Doc_D

Not to throw another wrench into the equation, but what about pinion strength? I'm going to regear my 6 speed probably at the end of the summer. 4.56s on 35s would put me almost exactly to the same place I was with 4.10s and the stock 32s. 4.88s would give me a little more oomph. But I saw a comparison of pinion strength somewhere a long time ago and if memory serves me right a 4.56 pinion is stronger than a 4.88 pinion. By the time you start talking 5.38s there was a pretty considerable difference.

I don't have the original article to reference so if someone has some real data on it, please post it up.

JKsJK

hell of a deal right there - that's the best kind of research you can do.

chuck45

I think AEV is a little Hemi warped and sometimes forgets about the lowly 3.8. You will be extremely happy with the 5.13's once you get them in. Gears are the single best JK mod.

blkjkchicago

Same question, different tire size. What is a good gear for someone going to run 33's?


E

redbull1969

What I really want to know is replacing my gears with 5.13's going to fix the problem of bogging down in speed when going up hill? I'll be crusing at 75 mph and hit a up hill grade and slow down to 50 mph and I hate that lease let me know.

WilliamAWebb

What part of VA are you in?

magilla97

I appreciate the feedback and have been researching the heck out of this. I have looked on this forum as well as others and there is a considerable amount of contradictory information out there. The gist seems to be 4.88 or 5.13 depending on who answers the question. I figured I'd talk with someone who installs ring and pinions in the JKs for a living and in each case they thought that 4.88s was the answer. No offense to anyone, but the advice of two techs that do this for a living holds a lot of weight with me as I'm sure it would with many. Unfortunately it has only added to my confusion.

magilla97

Here's another thread asking for a recommendation running d60s and 40" tires. Interestingly enough the recommendation from SLC is for 5.13. Once again someone that installs these things for a living. Now I am really confused.

https://www.jk-forum.com/forums/modified-jk-tech-2/what-gearing-40-inch-tires-86744/

RCJeeper

I recently put 5.13s in and would been bummed if I went any lower (4.88 or less) I'm at about 2400 @ 72mph. I thought it was gonna be extreme. Nope. In fact I'd gone to 5.38 if I didn't think the pinion would get too small in a D44.

chuck45

What special knowledge is conferred upon somebody by dint of their knowing how to install gears? Do either of them own JK's? Have they spent an appreciable amount of time in JK's? Are they differentiating between the auto and stick? Do they have a clue as to the OD ratios of the JK trannys? Oh, they only do gears in JK's? I guess I'm mystifyed as to why you would listen to a tech rather than people who own JK's and have expereince with them.

I can tell you what non-techs JK owners, who apparently shouldn't be listend to, have told me. I haven't come across a single person with an auto, 35's or 37's and 5.13's who wished they had went with 4.88's - not a single one. On the other hand most every automatic owner who went with 4.88's wishes they went with 5.13's. Heck I went with 5.13's and wish I 5.38's had been available and that I'd have been smart enough to go with them.

Actually it seems there is little contradiction on gears for a JK with 35's. The consensus answer is 4.88's with a stick and 5.13's for an auto. Question - if 4.88's are good behind a stick with an OD of .84 who in their right mind would choose them over 5.13's when used with a tranny with an OD of .69?

I think you're overly impressed by "experts". My experience when dealing with shops is amazement that people can be in the business and remain so ignorant.