4.88 gears versus 5.13 for 4 door auto jk
06-23-2011, 08:48 AM
#21
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My top speed is no different with 5.13's then it was with 3.73's, other then I can actually hold the higher rpm, maintain speed on inclines, and pass other vehicles at 80 mph. Before I would have been climbing a slight hwy incline in the far right lane, pedal to the floor, going 55 mph with the truckers.
06-23-2011, 08:57 AM
#22
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gears
if you have a dana 30 up front the pnion head on a 5:13 set gets very small under heavy load you might get gear failure as long as you dont live in mountainous terrain 4:88 will get by just my .02
06-23-2011, 09:08 AM
#23
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I don't see how you can get 3 different rpms at 70 mph. The tow mode turns off the od so you can have 2 different gears at 2 different rpm's but there is no way a tuner can change the gears in your transmission. running 3rd gear at 70 mph will have the same rpm no matter what tune you have. The tuner will just adjust the rpm point at which the gears shift.
06-23-2011, 09:52 AM
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06-23-2011, 10:14 AM
#27
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Bingo. Auto's are under-geared straight from the factory. If you all haven't done so already, follow the link posted back on page one of this thread and look at the numbers. An auto with 5.13's and 35's produces 75 rear wheel horsepower at 70mph!!! And that is with 5.13's. 4.88's would have your rpm lower, which means your hp at 70 will be correspondingly lower, and your ability to hold OD will be lower, which means you will drop out of OD more frequently, which means your gas mileage drops, which means...
I realize that I may be a bit biased, living at altitude and driving inclines all day long, but even down at sea level I will take my 5.38's over 4.88's any day of the week. (I have a light foot, and don't spend much time in rocks, so the strength difference between 4.88/5.13/5.38 is not an issue for me. I figure that if I am doing something stupid enough to break 5.38's, it's a good bet that 4.88's would have snapped as well).
I realize that I may be a bit biased, living at altitude and driving inclines all day long, but even down at sea level I will take my 5.38's over 4.88's any day of the week. (I have a light foot, and don't spend much time in rocks, so the strength difference between 4.88/5.13/5.38 is not an issue for me. I figure that if I am doing something stupid enough to break 5.38's, it's a good bet that 4.88's would have snapped as well).
06-23-2011, 10:50 AM
#28
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I have a 2011 4-door auto with 4.88's. I have a light foot and it drives great around town. However, in hills, with cargo or the added weight aftermarket bumpers there is a significant degradation of performance. If I had to do it over I would go with 5.13's.
06-23-2011, 11:36 AM
#29
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Everybody seems to compare 4.88's to 5.13's. Not much said about 5.38's. I see the chart will put me in the blue w/ 33"s and in the green if I go 35's in the future running 5.38's. So for me I have ruled out the 4.88's thanks to all of your input, but still undecided on the 5.38's. Is there a good reason to stay away from them?
06-23-2011, 02:23 PM
#30
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