Novak Conversions Jeep Wrangler JK shifters

Talk me out of 4.88 re-gear

jjvw said:
Overdrive for your specific transmission?

The point here is that this is a fairly simple math problem. And gear ratios are not very mysterious. A stock JK ran various gear ratios for it's tire andt transmission combinations. Knowing what those were is a good starting point for deciding what to choose for a larger tire.
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I see what your what saying. Good point
 
jjvw said:
Be careful of the charts. Does it include the overdrive ratio?

What does a stock JK run for rpms at 75mph?
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if we went by the way the factory set mine up, it would be;
32" tire
1:1 4th gear = 70 mph @ 3014 rpm
0.83:1 5th gear = 70 mph @ 2501 rpm
 
Now we are getting somewhere.

NAG1/4.10/31" = 2766rpm @ 75mph
NAG1/4.56/31" = 3077rpm @ 75mph
NAG1/4.88/31" = 3293rpm @ 75mph
NAG1/5.13/31" = 3461rpm @ 75mph

NAG1/4.10/34" = 2522rpm @ 75mph
NAG1/4.56/34" = 2805rpm @ 75mph
NAG1/4.88/34" = 3001rpm @ 75mph
NAG1/5.13/34" = 3156rpm @ 75mph

NAG1/4.10/36" = 2382rpm @ 75mph
NAG1/4.56/36" = 2649rpm @ 75mph
NAG1/4.88/36" = 2835rpm @ 75mph
NAG1/5.13/34" = 2981rpm @ 75mph

Based on a stock JK with 32" (closer to 31") tires, NAG1, and 4.10 gears, the appropriate gears for 35s looks to be 4.56 minimum; for 37s looks to be 4.88 minimum.
 
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jjvw said:
Grimmjeeper.com is a gear ratio calculator. Your transmission is the Dodge WA580/NAG1. Your true tire size is the center height of your hub from the ground x2.
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his gear ratio currently is 3.21:1
not sure what the factory tire size was for his model
jjvw said:
Now we are getting somewhere.

NAG1/4.10/31" = 2766rpm @ 75mph
NAG1/4.10/31" = 3077rpm @ 75mph
NAG1/4.10/31" = 3293rpm @ 75mph

NAG1/4.10/34" = 2522rpm @ 75mph
NAG1/4.56/34" = 2805rpm @ 75mph
NAG1/4.88/34" = 3001rpm @ 75mph

NAG1/4.10/36" = 2382rpm @ 75mph
NAG1/4.56/36" = 2649rpm @ 75mph
NAG1/4.88/36" = 2835rpm @ 75mph

Based on a stock JK with 32" (closer to 31") tires, NAG1, and 4.10 gears, the appropriate gears for 35s looks to be 4.56 minimum; for 37s looks to be 4.88 minimum.
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I would agree, if the OP was going to go to 35's 4.56's are appropriate.
 
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So mine stock is 3.21 but I couldn't tell you orginal tire size unless I get the window sticker from the dealership. It's a sport s
 
DrDmoney said:
his gear ratio currently is 3.21:1
not sure what the factory tire size was for his model

I would agree, if the OP was going to go to 35's 4.56's are appropriate.
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Knowing what I know from elsewhere, I would have to wonder why pushing the rpms closer to 3k at 75mph is a bad idea. Do JK owners suffer from the same problem of lugging their engines as TJ owners do?
 
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4.56 and 35's it will be. Should I still sleeve and gusset the inner C's for strength on the Dana 30 til I can upgrade?
 
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jjvw said:
Knowing what I know from elsewhere, I would have to wonder why pushing the rpms closer to 3k at 75mph is a bad idea. Do JK owners suffer from the same problem of lugging their engines as TJ owners do?
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no the 3.6 has good power, even though i didnt regear when i went to 35's the ProCal module allows you to reconfigure shift points for your set up and recalibrates the speedo.
 
DrDmoney said:
no the 3.6 has good power, even though i didnt regear when i went to 35's the ProCal module allows you to reconfigure shift points for your set up and recalibrates the speedo.
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That helps some. The middle gears should be good, but the 1st and last are the most effected.
 
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Mean Green said:
4.56 and 35's it will be. Should I still sleeve and gusset the inner C's for strength on the Dana 30 til I can upgrade?
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I ran 35's on a D30 for years with no extra work done to it, albeit the JKU is much heavier than my TJ. After all Jeep has learned from the JK's predecessors, I dont think they would have kept it if they thought it wouldnt handle a 35.

to your question, dont waste your money beefing it up if youre going to upgrade to a D44
 
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DrDmoney said:
I ran 35's on a D30 for years with no extra work done to it, albeit the JKU is much heavier than my TJ. After all Jeep has learned from the JK's predecessors, I dont think they would have kept it if they thought it wouldnt handle a 35.

to your question, dont waste your money beefing it up if youre going to upgrade to a D44
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That's the thing though. The upgrade is literally years away. I do want to off road a bit, not rock crawl but two tracks and gravel roads. I don't abuse my rides. My cj is still on stock AMC 20 with two piece axle shafts and 33's. Dana 30 still enough for 35's and my style of driving? I appreciate all of your responses,this has been very helpful
 
Novak Conversions Jeep Wrangler JK shifters
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