Spot on. The Revolution Gears 5.38 is perfect for the TJ Rubicon Auto with 35”+ tires. Great info! I’ve been hearing 4.88 is perfect for 35” tires. Yeah, in some vehicles, but there are so many variables. Thank you!
Not criticizing some one if they are running 3000 plus rpms but we shy away from those rpms for longer road trips and our preferences. The main purpose of this video is to help a person figure out exactly the rpms they will be running.
My '97 TJ Sport came from the factory with an AX15, 3.07 ring and pinion ratio, open diffs and 28" rubber. I think that was standard issue for the Sport model, the auto trans being an option. Thanks for sharing your knowledge. The overdrive ratio is a factor I hadn't considered when thinking of re-gearing and the info you supplied is very helpful.
It’s so true about the 42rle we have a jku with the 42rle run 5.38 gears and 42’s and it’s still a dog because the engine rpm isn’t high enough. Luckily Offroad we have a 4:1 transfer case so in 4low it doesn’t suck.
Great info Darrin . I run 4.56 in my 03 TJ with 33'' tires ( really 32.5 ) and I will be stepping up to 35'' tires ( really 34.5 ) and keeping my 4.56 gears for a while just to see how it is . I should be only losing a couple hundred RPMs . My Jeep only sees highway speeds once or twice a year. I was wondering if your going to do a walk around of your Jeep soon as I'm really interested in your set up and what front axles you are using. Take care my friend and be safe.
2740 rpm at 70 mph with that combo. From our experience your right there at the top end. A lot would go into making your decision. How much interstate travel? How many hills. Since you have that Manuel I’d run it in 5th gear and try and mimic these rpms to see what you think.
That’s what I’m running right now and its great for my driving. I don’t interstate very much but some. It is not a speed demon but doesn’t sound or feel like it too high rpm at 70mph. I’m not going to go much over 70 with this ratio though.. I am going to up size tires to 35s soon and I think it will be perfect blend for me. The 4.56 and 33s is really good in the woods and trails. I am hopeful that try 35s do as good on in the woods with 4.56, it should be since it’s what Harley has in his too. I think he is pretty happy sounds like.
I wish you had done the 04 with the 5-speed manual. I tried getting my rpm's up to 2600 using different size tires and gear ratios but after figuring for the OD ratio I could not get there. I have the 4.0 with the 5-speed manual and stock 3.73 gears. I am running 32" tires. Now I don't plan on regearing, but I am trying to learn about gears and tires for future mods. Thanks Ron S. from Texas.
I’ll say again I think the sweet spot is between 2500 to 2700 rpms. I’d prefer 2600 at 70 mph if I could get it. Also, what gear, transmission and tire size are you running. Leave in the comments.
2004 SE with 35x12.5R15 (MT Baja Boss) + 2.4L Powertech + 5 speed manual (nv1500/nv2550 depending where you look) + 4.88 gears + NP231 + HP D30 front (1999 XJ) and D44 rear (2000 TJ) Kinda wished I went with 5.13 gears, not sure how much of a difference that will be and at the time I wasn’t sure how strong the 5.13 gears would be. Maine is a hilly state. 13.30ish mpg on hilly highways (with camping gear) and 16ish mpg around town / dirt road driving. In either case, there’s not enough power and I really want to do a 1.9 TDI swap. There’s no saving the the 4cly.
2003 rubicon 5 speed manual 4.88 gears 35” baja boss tires I think it’s perfect, can drive it all day down the highway and it’s super low geared on the trail
So I use my 1999 Jeep TJ on the highway a decent amount with 30.5” tires and factory gearing. I actually want to bring the rpm down a little bit. How would that ride in town at lower speeds? Would it be better to leave it be and deal with the higher highway rpm?
This is a great piece and timely for me. My son's LJ is the 2005 with the 42RLE Auto. The only thing I can find on-line relative to gear ratio is 3.73 (seems whether it has the 4 speed auto or the 6 speed manual). So, on to my question. Since this is the 4 speed auto, why would I want to focus on the field that states RPM for 3 Speed? Shouldn't I be focused on the Automatic In Overdrive field for my on highway RPMs?
Spicers site is using a generic overdrive ratio in the 4 speed area. Not sure what overdrive ratio their using but there’s way to much variation from the 42RLE .69 ratio to the nsg370 .838 ratio. By using the 3 speed figure which is 1.1 final we only need to multiple by the overdrive ratio thats in the Jeep in question.. I have a lot of confidence in this method and it’s spot on with our Jeeps. I tried to explain this in the video but may not have came across clear enough. Hope it helps John
@@RubiKidd06 ok, that's what I thought you were saying. Just wanted to clarify. We are going 35s and I was originally thinking 4.88. This has me totally rethinking that we need 5.+ diff gears. You just saved me a really bad decision.
@@johnfitzgerald5158 that .69 overdrive is a tuff one. The Toyota guys are dealing with the same issue on the newer Tacoma’s. Right off the dealer lots Toyota the combination of gearing and their overdrive ratio making the transmission struggle to stay locked in. Not sure what the Toyota is sent with but I’m assuming it’s close to your overdrive ratio. One thing is John, check me and my math. Take your sons LJ out and measure what tires your running know. Run the LJ down the road to compare numbers with spicer and how I’m saying to calculate.👍👍
@@RubiKidd06 just ran it at 70 on the highway. Yep, confirmed,.29.6" tires, runs at just over 2,000 rpm. BTW, I found another calculator at Crawlpedia that allows you to enter trans ratio, as well. So, I punch the .69 in there and behold 2,045 rpm at 70 mph. I think the hard part is going to be to get gears in the 5.13-5.38 range to work in the D30 up front.
My Rubi Auto is at 2150 at 70mph. It is sluggish, no power in that RPM at that speed. Many have increased MPG, cooling and more at higher RPM at higher speeds.
So I think I am undergeared I am running a 2001 TJ with 35s and the 32rh and I believe the stock the car can’t drive on the freeeay I mean I can’t get it past 60mph at all with the accelerator on the floor… I keep telling my dad it’s need regearing but says oh it’s old but no I can’t the car past 60 I’m spinning like 2350 which is way too low what should I do regear could this be the issue ? 😊
I would assume your Jeep has stock gearing. With that your lack of acceleration and top speed is an indicator of that 3:08 or 3:23 stock ratio. 3:73 is going to get you close to a stock equivalent ratio but you could go to 4:10 as well but a bit revy.
im trying to correct my 05 TJ. why is lower rpm at 70mph a bad thing? isnt that better for mpg? how does lowering rpm while cruising affect off roading in lower gears etc
The manufactures will set the gear ratio up for general use. They don’t know where your going to be driving this rather it’s the mountains or flat areas that are close to sea level. So it’s a happy medium. The only Jeep TJ that we believe that could run larger tires is the 05/06 Rubicon with the 6 speed trans. They came with 4:10 gears from the factory and very little overdrive in the nsg370. From our experience the average TJ/LJ 4.0L has adequate power for stock size tires. When you increase tire size without changing the gear ratio you are lowering the rpm that is used at highway speed. Gas engines need that rpm to make enough torque to accelerate and maintain speed. You failed to say which location, transmission, engine and tire size you have.
Need to clarify? When you were doing the calculations for your buddies Jeep (nsg370) you were taking the 3rd gear #(middle column of the spicer calculator) not the bottom number which is different and was for 5th and higher.... Is this correct or does it not matter? Thanks for the info
Spot on. The Revolution Gears 5.38 is perfect for the TJ Rubicon Auto with 35”+ tires. Great info! I’ve been hearing 4.88 is perfect for 35” tires. Yeah, in some vehicles, but there are so many variables. Thank you!
Not criticizing some one if they are running 3000 plus rpms but we shy away from those rpms for longer road trips and our preferences. The main purpose of this video is to help a person figure out exactly the rpms they will be running.
Can't tell you how helpful this video is. I appreciate you showing the math.
My '97 TJ Sport came from the factory with an AX15, 3.07 ring and pinion ratio, open diffs and 28" rubber. I think that was standard issue for the Sport model, the auto trans being an option. Thanks for sharing your knowledge. The overdrive ratio is a factor I hadn't considered when thinking of re-gearing and the info you supplied is very helpful.
It’s so true about the 42rle we have a jku with the 42rle run 5.38 gears and 42’s and it’s still a dog because the engine rpm isn’t high enough. Luckily Offroad we have a 4:1 transfer case so in 4low it doesn’t suck.
NV3550 has .78 overdrive.
Your list shows .73
Great video 👍
I have a 2000 Sahara with nv3550
I just switched to 4:88s with from 3:73s on 35's.
Thanks for catching that. 4:88 gears are probably spot on for that with 35’s.
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I enjoy my 2002 TJ 4.0 with the 32RH auto, 5.13 gears, truetrac lockers with 33" tires. 35s when they wear down.
I should clarify it's mostly city driving, rarely sees the highway and I wanted some good tug while trail riding. So I'm happy.
That thing would be fun to drive of a stop light 👆. Probably pretty excellent acceleration. Thanks for sharing
Hi, great video. Question, you mentioned doing a TJ 98 4.0 and 5 speed manual yet you kept referencing the 3 speed numbers. Is that correct?
Great info Darrin . I run 4.56 in my 03 TJ with 33'' tires ( really 32.5 ) and I will be stepping up to 35'' tires ( really 34.5 ) and keeping my 4.56 gears for a while just to see how it is . I should be only losing a couple hundred RPMs . My Jeep only sees highway speeds once or twice a year. I was wondering if your going to do a walk around of your Jeep soon as I'm really interested in your set up and what front axles you are using. Take care my friend and be safe.
So I have a nsg370 with 33s and I was thinking about regearing to 4.56 gears. You think the rpm’s would be too high?
2740 rpm at 70 mph with that combo. From our experience your right there at the top end. A lot would go into making your decision. How much interstate travel? How many hills. Since you have that Manuel I’d run it in 5th gear and try and mimic these rpms to see what you think.
That’s what I’m running right now and its great for my driving. I don’t interstate very much but some. It is not a speed demon but doesn’t sound or feel like it too high rpm at 70mph. I’m not going to go much over 70 with this ratio though.. I am going to up size tires to 35s soon and I think it will be perfect blend for me. The 4.56 and 33s is really good in the woods and trails. I am hopeful that try 35s do as good on in the woods with 4.56, it should be since it’s what Harley has in his too. I think he is pretty happy sounds like.
@@andymilton17 Harley’s RubiKidd has 4.88 gears. Appreciate the comment Andy
Oh that’s right i got 35s i think they will be good with 4.56 and i will have better highway too. Great video
I wish you had done the 04 with the 5-speed manual. I tried getting my rpm's up to 2600 using different size tires and gear ratios but after figuring for the OD ratio I could not get there. I have the 4.0 with the 5-speed manual and stock 3.73 gears. I am running 32" tires. Now I don't plan on regearing, but I am trying to learn about gears and tires for future mods. Thanks
Ron S. from Texas.
I’ll say again I think the sweet spot is between 2500 to 2700 rpms. I’d prefer 2600 at 70 mph if I could get it. Also, what gear, transmission and tire size are you running. Leave in the comments.
2004 SE with 35x12.5R15 (MT Baja Boss) + 2.4L Powertech + 5 speed manual (nv1500/nv2550 depending where you look) + 4.88 gears + NP231 + HP D30 front (1999 XJ) and D44 rear (2000 TJ) Kinda wished I went with 5.13 gears, not sure how much of a difference that will be and at the time I wasn’t sure how strong the 5.13 gears would be.
Maine is a hilly state. 13.30ish mpg on hilly highways (with camping gear) and 16ish mpg around town / dirt road driving. In either case, there’s not enough power and I really want to do a 1.9 TDI swap. There’s no saving the the 4cly.
@@jeremy8715 not sure of the strength 5.13’s in a d30. Of course due to pinion size. Probably wouldn’t be a problem but.....
@@RubiKidd06 I believe 4.88 is biggest gear that will fit is a dana 30 housing.
@@davidhoops40 Yukon and Revolution sell 5.13 for the Dana 30 but not sure if there is a fitment issue.
2003 rubicon
5 speed manual
4.88 gears
35” baja boss tires
I think it’s perfect, can drive it all day down the highway and it’s super low geared on the trail
So your NV3550 has a .73 overdrive. That should put you a little over 2400 rpm at 70. 👍👍👍 thanks for sharing
So I use my 1999 Jeep TJ on the highway a decent amount with 30.5” tires and factory gearing. I actually want to bring the rpm down a little bit. How would that ride in town at lower speeds? Would it be better to leave it be and deal with the higher highway rpm?
What gear ratio did it come with?
This is a great piece and timely for me. My son's LJ is the 2005 with the 42RLE Auto. The only thing I can find on-line relative to gear ratio is 3.73 (seems whether it has the 4 speed auto or the 6 speed manual). So, on to my question. Since this is the 4 speed auto, why would I want to focus on the field that states RPM for 3 Speed? Shouldn't I be focused on the Automatic In Overdrive field for my on highway RPMs?
Spicers site is using a generic overdrive ratio in the 4 speed area. Not sure what overdrive ratio their using but there’s way to much variation from the 42RLE .69 ratio to the nsg370 .838 ratio. By using the 3 speed figure which is 1.1 final we only need to multiple by the overdrive ratio thats in the Jeep in question.. I have a lot of confidence in this method and it’s spot on with our Jeeps. I tried to explain this in the video but may not have came across clear enough. Hope it helps John
@@RubiKidd06 ok, that's what I thought you were saying. Just wanted to clarify. We are going 35s and I was originally thinking 4.88. This has me totally rethinking that we need 5.+ diff gears. You just saved me a really bad decision.
@@johnfitzgerald5158 that .69 overdrive is a tuff one. The Toyota guys are dealing with the same issue on the newer Tacoma’s. Right off the dealer lots Toyota the combination of gearing and their overdrive ratio making the transmission struggle to stay locked in. Not sure what the Toyota is sent with but I’m assuming it’s close to your overdrive ratio. One thing is John, check me and my math. Take your sons LJ out and measure what tires your running know. Run the LJ down the road to compare numbers with spicer and how I’m saying to calculate.👍👍
@@RubiKidd06 really good idea. I will check it and compare to Spicers calculations. Will shout back my findings.
@@RubiKidd06 just ran it at 70 on the highway. Yep, confirmed,.29.6" tires, runs at just over 2,000 rpm. BTW, I found another calculator at Crawlpedia that allows you to enter trans ratio, as well. So, I punch the .69 in there and behold 2,045 rpm at 70 mph. I think the hard part is going to be to get gears in the 5.13-5.38 range to work in the D30 up front.
Build sheet says my 2004 Auto came with 225/75r15 ... 28.5" tyres 3.73 diff ratio about 2650rpm at 60mph by my calculations.
Can you clarify why you want to bring the RPM up instead of lowering it for highway speeds?
My Rubi Auto is at 2150 at 70mph. It is sluggish, no power in that RPM at that speed. Many have increased MPG, cooling and more at higher RPM at higher speeds.
So I think I am undergeared I am running a 2001 TJ with 35s and the 32rh and I believe the stock the car can’t drive on the freeeay I mean I can’t get it past 60mph at all with the accelerator on the floor… I keep telling my dad it’s need regearing but says oh it’s old but no I can’t the car past 60 I’m spinning like 2350 which is way too low what should I do regear could this be the issue ? 😊
I would assume your Jeep has stock gearing. With that your lack of acceleration and top speed is an indicator of that 3:08 or 3:23 stock ratio. 3:73 is going to get you close to a stock equivalent ratio but you could go to 4:10 as well but a bit revy.
I got 5.13 with 38.5 boggers with 20s and I can start it 2nd if wanted. Pulls fine but at 65mph it’s reading 50-52 on dash lol
I can't find anything about any 4.0 which I understand, but never 3.21 14-45 or 3.31 13-43
im trying to correct my 05 TJ. why is lower rpm at 70mph a bad thing? isnt that better for mpg? how does lowering rpm while cruising affect off roading in lower gears etc
The manufactures will set the gear ratio up for general use. They don’t know where your going to be driving this rather it’s the mountains or flat areas that are close to sea level. So it’s a happy medium. The only Jeep TJ that we believe that could run larger tires is the 05/06 Rubicon with the 6 speed trans. They came with 4:10 gears from the factory and very little overdrive in the nsg370. From our experience the average TJ/LJ 4.0L has adequate power for stock size tires. When you increase tire size without changing the gear ratio you are lowering the rpm that is used at highway speed. Gas engines need that rpm to make enough torque to accelerate and maintain speed. You failed to say which location, transmission, engine and tire size you have.
@@RubiKidd06 how about an 05 with the 6 speed trans, but not a Rubicon?
Need to clarify? When you were doing the calculations for your buddies Jeep (nsg370) you were taking the 3rd gear #(middle column of the spicer calculator) not the bottom number which is different and was for 5th and higher.... Is this correct or does it not matter? Thanks for the info
Every calculation I did came off that 3rd gear column. Then I multiplied that number using the correct transmission overdrive ratio.
Shouldn’t the 5 gear manual example have been using the 5th and higher numbers? I’m a little confused. Can you clarify?
@@scottgoodman5288 I'm also confused by this.
99 TJ 3” lift 33’s 5 speed. Who in Sacramento ca can help me
Wow you talk in circles 🤦🏻♂️
Yes, the wheels on the school bus go round and round for some people. Go get on a Jeep forum and let some clown educate you