Project Hellraiser 3

Page 10


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I had been holding off on finalizing the motor position in part because I was not sure what to do about the exhaust.  The stock exhaust manifolds I was using had been modified for more flow and the original plan was to re-use them.  Two thing got me thinking otherwise, one being the dump on the passenger side where the two sides merge ended up being right in the middle of the chassis frame rail and two the driver side manifold was cracked. What I really wanted the first time around was a set of headers but the Grand Prix headers are ridiculously expensive to the tune of 6-800 dollars and would still dump in the same location.  Custom headers were another option but I was quoted $800+ from several places which was a little rich for my blood.

I then remembered a thread on Pirate 4x4 where someone mentioned the Camaro 3.8L V6 having the same flanges as the FWD 3.8L I was using.  Unfortunately I could not find any pictures of these bolted to my motor so I decided to bite the bullet and order a set.  The ones I picked up were made by Pacesetter for a 95-02 3.8L Camaro.  I went with the Armor coat option which ads about $200 to the headers ($424 total) in the hopes it would cut down on the heat in the interior.  There is a painted set available for a hair over $200 if you want to save money and skip the coating.

One other thing, if you go the Camaro header route be sure and pick up a set of plug wires for a 96 3.8l Camaro as well.  These wires have 90 degree ends on both teh coil and plug side and will clear the headers.  The Stock L67 wires have a straight on the plug side and there is no way to keep a few of them off the headers.

Anyway, the headers arrived about a week later and I crossed my fingers and did a test fit.  The bolt pattern in the flanges lined up perfectly and both sides dumped nice and close to the block (passenger side shown above).  The header set does come with a Y pipe which runs under the oil pan an ties both headers together, I could not use it without changing the oilcan for a Camaro pan and my passenger side drop t-case meant the driveshaft would collide with the Y-pipe.

Drivers side fitment.

I ended up chopping up the Y-pipe to re-use the flange it had on the passenger side.  On the driver side may try and get the flange re-flared a bit lower down to pull it up above the lower frame rails.  Despite this  the fitment was better than I could have hoped for and I tacked in the motor mounts for the last time.

My tube coupling finally showed up (ordered in December) and since the motor was in position I could go ahead and make the engine cage. While I like the locking feature a lot of these fabricated tube coupling come with the flaw in the design is they really only work if all the coupling on the tubing are in mounted in the same plane.  The two mounted in the angled section of my engine cage required me to grind the front keyed section down to be able to remove the cage from the top.  On my previous chassis I made my own couplers with flat joining sections and never had any issues.  I went with the purchased option this time to save a week of lunchtime lathe/mill work.

Next up was mocking up the intake which sticks out way past the engine block as seen in the first picture. I should have the motor far enough forward in the chassis to hid the intake in the dash (or at least that is the plan).

I added two braces that tie the center section of the dash to the frame rails.  On the drivers side the brace hugs the transmission for maximum foot room. I did not make it removable to the passenger side brace would have to allow lateral movement of the transmission for servicing. The passenger side brace also jogs around the intake.

A pair of braces from the windshield down bars to the shock hoops rounded out the chassis additions for this update. I spent a good part of the next week drawing up brackets and plates to be cut at a local laser cutter (more on this later).  While I waited for those parts to get cut I decided to jump ahead to something I have ready to go, the rear link mount brackets.

My Ballistic fabrication link mount brackets were not quite what I wanted so I set about modifying them.  One of the golden rules of rock buggy building is to leave no hang-up points on the underside of the chassis.  I did not realize it at the time but the bracket system hung down below the mounting bar by nearly an inch to accommodate the larger cartridge style joints.  Since I was using smaller 7/8" rod ends I was able to cut .50" out of the tabs and then slot the top and bottom covers to eat up another .50" of height.  The one catch was I needed to ensure I could get the link mount bolts out, so the center tabs were clearanced for the bolt head and positioned far enough out so the bolt heads cleared each other when pulling them out.  I then welded the lower section together on the bench, transferred it to the chassis, added some internal bracing before dropping the cover onto the assembly.

I will need to re-do the lower link tabs on the axle since the rod ends are maxxed out as is. The upper links tie into the chassis roughly the same height as my old chassis. Once I figure out the bracing in that area I'll double shear the mounting bolt and final weld the bolt sleeve into the frame.

I did run my link mounting options thru the 4 link spreadsheet and here's the theoretical numbers I came up with.  Despite the lowers being 3" higher than the old chassis I came up with very similar numbers.  For reference my old numbers can be seen here. The main difference is the slightly higher roll center and anti-squat percentage. For reference I used a 42" tall tire for my calculations, so the centerline of the axle tube is 21" and I am aiming for 8" of up travel.

The rear seat frame was shortened in the back to clear the upper links at full stuff.

Later in the week I added some bracing as well as a gusset over the top of the link bolt sleeve.  I will eventually add a tab so the mounting bolt is in double shear but am holding off till I figure out where the exhaust will run.

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