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

So your NV3550 has a .73 overdrive. That should put you a little over 2400 rpm at 70. 👍👍👍 thanks for sharing

Thanks for catching that. 4:88 gears are probably spot on for that with 35’s.

What gear ratio did it come with?

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.

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.

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

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?

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.

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.

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