4.88 vs. 4.56 in a 2006

[Dave Bennett]

I have been in this quandary myself for quite some time now... 4.56 vs. 4.88...

JT is releasing 4.56 for my Taco any day and I am leaning that direction.

Overall, I am more concerned about fuel economy, or in my case, the lack thereof...

I need lower gears to move the truck easier, but too low could be a bad thing for me so I am reluctant to go to 4.88's...

.02

 

[heeltoe989]

I have been in this quandary myself for quite some time now... 4.56 vs. 4.88...

JT is releasing 4.56 for my Taco any day and I am leaning that direction.

Overall, I am more concerned about fuel economy, or in my case, the lack thereof...

I need lower gears to move the truck easier, but too low could be a bad thing for me so I am reluctant to go to 4.88's...

.02

I was the same way. But now having lots of HP to move the truck and getting better milage, I'm kinda on the fence to install the 4:56 gears. I know I will like them around town and for wheeling, but unloaded on the highway I like to sit around 75-80 mph, but with the holiday trailer I'm usually at 65, and I know my 4:56 gears will be a welcome addition pulling the trailer & being loaded.

I think I just answered my own concerns:safari-rig:

 

[Redline]

Your post 'could' be used as an example of why 4.88s would be okay because the motor doesn't seem to be loud or unhappy up there near 3k.

Doc:

I agree, I would like to maintain decent MPG too. But one of the reasons most modified rigs get poor fuel economy (other than weight/load) is that they are geared too high, not too low

I hadn't given 4.88s much thought because I thought they sounded far too low, but there is not much difference between 4.56 & 4.88. I think both will work but there is only one chance to pick the 'best' for my application. Don't go low enough or go too low, either could lead to gearing remorse :smiley_drive:

For what its worth, we tow a 5500lb. travel trailer all over Southern and Central California, including up over 8000' passes. I think our 2wd '04 Sequoia has the same engine and trans as yours. We have a totally stock drivetrain and tire size.

I always tow with the O/D off, which translates at 60-65mph to around 2800-3000 rpm. It sounds like it should be noisy and high strung, but it isn't. That engine is smooth and quiet and makes all of its useful torque between 3 and 4k, so its a good place to be under load.

That said, couldn't you just keep taller gears for unladen economy, and on long and slow climbs simply downshift? Might be simpler and more economical overall. I suppose that you're unladen far more often than laden, and you might keep the rev's low when you don't need them. The only time you would really appreciate the lower gears are on startoff from a dead stop while under load. At higher speeds with the trailer, a quick downshift would give you all the torque you need.

 

[Redline]

I did some more math and I find the numbers very interesting:

RPM for the stock 3.73 gears with the stock, 30-in. tires:*

3.73 in O/D
@ 60 = 1795
@ 65 = 1944
@ 70 = 2093
@ 75 = 2243*

The 4.56 may work great, but the RPM increase is only about 200-RPM at each speed over stock.*
With 4.88s the RPM increase is 400. I will have to drive the car in direct/4th this weekend and listen to the engine/rpm noise. But 200- is almost nothing and a 400-rpm increase doesn't seem crazy for the work it needs to do.*

Imagine how much (big) trailer I could pull with 4.88s. Hell, the 4Runner has a 7,000-tow rating (probably too much, 5k would be better) but it would probably pull really nicely with 4.88s, not so much w/ 3.73

I have thought of another way to look at the difference between the ratios. Instead of thinking of the RPM difference at a certain speed, one can consider the speed difference for a certain RPM. Basically for a given RPM I could drive 5-MPH faster or slower depending on the gears.

So, if I don't mind cruising at 2500-RPM then I can go 70-MPH w/4.88s or 75 w/4.56

2300-rpm = gives 70-mph w/4.56 or 65 w/4.88*

Though I don't mind going 65-much of the time there will be times when I will drive faster, 70-75 (passing doesn't count, then all bets are off *
I do think the noise of the engine is possibly the biggest factor of going with the lower 4.88s on long trips.*

One thing I have been thinking about is that compared to having almost no roll-on toque now, I should have much more with the lower gears, hopefully keeping the torque-converter locked most of the time.

4.56 in O/D
@ 60 = 1994-rpm
@ 65 = 2160
@ 70 = 2327
@ 75 = 2493

4.88 in O/D
@ 60 = 2134-rpm
@ 65 = 2312
@ 70 = 2490
@ 75 = 2668*

With 4.88s I can adjust my driving style/speed slower for the lower gears if I need to, but if I don't go low enough the only solution would be to do the gears again (not going to happen!). That said, I bet 4.56 would still be terrific compared to my low/slow 3.73s.*It would be nice if more people had already installed lower gears on the new trucks but we are in mostly uncharted territory here.

 

[Redline]

Quote from ih8mud thread. The guy I spoke to yesterday at JT Gears told me almost exactly the same thing. I discounted what he said on the phone, but I'm giving it plenty of thought now.

...I come up with a difference of only 170 rpm between 4.56 and 4.88
at 75mph and only 100 rpm difference at 60 mph. Just to give you an example
of another vehicle with the same motor as yours, I have a late model
landcruiser with the 4.7 v8 and AT, I ran a 32.8" tire w/ 4.88 and was happy
with the performance and economy. I now run a 35" tire and lost a bit of
the performance and economy, but it is decent considering the weight of the
vehicle. I did get a bit better economy w/ the 33's than the 35's even
though I was turning a few more Rpm's.
We see this in all newer vehicles. The people who change ratio early on
after a new vehicle is released are generally reluctant to go with lower
gears fearing that they will lose highway driveability and economy. This is
not necessarily true. We have done 1000's of gear changes on just about any
vehicle imaginable. We generally shoot for as low (high numerical number)
of a gear as possible that will still suit customer's highway driving needs.
There is no question that lower gears provide better low-end performance.
Late model vehicles w/ overdrive transmissions, are able to run much lower
gear ratios, than many people expect. With the added weight your running, I
think you would be real happy being a bit lower geared.
I think I may go with the 4.88s..

 

[Scott Brady]

Easy decision in my mind. Go with the 4.88. With pulling a trailer and lots of driving in the mountains and living at elevation, no question. You are also running a true 33" tire.

I have never regretted installing lower gears than typical, including the 5.13s in the Jeep now, or the 5.29s in the Tacoma.

 

[kjp1969]

Your post 'could' be used as an example of why 4.88s would be okay because the motor doesn't seem to be loud or unhappy up there near 3k.

If anyone is worried about noise or vibration at 3k, don't. Its like butta up there. Gas mileage, I don't know. I get around 8 or 9 pulling that big brick of a trailer on the highway.

 

[Redline]

Engine Noise/Vibrations

I just came back from a short errand and returned home on the freeway, using 4th/direct instead of overdrive. Drove 70-75 -mph which is a higher RPM now in direct than it would be in O/D with 4.88s.

At highway speeds I can't really hear the engine over my tires, even at 2700-3000 RPM. I can hear the difference between 2000 and 2500 at slower road speeds where there is less tire & wind noise, but at faster speeds the tires make the most noise and dominate. Of course, if I run a quieter tire then surely I will be able to hear the engine more.

The engine is so quiet and smooth this has become much less of an issue in mind, the bigger unknown is fuel economy. If I go with 4.88s it will be very interesting to see what economy can be obtained at lower road speeds (where the economy potential lives). I have plenty of before data to compare.

If anyone is worried about noise or vibration at 3k, don't. Its like butta up there. Gas mileage, I don't know. I get around 8 or 9 pulling that big brick of a trailer on the highway.

 

[kjp1969]

Try running through a tank or two out of O/D. That should give you some indication of what gas mileage will be.

 

[jbs]

This is an interesting topic to me since I am also considering which gears to get for my (V6) 06 4Runner. Many good points have been made.

Are there any practical considerations regarding the strength of 4.56 vs. 4.88 gears? I.e. size teeth on the ring and pinion.

 

[Sloan]

If you can re gear just the rear and drive it around for a bit to see how you like it. A gearing chart will not tell you how your particular vehicle is going to react.

 

[slooowr6]

I don't think Redline can re gear just the rear, the 4Runner V8 is a full time awd if I remember correctly.

 

[ntsqd]

This is an interesting topic to me since I am also considering which gears to get for my (V6) 06 4Runner. Many good points have been made.

Are there any practical considerations regarding the strength of 4.56 vs. 4.88 gears? I.e. size teeth on the ring and pinion.

The Toyota 8" 5.29's are known to be weaker than any of the taller ratios by a noticeable amount. In something less strenuous than hard core rock crawling on very larger tires I suspect that even that will not matter.

 

[jbs]

The Toyota 8" 5.29's are known to be weaker than any of the taller ratios by a noticeable amount. In something less strenuous than hard core rock crawling on very larger tires I suspect that even that will not matter.

Good to know. One less thing to worry about in my deliberations then. thx

 

[Redline]

I may do MPG test this weekend if I can make the time. I have a test circuit I use and won't need to run a hole tank of gas. I have baseline stock and modified data and a simple 55-mile loop freeway run will give me enough comparable data to get a good idea of how it will run on the highway with 4.88s.


I do have a full-time V8 so it will be all at once, gears & lockers. The only part of the installation I haven't completely decided on is if I'm going to go my own air lines & wiring as I had planned or let the shop do it. I don't mind paying the money but think I might be happier in the long run if I do this portion of the modification/installation.

Try running through a tank or two out of O/D. That should give you some indication of what gas mileage will be.