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JB Conversions LoMax 4:1 Gears
for the Dana 300

By Jack Brinks

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Road Testing
Well, I must have gotten every thing back together right, because I didn’t hear any unusual noises from the drivetrain! After driving around in 2 wheelhigh for awhile, I shifted the transfer case into 2 wheel low. Wow! What a difference this 4 to 1 low range makes! I can’t even walk that slow!

With a T-18 transmission first gear ration of 6.32, 4.88 ring & pinion gears, and the original Dana low range of 2.62:1, I had a crawl ratio of just over 80 to 1. With the new LoMax gears, that crawl ratio is over 123 to 1!

With the type of wheeling I usually do, requiring some momentum and wheel speed, I’ll have to learn how to drive all over again, but I’m looking forward to it! There’s no question in my mind that I’ll be in much more control when I’m going slow!

Note: Remember earlier when we were installing the 2 new heavier detent springs, I said to read Road Testing comments first? Well, this is because you may not want to install them if you are not using a twin stick setup, for one. Also, if you are using twin sticks, but have not experienced problems with the t-case popping out of gear, you may wish not to install them, as well. The reason is that they definitely make it a bit more difficult to shift into the various ranges, and even more so if you’re using a modified Spicer 18 transfer case twin stick setup like mine.

The passenger side lever, which engages the front axle, is about 5 inches shorter than the driver side lever, decreasing the amount of leverage significantly. Personally, with a little practice, I was able to shift into whatever range I needed without much difficulty at all. I like the added pressure provided by the new springs, and feel it will eliminate my popping out of gear problem. We’ll know much better after the off-road testing!

Off-Road Testing
To test my new LoMax gears off-road, I attended a Southern High Rollers (www.southernhighrollers.com) club run to Shiloh RidgeOHV Park near Alto, Texas. Shiloh doesn’t offer much extreme wheeling, but I thought it would be a good place to check out my new 123 to 1 crawl ratio and re-learn how to drive my Jeep. It also offers some fairly steep descents to test those detent springs!

To state the obvious, on terrain where I had all the traction I wanted, such as rocks, the gears are a significant advantage over stock, giving me much more time to control my Jeep and pick the best line possible without slipping the clutch or stopping.

JB Conversions LoMax JB Conversions LoMax

On loose or wet terrain, such as wet rocks or hill climbs, I just shifted to 2nd gear, which with a 3.09:1 ratio, still gives me a decent 60:1 crawl ratio. In the following photos, the ground was somewhat moist, not allowing enough traction to utilize first gear. Second gear, with a little momentum and wheel speed was needed.

JB Conversions LoMax JB Conversions LoMax JB Conversions LoMax

Another consideration here is going downhill. Going too slow can be as much of a problem as going too fast (well, almost), causing the tires to slide, resulting in a loss of steering control. Most declines required use of either 2nd or 3rd gears, but definitely not 1st! It’s just too low!

The following comparison chart helped me considerably:


T-18 Transmission Gear Ratios






T-Case Ratios




















As you can see, in situations where I used to use 2nd gear, 3rd gear is now more appropriate, providing the momentum and/or wheel speed to overcome the obstacle. Closer comparisons are between 3rd and 4th gears.

Regarding transfer case operation, I experienced absolutely NO popping out of gear! In fact, by the end of the day, I forgot that I had even had the problem with the original detent springs. Yes, it was still just a little difficult shifting the front axle into either high or low range. I now believe most of this is due to the much shorter Spicer 18 shifter and the actual location of the levers, which is 5 ½ inches rearwards of stock due to the transmission to transfer case adapter required to mate up my T-18 to the Dana 300.

JB Conversions LoMax

Also, compared to several other 4:1 transfer cases on this trip, these LoMax gears are quiet! Even in low range and 4th gear, there was no discernable noise from the transfer case! In my opinion, this speaks to the quality of the design and workmanship that JB Conversions has put into these gears. There’s no question they’ve got a winner in my book!


JB Conversions, Inc.
P.O. Box 2683
Sulphur, LA 70664-2683
Phone: 337-625-2379


Jack Brinks

Jack Brinks is an avid four wheeler and contributor here at ROCKCRAWLER.com. Jack resides north of Houston, TX and frequents many events in the Southwest.

Contact Jack at jb77cj7@aol.com

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