New Dana Gears
- Thread starter sandhu07
- Start date
doubletapdaddy
Caught the Bug
Kudos to WJCO for bringing closure to this discussion. Lol.
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OverlanderJL
Resident Smartass
Holy shit that bill arnett Guy makes me want to swallow a fucking 12 gauge. I hope you don’t reproduce or haven’t reproduced.
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BillArnett
New member
Good idea; don't forget to pull the trigger.
:cheesy: I was going to try and catch up on this thread but then saw this. Thanks for the Cliff notes :thumb:
notnalc68
That dude from Mississippi
Absolutely. Thanks 13_gecko_rubi! Very informative, and I trust your opinion.
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BillArnett
New member
Well, I'm back and my opinion hasn't changed.
I have a JLUR 3.6L automatic with 37" tires and the stock 4.10 gears.
As 13_gecko_rubi predicted, on the freeway at 70 to 80 mph I don't see 8th gear very much. It does drop into 8th sometimes on downhills or when there's a tail wind but mostly I cruise in 7th. But that's just fine. What matters is the engine RPMs. If I had 5.38s I would be doing the same RPMs in 8th as I do now in 7th. That doesn't seem like a big deal. Also, I noticed that even at freeway speed I'm often in 6th or 5th or even 4th when climbing a hill. Lower gears wouldn't help there, either. It's really nice to have so many ratios!
At the other end of the spectrum, running 5.38s would mean crawling slower at a given RPM. I played around a lot to see if this would matter to me. This trip didn't involve much really serious rock crawling but I did encounter a couple of situations which may shed some light on it. In one case, I was at about 12,000 ft above sea level climbing a 15-20 degree rocky slope (in 4Lo, of course). If I left the transmission in D it would use 2nd or 3rd most of the time, only going into 1st briefly when starting from at stop. I put it in M3 and was able to crawl at whatever speed I chose. It would pull strongly at 2000 RPM. Even at 1500 RPM it would accelerate up that slope albeit not very rapidly. And that's in 3rd gear! So in this case I can't see where lower gears would help much.
In another case in Moab, I found a short slickrock hill that I could drive up and the easily loop around and try again ("Triple Threat" on Fins N Things). The slope was almost exactly 30 degrees. (I know that my JL could probably climb something considerably steeper but 30 degrees seems VERY steep from a seat of the pants perspective!) In M2 it climbed up no sweat. In M3 it needed a big dose of the right pedal but didn't bog down and climbed up easily enough. In M1 I was able to crawl up at less than 1 mph. So again, lower gears wouldn't be much help.
(I also tried that hill in D to see if I could provoke the loss-of-power bug that Eddie and others have seen. No luck. It went up just fine.)
I did use M1 a couple of times when crawling over boulders. But that was more out of laziness than necessity. I used M1 going down the tricky section of Black Bear Pass but it was really too slow. I just did that to keep my wife happy. If I had had 5.38s I would have been in 2nd.
The final factor might be acceleration. With a lower final drive ratio straight line acceleration is probably a bit better. But a JL is so awful in that respect that a small improvement wouldn't matter much to me. YMMV.
Maybe someday I'll find a different situation. But for me the stock gears seem just about perfect with 37s for now.
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13_gecko_rubi
New member
Glad you enjoyed the trip. I imagine most people will leave stock gearing with 37s just live with owning a 7 speed. It's a big investment for minimal gain. Me, I'd run 5.13s or 5.38s all day but I'm silly lol
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Deezus
New member
If you have 4.10s in the new JL and are running 37s or smaller I don't see why you would regear. I myself like doing 70mph at 2000 rpms. I'm gonna save my money.
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Deezus
New member
Deezus
New member
It won't. I've been running 37s with 4.10s since it was new almost and did a lot of freeway driving. At one point I went from Sacramento to Mammoth mountain and back taking 50 to 89 to 88 to 395 and Monitor pass. I had good power and when I got home was able to achieve 20mpg! I was able to pass with ease and going up and down the pass was effortless, unlike my jk with 37s and 5.13. I dont know what gears I was in but since that trip and going to Oregon and back I decided I'm not doing gears. I'm using that money for other mods.In my limited experience so far, I seem to stay in 8th when it's flat or downhill, ie about 1/2 the time. And even when I drop down to 7th I'm spinning at 2378 RPM at 75 mph which is comfortable enough whereas with 5.38s it would be 2489 RPM at 75 in 8th (according to the above calculator). The difference is insignificant but it should be very slightly more efficient with the 4.10s; even though I'm in 7th gear I still have a higher final drive ratio.
So maybe I have a 7.5-speed
The real reason I'm not going with lower gears is just that I don't want to spend a lot of money for what seems to me to be at best a very slight benefit. I'm going on a long trip next month. Maybe my opinion will change.
IMO, 4.10s with 37s = regearing is unnecessary.
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One thing I haven’t seen anyone talk about on this thread and is the real reason to regear is stress on that very likely expensive 8 speed trans that I have. Drivability wise I would agree that the stock 4.10 are not horrible with 37s. Got about 6500 miles on mine now and really the stress on the trans is what concerned me. I’ll likely regear some time in the future.
The 8-speed automatic is computer controlled and smart enough not to get stressed. While there are certainly some benefits to re-gearing, it's a big cost and one that simply isn't "needed" the way it was back on the JK, especially after installing a larger set of tires.
Not sure you’ll convince me that there isn’t more strain on the trans but I don’t plan to regear too soon anyway so I guess we shall see.
LOL!! Trust me, I'm not trying to convince you of anything. I'm simply stating what I know is true. If I really thought it was a problem, I would have done it a long time ago. Not like any of my other 4 JK's haven't been re-geared and more than once. But of course, you're free to believe what you want
NFRs2000NYC
Member
Nothing to convince here. Facts don’t care about feelings. If a transmission gets “stressed” the computer will simply have it downshift as many gears as necessary to eliminate the stress.
The one thing I don’t think anyone mentioned here, is the simple fact that regearing a stock axle weakens it, thanks to a smaller pinion. You are greatly increasing torque and passing it through smaller teeth. Is that little bit of power and slightly better highway rpms in 8th worth weakening the pinion? Not for me.