4.88 Gears Safe For Distance On Highway?

[Zachanadandy]

We all see you advocating for 3,000 rpm in 5th on an 8 speed because who wants to use the full range of gears.

Or 3k rpms in 7th and actual low rpms in 8th as intended? All you do by gearing super low as you suggest is turn your 8 speed into a 4 speed. It will be in 8th at any speed over 40mph from experience. Not bad gearing, if you have a 10 speed or never drive over 60mph.

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[steve68]

Your mechanic must be thinking old school, 4:88's, a SBC, and a T350 3 speed transmission!!!

Then yes, you'll be winding the ever loving shit out of the motor, probably real close to 4000 rpms@65mph

4:10's 26" tires, 3500 stall convertor, T400, 3600 rpms at 65mph with a 454, in a 68 Camaro, you could watch the speedometer and the gas gauge move equally while driving on the highway,

8spd and 4:88 have a set F/R ready to go in and I agree with the forum,

 

[Hemy5587]

I am on the opposite end of the spectrum, stock 3.73s with BFG 37s (35.5-ish mounted) and am completely happy with my set up. I gained 1 mpg over the heavier/wider tread Goodyear 35s (33.5-ish mounted) I replaced. I stay in 7th for the most part while cruising 65-70mph at 2000-ish rpms, sometimes I dip into 8th but I feel like it does less gear hunting with the 37s than the 35s. I can still bark them from stop if I want and feel like if I need more power while wheeling that is what 4Lo is for. As previously mentioned the 8 speed really makes up the difference regardless of what tires or gears you go with, within reason. Good luck in your decision!

 

[Gladiator85]

where do you live?! Killimanjaro?!

Hill counrty Northwest Austin. Only see 8th at 65 mph plus with no wind, hills. Any one of those two I'm in 7th and sometimes 6th. For the people who say re gearing don't help or make a difference is either retarded or never regeared there Jeep.

 

[PuddleJumper]

Hill counrty Northwest Austin. Only see 8th at 65 mph plus with no wind, hills. Any one of those two I'm in 7th and sometimes 6th. For the people who say re gearing don't help or make a difference is either retarded or never regeared there Jeep.

I have mountains and don’t have your issue. How much weight per corner you turning?

 

[Gladiator85]

Tires are 68 pounds each rims 13 each.

 

[tysongladiator]

I'm going to give you my experience. I have 181,000 on my JT. I had 4.88 gears installed along with my 37s around 68k in Mar 2021. I ugraded to lockers and 5.38s around 140k in April 2023. That's 72k miles of traveling, offroading, rock crawling, and daily driving on 4.88 gears.

In my opinion and experinece, You'll be fine.

 

[Koolcarguy]

So I am re-gearing my 2020 Jeep Gladiator, I have 35" tires now and am moving up to 36" or 37" and think I will probobly go with 4.88 Gears.

I see a lot of threads about Gears & Tires & Ratios, but my mechanic cautioned me about taking 4.88 gears on long road trips as thats a lot of RPMs and can wear down the gears quickly and cause failure.

Now I off-road and rock crawl, but it's also my daily driver. Should these gear ratios be saved more for dedeicated off-road vehicles... can I drive 300 miles on the highway to a trail semi-often with 4.88s and not worry about gear failure? Also would 37"s be easier on the gears since it takes longer to rotate 37" tires then a 36"... or is my math way off base lol.

I've been running 4.88 for years in my Jk and Jku with 37's. O issue's great combination

 

[TheSolarWizard]

Tires are 68 pounds each rims 13 each.

Ive seen exactly zero 17” wheels for a jeep that weigh less than 24lbs

edit: theres probably a couple that are 7.5 wide somewhere that are a couple lbs less but they are gonna be expensive and not very strong.

 

[Gladiator85]

There ya go.

 

[Stan H]

Wow thanks everyone! All this makes me think running 5.13 might not be a bad idea. I have a full steel exo-cage (not pictured) and loaded down bed (~ 600lbs in the bed at all times usually). I was worried I was getting a bit too low, but it seems like no one is having isues with the gears atthis size at distance.

@Zachanadandy - Based on what you were saying though if I can get away with 4.88s it might work out better in the long run as the deep gears might not be worth it unless it's really nessisary. I don't tow, just have a ton of overlanding gear and roll cage.

I only have one thing to say make sure the shop or person thatvsets up your 5.13 has a good reputation for doing them well. As the ratio is lower 5.13 and 5.38 etc.. the pinion gear gets smaller and smaller the size of the pinion you get for a 4.10 to a 5.13 is a fair amount different . I have just seen some you tubers that set them up themselves and didnt get 10,000 before they had broken teeth etc..

 

[Stan H]

Ive seen exactly zero 17” wheels for a jeep that weigh less than 24lbs

My factory 17x7 aluminum Rubicin wheels were 44ibs. The steel rims I replaced with 17x9 are 47ibs. The tires are 68ibs. I think at any rate 13ibs sounds like a mistyped reply.

 

[PuddleJumper]

Tires are 68 pounds each rims 13 each.

The lighest wheel I've ever seen in a 17 in wheel is 21lbs on the dot. What wheel are you running?

 

[PuddleJumper]

There ya go.

you sure about that?!

 

[Wheelin98TJ]

I only have one thing to say make sure the shop or person thatvsets up your 5.13 has a good reputation for doing them well. As the ratio is lower 5.13 and 5.38 etc.. the pinion gear gets smaller and smaller the size of the pinion you get for a 4.10 to a 5.13 is a fair amount different . I have just seen some you tubers that set them up themselves and didnt get 10,000 before they had broken teeth etc..

The pinion head is smaller with deeper ratios, but I don't think it matters enough to influence what ratio you pick.

There are tons of people running 5.13 and 5.38 without issues. If these ratios were much weaker, we'd see more failures.

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