be measured across the seat rails or vertically off the rear wheel...
Truing stand has adjustable legs to level the bike...
A plumbob hanging off the centre of the headstem and another one down the centre of the rear tyre allows us to true up the bike over a centre line...
Sunday I can give him my full attention and I then cut the headstem from the rest of the frame leaving just a 20mm hinge at the top. Most is doen with a 125mm angle grinder blade and the final inner cutting is done with a recipro saw...
Steering head now pulled forwards to 38 degrees...
We put a block out front an inch higher than the rear to mimic the planned 21" wheel and set the forks up to see how the land lies. I have suggested around 38 to 40 degrees of rake. Although he wants to extend the forks this traditional style of rake does not raise the steering head. Because we are lowering the bike 2" standard length forks actually require 42 degrees because he also plans to run a 21" which adds 1" to the height over the standard 19 incher. Phil still wants extensions, so the front of the bike will sit up in front. We will work just how much he wants to set up the front once we have finished the rake welding and then know how much longer to extend the forks...
Next question is how close we are getting to the 550 Ridikulus Rool imposed on us in 1974 by the head of the road gestapo. At this rate it comes to 480 so we have plenty to play with . Because he wants extended forks they will increase the rake so...
Pull the rake back to 37 degrees...
Phil now sets to straightening up our original cuts and grinding things back ready for making up the new plates to rebuild the neck...
He also uses a flap disc and mini sander and die grinder to remove all paint from the weld areas. Paint will contaminate and weaken welds so must be removed...
Now to rebuild the neck. This job is not to be taken lightly. It not only needs to be straight (I use a laser), and not just as strong as original but stronger due to the extra stresses of extended and raked front ends. Time is taken to assess where the stresses are coming from and how they impact the area. This does not require an engineering degree, but a lot of common sense and some knowledge. Ask people who know, before you go cutting necks. It is much simpler to rake the neck by extending the front down tubes and bending the backbone. The GSX has a number of inner plates which I will tie together.
A big concern is where the backbone has been cut at the back of the steering head. We need to get some strength back into the bottom of that tube. this 4mm bracket ties the side plates to the steering head at two places...
The top weld also contacts the bottom of the cut backbone (not welded yet in this pic) and ties it to the steering head
Patterns are made to make the side plates...
...which are cut out of 3mm plate...
Welded into place. The heating and cooling of the headstem area from welding expands and contracts the metal and moves the alignment, hence the use of the laser. Phol was quite amused and surprised to see how much the laser dot moved around. Continuous welds are not wise as they will pull the steering head out of alignment, so tacks are done and allowed to cool and then gradually stitch welded. Takes care, thought, time and patience and vigilance.
The side plates are purposely not made down to the bottom of the steering head, so we can add some more strength into the whole shebang. This view shows inner plates that we tie together with...
... an angled and shaped 3mm flat bar. The less gaps you have when joining metal the less movement you will get, so care with shaping is important...
Final bottom piece of the box is made from 4mm plate. Here it is curved on the anvil with a neat little hammer that is perfect for the job... a great swap meet purchase that has been well used in this shop.
This plate is set up to join to the steering head above the bearing area to prevent distortion. It is welded from above and then the final gaps filled with a triangular piece. Last thing to do is to cut some 30mm tube to extend the ends of the down tubes back into the area we have boxed (red arrow). I am confident what we have done is considerably stronger than the original and will last for as long as Nanny allows us to use petrol motors on the road!!
Phil doesn't expect to be able to get back for a month or so. We'' ll up date you on the next steps then...