FordGuy1
Adventurer
If I remember right, on the d30, it is very significant. The 4.56 has 3 tooth contact and when you go to 4.88 it is only two teeth.
4.56 or 4.88s?
- Thread starter ngirondo
- Start date
If I remember right, on the d30, it is very significant. The 4.56 has 3 tooth contact and when you go to 4.88 it is only two teeth.
Jeeper4life
Adventurer
I just picked up some 4.56 gears for my JK. Haven’t had them installed yet though.
Mitch502
Explorer
When I was asking between 4.10 and 3.73 for my Wrangler (only running 33's, but with a 5.9L swap) someone said, "I've never heard anyone regret going with the higher gear"
I went with 4.10 and have ZERO regrets. Just a thought there.
However, if they're saying the strength is greatly diminished, that is something to consider.
I went with 4.10 and have ZERO regrets. Just a thought there.
However, if they're saying the strength is greatly diminished, that is something to consider.
Happy Joe
Apprentice Geezer
Have run many gears and tire sizes with many underpowered engines (< 200 hp & 200 ft pounds), along with mostly manual transmissions but also some automatics, over the years. In small and light, dual purpose, highway and difficult trail, vehicles.
I was most happy with;
4.10 gears and tires less than 32 inches in diameter (29s or 31s worked well),
4.27 gears and 33 inch tires... also ran 4.56 gearing with a mileage hit and higher rpm on the highway with 33s.
4.56 gears and 35 inch tires... this was my favorite tire size gear combination as it let me get into overdrive at 45 mph (T-5 five speed) and would do moderate highway hills in the Rockies without hassle (190 horse, 4.0l, I-6); though occasional downshifting is necessary (the gears are there for a reason and down shifting is no hassle).
I have never had an engine so underpowered that it needed 4.88 gears for the above tire sizes... I ran ~110-120 horse 258, I-6 engines and 33 inch tires for years (with much frustration before sequentially injecting the engines)... Traditionally people running 4 cylinders and wanting 35 inch tires have gone with 4.88s... gave a way the last set that I had for Dana 44s because I had no use for them.
Automatic transmissions were much more forgiving of tire sizes that were slightly too big; because their internal slippage effectively reduces their gear ratio when starting from a stop...
Anemic engines (significantly less than 200 horse & 200 ft-pounds) appreciated larger gearing for the tire size.
when going for much to big tires (38s and bigger), on more extreme terrain the axle gearing installed gets much lower (higher numbers) but these vehicles rarely saw highway use since the tire compound would not stand up (highway tires will not do extreme terrain enjoyably).
For towing, or hauling heavy loads, I would expect lower gearing to ease the strain on the engine... My typical camping load out is and has been, for years, approximately 600 -800 pounds in a Jeep CJ, YJ, TJ, or Ford Explorer).
Enjoy!
I was most happy with;
4.10 gears and tires less than 32 inches in diameter (29s or 31s worked well),
4.27 gears and 33 inch tires... also ran 4.56 gearing with a mileage hit and higher rpm on the highway with 33s.
4.56 gears and 35 inch tires... this was my favorite tire size gear combination as it let me get into overdrive at 45 mph (T-5 five speed) and would do moderate highway hills in the Rockies without hassle (190 horse, 4.0l, I-6); though occasional downshifting is necessary (the gears are there for a reason and down shifting is no hassle).
I have never had an engine so underpowered that it needed 4.88 gears for the above tire sizes... I ran ~110-120 horse 258, I-6 engines and 33 inch tires for years (with much frustration before sequentially injecting the engines)... Traditionally people running 4 cylinders and wanting 35 inch tires have gone with 4.88s... gave a way the last set that I had for Dana 44s because I had no use for them.
Automatic transmissions were much more forgiving of tire sizes that were slightly too big; because their internal slippage effectively reduces their gear ratio when starting from a stop...
Anemic engines (significantly less than 200 horse & 200 ft-pounds) appreciated larger gearing for the tire size.
when going for much to big tires (38s and bigger), on more extreme terrain the axle gearing installed gets much lower (higher numbers) but these vehicles rarely saw highway use since the tire compound would not stand up (highway tires will not do extreme terrain enjoyably).
For towing, or hauling heavy loads, I would expect lower gearing to ease the strain on the engine... My typical camping load out is and has been, for years, approximately 600 -800 pounds in a Jeep CJ, YJ, TJ, or Ford Explorer).
Enjoy!
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pittsburgh
tacocat
In my 1995 YJ with 2.5L and manual transmission I ran 33x10.5x15’s, I got 22MPGs around town and 16-17 at highway speeds of 70-75MPH. I had zero regrets with those gears.
Happy Joe
Apprentice Geezer
Which gears???
4.56s or 4.88s.. .many folks with 4 cylinders go for the 4.88s.
Enjoy!
Ragman
Active member
Going through same mental exercise. I have 6 speed with 4:10s. With 35s I calculate 3:56s get me back to stock so going that way as was very happy with the combo.
I think that will be great combo for road and trail. Now to add a question of my own anyone want to recommend a brand of gear sets?
I think that will be great combo for road and trail. Now to add a question of my own anyone want to recommend a brand of gear sets?
pittsburgh
tacocat
I forgot the most important part of my post lol. Yes 4:88’s
Lucky j
Explorer
I was running 4,56 with my 4.0L 5 sp manual. When on 35", it was not that great on roads and gojng up-hills. And had to be patient with my off-road trailer. But is was good on 33". I was swithching from 33" to 35 between road and trails.
The TJ will be getting the 4,56 but will always be on 33" including overland travel pulling a trailer most of the time for those occasion. If 35 was the norm, I would also go with 4.88.
But remember that you will have the week D30 with 35" tires and more tork with the 4.88 making it eaiser the snap those axle.
The TJ will be getting the 4,56 but will always be on 33" including overland travel pulling a trailer most of the time for those occasion. If 35 was the norm, I would also go with 4.88.
But remember that you will have the week D30 with 35" tires and more tork with the 4.88 making it eaiser the snap those axle.
ROKTAXI
Adventurer
When I changed the TC to a 241 in my '94 XJ (on 33's), I also changed out diff gears from 4.10's to 4.88's. Was the perfect combo for me. I'm a 65 mph (max) driver no matter what gears. Fuel mileage stayed the same. Off pavement it was perfect for the auto trans. If you'll be pending lots of time in 4-low you'll be liking 4.88's. So pick your gears based on how much REAL crawling you do.
edit: I had also upgraded to Warn front axles (with locking hubs) / 44 rear
edit: I had also upgraded to Warn front axles (with locking hubs) / 44 rear
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Happy Joe
Apprentice Geezer
Ran an old/narrow d30 front with 35s for years (also had a 4:1 low range transfer case). The only front axle problem that I had was breaking the old/smaller axle u-joints.
Jeep went to the bigger stronger (Dana 44 sized) u-joint in/around 1995 for the Dana 30 front axles, it is my understanding that they should be able to handle 36 or 37 inch tires if driven with care.
I did notice that using medium traction (12.50 x 35, BFG mud) tires helped the small u-joints last longer... high traction tires (Boggers) can break them easily, even when the tires are 33s. (Note; Boggers and/or Swampers are to soft for street/highway use they can wear out very quickly).
Enjoy!