Project Hellraiser

Page 12


It's never really finished.

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I have been enjoying driving buggy and not having to do fabrication every weekend but there are still some small tasks that I need to finish up.  As shown above I am mocking up some fenders for the rig to better protect some of the wiring and air cleaner from the elements.  Still not 100% sure on the final shape of the panels but this setup is the front runner. 

Another little project I completed was getting the passenger OS (Oh sh!#!) handle mounted. I no longer had a 1" round tube to attach the handle to on the dash so I welded a pair of tabs to a piece of 1" tubing and attached it to the firewall tubing.

I bought 2 air bumps for the front of Project Hellraiser to try them out and see what kind of difference they would make.  I was worried the ride quality would be compromised since I was adding in another dampener but my concerns were unfounded.  The addition of the air bumps to the front suspension really smoothed out the bumps so the only jarring hits you could feel when driving at speed down dirt roads were the rear polyurethane bump stops when they bottomed out. It was time to get rid of the old polyurethane bump stops.  This little project highlights how handy a plasma cutter can be.  With surgical precision I was able to cut out the old bump stop mount and at the same time carve a pocket for the new air bump can while saving the original gusseting.    

The new air bump in place.  These are the same as the front, Fox 2.0" x 4" travel.  The only issue I encountered was when I went to install the air bump into the can, I could only get the air bump about 3/4 of the way into the can before it stopped solid. I tried a little coaxing with a hammer and then dropping the rig on the air bump to push it to it's seated position to no avail. The final solution was to split the can, I made a small cut going from the top of the can to the tail of the "X" in the logo.  The air bumps slid right into place after that. 

After a few runs I determined the air bumps were still a little too stiff with the default nitrogen pressure so I lowered the nitrogen charge to 150psi.  This change has made the ride a bit smoother and I no longer notice the bumpstops contacting the bump pads when driving at slow speeds.

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It has been a year and I finally tried using the lower adjustment hole on the axle bridge.  This change lowered the rear upper link approximately 1.5".  In theory this adjustment reduces the rear anti-squat about 30%, lowers the roll center height about 2" and increases the roll axis 2 degrees, After driving several trails I noticed the rig climbs better and the little bit of hop I would experience on really vertical obstacles is gone.  Overall I like the change and was surprised I could notice such a small adjustment. The specs on the original setup can be seen here.

Update 11-2-06 - I had a few issues with the motor cutting out at full throttle.  The first thought was a fuel delivery problem but after replacing the 43gph pump with an 80gph pump the problem remained. A scan of the PCM showed a random cylinder misfire code.  I did a little research and made a list of all the things I could try to eliminate this code.  The first things I tried were a different set of spark plugs, pulling and cleaning the MAF and adding a ground wire to the coil pack assembly. One of these things did the trick and the buggy ran really good for several trips.  The last time out I got a slight hesitation and a backfire when driving at speed to and from the trails, hopefully a one time occurrence.

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I have also had all sorts of transmission related problems.  So far they all seem to have been related to a shoddy rebuild.  For starters the transmission chewed up one of the bands due to the band not having been adjusted properly after the first rebuild. I had a transmission shop clean out the transmission and replace the bands but there was still a lot of debris floating around in the system causing some of the valves to stick when the transmission was cold (note the debris on the filter shown in the first picture above).  I also had some fluid leakage from the torque converter.  

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Due to the leakage and the knowledge that I would most likely never get all the debris out of the torque converter I went ahead and ordered a new torque convert from Art Carr. This particular converter is designed specifically for rockcrawling and is designed to spin up faster, provide more torque multiplication than a typical converter and should generate less heat.  All of these things are possible due to the converter being custom tailored to my buggies gearing and power output. It took 3 weeks to receive the first converter and unfortunately it would not work with my motor.  I sent my original converter back with the incorrect converter and waited another 3 weeks before a new unit arrived.  Art Carr ended up using the motor side of my old converter to get the proper pilot for the motor end but the internals are still their custom formula.

 For reference the tear down to get the transmission disconnected from the motor takes about 6 hours and consists of pulling most of the interior out, removing the seats, floors, lower belly pan, both drive shafts, transfer case, battery and a few other things I am forgetting.  I was able to roll the transmission over as it sat on the lower link cross member so it did not have to be pulled from the vehicle.  I installed a new filter and then sealed up the transmission pan with some right stuff sealant and a new gasket.

After a few runs with the new converter installed I feel some differences compared to the original torque converter.  First, the rig is easier to hold at a stop when in high and low range. Part of that is due to a higher stall speed, we aimed for 2500rpms with this converter and I have no idea what the original was.  Second, the transmission temperatures stay a bit cooler than before.  I could easily get the temperatures up to 240+ deg with some spirited driving but now they hang closer to 220 deg. Third, the engine does feel like it has more torque.  I notice this effect the most when crawling. Lastly the motor definitely feels like it spools up faster from a dead stop.  There was a slight lag before which feels like it is nearly gone when attempting steep waterfalls.

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