DEFCON1
New member
285/70/r17 is a tire that is actually 32.7” tall bud.
Sent from my iPhone using JL Wrangler Jeep Forum mobile app
4:88s, not so popular, but gonna try it
- Thread starter GrayBeard
- Start date
285/70/r17 is a tire that is actually 32.7” tall bud.
Sent from my iPhone using JL Wrangler Jeep Forum mobile app
OverlanderJL
Resident Smartass
Okay so you would have to compare it to a metric 37 not a standard 37. Bud.
Sent from my iPad using JL Wrangler Jeep Forum mobile app
DEFCON1
New member
He didn’t provide the exact height of the tire. Lmao. The calculation is just using the most accurate numbers provided. [emoji38]
Sent from my iPhone using JL Wrangler Jeep Forum mobile app
wwood
New member
Hopefully I won't get too much heat from this but I just want to clear up some terminology since different people use different terms when talking about higher or lower gear ratios.
The "gear ratio" we are talking about is determined by the number of teeth on the ring and pinion gears in the diffs. We divide the number of teeth on the ring gear by the number of teeth on the pinion. So if the ring gear has 40 teeth and the pinion gear has 10 teeth the gear ratio is 4.00. That also means for every full turn of the ring, the pinion turns 4 times. The more times the pinion has to turn to produce a full turn of the ring, the lower the gear ratio. So, for example, 5.13 is lower than 4.10. This is sort of confusing because the bigger the number, the lower the ratio. Generally when mechanics or auto people say they want lower gears, they mean they want something like 5.13 gears instead of the factory ratio of 4.10. The 5.13 ratio is lower than 4.10 but the number 5.13 is higher than 4.10.
This is potentially confusing at least to me since I don't always know what the person is saying when they say lower or higher - do they mean lower/higher ratio or lower/higher number?
Defcon's post is an example where he says, "A little lower would get better mileage, a little higher would get more power." I assume he is saying in his example that the 4.22 gears will get better mileage (which is correct) than 4.63 gears because 4.22 is a higher ratio even though the number 4.22 is lower than 4.63.
For whatever its worth I think we should mean gear ratio, not the actual number, when using the terms higher or lower gears. So lower gears means 5.13 as compared to say 4.10.
Last edited:
JTCO
Meme King
I think you meant for every full turn of the ring gear, the pinion gear turns 4 times.
OverlanderJL
Resident Smartass
Hopefully I won't get too much heat from this but I just want to clear up some terminology since different people use different terms when talking about higher or lower gear ratios.
The "gear ratio" we are talking about is determined by the number of teeth on the ring and pinion gears in the diffs. We divide the number of teeth on the ring gear by the number of teeth on the pinion. So if the ring gear has 40 teeth and the pinion gear has 10 teeth the gear ratio is 4.00. That also means for every full turn of the pinion, the ring turns 4 times. The more times the pinion has to turn to produce a full turn of the ring, the lower the gear ratio. So, for example, 5.13 is lower than 4.10. This is sort of confusing because the bigger the number, the lower the ratio. Generally when mechanics or auto people say they want lower gears, they mean they want something like 5.13 gears instead of the factory ratio of 4.10. The 5.13 ratio is lower than 4.10 but the number 5.13 is higher than 4.10.
This is potentially confusing at least to me since I don't always know what the person is saying when they say lower or higher - do they mean lower/higher ratio or lower/higher number?
Defcon's post is an example where he says, "A little lower would get better mileage, a little higher would get more power." I assume he is saying in his example that the 4.22 gears will get better mileage (which is correct) than 4.63 gears because 4.22 is a higher ratio even though the number 4.22 is lower than 4.63.
For whatever its worth I think we should mean gear ratio, not the actual number, when using the terms higher or lower gears. So lower gears means 5.13 as compared to say 4.10.
It was not confusing until you posted this novel of a post. Nobody ever talks about actual number when referring to gears.
Sent from my iPhone using JL Wrangler Jeep Forum mobile app
wwood
New member
Yeah, you are right I f'ed that up. Thanks!
PS: I fixed my original post, appreciate the heads up.
Last edited:
wwood
New member
Yeah, I was pretty sure you would give me a smack or two for that post.
No problem, I love your jabs always entertaining!
GrayBeard
New member
Well, got my JLUR back from the dealership today. 4:88 Spicer AdvanTEK gears installed as well as DANA AdvanTEK 44 Front & Rear differential covers and a Rancho Front Diff Skid.
Drove home from dealership, via the highway, and stayed in 8th gear 90% of the time. Before gear change, same route, 6th& 7th gear, constantly shifting. I think there is a noticeable difference so far, time will tell. But so far very happy.
Sent from my SM-N950U using JL Wrangler Jeep Forum mobile app
Drove home from dealership, via the highway, and stayed in 8th gear 90% of the time. Before gear change, same route, 6th& 7th gear, constantly shifting. I think there is a noticeable difference so far, time will tell. But so far very happy.
Sent from my SM-N950U using JL Wrangler Jeep Forum mobile app
doubletapdaddy
Caught the Bug
I've got to hand it to Rancho. They offer some great options at excellent price points for the JL, which they were able to bring to market in a very timely fashion. :thumb:
However, I sure wish they would offer that skid in black. I know that I can just spray it, but everytime it gets hit, it's going to look like it's bleeding. LOL.
However, I sure wish they would offer that skid in black. I know that I can just spray it, but everytime it gets hit, it's going to look like it's bleeding. LOL.
GrayBeard
New member
doubletapdaddy
Caught the Bug
Sorry, I was so focused on the red diaper I forgot to congratulate the performance you were looking for. Also those Dana AdvanTek covers are pretty sweet. I don't need them, however I really, really want them. Lol.
I don't need them, however I really, really want them. Lol.that's good to hear, I plan to gear to 4.88 when that time comes
i'd take it and have it powder coated black.
But I like the red, makes leaks much easier to see
OverlanderJL
Resident Smartass
You can take the powder off with a grinder. Then no more red.
Sent from my iPad using JL Wrangler Jeep Forum mobile app
Sent from my iPad using JL Wrangler Jeep Forum mobile app
GrayBeard
New member
So just to clarify because the 8 speed does change the normal equation.
33s good for 3.45
35s good for 4.10
37s good for 4.88?
40s good for 5.38?
Is it better to go extra on the gearing to find better overall balance?
Is the risk of the extra gearing being weaker the same with Dana 60s?
Or is it a Dana 44 and smaller issue?
It seems to me the extra gearing is allowing the engine and transmission to work at an advantage or less work with extra gearing. The transmission will do the same amount of work at lower rpms and less strain. Then at highway speeds the trans is better at maintaining with the same leverage. If 8th gear is being lost the total resistance needed to maintain speed is too high. Needing more gearing. Trying to understand.
Stock Rpms with 32s
1500 at 65 mph
1700 at 70 mph
1800 at 75 mph
2000 at 80 mph
33s good for 3.45
35s good for 4.10
37s good for 4.88?
40s good for 5.38?
Is it better to go extra on the gearing to find better overall balance?
Is the risk of the extra gearing being weaker the same with Dana 60s?
Or is it a Dana 44 and smaller issue?
It seems to me the extra gearing is allowing the engine and transmission to work at an advantage or less work with extra gearing. The transmission will do the same amount of work at lower rpms and less strain. Then at highway speeds the trans is better at maintaining with the same leverage. If 8th gear is being lost the total resistance needed to maintain speed is too high. Needing more gearing. Trying to understand.
Stock Rpms with 32s
1500 at 65 mph
1700 at 70 mph
1800 at 75 mph
2000 at 80 mph
So it isn't missed, factory Rubicons come with 4.10's and 33's. This is a great setup and I would argue, still a good setup for 35's. I have personally run the 4.10's with 37's and felt no need to regear the way I did with the old JK. Now, with 37's, if you want to bring things back to about stock performance, 4.88 would be the ratio that you'd want. 5.13's will give you more power but I would NOT recommend it in anything other than a set of Rubicon axles. A 5.13 pinion will be too small on a Sport or Sahara front axle and will therefore be a weak point. Same can be said of a 5.38 pinion on a Rubicon front axle. You're just looking for trouble or at least, if you actually play with your Jeep as hard as you think.
Depends on what's more important to you. MPG or power. Going with a higher ratio will have you running at a higher RPM at highway speeds and therefore, suck more gas.
No. A 60 will have significantly larger ring and pinions.
Yes.
With 5.13 and 37's, you'll be looking at about 2400 at 75 and more like 3000 at 80 mph.