Project Hellraiser 4

Page 16


Previous Update

After a few more runs I still had overheating issues so the electric water pump was pulled and a new belt driven pump put in its place.  The rig ran a bit cooler but still was heating up over 230 degrees on the gauge.  I then noticed that the fans were not coming on when they were supposed to  after hearing the fans kick on after coming to a stop with the temp gauge at around 240 degrees.  The PCM is supposed to keep both on until the temp drops to 180 degrees, then run one till the temp drops to 160 degrees. It appeared like I had multiple issues, number one being the motor was heating up much more than it should even when driving at slow speeds and number two the fans were not being reliably controlled by the factory PCM. This may seem like one issue (fans not working properly) but I discovered even with the fans forced on all the time the rig was running hot even at slow speeds.

To take care of the fan control once and for all I ordered a SPAL electronic fan controller from  JayCorp Technologies for $69. This is the first time in a long time where something I bought greatly exceeded my expectations. Besides the compact size, this Spal fan controller came with a very impressive wiring harness, all the connectors are water tight and the leads are around 3 feet long (the unit itself is waterproof). It can be connected to a factory temp sensor or an optional sender that can be purchased from SPAL. I tried hooking mine to my Autometer temperature gauge sender and it appeared to work but at the last second I chose to tap into the stock temperature sender on the engine which is located just below the thermostat housing ( I tapped into the yellow wire, the black wire appeared to be ground and the green did not show any voltage variation as the engine warmed up). 

This unit controls one fan directly, you set the low turn on point by warming up the engine to the desired temperature by pressing and holding the "low" button for 3 seconds. The high point is set the same way. When the low point is reached the first fan comes on at 50% power and slowly ramps up to 100% by the time the high point is reached. You can also run a second fan via a negative trigger that engages when the high point is reached or when the A/C trigger is supplied with 12V. The other cool thing is the indicator lights: one for high, low and A/C override so now I will know which fans are powered at a glance.

Update - the fan controller works beautifully and most of the time I only have one fan running at around 60% which cuts down on the amount of heated air flowing thru the passenger compartment. The only quirk I discovered that is not mentioned in the instructions is both fans kick on at 100% sometimes after starting the engine, but after about a minute the proper programming kicks in.  It is almost as if the temperature sender is holding a voltage for a short while before it drops to coincide with what the current engine temperature is. 

I tucked the fan controller under the dash next to the steering column so I could see the indicator LED's when driving. After programming the unit I have the first fan starting at 150 degrees so it is turning maybe 75% by the time the thermostat fully opens at 180 degrees.  The second fan kicks on 100% when the engine temperature reaches 200 degrees and turns itself off again at 180 degrees.

Back to the motor running hot.  After a lot of back and forth with Jim at Jim's Performance he came up with one possible reason for the motor running hot: a bad ground on one of the knock sensors. The knock sensors screw into the engine block, one on each side of the motor and ground via their threads thru the engine block. If they are not grounded properly so the motor isn't seeing their signal, the PCM can retard the timing to eliminate the chance for detonation (at least that's the way I understand it). In my search for a place to plug my Autometer temperature gauge sender into the water jacket of the motor I installed a brass T along with a few adapter fittings to allow me to plug the sender and drivers side knock sensor into the block. Out of habit I used teflon tape on the threads to ensure a good seal but this may have insulated the knock sensor ground.  So I removed the adapters, plugged the knock sensor back into the block and then relocated the Autometer temperature sender to the heater core loop next to the alternator.

About this time the rig quit starting for me, when turning the key the starter would click and the voltmeter would drop to 8v but no cranking.  I chased this problem on the last wheeling trip and was sure it was a bad battery, we actually swapped my battery out with another and the starter worked.  I had the original Optima tested on two different occasions, both after sitting on a trickle charger overnight but both tests claimed it was a good battery but with a low charge.  After the second test I had lost faith in the old battery so I had it swapped out under warranty for a new one.  After reinstalling the new battery I still had a dead starter (!*@!). So the next step was to take the starter in and get that tested, of course it tested OK on the test bench but since they don't put a load on the starter I still had my doubts.

The last thing to check was the wiring, I tore into the center console and traced everything finding no shorts of frayed wires.  I also tried jumping the starter solenoid directly from the battery with the same results (no cranking) so it looks like I needed a new starter.  About this time I discovered the primary ingredient in the starters used on this motor must be gold because rebuilt units ranged in price from $140-200 not including the core charge! 

After some online searching I discovered a rebuilt starter listed for a 97 Pontiac Bonneville for $68.99+ Core (BECK/ARNLEY Part # 1876108) from That year car had the same L67 motor so the starter should fit.  A week later I had the new starter in hand and I discovered it was a non gear reduction starter which really isn't a big deal other than it is physically much larger than the original gear reduction starter and heavier.  It seemed like a fair tradeoff for the monetary savings.  I installed the new starter and hit the ignition button and the rig fired in about a half a second which was much quicker than with the old starter.

I had also ordered a 200amp alternator from DB Electrical to upgrade the power output of my electrical system. This alternator puts out 200 amps at 1200 rpms which should really help when I am using my winch.  The first time my rig stalled and I was hit with the starter issue I was winching someone's rig over and had both front fans on high.  I think the recovery really drug the battery down because as we were spooling in the winch, the rig just died and then I couldn't get it to turn over the starter. I then noticed DB Electrical sells starters as well, not as cheap as the one I got but they do list a chromed gear reduction starter for $100 that should work with this motor

Ok, so now I am hoping all of my bad luck when it comes to electrical systems is over with for the year (besides the buggy issues I also had a hard drive die in my raid array and then 2 gigs of my system memory just quit working).

The next project was to start playing with the valving on my shocks with the goal of tuning them for a more comfortable ride on the dirt roads.  Keep in mind you most likely can't copy my settings unless you are setup exactly the same.  I am posting my results and findings just to give you an idea on how I proceeded thru the process. The most important part of this process is documenting the settings and your thoughts on the handling and ride quality with each so you can compare and contrast as you zero in on the ideal settings for your rig and backside.

The first step was to pull all of the coilovers off of the rig and let it rest on the bumpstops.

I noticed I needed to re-route my transmission cooler lines to avoid getting pinched by the front upper links at full stuff.

Disassembly of the shocks was pretty simple (instructions here) and once you have the shaft out you can look at the valve stack.  Starting from the nut you have a washer, followed by a stack of shims which is control the rebound valving, then comes the shock piston followed by another stack of shims that controls the compression valving. I then measured the shims in the rebound and compression stack and recorded them in an excel file seen below.  I also noted the springs used on the coilovers and whether or not the bleed ports in the shock pistons were open or not.

Front Shocks Stock   Config 1 Rear Shocks Stock   Config 1
Spring Rates 12/14 inch 150/175 150 /200 Spring Rates 12/14 inch 90/200 130/175
Rebound Shims Fox 90   Fox 70 Rebound Shims Fox 70   Fox 50
  1.34 x .015 1.34 x .012   1.48 x .012 1.45 x .010
  1.20 x .015 1.20 x .012   1.35 x .012 1.35 x .010
  1.05 x .015 1.05 x .012   1.20 x .012 1.20 x .010
  .09 x .012   1.05 x .012 1.05 x .010
              .09 x .012
Bleed Screw #1 Closed Open Bleed Screw #1 Open Open
Bleed Screw #2 Open Open Bleed Screw #2 Open Open
Compressions Shims Fox 50   Same Compressions Shims Fox 50   Fox 35
  .09 x .008 Same   1.53 x .010 1.53 x .008
  1.53 x .010 Same   1.35 x .010 1.35 x .008
  1.34 x .010 Same   1.20 x .010 1.20 x .010
  1.20 x .010 Same   1.05 x .010 1.05 x .010
  1.05 x .010   Same        

  The biggest point of interest was on the front shock compression stack, the small .09 x .008 shim between the piston and 1.53 x .010 shim should not have been there and was allowing a lot of oil thru the valve stack which would make for more body roll. I would describe my stock setup as harsh riding on dirt roads with the front end bottoming out too easy and the rear being too hard (seemed to stop upward axle movement too sharply)

Since Sway-away doesn't have a valving chart available yet I used a Fox Racing chart to come up with my baseline valving.  My front shocks seemed to be closest to a Fox 50/90 and the rear shocks a 50/70.  

My changes:

Front: I decided to soften up the rebound up front (this would allow the shock to extend faster and recover quicker after a bump).  On the compression side to keep it from bottoming out I eliminated the .09 x .008 shim between the 1.53 x .010 shim and shock piston.  I also opened the second bleed screw in the piston knowing from past experience this allows the valve to flow a bit more. 

Rear: Both compression and rebound are now valved softer. I want the shock to have less resistance both in and out but I am also taking into account my air bump which is like a secondary suspension which kicks in the last 2" of suspension travel.


Planning on running some trails this weekend so I'll post an update on the changes next week.

You'll notice I also moved my coil springs around to get the rig sitting a bit lower and to soften up the ride in back.  I am now closer to my desired ride height with a 20.5" belly height and 79" roof height.

Another thing I discovered last week was my air filter had collapsed. It didn't appear clogged but apparently the supercharger has enough suction to do this to a fairly clean filter! I ended up inserting a large hose clamp inside to keep the center section from caving in.  For reference I run a K&N outerwear filter and clean that every few trips with the main filter being cleaned every few months.

Update 10-15-07 - After running a bunch of trials yesterday my initial thoughts on the valving changes are very positive and the changes were very noticeable.  If I didn't get the valving spot on I am really close.  At low speeds the buggy oozes over the terrain instead of bouncing like the old setup.  At moderate speeds it handles the standard dirt roads as if they were pavement.  Rougher stuff with 1-2 foot deep ruts can still bottom the suspension at moderate to high speeds so some additional nitrogen in the bumpstops may be in order (they are at 120 psi right now).

At crawling speeds everything worked great and there was a bit less body roll than before the valving changes.  Shooting waterfalls was the same story and if anything the rig worked better than before as I had my easiest run up the Money Shot on S&M to date and even made the last fall for the first time (with no water in the tires).

  If you are building a chassis from my plans, the above spring rates and shock valving would be a very good starting point.    If you have the rear shocks angled more than 5 degrees in either plane you could get away with slightly stiffer valving for both compression and rebound.

Here's a few shots of the suspension at full stuff.  As you can see I am not relying on the air bumps to stop up travel when crawling and instead use the coilover itself.  The lower coils in these shots are really close to coil bind so I adjusted the dual rate stops up about 1.5" both front and rear. I plan on driving this setup for a month or so before deciding if I want to tweak the valving more or not

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