Posted by Clint Dixon [216.248.73.1] on Thursday, August 01, 2013 at 12:37:04 :
In Reply to: If you could have any gear ratio for the Chrysler corp 9,5/8 posted by Jens Butler [76.76.230.60] on Thursday, August 01, 2013 at 10:44:01 :
With over 25 years of experience in driving my trucks with 4.89:1 gearing, I have developed an opinion on the subject. Thanks for considering the project and thanks for asking.
My trucks both have the stock 230 L-head engine and 9.00x16 NDT tires. I drove about 10 years with 5.83:1 gearing. Immediately after installing the 4.89 gears, I noticed a big improvement that the 20% made. The trucks now keep up with traffic at 55mph, still carry over a 2-ton load, and do not feel underpowered. If anything, I have found that the extra momentum of traveling 10mph faster, helps carry the trucks up and over the rolling hills we have here in the Midwest.
For off-road, the 4.89 gears still work very well. The 20% difference in low range first gear is literally not noticeable. I believe any gears higher than 4.89 would have an adverse effect when using the stock engine and tires. I also feel that if someone is going to modify a Power-Wagon to the needed extreme to make it a 70mph vehicle, there are better ways to do it than installing gears higher than 4.89.
I feel that 4.89 gears will satisfy the most people, from those like me who want to keep their trucks as stock as possible, but still have the need to use them to carry heavy loads and drive hundreds of miles at a time, to those who upgrade to bigger engines, brakes, etc. to make their trucks more modern and comfortable.
There is also the issue that the physical size of the ring gear determines what ratios are possible. Not every ratio that may sound promising can be physically cut on a 9.625 ring gear. And, some of those that can will end up with weakened teeth. I have found no reduced longevity or strength in the 4.89 gears compared to the 5.83 versions.
4.89's get my vote.
Jens, sometime we need to talk about a theory I have. I think it is possible to convert the NP200 transfer case from 1:1 and 1:1.96 ratios to something like 1.25:1 and 1:1.96 ratios resulting in an effective overdrive while retaining the stock under drive - all internally. I have not pursued the idea because it would involve cutting nearly all near gears for the transfer case, but since you are considering ring and pinion gears anyway, I believe the straight cut gears in the transfer case may actually be cost effective in comparison. (The idea would not work if one were to use the straight through output to a centered differential).
Junior
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