Except when the acorn sized pinion gear breaks.
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4.56 gears and 35??
- Thread starter cherokeeforbyer
- Start date
Except when the acorn sized pinion gear breaks.
- Location
- Wasatch Range
Over time, I've had both gear setups behind an AW4. 4:56's will leave your tranny hunting between 3-4th on any hill larger than an overpass.
I've never regretted going with 4:88s in my current rig, which I've daily driven 60 miles round trip for 3.5+ years.
Living at 4,300 ft elevation and often driving up canyons and over passes at 7,500ft +, they are perfect for my 285/75/16 tires (33's). I average 17mpg on the hwy at this elevation.
Maybe 4:56's are OK with 35's at sea level, but they are too tall for the mountains.
Bolt on a buddys 33's and drive some routes you normally travel, including freeways and hills. Note acceleration and cruising characteristics. Then do the same with 35's, before making your decision.
PS, fuel economy will likely be 3-5mpg lower with with 35's than 33's.
I've never regretted going with 4:88s in my current rig, which I've daily driven 60 miles round trip for 3.5+ years.
Living at 4,300 ft elevation and often driving up canyons and over passes at 7,500ft +, they are perfect for my 285/75/16 tires (33's). I average 17mpg on the hwy at this elevation.
Maybe 4:56's are OK with 35's at sea level, but they are too tall for the mountains.
Bolt on a buddys 33's and drive some routes you normally travel, including freeways and hills. Note acceleration and cruising characteristics. Then do the same with 35's, before making your decision.
PS, fuel economy will likely be 3-5mpg lower with with 35's than 33's.
xj bmx
NAXJA Forum User
- Location
- Detroit, MI.
What rpm are you guys at with an AW4 and 4.88s on 35s? Im debating if i should go with a 44 front so i can go with 5.13s with 35s.
- Location
- Patterson, Ca
About 2600 rpm's at 75.
bobnoxious
NAXJA Forum User
- Location
- Marion, MA
Is that actual 75, or what the speedo thinks?
cherokeeforbyer
NAXJA Forum User
- Location
- Bonney Lake
i was told that 456 and 33 is basically where it would be stock
bobnoxious
NAXJA Forum User
- Location
- Marion, MA
xj bmx
NAXJA Forum User
- Location
- Detroit, MI.
Ya is this with a corrected spedo?
- Location
- Patterson, Ca
Sort of. My speedo is off by 8%, so at 75 it reads 80. At 80 on the speedo, rpm's are between 2600 and 2700. Also checked it on the gear calculator and it says 2634 at 75. My aw4 has the .705 od not the .75 of the later models. The 5% diference would put a late modEl closer to 2770.
xj bmx
NAXJA Forum User
- Location
- Detroit, MI.
Do you ever feel that you want lower(numericaly higher) gears on or off road?
I'm gonna go see where my DD jeeps rpms are on the freeway. I really want a lower gear since I only drive my toy it to the trail and back so I want as much ompf as I can get. Maby I will go to a 44/9 to get 5. somethings.
I'm gonna go see where my DD jeeps rpms are on the freeway. I really want a lower gear since I only drive my toy it to the trail and back so I want as much ompf as I can get. Maby I will go to a 44/9 to get 5. somethings.
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Darky
NAXJA Forum User
- Location
- 29 Palms, CA
Hearing from some of the older members who've been around XJs for a long time, 4.88s don't have any practical liklihood of breaking more frequently than 4.56. Sure, based solely on looking at them and thinking, it would seem they would, but experience of our older members says otherwise. That said, I love my 4.88s on 33s. If you've already geared to 4.56, I'd say stick with 33s vs 35s. Gearing will be better, mpg will be better, parts will last longer, etc etc.
bobnoxious
NAXJA Forum User
- Location
- Marion, MA
39/8 vs. 41/9
It's math and physics. Denying it doesn't make it not true...it just makes you stubborn.
It's math and physics. Denying it doesn't make it not true...it just makes you stubborn.
- Location
- Patterson, Ca
8 teeth makes an acorn 9 teeth is just massive? In some people's experience, 4.88 fail more, others not so much. I would rather have gearing I like than worry about breakage. 3.55's fail far less often, and that pinion is significantly larger than an 8-9 tooth acorn. Should we all just not wheel, then we won't break anything.
cherokeeforbyer
NAXJA Forum User
- Location
- Bonney Lake
yep i agree if we are gonna break stuff then we should all just drive cars and not worry about it...
bobnoxious
NAXJA Forum User
- Location
- Marion, MA
Pay attention...I never said 4.56's were unbreakable, and that 4.88's were guaranteed to blow up. Quote the part where I said 9 teeth was "massive" 
Are you really trying to blow smoke up my ass by saying that 39/8 is just as strong as 41/9? I said 4.88's were weaker and more likely to fail than 4.56. This is factual, based on math, science, physics. The quantifying amount doesn't matter, I'm still stating a fact.
Using your own argument...while it's true that it's only a little weaker, it's also true that it's only a little more ratio. Is the extra .32 worth about the same % in strength reduction? Not for me, but I need ability to take a beating more than I need to hold 80+ on the highway, and with a D30, every little bit helps (or hurts). Your needs may be different
The higher the ratio, the weaker the gear set. Period.
Are you really trying to blow smoke up my ass by saying that 39/8 is just as strong as 41/9? I said 4.88's were weaker and more likely to fail than 4.56. This is factual, based on math, science, physics. The quantifying amount doesn't matter, I'm still stating a fact.Using your own argument...while it's true that it's only a little weaker, it's also true that it's only a little more ratio. Is the extra .32 worth about the same % in strength reduction? Not for me, but I need ability to take a beating more than I need to hold 80+ on the highway, and with a D30, every little bit helps (or hurts). Your needs may be different
The higher the ratio, the weaker the gear set. Period.
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- Location
- Cheyenne, Wyoming
not in some cases. with some gears you get better contact with the higher gears, thus making it stronger.
bobnoxious
NAXJA Forum User
- Location
- Marion, MA
Examples
Hammered
NAXJA Forum User
- Location
- Jeep Fiend Club
Just to throw it in there, would it be worth getting 16 inch rims... that way you can do a 315 75 r16 wich is like a 34" kind of a happy medium PLUS... you have a thicker sidewall with the bigger rim in most cases.
(someone check me on this but it seems like a fair option)
I have 4.56 & run 285 75 16s and the go pedal seems real touchy, hard to baby it on rocks.
(someone check me on this but it seems like a fair option)
I have 4.56 & run 285 75 16s and the go pedal seems real touchy, hard to baby it on rocks.
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bobnoxious
NAXJA Forum User
- Location
- Marion, MA
PS: I'm one of the "older members who's been around XJ's for a long time" :rtm:
ford 9in is an example of a differential that has more contact area the numerically higher the gears are.
math and physics are solid and all, but there is a difference from paper and numbers and real world applications. hence the feud between engineers and builders.
i've seen a number of 4.88 gears fail, but most were the ring gear, not the pinion.
as far as what to run, different strokes for different folks.
math and physics are solid and all, but there is a difference from paper and numbers and real world applications. hence the feud between engineers and builders.
i've seen a number of 4.88 gears fail, but most were the ring gear, not the pinion.
as far as what to run, different strokes for different folks.
