Mitsubishi Transfer Case to Tera Low231 NP231 ...
Update: April 30, 2009 Well, it wouldn't be a good trip unless you end up with some good stories, right? One alternator, air conditioning belt and O2 sensor later ... some stories I can live without. On a more possitive note, however, the new transfer case/doubler assembly functioned perfectly!
We decided to keep the testing relativly mild for the first couple days so we started out with Horse Canyon in the Needles District and moved on to Klondike Bluffs and Tower Arch north of Arches park. The only thing of note these two days was the noise from the new Terra Low231 4-LO gears. The people at Terra warned me so I was somewhat prepared. 4-LO in 1st and 2nd are no louder than a well broken in Mitsubishi transfer case. 4-LO in 3rd and 4th are a different story. Still, after running the gears for a few hours everything quieted down to a tollerable level.
The last two days, after it was apparent that the entire assembly wasn't going to decide at some random point to just blow up in a million flaming shards we figured we'd try something a bit more challenging. Gold Bar seemed like a good test. I've only been on this trail once and then from the opposite direction but what I remembered should be challenging but not suicidal. For once my memory was correct. Again, nothing eventfull to note. Poison Spider was our choice for the last day and is quite a bit more challenging than Gold Bar now but still not particularly death defying. A short run up to the waterfall and then head home. Even on Poison Spider everything behaved as designed.
So, good, bad, indiferent ...? As expected 4:1 (4-Lo-Lo) was AWSOME!!! Crawling up and down 4-5' ledges was suddenly child's-play. With the manual transmission in 1st gear it was possible to navigate down all but the bigest steps without using the brake at all. Crawling up 2' steps at 900-1000 RPM soon became almost booring. The increase in control that you get with the gearing increase is simply amazing! No more using the 'velocity method' to navigate obstacles. No more being bounced around inside the vehicle like a marble in a box car. I can't imagine how much this will decrease general wear and tear on my Sport.
I did do a minor test of 10.88:1 (4-Lo-Lo-Lo) in at the beginning of the Klondike Bluffs trail. In this range no one is going anywhere fast! In fact, there is little noticeable difference in speed between 750 RPM and 3000 RPM. What is noticable is the ability to go up hill with my foot off the gas pedal allowing the vehicle to idle at 700 RPM with no decrease in idle speed. Unfortunately, without the shifters installed I wasn't up to testing the doubler under actual obstacle use. 10.88:1 is usefull but only under very specific conditions and for VERY limited lengths of time. Since my shifting was done this week with a 9/16" wrench from under the truck it wasn't really practical to try to use 4-Lo-Lo-Lo. Once I get the shifters installed then it'll be time to test the entire range of gears.
The best news has been the new 2-piece front drive shaft. Even slightly miss-aligned it's smooth as glass off road in 4-Lo+. There is a sligh vibration in 4-Hi at about 20 MPH through about 28 MPH but then immediately smooths out. At 30-50 MPH in 4-Hi it's smoother than the original one piece drive shaft was. I'm sure that I can get the entire range smoothed out but that is going to require a few hours of tweeking I haven't had. The rear drive shaft proformed great, too! No vibration AT ALL through 80+ MPH.
Over all, up to this point I'm very, VERY happy with things! The gearing and range choices are absolutely perfect. I've now got gearing for everything from deep snow and sand to slick granite at 13,000 feet to sandstone slick rock.
I still have to install the transfer case and doubler shifters. I'm hoping to get those done before the end of May so I can test everything out before our end of June trip.