Re gearing

[AKLespaul]

I have a Sport 2 door with a 3.6 man trans. I have Baja Boss 35's with 4.88 gears. Took a month to get used to the change from 3.45's. Totally worth it. I had questioned 4.56 gears and wondered if I made a mistake... Nope, 4.88's were the perfect choice. Sea level to 6K feet this does all I need with power to spare. Has noticeable power/speed increase in all gears. First gear is a bit quick, but second will stretch out for you just fine.

I'm glad I did the 4.88's and it cost $2200 for the Yukon Master kit installed with the oil change after 500 miles.

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[Ratbert]

Any way you can attend a large jeep meet and politely ask (assuming they have 4.56 on 33s) for a quick test drive?

Wish I could, but not many have my 3.0 engine.
I'm on 3.73 factory, but want to feel the 4.56 or even 4.10 on 38s. I hit 8th fine, but some have said you feel like you gain power with 4.56 on 38s with the diesel.

4.56s work really well with 37s on the EcoDiesel. I assume 38s wouldn't be significantly different.

 

[JINO]

4.56s work really well with 37s on the EcoDiesel. I assume 38s wouldn't be significantly different.

Funny thing is that i notice a big difference in MT baja legend exp 37x12.5x17 and nitto TG 38x13.5x17 in weight when driving.
But I'm sure it's better than the 3.73 I have now, and I don't even have complaints. Feels nearly stock, just not as whippy.

 

[aeonixx1001]

So I have 2020 jeep JL sport s with stock 345 gears. I bought a set of take off rims and tires 285/70/17 along with a rubicon suspension takeoffs my question is how will 456 gears do with 33s for the meantime. I plan to go 35s so that’s my next question lol. do 35s rub on stock rubicon suspensions any input would be great I plan on keeping the same 17 inch rims as well shop is asking 2600 after tax for full regearing UConn gears is that fair? I’m new to this any input is appreciated

I am running 17x12.50x35's with a 3 1/2 lift, I changed(had to no power) to 4:56 gear ratio and it is perfect for a 35 inch tire. Spend $100 and buy a Mini Tazer and you can play around with settings. This was pretty much dead on for shift points and acceleration. 35's wont rub on a Rubicon if they are OEM, but if you get into a side winder trail you may get some rubbing

 

[Coreyb516]

I think people are looking at the wrong end of the range of gears. Even massively over-geared like a 3.45 with larger tires the drive train manages fairly well. You may never see 8th but it really doesn't make the much difference to fuel consumption or driving.
Where the correct final ratio does make a big difference is in the lower gears. Pulling out into traffic is night and day with even a single step up in (numeric) ratio. eg 4.10 to 4.56 makes a noticeable change in acceleration in the lower gears. Something like the 3.45 with 33s feels like you are hauling a boat behind you the whole time.

I am running 17x12.50x35's with a 3 1/2 lift, I changed(had to no power) to 4:56 gear ratio and it is perfect for a 35 inch tire. Spend $100 and buy a Mini Tazer and you can play around with settings. This was pretty much dead on for shift points and acceleration. 35's wont rub on a Rubicon if they are OEM, but if you get into a side winder trail you may get some rubbing

I think my issue on 35 would be the fenders because I have the sport s so I’m hunting things on eBay lol

 

[Whaler27]

So I have 2020 jeep JL sport s with stock 345 gears. I bought a set of take off rims and tires 285/70/17 along with a rubicon suspension takeoffs my question is how will 456 gears do with 33s for the meantime. I plan to go 35s so that’s my next question lol. do 35s rub on stock rubicon suspensions any input would be great I plan on keeping the same 17 inch rims as well shop is asking 2600 after tax for full regearing UConn gears is that fair? I’m new to this any input is appreciated

Asking about gearing is a bit like asking folks what ice cream flavor is best. People have their favorites, and they advocate for them, but in the end it comes down to personal preference on the tradeoffs. The JL’s transmission is much better than previous generations, so your jeep will run well with a range of options.

The gearing debate has been had many, many times, so you’ll find plenty or reading material using this site’s search engine. I can’t make the point better than #zandcwhite, so I’ll link one of the many threads where he’s weighed in on this. The bad news is the decision doesn’t get easier/clearer as you read. The good news is you’ll see it’s hard to make a decision that’s really wrong, because your transmission has plenty of grace.

Another gearing discussion

 

[Coreyb516]

Asking about gearing is a bit like asking folks what ice cream flavor is best. People have their favorites, and they advocate for them, but in the end it comes down to personal preference on the tradeoffs. The JL’s transmission is much better than previous generations, so your jeep will run well with a range of options.

The gearing debate has been had many, many times, so you’ll find plenty or reading material using this site’s search engine. I can’t make the point better than #zandcwhite, so I’ll link one of the many threads where he’s weighed in on this. The bad news is the decision doesn’t get easier/clearer as you read. The good news is you’ll see it’s hard to make a decision that’s really wrong, because your transmission has plenty of grace.

Another gearing discussion

I totally understand that and I’m very appreciative of everybody’s opinions everyone’s got perspective and I take all that into account for sure

 

[arnie_mueller]

I just did this myself.

I used Colorado Axle & Gear (https://axlengear.com/), who supposedly do this every single day. They recommended Dana Spicer gears as they're the highest quality, lowest noise. I paid $3150 out the door for gears with install, and installing my own brand new ball joints. They quoted me $2900 for the re-gear and $150 for the ball joint install, at the same time.

Unfortunately, I cannot give you an opinion. The front gears are really loud starting around 40mph and stay loud while coasting down. The rear gears are pretty loud starting around 62mph. I'm at 300 miles in the 500 mile break in. I haven't gotten on it. I have the 2.0L JLUR. I do notice that I'm not in 8th gear more regularly while cruising.

I mostly just wanted to bitch there because I find it frustrating that a shop with "axle" and "gear" in their name couldn't get this right. They did it all in 5.5 hours, turned it over, said, "we don't hear any noises, it shifts well, call us if you hear anything." I'm going to call them next Monday. They seem nice when I talk to them.


Now that I'm done venting....

After most of the research I've done, the consensus is that for 37s:
4.88 for the 2.0 - Peak torque comes on and is flat at 3k RPMs, more torque than the 3.6
5.13 for the 3.6 - Peak torque comes on around 5k RPMs, near redline, less torque than the 2.0


More torque = engine is stronger to spin the torque converter so a lower ratio (am I saying that right? 4 < 5 so I'm using the word lower) is okay.

Less torque = engine is weaker to spin the torque converter so a higher ratio is preferred


All that said, I wheeled my JLUR on 37s and 3.5" of lift with steel bumpers, winch, overlanding loaded with the rear seats down, all that just fine with the stock 4.10s. This past summer, climbing the beginning of our CO mountain pass, twice my Jeep overheated and I had to slow to 55 and move to the right lane. Both were loaded up pretty heavy and both were on 100+ degree days. I'm hoping the re-gear resolves that on hot days, fingers crossed.

I have another suggestion, would love for those with greater wisdom to chime in. What about installing a Rubicon transfer case to give you a slower crawl, instead of the re-gear?

 

[azjl#3]

Do you really just want to crawl, then yes. That's what makes the rubi so nice, so much is already there.

 

[Ratbert]

Unfortunately, I cannot give you an opinion. The front gears are really loud starting around 40mph and stay loud while coasting down. The rear gears are pretty loud starting around 62mph. I'm at 300 miles in the 500 mile break in. I haven't gotten on it. I have the 2.0L JLUR. I do notice that I'm not in 8th gear more regularly while cruising.

They're loud? Yeah, that's fucked up. You shouldn't be able to hear your gears.

 

[DubaiMarauder]

So I have 2020 jeep JL sport s with stock 345 gears. I bought a set of take off rims and tires 285/70/17 along with a rubicon suspension takeoffs my question is how will 456 gears do with 33s for the meantime. I plan to go 35s so that’s my next question lol. do 35s rub on stock rubicon suspensions any input would be great I plan on keeping the same 17 inch rims as well shop is asking 2600 after tax for full regearing UConn gears is that fair? I’m new to this any input is appreciated

No, 35s do not rub on stock Rubicon suspension, but you really should regear to at least 4.56 if you're gonna toss 35s on. 4.88 would be better, but at least 4.56, especially if you have a gas motor.

I have a diesel on stock 3.72 gears and 35s, but due to the amount of power mine has, I'm not overly worried about regearing for the time being. I will eventually go to 4.56 myself.

 

[aeonixx1001]

I think my issue on 35 would be the fenders because I have the sport s so I’m hunting things on eBay lol

Yeah they would rub like a big bitch. Stock Sport can handle 285x7x17 no problem. The Rubicon is stock 2 1/2 inches higher, so you could get away on a Rubicon. Love the sport though. Most of the fun is building it..

No, 35s do not rub on stock Rubicon suspension, but you really should regear to at least 4.56 if you're gonna toss 35s on. 4.88 would be better, but at least 4.56, especially if you have a gas motor.

I have a diesel on stock 3.72 gears and 35s, but due to the amount of power mine has, I'm not overly worried about regearing for the time being. I will eventually go to 4.56 myself.

I wouldn't regear with the 285x7x17. Your mileage will go crap, it will be a torquey thing, too much wasted energy. leave it 3:45 until you put the 35's on.

 

[moeman]

True story i got the 3.6 I have 8 speed auto kinda having a hard time staying in 8th with the 33 inch tires as soon I step on the gas jeep wants 7th gear back

I think that's normal. When it sees you looking for more power it down shifts to get the RPM in a higher range then will switch after it finishes riding the RPM

 

[Coreyb516]

I think that's normal. When it sees you looking for more power it down shifts to get the RPM in a higher range then will switch after it finishes riding the RPM

It is normal, as I elaborated later on though it’s just a pig now with a 33 and a steel bumper I feel like it’s just very sluggish and that’s really the main reason that I am bumping it up

 

[KG4NEL]

I have a Sport 2 door with a 3.6 man trans. I have Baja Boss 35's with 4.88 gears. Took a month to get used to the change from 3.45's. Totally worth it. I had questioned 4.56 gears and wondered if I made a mistake... Nope, 4.88's were the perfect choice. Sea level to 6K feet this does all I need with power to spare. Has noticeable power/speed increase in all gears. First gear is a bit quick, but second will stretch out for you just fine.

I'm glad I did the 4.88's and it cost $2200 for the Yukon Master kit installed with the oil change after 500 miles.

This was part of why I went with a factory order, I knew I'd end up with a manual and the $1k option from Jeep was a no-brainer. No plans to go larger than 35x12.5.

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