Posted by Matt Wilson on Tuesday, November 07, 2000 at 23:48:35:
In Reply to: Does the 4.89's make any difference off-road? posted by Roy Sanders on Tuesday, November 07, 2000 at 05:13:59:
Roy,
To help answer your question, I guess I have to say it depends on what kind of off-roading you intend to do. Most people, I suspect, don't try to do anything with their Power Wagons that requires high-speed driving, such as high-speed mudding or running up sand dunes. These trucks are mostly not well-suited for anything fast, without significant modifications, so you're going to be hard-pressed to do these things quickly regardless of your axle ratios. Just for the sake of conjecture, let's scratch the surface of what you would need for high-speed off-roading. I imagine you would probably do better with the 4.89's (because you can go faster). However, you would only have 83% as much torque to the wheels compared to what you had with the 5.83's. In conjunction with a stock engine that's not intended for propelling a heavy truck at high speeds, this torque loss would work against you for high-speed situations. To make up for this, you would probably need an engine with quite a lot more output. But then you'd get into the issues of drive train reliablity under the added strain. I think most PW owners would agree that any attempt at high-speed off-roading should be avoided in order to preserve the drive train and especially the suspension and frame.
Now, back into reality, you're probably more interested in slow-speed off-roading, such as rock-crawling, etc. My truck is a '49 civilian 1-ton Power Wagon. I used to have 5.83's, but didn't drive the truck much before I replaced them with 4.89's, so I don't have much experience with 5.83's. I can say that I haven't ever thought that the truck's off-road abilities were compromised with 4.89's. I used to live in El Paso which is a very mountainous area. When I would go off-roading, that Power Wagon would creep right up the sides of some fairly steep rock faces. It would do pretty well even in second gear (transfer case in low), although occasionally, sometimes that would allow the truck to get going too fast for safety (even at 7 mph). (The springs are so stiff, and I don't have seat belts yet, so I thought my head was going to punch right through the headliner and leave an impression in the roof!) So I often just kept it in first gear and crawled along. Occasionally, on a steeper hill, I would have to give it a little more gas, but I never had the feeling that I didn't have the torque I needed. And that was with a very worn engine! Of course, most of the time I didn't have any significant weight in the bed.
Despite the fact that the flathead engines don't put out nearly as much torque as modern V-8's, they partly compensate for this in the fact that their peak torque occurs at such a low engine speed (around 1200 rpm), whereas truck V-8's typically peak out at around 2500-3500 rpm. This makes it particularly suited for low-speed use.
Another thing to remember is that, I think there are very few situations off-road, when you really need all the torque that the engine will produce. This is especially true if you are 'wheeling for fun, without pulling much weight. Torque multiplication through transmission and transfer case gearing takes much of the burden off the engine. I think I can say confidently that, if you are happy with the performance you have now, with your 5.83's, then you'll be satisfied with the performance if you install 4.89's.
Does anyone else agree/disagree??
Sorry I've rambled on for so long! Hope this helps.
Matt