bamachem

hopefully i can fill that in soon.

stock 4.10's on 265/70-16's was about 18.5 mpg

stock 4.10's on 265/75-16's was about 17 MPG

stock 4.10's on 285/75-16's was about 15.5 MPG

stock 4.10's on 285/75-16's w/ a SC is about 18 MPG

next weekend, i'll be 4.56's on 285's w/ a SC (for about a week or so to get some data), then the SC will come off when I go back to NA, and then I'll have 4.56's on 285 numbers to share...

boogyman

ok so i understand that regearing is chaning the differential ratio, but what PARTS do you actually need to do this? i have 4.10 in my tacoma but don't know exactly what i need to do to get 4.56s. I don't want to walk into a shop and be like, "here's my money, make it happen" i want to know what's going on.

So from what I understand, I have to get both the front and rear diffs regeared. what's necessary to do this?

Road Head

You need the gears (ring and pinion) for both front and rear. It is also a good idea to get a diff rebuild kit when you re-gear. And then labor.

That is interesting to see that the gas mileage dropped by 3 mpg. Do you drive the same with 285s, or do you get on it, to compensate for the sluggishness? In theory, larger tires would actually get better gas mileage because they go farther for every revolution than the smaller ones, but having to keep your foot in the gas more often, actually causes you to burn more. The end result being, 4.56 gears will allow you to have stock acceleration and highway rpms, and you can use the same amount of pedal that you do with 265s and 4.10s, thus equaling similar gas mileage - but then add in the SC .

bamachem

I had to get on it ALOT more on the highway to maintain speed on ANY incline at all. It was CONSTANTLY downshifting to try to keep up. W/ the SC, I have plenty of power to spare and it doesn't downshift anymore, but now I'm using 93 octane and opening up another can of worms since I'll either need to get rid of the SC or upgrade the fuel system and possibly the transmission over time. I'm opting to remove the SC and sell it and then put a front ARB locker and 4.56's in and the money for the SC is paying for it. In all, I'll still have the same fuel economy, have less problems, have lower crawl gears, a front locker, and won't spend a penny out of pocket and pay $0.20/gallon less for gas - NO BRAINER.

Road Head

Personally, I think I would go with the 4.56s and ARB versus the SC. Dont get me wrong, the supercharger would be awesome, but I would also be worried about possible tranny damage more than anything.

BTW, before the SC (when you were just running 285s and 4.10s), did you ever try turning off O/D, just for kicks? I know that isnt a solution, O/D is there for a reason, I am just curious if that would help in really hilly situations. In Nashville, everything is pretty flat, but I recently went to Gatlinburg, and at times on the interstate, mine (stock) even had some difficulty choosing gears.

CynicX

if 4.56 will put you back to they way if felt with stock tire size you have to ask yourself if its really that bad now...I didnt read if you had an auto or a stick but by the looks of your last post and the OD question I'm going to assume auto....and auto will handle and increase in tire size better then a stick ie its less noticable....

I say, if you have the cash since having 2 axles regeared professionally can be quite expensive (of course doing it yourself can be even more expensive if you dont know what your doing). Then go for it. If money is tight I would just live with it. On a side not...to get it back to the stock ratio...if my math is correct you would want 4.36 (this is math not an actual gear size)....so 4.56 is past what you really need....now I just realized you have a 4runner...I was comparing 31" tire with 4.10 to a 33" tire with 4.10's...I dont know what your stock tire size was so I used my stock tire size....if your orginal tire was smaller then 31" then 4.56 will be more stock like then my calculation....

bamachem

1. yeah, i'm opting to do the gear swap and sacrifice the SC to pay for it. that's the point of my post...

2. yeah, i tried w/ the OD off on the highway and got a whopping 13 MPG at 75 MPH going from Alabama to Mississippi - about as flat as you can get.

3. the thing w/ the 4.56's is that they're LOWER gearing than what I had stock even taking the tire change into account. it will be the equivalent of running 30.5" (265/70-16's) on 4.30's. my runner came w/ 265's on 4.10's. the slight difference should make up for the added weight and still have nearly stock RPM's and MPG's.

Road Head

wow - 13 mpg is awful. I am surprised it was that low (at least it didnt have to choose gears though )

And yes, definitely have to incorporate additional rotational mass to the equation. Math will get you the "ideal" number, and its typical to round up to the next gear set. Thus, bamachem is right, slight overgearing should make up for more tire mass, plus it will help if you are ever towing, or have a rig full of people, luggage, whatever.

4.56 are definitely the solution, its just so darn expensive!!

RTdawgs

I've been debating this topic for a few weeks now, just saw this thread with tons of great info. I have 4.10s, AT, and S/C, plus lots of extra weight from TJM, winch, sliders and skids. Once I get back to 33" tires, I will be regearing. I travel lots on the highway so I think 4.88 is too low.

This rationale really hits the nail on the head in my book. Leaning strongly towards 4.56 now....

Jeff the marmot

As was mentioned earlier, I have a 2000 SR5 3.4L auto with lots of mods and Yukon 4.88's. On average I drive 25K miles per year, often at 75 mph or so. My stock gears were 4.30's with the stock e-locker and 265/70R16. I also have the supercharger and TRD headers. I've driven a total of about 85K miles between 2 sets of 285/75R16 MT/R's. I know for sure that mine is now 2900 rpm at 81 mph.

I love the 4.88's and wouldn't want any other ratio. They're great both on-road and off-road. I average 17 mpg on the highway now, although just yesterday I had a tank that was almost 20 mpg, mostly highway (55 mph). Including the tires, I intentionally chose a little lower than stock gearing due to the extra 500 pounds of stuff and basic supplies always in/on my 4Runner. Plus larger tires have a lot more rotating momentum, so if you want to have a chance of accelerating just as fast with larger tires, you need to go with a little lower gearing than what the simple calculation from stock gears says.

People who have a stick shift with the 3.4L have very different gear ratios in the transmission. They're better off with 4.56. But the question is tougher for the people who have the 3.4L and auto but with stock 4.10 gears. I don't know why Toyota had such similar vehicles with both 4.10 and 4.30 gears available. It would initially seem as though those people should also jump to 4.88's, but I'm not clear on Toyota's reason for different gears in otherwise the same vehicle and drivetrain, so I don't know. I also don't know if there's some other obscure difference, such as different transmission ratios between the 4.10 and 4.30 crowds, although I'd be surprised.

Note that I also kept my puny stock tires/wheels for other purposes that never panned out... Anyway, I've used them on occasion in the summer and gotten about 20 mpg on the highway at 75 mph with the 4.88 gears. Some of that difference may be less wind resistance and lower rolling resistance, but at any rate the noticably higher rpms don't hurt the mpg THAT much. However, I didn't exactly like to go over 75 mph with the rpms screaming at me though.

rmundarain

Hello guys, I don't want to jump here but I killed my gears of my front diff last saturday; I have 4.56 and will ask for your knowledge where to get gears at fair price; I don't want to go to the junk yard probably getting too used gears.
Thanks
RM

86runner

I also want to know where i could get a good price. I am too thinking of changing gears and had the problem of deciding 4.56 and 4.88. this thread has helped a lot and i think im gonna go with 33 tires and 4.56 gearing. but im looking for a good price.

Yobroe

Anyone have ideas on how to get new gears installed for a cheaper price? I priced them at Randy's Ring and Pinion and they are going to want around $1500 for parts and install. The installation labor for just the front end is $450. I may just have to keep the stock gears and try to bump up my power instead...I could get supercharged for that price! And, I am getting about 16.5 mpg with stock gears and 285s fyi...

mt_goat

What's that tire size in inches, any idea?

Yobroe

Should be 32.8" tall...

Gadget

I have a 96 4Runner 4x4 with an auto.

My truck came with the 16" wheel option and the larger brakes.

It had 4.10 gear ratio in the diffs.

I am running 33" tires.

I regeared to 4.56 gears. That was the wrong ratio for me. I should of done 4.88. The speed reads about 7 MPH under true speed and the truck still labors more then it should on the highway.

My plan is to regear to 4.88 as soon as I can get them from Precision Gear. They have been on back order for a while now.

The manual trucks have a different final gear ratio in the tranny and 4.56 gears are perfect for 33" tires, but the auto's final gear ratio is a bit steeper and the better choice is 4.88 in the diffs for 33" tires.

Just thought I would share real experinces so you don't make the mistake I did.

Gadget

SLC97SR5

Me too, I've got the 285's with 4.56's and sure wish I'd done 4.88's. The passing power just isn't there. The 4.56's with the stock 265/70/16's was great...should of been factory! Get the 4.88's.

mt_goat

I'm going to be trying 5.29s with 33's and the 3.4 auto. 5.29s were acually a little too tall for the 3.slo auto but with a charged 3.4 I guess it will be a different story. I was pretty happy with my ratio when I was running with 5.71s with 33s on the 3.slo auto. I could actually pass on the 2 lane highways!