Novak Conversions Jeep Wrangler TJ engine mounts

Still another gear question

mainegoat68

mainegoat68

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lewiston maine
I have an 04 X with the ever popular 3:07 gears. My boss has a set of 4:11s sitting on a shelf that he took out of another TJ, to put in 4:88s. I can have them for free. Question is, would that be too much gear for my needs. I had a Chevy K20 with 4:11s that was horrible on the highway. That thing screamed bloody murder over 60 mph. My main use is around town, which my current gears are ok with, but when I hit the Maine logging roads, I have to ride 2 to 3 hours of interstate. The 3:07s make the TJ so numb, but would the 4:11s make it a screamer? I have Toyo Open Country's, P265/70R16s, which measure a bit over 30.5" tall. I don't know if 3:73s would be better. I would hate to solve one problem, only to cause another. Any thoughts from those of you who have "been there-done that" ? I was even thinking of selling it to buy a newer Wrangler that had more power, and better on the highway. The thing is, my TJ is in unbelievable condition, and I really like it, other than being kind of numb. I've even had guys laying on the ground looking under it when I come out of a parts store, commenting on it's rust free condition.
 
I think the missing information I'd need is who's setting up the gears? If it's you and you've got time then go for it.

If you're paying someone then it's a different answer...are you set on that tire size? What transmission, what engine?

I had a 69 K20. Gear ratio is almost incomparable due to different tire sizes and transitions.

-Mac
 
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Use grimmjeeper to check.

With your NV3550 transmission, NP231 transfer case, 4.11 gears, and 31" tires:
At 75 MPH your 4.0L will be turning 2606 RPM. The goal with that engine is to get close to 3000 RPM. So 4.11 will be much better than 3.07, but ideal would be 4.56 (2891 RPM) or 4.88 (3094). That's if you're staying with those 31-ish inch tires forever.
The 4.0L engine really likes 3K RPMs, and will run all day at that speed.
 
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mainegoat68 said:
I have an 04 X with the ever popular 3:07 gears. My boss has a set of 4:11s sitting on a shelf that he took out of another TJ, to put in 4:88s. I can have them for free. Question is, would that be too much gear for my needs. I had a Chevy K20 with 4:11s that was horrible on the highway. That thing screamed bloody murder over 60 mph. My main use is around town, which my current gears are ok with, but when I hit the Maine logging roads, I have to ride 2 to 3 hours of interstate. The 3:07s make the TJ so numb, but would the 4:11s make it a screamer? I have Toyo Open Country's, P265/70R16s, which measure a bit over 30.5" tall. I don't know if 3:73s would be better. I would hate to solve one problem, only to cause another. Any thoughts from those of you who have "been there-done that" ? I was even thinking of selling it to buy a newer Wrangler that had more power, and better on the highway. The thing is, my TJ is in unbelievable condition, and I really like it, other than being kind of numb. I've even had guys laying on the ground looking under it when I come out of a parts store, commenting on it's rust free condition.
Click to expand...

Everyone is missing the main point that these are used gears, not new. When gears are set new, they work harden. If you don't get these gears set up exactly like they were when he pulled them, then it's going to be a complete crapshoot.

Setting them up to new install specs isn't the answer. If you want to install used gears, the specs should have been recorded prior to pulling them. This includes pinion pre-load, backlash, and a pattern. The goal would be to set them up exactly as they came out and that is wayyyy more difficult than most think.

I'll leave it at that for now, but you need to understand you will be chasing your tail trying to get these set up.
 
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hosejockey61 said:
Everyone is missing the main point that these are used gears, not new. When gears are set new, they work harden. If you don't get these gears set up exactly like they were when he pulled them, then it's going to be a complete crapshoot.

Setting them up to new install specs isn't the answer. If you want to install used gears, the specs should have been recorded prior to pulling them. This includes pinion pre-load, backlash, and a pattern. The goal would be to set them up exactly as they came out and that is wayyyy more difficult than most think.

I'll leave it at that for now, but you need to understand you will be chasing your tail trying to get these set up.
Click to expand...

Mike's right. I just installed used gears in my rig and it still made a bunch of noise...

😳

OP - pay no attention to me, that's an inside joke.

Mike is, however, spot on about the used gears.
 
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mainegoat68 said:
I have an 04 X with the ever popular 3:07 gears. My boss has a set of 4:11s sitting on a shelf that he took out of another TJ, to put in 4:88s. I can have them for free. Question is, would that be too much gear for my needs. I had a Chevy K20 with 4:11s that was horrible on the highway. That thing screamed bloody murder over 60 mph. My main use is around town, which my current gears are ok with, but when I hit the Maine logging roads, I have to ride 2 to 3 hours of interstate. The 3:07s make the TJ so numb, but would the 4:11s make it a screamer? I have Toyo Open Country's, P265/70R16s, which measure a bit over 30.5" tall. I don't know if 3:73s would be better. I would hate to solve one problem, only to cause another. Any thoughts from those of you who have "been there-done that" ? I was even thinking of selling it to buy a newer Wrangler that had more power, and better on the highway. The thing is, my TJ is in unbelievable condition, and I really like it, other than being kind of numb. I've even had guys laying on the ground looking under it when I come out of a parts store, commenting on it's rust free condition.
Click to expand...

I think4.20s would be perfect for your tires. Rubicons come with 4.10 gears & 31” tires.
 
Mudflat said:
I think4.20s would be perfect for your tires. Rubicons come with 4.10 gears & 31” tires.
Click to expand...

The Rubicon came from the factory with that tire size and axle gearing using three very different transmissions. Which one was correct?

42rle/30.5”/4.10=2337rpm @ 75mph
NV3550/30.5”/4.10=2473rpm @ 75mph
NSG370/30.5”/4.10=2846rpm @ 75mph

Also, where does one find 4.20 gears?
 
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hosejockey61 said:
At the pot shop, duh.
Click to expand...
Screenshot_20260207_140715_Google.jpg
 
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I have 4:10 in my 05 Rubicon 6sp. I’m running 32s and am very happy with power and acceleration. I travel with 300-400lbs of gear in the back and a 1200lb teardrop. No problem pulling long 6% grades at 55mph. I do have to down shift to 4th.
 
bucky said:
I have 4:10 in my 05 Rubicon 6sp. I’m running 32s and am very happy with power and acceleration. I travel with 300-400lbs of gear in the back and a 1200lb teardrop. No problem pulling long 6% grades at 55mph. I do have to down shift to 4th.
Click to expand...

good to know, thanks
 
bucky said:
I have 4:10 in my 05 Rubicon 6sp. I’m running 32s and am very happy with power and acceleration. I travel with 300-400lbs of gear in the back and a 1200lb teardrop. No problem pulling long 6% grades at 55mph. I do have to down shift to 4th.
Click to expand...

Yours has a different transmission. And you would be even happier with deeper gears.
 
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@mainegoat68 good plan looking into a limited slip or some other form of traction aide while you're in there. I went with a tracloc LSD when I did gears and it's been fabulous. Best of luck to ya!
 
Novak Conversions Jeep Wrangler TJ engine mounts
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