What gear ratio should I install in my Jeep Wrangler TJ / LJ? (and other re-gearing FAQs)
- Thread starter Chris
- Start date
UKTJ
TJ Addict
That's exactly the start point for my questions. I'm trying to work out how much I need to spend just to regear vs the cost of doing a locker at the same time.
In your instance, with the gears you have you are going to have to replace both front and rear carriers. I don't believe you would be able to reuse the spider and side gears with the new carrier (not 100% sure on that) but even if you could I would not. The big question is how far do you want to go with your build? Limited slip carriers can be had for not much more than an open diff and while not a locker they do make a substantial difference. You could go with open carriers and a Lock-Rite (replaces the spiders and sides) for a few hundred more per axle (would put you in the neighbor hood of $400 for carrier and locker combined). A Detroit would be a hundred or so more per axle. Going with selectable lockers would just over double the price per axle in parts alone. This may be more information than what you asked for and you may already know this but it may also help someone else down the road.
UKTJ
TJ Addict
Not too much info at all.
Out of curiosity, why are the spider and side gears not reusable? Is it about size / fir or just that near 20 year old gears are about ready for a change regardless?
I hope this will be useful for others that read this in the future, because while the thread covers in great depth the choice of gearing, but the practicalities of what it takes to regear seems less fully explored.
Like I said I'm not 100% sure on if they are re-usable with different size carriers, but yes years of wear would be the major concern.
I have a 4-cylinder 2.4L 2004 TJ. Nv1500 transmission.
My goal is a 2" lift running 31" tires and a rear locker.
My budget is limited, and parts are more expensive since I dont live in USA. So, I will do one upgrade at the time.
SO, which would be better? First install the lift kit, and the tires? (and when I have the money regear/install the locker?) or the opposite?
I guess my main question is, is it better to run for a year or more with 4.10 ratio on 31" tires, or 4.56 ratio with 29" tires?
My goal is a 2" lift running 31" tires and a rear locker.
My budget is limited, and parts are more expensive since I dont live in USA. So, I will do one upgrade at the time.
SO, which would be better? First install the lift kit, and the tires? (and when I have the money regear/install the locker?) or the opposite?
I guess my main question is, is it better to run for a year or more with 4.10 ratio on 31" tires, or 4.56 ratio with 29" tires?
Are you being forced to do it in steps? Why not save the money up and do it all at the same time?
If I had to chose, I’d rather have too much gear than not enough.
I'd wait until installing larger size tires like 33's before I'd pay the big $$$ required for a regearing.
Running 31's on 4.10 gears isn't going to be a huge issue while you save up the money for a gear change if you don't want to wait to do the lift and tires first. Worst case scenario you end up using 4th gear a little more often than you used to at higher speeds.
If you find that it ends up being too much of a power loss, (doubtful) running stock tires with a 2 inch lift wont look all that bad.
Brandough
Member
I plan on regearing and putting e-lockers lockers in. When I call to get quotes for 5.13 a lot of the places recommend 4.56 or 4.88. I currently have 33's and when I go 35's I will be putting in chromoly axles at the same time. I feel a little lost in all this. I have the 4.0, nv3550, Dana 30/Dana 44.
4.56 would be more than a little on the high side for 35s IMO, if you were staying with 33s the 4.56 would be okish, you'd probably shift out of high gear a little more often than you do with stock tires and gearing. 5.13s would be to 35s what 4.56 is to 33s
I preferred 4.88 with my 33s and the nv3550. Now with 35s, I want a deeper gear to the point that I'm considering 5.38 because I'm able to go that low on my daily driver.
Bottom line is that the shops you are talking to are incorrect.
Most shops recommend less than appropriate gearing. You will get better advice here from guys who actually own TJs and run 35s and 4.88 or 5.13 gears. With your .79 OD you'll want at least 4.88 (and possibly 5.13) for 35" tires.
I have the same transmission you do, I live in the mountains and my TJ is not a DD so 5.38’s work great for me, if I lived in the Valley or the Bay Area and it were a DD I would probably be ok with 4.88 or 5.13 but definitely not 4.56’s.
To add to this, if you are using your Jeep off-road for forest roads and plan on keeping the NP231 TC you have then 4.88’s would suffice but if more difficult trails are something you plan to tackle then go deeper, 5.13 or 5.38 the latter will get you down to 58.6:1 crawl ratio in first low with the stock TC.
Brandough
Member
thanks for the advice guys, ill stick to asking for 5.13.
2000 TJ 4.0 w/ the manual (NV3550) sitting on a 4" lift and 33's
My jeep currently has 3.73's and the jeep performs really well driving around town. Highway speed is another story. When cruising around 65 miles an hour I'm sitting around 2100 RPMs. It's also a dog getting up to 65mph and anything above that I need the wind at my back or going downhill. According to this thread, I need to put in 4.56. My brain tells me that now my RPMs will be significantly higher at 65mph on the highway. I suppose I'm not able to wrap my head around this recommendation. When driving at highway speeds, I lose speed when coming to inclined grades of only 3%. I typically have to downshift into 4th just to keep it above 60.
Knowing that little bit of information, is 4.56 really where I need to regear to?
My jeep currently has 3.73's and the jeep performs really well driving around town. Highway speed is another story. When cruising around 65 miles an hour I'm sitting around 2100 RPMs. It's also a dog getting up to 65mph and anything above that I need the wind at my back or going downhill. According to this thread, I need to put in 4.56. My brain tells me that now my RPMs will be significantly higher at 65mph on the highway. I suppose I'm not able to wrap my head around this recommendation. When driving at highway speeds, I lose speed when coming to inclined grades of only 3%. I typically have to downshift into 4th just to keep it above 60.
Knowing that little bit of information, is 4.56 really where I need to regear to?
4.56 will be perfect. Personally, I'd go 4.88 with 33's but I prefer a higher crawl ratio to highway speed. I wish I went 5.13 or 5.38 with my 35s / NV3550.
On 4.88 with 35's I can easily cruise at 75-80MPH
That's why I preferred 4.88 with 33s on the highway. And it's why I want at least 5.13 with 35s.