After Taupo, the car was still in one piece and running good. But it got a few battle scars and few other issues arose that I want to sort out. After clipping the tyre in the morning it had bent the exhaust some where, along with scratching up my freshly paint fuel tank and denting some of the panels/floor under the car. Tried to tweak it back into place at the track but it no longer sat where it used to, which caused the hot muffler to melt a wider cut out in the bumper. So new exhaust was in order.
Other thing that bugged me was the lack of suspension travel in the rear. So I pulled the springs out and start moving the diff through its travel to see whats what. From ride height to bumpstop is only 25mm. Bumpstops have been trimmed to as minimal as possible, the diff head hits the floor the same time bumpstops bottom out. A bit of a major cutting the floor out for clearance, so decided to put it back to how it was for now. Long term plan will be to equal length the rear arms and add some diff clearance into the floor. May add some coilovers to the rear in the mean time and raise it ever so slightly to get a touch more room.
The exhaust manifold had developed a few cracks also. The cause I believe is inadequate and improper bracing. You can see on the picture below, I have 2 small braces between the collector and runner.
They both cracked around either side of the weld. This is just and educated guess, but I think the cause for these cracking was that the runner would be heating up and expanding in one direction, and the collector heating up and expanding in the opposite direction, creating a bending force through each weld, combined with many heat cycles has caused the metal to fatigue and crack. The whole point of the braces was to reduce harmonics and vibrations to stop the collector shaking about between the runners.
So after getting the manifold off, removing those braces and repairing the cracks I needed to come up with a better idea. I decided to do this:
I used 15x3mm flat bar and welded it like so, so when the manifold heats up and wants to expand in the direction of flow, there should be enough flex in the flat bar to allow for that, but the flat bar should have enough lateral strength to stop the collector vibrating about. Thats the plan anyway. You may also notice I welded some tabs on too. These will be to brace it back to the block, to take the load of the header flange.
Also added a wastegate flange brace too.
I had a bent exhaust to fix now… I decided to redo the whole lot, from the down pipe flange back. I went with V-Band Flanges all around now, makes it a lot easier to remove and refit. Only problem with V-Band flanges is that they wont take a beating (or scraping) like a steel flange will, which meant I need to get the new exhaust up nice and high. So at the front it kinks to the right and up into a bit of a cavity in the floor, then maintains that height throughout the length of the exhaust, which is about 10mm below the sill.
With the exhaust up nice and high I had to work out a way to keep it up there. Because I had moved it so far up, it had become quite difficult to hang the usual way with hangars. Decided to still use the hangar bush, but like this instead.
It allows for a sturdy exhaust mount, which wont swing around like a normal hangar, and should give good vibration dampening. I was going to try my luck using a lock nut and sandwiching the hangar, but ultimately I may need to add some crush tubes. I currently have a solid mount at the front, so I may chop that off and do the same up front, and most likely the same on the third and final rear hangar, when I decide what I should do with the rear of the exhaust.
two8six 