Hakosuka restoration part 4 : Exhausted.


Posted on August 18 2010

When we last left off I had installed the refinished wats, replaced some coolant lines in the heater core, and also some neglected fuel lines just to name a few.  The car seems to be humming along pretty well now but I still want to get a few more miles on it to be 100 %  sure ALL  the bugs are worked out before I go into full celebration mode.   When this car arrived at the shop from Japan I was pretty pleased with the  overall condition, but when I was writing up my list of things that had to be done to the car before it was fit to be sold there was one thing that was very high on my list of priorities.   That would be this.

Yes, that muffler.  Wrong on  a multitude of levels for this car.  First off, it’s really not a poor quality muffler, it’s an HKS Dragger.  The bad thing is that it’s not 1997, and this isn’t a JZA80 Supra.  From the manifold back the exhaust is pretty decent.  2.5″ mandrel bent with nice resonator, but for the muffler section they decided to add this abomination.

Yes that is 3.5″  piping (about 90mm)  for a small displacement 2 liter straight six.  Probably a bit of overkill.  And if your unsure if your muffler tip is too big or not, here’s a quick test.  If you can double fist it, it probably is ;)

I wouldn’t sleep well at night with one of our cars running around with that thing sticking out of the back so it’s tome to rectify the situation.   After a great deal of searching for a suitable muffler for the Hakosuka I decided on this.

It’s a 2.5″ stainless steel muffler with dual 2.5″ tips. The sizing is right and  I think this will fit the classic looks of the Skyline perfectly.  Time to get it into place.

With quite a few years of designing exhaust systems for Cobb Tuning these one-off jobs are pretty simple.  Note the  2 little plastic spacers on each side if the tips to make sure it sits centered perfectly in the cutout.  A couple of stands and a cart full of 2.5″ mandrel bent stainless steel piping and flange to connect it to the rest of the exhaust.

With the piping all tacked together it’s time to make some hangers.  I’ll show you a little trick I use to make the a bit quicker and easier.  I use welding rod to get a good idea of what shape the hanger needs to be.

I then take it over to the press where I have this tool we made out of some burly angle iron  that makes bending this 1/2″ thick SS rod a breeze.

And luckily I needed the exact same shape for the other side…

Now I could just TIG weld them on to the muffler just like that but I’m going to show you something else I learned that will prolong the life of the hangers and will allow the exhaust system stand up to a bit more abuse.

These are just basically stainless steel plates that get welded to the muffler body where the hanger sits to give the hanger more surface area distribute the load.  If you just weld the hanger directly to the body, it will eventually tear itself out.

And here’s the entire axle back all fully welded up.

The only thing I need to do now is extend the tips just a wee bit….

That should about do it.   I thinks this looks much more appropriate don’t you think?

And here’s a little clip I took with the camera, obviously it sounds MUCH better in person but you get the idea.   It would be a shame to hide the beautiful sounds he straight 6 – L series motors make and I think this one turned out perfect.

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