The 4.88 mega thread!!

I'm torn between 4.88 and 5.29... Have an appointment late next week and "think" I want to go w/ 5.29 but don't know. Any advice is appreciated based on real world experiences given similar variables...

* Live in Denver, CO and head up to the mountains regularly in both winter and summer - at least 2x per month. Steep 6-7% grades. Truck STRUGGLES. Trying to maintain 70mph going up grades requires regular 3rd gear downshifts. Its painful.
* I do drive 75-80mph when on the freeway, but usually not faster than that.
* Current Specs: 2020 TRD OR AT // 275/70/17 BFG A/T (E Load so heavy) // 2" Lift // ARE Topper // Steel Sliders // OTT Tune (which I can get refreshed w/ the gearing upgrade)
* Potential Plans: Covert front bumper w/ light winch // May increase tire size to 285/70/17 A/T (but likely will not go larger than that).

Any thoughts or advice specifically from those who live at altitude and have a similar-ish setup?

 

Auto or MT?
4.88 for MT, 5.29 for AT. Opinions vary.

 

Auto

 

I really like 5.29s with my MT

 

Wish I would have gone 5.29 with my MT. No real complaints with the 4.88's, but would have better with going 35's and probably bigger next tire set.

 

Yeah, mine is pretty dang low on 32’s but that’s just how I like it. I debated a long long
time back and forth on mine about which to go with, and even bought both. Happy I chose 5.29 now. With 33’s or 35’s, 5.29s would be a no brainer for me. Especially if there are plans for even bigger. At least you have the crawl box so you aren’t lacking off road regardless lol. And the supercharger for the road. NA, these things need all the help they can get.

 

How are the noise on 4.88s? Specifically Revolution brand if anyone has experience? In talking w/ my shop, they mentioned that the 4.88 Revolution gears are sometimes notably louder than the 5.29s.

 

i have Yukon 4.88 and i never noticed a noise. Just throwing that out there.

 

Use 75w-110 and you won’t have noise.
had them for years.

$29 75w-90 Synthetic Gear Lube - 1 Quart (Pack of 2)

75w-90 is a tad too light

best to break in the gears with 85w-140 non-syn

 

I have Rev 4.88’s no issues at all

 

I’ve been going back and forth on if I get my truck regeared if I should go 4.88 or 5.29. I have 32’ almost 33’s but don’t plan on going any higher than that. I live in Arizona don’t tow but I do have a little bit of amor. Sliders and front to transmission skids. Any opinions on which route would be better would be greatly appreciated.

 

FWIW, after a few years on my 4.88s from Nitro, running dino Lucas 84W140, I did the first post-break-in-period oil change. I’ve put about 60,000kms on the new gears and was changing the diff oil, just a precaution before a major road trip. The truck has been off-roaded, loaded, and driven for long intervals at highways speeds, and stop and go around town, in all weather.

The oil came out clear and clean, with nothing but a very slight pasty film of metal dust on the drain magnet, no flakes.

So I will say that although the Nitro gears whine more than OEM, they are not wearing in any detectable way, and the Nitro-recommended 85W140 Dino oil was protecting them. So I will say I’m impressed.

 

I’m part of this club now. Yay. I can go up hills in 2nd gear now, like a normal truck.

 

I have skinny 34"s and about 200-250lbs extra weight at all times. I accelerate just fine. I tow a 2500lb trailer and accelerate just fine with that. The only time I ever thought it would even be helpful to have 5.29 was in Colorado towing, but even then I just put it in sport and pick a gear. I have no idea how that would work with big heavy, wide, tires but with my skinny tires I have been getting 17+ mpg at 70mph on the way to work. I have a build thread of you want all the details

 

Thanks for that! From everything I’ve been reading, when I do decide to go through with it I’ll most likely just go with 4.88 cause 5.29 will probably be over kill for my use with the truck

 

I went 488s with Yukon - my setup is mostly stock, 33s, Fox2.5 suspension. There is little howl thing at 60mph when I let off the gas but other than that the low end torque is good. I didn't want to go with 529s because of the high rpm's as I also run a SC .

 

Does anyone with a manual truck (factory 4.30s and e-locker) plan on regearing soon? I would consider swapping to 4.30s and giving you my factory 3.91s as core plus cash. I had a deal with someone on this but it's fallen through. I have all the misc parts and fluids to do the swap. I would to 5.29s but i'm okay cruising at 1700rpm. 4.30s and 295 tires get me to identical rpms as bone stock.

 

Well, the discussion continues on this topic - I drove today a 2019 with 5.29's and on 33's KO2 and not very heavy, and the RPM's were way too high for my taste. I could also hear the diff at higher speeds....so I'm not sure really, maybe this one is an outlier but I'm just happy I got 488's for now. I'm sure there are other nice units out there running happily the higher 5.29's.

 

Which trans? MT or AT?

 

I have AT on mine. The other truck was also AT.