The Wrangler is very suitable for modification. The more conventional plan is: 2.5-inch lift + 35-inch tires + 4.56 speed ratio, 4-inch lift + 37-inch tires + 4.88 speed ratio, 6-inch lift + 40-inch tires + 5.13 speed ratio, The visual effects, handling and performance of the perfectly modified Wrangler will all have a very good improvement. However, after the Sahara is modified with large-size tires, it is very prone to mechanical failures such as damage to the front speed ratio. It often occurs when using low-speed four-wheel drive to get out of trouble, pass large obstacles, climb, etc., while Rubicon rarely occurs. Such problems.
Here we use Dana30/44/60 to do a comparative analysis: the front axle model of the original Sahara is Dana-30, the rear axle is Dana-44 (without lock), while the front and rear axles of the Rubicon are Dana-44 (with lock), Dana-30 front axle peripheral and internal parts are smaller than Dana-44. The final drive ratios of the Sahara and Rubicon transfer cases are 2.72:1 and 4.11:1 respectively, which means that the Rubicon has a larger transmission torque, plus the modification of large-size tires will add a greater load to the transmission system The strength requirements will be relatively high. From the following pictures, it can be seen that there are obvious differences in the size of the axle tubes and final drive housings of the Sahara and Rubicon. A larger-sized axle can accommodate a larger-sized differential, speed ratio and other accessories. The strength of these components It is also relatively higher, which is one of the vulnerable factors of the Sahara speed ratio.
Let’s take a look at the speed ratio. The original speed ratio of the Sahara after Model 12 is 3.21 (45 ÷ bevel 14 = transmission ratio), and the Rubicon is 3.73 (41 ÷ bevel 11 = transmission ratio). The ratio is 41÷9=4.56, 39÷8=4.88, 41÷8=5.13. From the picture, we can see that the diameter of the D-30 tooth is 40mm smaller than that of the D-44. Under the condition of the same number of gears, the smaller the volume means the smaller the size of the single tooth, and its strength will be relatively weak.
Why can’t I change to a larger size ratio? The speed ratio is assembled on the differential case. The differentials of different specifications are completely different in size, and the speed ratio cannot be exchanged at all. The planetary gear assembly inside the larger differential is also larger and stronger. The following figure shows us See very clearly.
The damage to the speed ratio is generally caused by the broken driven gear (big gear). At this time, it is not recommended to continue driving. If it cannot be replaced in the damaged area, it is necessary to open the differential armor to clean the metal debris inside the main reducer shell, and then reinstall it. Fill the axle oil and prohibit the use of four-wheel drive, otherwise the debris will break the driving gear, planetary gear, and half-shaft teeth. After the planetary gear is damaged, the half-shaft may not be able to rotate smoothly and damage the half-shaft, so it will not be able to generate speed. If it is not in the same position (just like opening the front differential lock), it will lead to failure to turn normally and cause an accident.
The half shaft is also very different. The rear axle of the Sahara and the Rubicon are both D-44, but because of the relationship between the differential lock, the rear half shaft of the two models cannot be used in common. The same is true for the front half shaft. Not only is the Rubicon relatively larger , the ten-byte size of the front half axis is also larger, and their strength is also self-evident. By the way, let’s popularize the number of spline gears on the half shaft: Sahara has 27 front and 30 rear shafts, and the left and right rear half shafts have the same length. Rubicon has 30 fronts and 32 rear shafts, and the rear half shaft is longer on the right and shorter on the left.
After the above analysis, we believe that the higher the level of the bridge, the matching parts will be larger, and the probability of damage will be smaller. The Sahara is not suitable for medium and high-intensity off-roading, so a reasonable solution is needed-replacing Dana-44 or even Dana -60 front axle, through the replacement of a higher level of front axle, differential lock, speed ratio, axle shaft and other complete sets of accessories to achieve or even exceed the strength of the Rubicon, so that there will be almost no “speed ratio” accidents.