Final answer
Thread Starter
JK Newbie
Joined: Sep 2013
Posts: 40
Likes: 0
From: Martinez,ca
Why bother asking the question? Get 4.88s if that's what you want. Everyone will tell you it's too much. No idea what exactly you expect to gain from that. You have a standard transmission. Other than the first 5 mph, you have complete control over what gear you are in and what rpm you are running.
The 6th gear ratio is .797. Your driveshaft will be well over 3k rpm at 70. You will easily exceed the max constant rpm of the driveshaft. The increased driveline vibrations will add stress and wear on everything. That said, it's always cool to see pictures of JK transfer cases that cracked in half on the highway.
Light it up, man.
The 6th gear ratio is .797. Your driveshaft will be well over 3k rpm at 70. You will easily exceed the max constant rpm of the driveshaft. The increased driveline vibrations will add stress and wear on everything. That said, it's always cool to see pictures of JK transfer cases that cracked in half on the highway.
Light it up, man.
Thanks again for your imput
JK Junkie
Joined: Dec 2011
Posts: 2,256
Likes: 1
From: Madison, New Jersey
Thank you guys for your input, I am simply looking for someone with the same tires and trans with 4.88s so I know exactly what RPM ill be turning as I have used many different ratio charts and get anywhere from 2800 to 3100 as you all know it is a big chunk of money and i do not want to guess..but I am now leaning towards 4.56 it looks like that will give me a bit more gear while being manageable on the freeway Thanks again for your imput
JK Junkie
Joined: Jun 2013
Posts: 3,697
Likes: 2
From: Grosse Pointe, MI
Now that I think about it, I did have my 4.88s for a couple weeks while running 315/70-17 Duratracs. They had an actual rolling diameter of 33.75" I believe (or 33.5", I forget which made the speedo accurate).
I was running about 2950 at 70. I felt my Jeep was not happy about it.
Even with 37s, 4.88 felt like too much at 70.
I was running about 2950 at 70. I felt my Jeep was not happy about it.
Even with 37s, 4.88 felt like too much at 70.
JK Junkie
Joined: Jun 2013
Posts: 3,697
Likes: 2
From: Grosse Pointe, MI
I honestly don't know regarding the stock drive shafts. A typical 1310 shaft is usually around 3k rpm for constant speed. So, the math is your final drive ratio and engine rpm to get shaft speed. Part of the reason is that most places don't have machines that balance above that rpm. Vibrations increase and that can cause serious damage to the drive line.
Thread Starter
JK Newbie
Joined: Sep 2013
Posts: 40
Likes: 0
From: Martinez,ca
Now that I think about it, I did have my 4.88s for a couple weeks while running 315/70-17 Duratracs. They had an actual rolling diameter of 33.75" I believe (or 33.5", I forget which made the speedo accurate).
I was running about 2950 at 70. I felt my Jeep was not happy about it.
Even with 37s, 4.88 felt like too much at 70.
I was running about 2950 at 70. I felt my Jeep was not happy about it.
Even with 37s, 4.88 felt like too much at 70.
Thread Starter
JK Newbie
Joined: Sep 2013
Posts: 40
Likes: 0
From: Martinez,ca
4.56s installed
I had my 4.56s gears installed and picked it up yesterday
for those of you considering a gear change to your 6 speed with 34s (33.60 installed) they work out perfect I can now start out in 2nd gear all the time, at 75 MPH i am turning approximately 2800 RPM at 70 MPH 2650+- overall a lot more responsive so it worked out perfect, keep in mind most gear calculators say 2700 at 75 with that combo which almost had me convinced to go 4.88s but after hearing some real experienced comments from you guys i decided to go with 4.56s happy i did even though not a daily driver i still drive head out of state from time to time hope this helps when considering a gear change
thanks again
for those of you considering a gear change to your 6 speed with 34s (33.60 installed) they work out perfect I can now start out in 2nd gear all the time, at 75 MPH i am turning approximately 2800 RPM at 70 MPH 2650+- overall a lot more responsive so it worked out perfect, keep in mind most gear calculators say 2700 at 75 with that combo which almost had me convinced to go 4.88s but after hearing some real experienced comments from you guys i decided to go with 4.56s happy i did even though not a daily driver i still drive head out of state from time to time hope this helps when considering a gear changethanks again
JK Super Freak
Joined: Aug 2014
Posts: 1,813
Likes: 0
From: Nokesville, Va
I had my 4.56s gears installed and picked it up yesterday for those of you considering a gear change to your 6 speed with 34s (33.60 installed) they work out perfect I can now start out in 2nd gear all the time, at 75 MPH i am turning approximately 2800 RPM at 70 MPH 2650+- overall a lot more responsive so it worked out perfect, keep in mind most gear calculators say 2700 at 75 with that combo which almost had me convinced to go 4.88s but after hearing some real experienced comments from you guys i decided to go with 4.56s happy i did even though not a daily driver i still drive head out of state from time to time hope this helps when considering a gear change thanks again
for those of you considering a gear change to your 6 speed with 34s (33.60 installed) they work out perfect I can now start out in 2nd gear all the time, at 75 MPH i am turning approximately 2800 RPM at 70 MPH 2650+- overall a lot more responsive so it worked out perfect, keep in mind most gear calculators say 2700 at 75 with that combo which almost had me convinced to go 4.88s but after hearing some real experienced comments from you guys i decided to go with 4.56s happy i did even though not a daily driver i still drive head out of state from time to time hope this helps when considering a gear change thanks again
JK Super Freak
Joined: Aug 2014
Posts: 1,813
Likes: 0
From: Nokesville, Va
I never go above 65mph and don't like to run that fast for long. With 37s I think it'll be about right on the road but I'm looking at a 4:1 transfer case for a deeper feel while wheeling