4.88 or 5.29's

oly884

Member
Ok, so for at most, medium duty (nothing serious, just point A to point B trails) 5.29's are....?

Scott seems to like his, and every one else seems to suggest theirs. However, there are a couple of you that I can't quite judge whether you are talking about the use they would see with my vehicle or the use of some hardcore rock crawling.
 

Brian894x4

Explorer
I still think Zuk made some interesting points, but I disgress too.

As for crawl ratio for a serious rock crawler, I can see how the T-case is the way to go, when crawl ratio is all someone cares about but, I've notice that most heavy duty factory 4x4s, like Unimogs, Humvees, etc, use diff and hub gearing to get the low ratios they need. With vehicle dependent expedition travel, it's usually about reliability first, and crawl ratio and capability second, since tow rigs, friends and spare parts are usually not available like with a lot of rock crawlers. So, to that end, the argument about lower diffs verses lower T-case gears, might have some real merit. If you're out in the middle of nowhere it might be worth sacraficing some overall crawl ratio, knowing that you're putting far less stress on critical components such as drivelines, U-joints, etc. And thus, going to a 5.29 gearset (or maybe 5.71) might make more sense than a duel T-case or 5-1 low gear T-case. I never looked at it that way, until I read Zuk's original article.

Oly,

Scott clearly knows what he's talking about. The only thing I'm wondering about is that I think he has an automatic, so the transmission ratios and drivability will be different than your 5 speed rig. Particularly on the highway, where his overdrive is much higher.

I believe, the 5 speed Tacos have a .83 overdrive, while the autos have a .70 overdrive. I'm going off of the older tranny specs, but I think the Taco trannys are similar. That means if the auto and the 5 speed Tacos had the same diff gears and the same tire size, the rpms on the manual trans Taco, while in overdrive would be about 15% higher. That's pretty significant. If the auto trans Taco is doing 3000 rpm, the manual trans Taco will be doing 3450 rpm, if I did the math right.

If you have 33s and I assume your current diffs are stock 4.10s, then going to 5.29s will lower your overall ratio by about 22%. Which means your rpms will be 22% higher at any given time. Where it used to be 2000 rpm at a given speed, it will now be 2500 rpm. The current 3000 rpm will now be 3700 rpm, etc. That's not necessarily a problem, but knowing where your rpms are going to be at, at speeds like 60 or 70 rpms will help you to decide what gear ratio is best for you.

The difference between your 4.10s and 5.29 s is about 5% more than the difference between your current 5th gear and your current 4th gear. But it's a close enough that if you want to have an idea of what it will be like with 5.29s on the highway, go out on the highway and drive around, but leave it in 4th gear. Then imagine that your rpms will actually be about 5% higher than even that. This will be a good test, because the only real concern with going too low is on the highway in overdrive. I can't see any disadvantage to having lower diff gears in city or trail driving. In fact, it's usually always a major advantage.

All that said, the real question is the difference between 4.88s and 5.29s, because you're going to go with one or the other. The difference in those two ratios are a little less than 8%. So, what it comes down to is that your rpms will be 8% higher if you go with 5.29s verses 4.88s. That would mean, for example, 3000 rpms with 4.88s will instead be 3250 rpm with 5.29s. Probably not the end of the world.

I'm a huge 5.29/33” set up fan. In fact, I just recently downsize from 35s back down to 33s for the addition power and I'm loving every minute of it. I think our weight will be similar, if me not heavier. But I have half the power you do, and with my truck, I need the gearing to overcome that power disadvantage. I tend to wonder if I had twice the power, if I wouldn't be better off with slightly higher gearing. Whereas I need the gearing to scream up moderate hills at near redline just to maintain highway speed, you might be better with a higher ratio.

There's one final point. I don't know the details, but I've heard that late model Tacos have an issue with running high rpms on the highway. Something about the computer, speed sensor or something like that not liking the high rpms and putting the computer into a closed loop mode or something like that, that could severely reduce fuel economy. Might be worth researching or maybe someone could shed some light on that here.

Given that you don't plan on speeds faster than 70, the advantages of running 5.29s on the trail and in the city, the excessive weight you'll be carrying, I still lean towards 5.29s if it were me, but it's a harder decision than it would be on the gutless wonder older trucks, like mine.

Sorry for the super long winded post.
 
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erin

Explorer
:coffee:
Oly, I basically have your truck, except ext cab -vs- dbl cab, so your alittle heavier then me out of the gate. I run the 4,88's and at 70mph, I'm pulling right at 3000rpm. My mileage on the freeway and in town, stop and go is the same due to the higher running range. I have no problems on hills on the freeway at all any more. Sometimes on milder trails that due call for low range, to offer more control, I wish for a gear in between 1st and 2nd. I think 5.29's in a manual are a little to deep, except for maybe a crawler. But like some others have said, running a higher diff, with lower t case gearing is a trend a lot of guys are moving towards to avoid grenading rear ends. But, the guys I know who have done so are more rock cralwers, so a different need all together. I think even with your additional weight, you will be fine with the 4.88's, and better off in a daily driver. Personally, if i wanted lower gearing right now, I would up the t-case gears before the diffs, because mine is a dailt driver also.

Just my 2 cents:)
 

oly884

Member
Brian, thanks! Great post.

Erin, I too have an ext. cab. My main concern right now is the driveablility on the street more so than the trail. I'd go for the 4.88's hands down with out the camper on, but the camper on the truck is what's making me not sure which gears to go with. I guess I'll have to sit down and do some math.
 

erin

Explorer
I understand your weight concerns, but I haven't noticed a problem due to any pulling power, just load capacity due to my 7 leaf packs. I just wonder about daily driving with the 5.29's, as I can barely get across an intersection now and keep it in first gear. Either way, you will definitely be going through the gears faster then before.
 

BajaTaco

Swashbuckler
erin said:
:coffee:
Personally, if i wanted lower gearing right now, I would up the t-case gears before the diffs, because mine is a dailt driver also.

As far as I know, you can't go with deeper gearing in the Tacoma t-case because it is a chain driven unit with planetary gears. The physical size of the case won't allow the clearance needed to go with a larger planetary. I think the only way you can do it is to use adapters with an older t-case (if that is possible) or the dual case setup.
 

DaveInDenver

Middle Income Semi-Redneck
oly884 said:
My main concern right now is the driveablility on the street more so than the trail. I'd go for the 4.88's hands down with out the camper on, but the camper on the truck is what's making me not sure which gears to go with. I guess I'll have to sit down and do some math.
It's probably a coin toss in the end, but I think my 5.29/33" combo is perfect for me. But I have a tired 22R-E, which makes a pretty significant difference. My cruising speed is around 70MPH, which puts the 22R-E right where it's happy and I get good power and economy. Your 5VZ-E might be happier with a slightly lower RPM, I just don't know never having owned anything but inline Toyota engines. As for daily driveability, I happen to like the set up of mine. In bumper-to-bumper traffic I don't have to hardly ever disengage the clutch while in first gear and starting from a stop sign is a no effort for the truck. My WilderNest is always on the truck and that extra 350 or so pounds of weight is noticeable. When I do take off the 'Nest for a cleaning or refurbish, the truck feels much different. The change is enough that I think 4.88 with an open bed would be better. But when I do put it back on, I am reassured that 5.29 was the right choice. With anything taller I would be struggling. Gear the differentials for what you want the truck to drive like normally and regear the transfer for off highway gearing. The optimal diff gear is not always the absolute tallest, it's the one that puts the engine at a desired RPM with a tire size/transmission ratio/highway speed combo. Your decision variables are unique. I have an old engine, truck at rated GVW and higher elevation, which pointed me towards lower gears rather than higher. If I lived at sea level, 4.88 might have been easier to live with. But starting with a 115HP at sea level (maybe 85HP now?), add 185K miles and 4400 lbs of truck and my little motor really likes 5.29 gears.
 
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Howard70

Adventurer
4.88 & ETC Setting?

Hello:

I'm new to the forum, been soaking up ideas for the setup of our new (to us) 2004 Doublecab. After 20 years we've decided to "upgrade" from our 1987 4runner.

I'm curious about the use of the ETC setting and gearing. If you ran 4.88 gears with the 255/85/16s and used the ETC "on setting" when you were loaded or towing something, would that give you an effective gearing between 4.88 and 5.29?

I understand that the ECT slightly alters the shift points of the automatic transmission, but I don't know how much. I've played with mine a bit (I'm currently running 4.10 with 265/75/16), but haven't really concluded how significant the setting is.

Howard L. Snell
 

crawler#976

Expedition Leader
BajaTaco said:
As far as I know, you can't go with deeper gearing in the Tacoma t-case because it is a chain driven unit with planetary gears. The physical size of the case won't allow the clearance needed to go with a larger planetary. I think the only way you can do it is to use adapters with an older t-case (if that is possible) or the dual case setup.

You are correct Sir! Marlin is da man for gear reduction.

http://www.marlincrawler.com/htm/transfercase/taco_box.htm
 

oly884

Member
There's another, lesser, issue. It's not quite as easy for me to get lower gears in the T-case without spending some good cash, so 4.88's and t-case work would be a double hit to the bank.

After some calculations, my truck with 5.29's going 67 mph in 5th gear would put my truck at 3k rpms.

assuming I used this eqn. right:

gearratio-formula.gif


Now with the t-case not engaged, it's 1:1 right? I know it's 2.28:1 with it engaged. Just want to make sure.
 

Brian894x4

Explorer
That's probably pretty close. The tire size and overdrive ratio are the big variables, because your 33" tire, my 33" tire and Scott's 33" tire could all be different hieghts and may differ as much or more than an inch. And all of our overdrives are different. I think yours is .83, mine is .85 and Scott's is .70

My truck with 33" MTRs, in 5th gear on the highway, with 5.29s at a GPS indicated speed of 60 mph is about 2900 rpm. My 5th gear is just a hair lower than what I think yours is.

But your rpms at 60-65 mph with 5.29s should be something close to 3000 rpm. The question is how will your engine perform running at that rpm all the time. I think the engine can handle it fine, but I wonder if your fuel economy might suffer, whereas Scott's fuel economy improved, because his rpms were too low on the highway to begin with since his automatic has such a high overdrive.

It would be interesting to see what Scott's truck's rpm is at 60 in overdrive. With his taller than normal 33 and auto trans, I'll bet his rpms aren't much higher than 2400-2500 at a corrected 60 mph. Is that right Scott?

The Toyotas do have a 1-1 high ratio, unlike some makes like the Land Rovers, etc. I believe the 2.28 low range T-case ratio is only in the geared T-case ratio and the geared T-cases were only used in 22RE trucks with W56 trannys and manual hubs. I "think" your chain T-case has the same 2.56 ratio that the older V-6 trucks got. If so, you enjoy a slightly lower T-case gearing than I do, which is nice to have.
 
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erin

Explorer
Yes, the chain drive case is 2.57 , unless I've been miss informed. The crawl ratio in low is great for a truck w/o dual boxes, running intermeadiately difficult trails. But, I have already run into a couple of areas where lower gearing would have been helpful w/ my manual. I think either way you'll be ok. This morning on the freeway @ 70 mph(uncorrected), I was right at 2900rpm, so with the 5.29's, you'll be right where I said I was before, 3000-3100rpm, sorry about the mistake.
 

SOAZ

Tim and Kelsey get lost..
Hello first, I'm a newb.
Can someone explain to me why you wouldn't just want to the the marlin instead of touching the gears?
Gears are about a g installed and the marlin is 1300 or so?
I know I'm missing something so can someone explain it?
 

oly884

Member
It's for driving around too. If you get lower gears in the axles it fixes the gear ratio when you put larger tires on (like I did). A marlin is great if you're going to spend a lot of time in low range, where as, I'm not going to be spending enough time to make it worth while.

And I think I've decided to go with 4.88's. 5.29's ar just a bit too low if I ever take the camper off. We'll see though.
 

SOAZ

Tim and Kelsey get lost..
Okay, so a marlin will of course give you the ultra low gearing when you're in the low gear setting, but it won't also give you a lower normal running gear if you specify thats what you want?

Totally off topic: How are those tires holding up? I trust the BFG quality from years of baja racing, but the cooper st looks like a much better daily driver tread pattern. Have you had them aired down on some sharp rocks? I don't want to get a cut in the sidewall!
(for anyone who wants cooper st 255/85/16 they are $149 at arizona "jeff furriers western tire centers" right now.
 

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