I haven't paid close attention to my 80MPH RPM's, but my speedo is dead accurate as compared to GPS speed, with 35/12.50-18 tires and 4.88's. (4 speed, 2002) So whatever your tach reads at an indicated 80 is probably pretty close. 
Re gear to 4.88's or not? (2 Viewers)
- Thread starter Nottajeep
- Start date
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This was an interesting read.
And it had me thinking that the Cruiser Outfitters 10% underdrive gears for 4H would be perfet for someone who wont go bigger than a 33-33.5in tire
And it had me thinking that the Cruiser Outfitters 10% underdrive gears for 4H would be perfet for someone who wont go bigger than a 33-33.5in tire
If you do hard stuff offroad you may also want their low range gears for a 25% lower 4Lo, while you had the T-case open.
I need to do a new front diff and I run 33s with a lot of fast freeway driving. How did your mpgs change with the five speed and 4.88s and 33 tires?
I would consider the re gear especially with 33s and a 4speed if you ever get above 5k feet in altitude. Not to mention the ticking time bomb of the 4.30 front ring gear. I went 4.88 recently and had 33s it was a good combo for Colorados hills. I did ultimately go with narrow 35s and the truck drives good but they don't fit well. I just finished a 3000 mile trip pulling about 3k lbs and 33s would of made this better. Ects were high with a lot of gear hunting above sea level.
I have about 1200 miles on my 99 since putting in the Nitro 4.88's....some pulling offroad trailer, some just loaded vehicle, on and off road. I love every single thing about the change! Peppier in town. Far less downshifts on the highway, better hill climbing, transmission seems happier/less confused. No regrets at all. Do the math and you'll see that between 33inch tires and 4.88's my rpms are only up about 5%(using GPS for speed) over stock...that silky V8 doesn't even notice.
This is nice to read. A regear will be in my future at some point here. Got some other things to take care off first though. Body lift sitting in my garage. A body mount to fix. And a tiny bit of rust remedy to do where my brakeline burst and jizzed all over the frame.
I’ve read through several of these threads and is been mentioned that the Odometer and Speedometer can be calibrated for larger tires.
What is that process and or parts?
I’m likely moving to 35’s and re-gearing to 4.88.
What is that process and or parts?
I’m likely moving to 35’s and re-gearing to 4.88.
If you go 4.88 and 35s you won't need to touch the speedo. I ran 295 70r18 with 4.88s and the speedo was almost perfect.
Guys that do need recalibration use the "yellow box".
hoser
SILVER Star
4sp will be dead on. 5sp slightly off.
Listen to this guy, his speedo is absolutely spot on!
Lol, well it's your speedo now.
My 99 instantly performed better in every way once I went to 4.88s
trdcorolla
SILVER Star
Same here
Looking for a little,advice here. Mainly highway driving, did 100k miles in 3 yrs with my 04. Seems like the rear pinion is wearing Now at 300k miles. I run stock size tires (though 16” from my previous lx470). And predominately run 75mph on the freeways. Looking to go twin 40 gal tanks, though no other mods on vehicle. Would it be prudent to go 4.30’s On the rebuild? Heck, even 4.56? I like the thought of going a little easier on trans/motor and want to hit 500k with this vehicle.
You have 4.10 now, so 4.30 won't make much difference. 4.56 don't exist. 4.88 could be a worthwhile change, dependent on tire size
4.56 +\~ exists with with transfer case under drive gearing. But I wouldn’t touch anything-if all you’re doing is mainly hwy mileage.
What are the signs that you’re noticing where you think the rear diff is going? How often have you changed gear oil? Is there any play in the pinion bearing (up-down)? Constant noise at all speeds ? What’s the state of u-joints and rear wheel bearings?
What are the signs that you’re noticing where you think the rear diff is going? How often have you changed gear oil? Is there any play in the pinion bearing (up-down)? Constant noise at all speeds ? What’s the state of u-joints and rear wheel bearings?
it feels like my rear axle physically “rocks” up or down when I get to a stop. I replaced the 5 arms/bushings which did improve things, but is still there. At this point I do not know if it is u-joints or the pinion riding up the gear, will check when I get back home. Was just thinking of the whole “while I”m there” scenario if re-gear would be beneficial. Again, I know motor/trans are known to last, just thought about easing stresses on them also since adding a couple hundred pounds. Not steady weight like bumpers and winches, but 80 gallons of gas and the dual 40 tanks will be noticeable even as just a couple extra passengers. If the pinion/ring gear do need to be replaced then it is at least worth considering.
