Bigger tires, now need gear solution!

[dustboy]

I got my 235/85R16 BFGs, they being the "approved" ExPo Toyota tire size. Boy are they great, I would recommend them to anybody.

However, having gone from the 30" tires it was manufactured with, to almost a 32" tire, plus the extra 300+ unloaded lbs of shell/sleeping platform/armor I drag around daily, the poor little 2.7 L is struggling to start in 1st gear even on flat ground.

Gear code is B02A=3.58
Driving type: Daily Driver, trail use occasionally on the gnarly side
Transmission: 5-speed manual
Desired cruising RPM at 70 mph: 2400?

Looking at the Tacoma gear chart it looks like I'd like to be running 4.10s, hard to tell because it's based on 4th gear.

Am I on the right track? Is this project DIY-able? If not, who should do the work and how much will it cost?

 

[pyro4fun]

If your going to load your truck down anytime soon your going to want a little more gear. I would recommend 4.56 gears. If you plan on going any larger on tires and carrying a load I would go as high as 4.88. You don't want to pay for a set of gears only to find out you didn't get enough the first time.

Just my 2 cents

 

[dyogim]

You can do this yourself. Only special tool you really need is a digital micrometer. This will be used to help get your backlash within spec. With some time patience, you can get this done. Otherwise, if you bring it in to a shop expect to pay $800 - $1K front and rear (not including parts). Half that if you bring in the third members and the parts. This would be the perfect time to install a traction device. Some shops won't even charge additional. Unless, it's an air, electric or cable actuated then, that's additional. I've done mine (toy 8.4" rear and a HP44 front). However, I wouldn't be confident to work on someone else's rig until I have more installs under my belt.

If you plan on doing this, Zuk, helped me out a lot: http://www.gearinstalls.com/

 

[dustboy]

Wow, that Zuk guy knows his stuff..wish I lived closer, I'd just bring him my 3rds. It looks like you'd have to spend a fair amount on bearing pullers and presses. At least I already have a few mics.

How would I find a good shop near me? Can a regular mechanic do it or do I need a specialized shop?

I don't intend to go larger than these on tires, but I definitely do carry some weight on trips, and I may pull a light off-road trailer in the future. So the 4.56 probably makes sense. The slower crawl would be nice too.

Most important, how do I explain this expenditure to my wife? :snorkel:

 

[BLKNBLU]

The thing I've never understood about that tire size/gear/RPM chart is what engine they are referring to. It strikes me that there would be a big difference on that basis.

Sorry I can't directly answer your question though. My only experience is with the 22re. I ran that for years with stock 4.10s and 31s. (like you, about 2 inches over stock) I never found it to be that awful. A bit doggy yes, but not awful. I did not, however, have extra weight in the truck generally. With the extra hp your 2.7 produces, it strikes me that 1 step in gears ought to do it. That's a big fat guess on my part though.

Yes, ZUK is excellent. It might be worth shipping your diffs to him if you can afford the down time.

Don't tell your wife.....

 

[TangoBlue]

Most recommend for the 3RZ and manual at least a 4.88 gear.

My 3RZ AT comes stock with 4.56 and running 265/75/16 it is a little doggy with armor, bumpers, and minimal load. Now I have 285/75/16 and the slightest hill has the transmission searching for a lower gear. I'll be going 5.29 this summer.

Search on here and TTORA for opinions on re-gearing. Among the various debates I think you'll find that the least you should re-gear to is 4.88 with your 2.7 MT.

Visiting these forums will only contribute to the expenditures; explain to the wife that you are doing this for her and the families safety. That tactic has been successfully used here before -- like the safety snorkel.:snorkel: I always get a picture doing a water crossing to show my wife how that snorkel is paying for itself!:victory: Remember the children!

 

[dustboy]

I'm not so sure about 4.88s. Looks like 4.88s in 4th gear on 32's puts it at 3331 RPM. I don't know about your 3rz, but my motor does not sound happy at that speed. In fifth with those numbers, maybe it should drop to about 2800ish, which is still way too noisy for cruising.
I'm thinking about 2500 max for 70 mph, I wish that chart showed 5th gear.

 

[TangoBlue]

Good point, and I don't lay claim to be the most experienced wheeler out there, but the real problem to conquer is the 2.7/AT combination. As was explained to me by a far more knowledgeable Tacoma owner than I, "With the OE configuration of 31s/4.56s it works extremely well...but...go bigger and you can never get back to the same power ratio...regardless of regearing. The motor just doesn't have the power with a 4sp AT. So while a 4.88 gear will get you right back to OE configuration (approx. 4.58:1 adjusted ratio) with 33s it does not allow for the added aero drag, weight gain, etc, that are part of lifting these trucks and adding bigger tires....hence the 5.29 suggestion. Now, if you were to stick with a 265/75 (32s) (actual diameter is around 31.6") then yes, 4.88s would be the right gear. Depending on brand, the 285s can be 33.1" tall rather than a 33x10.50 which is 32.6"...another reason for the lower ratio. 255/85s are another .2" taller than 285s, on average."

With that rationale 4.88 for your 3RZ MT is on the money.

I believe the chart you reference was derived from the experience of a 6 cylinder owner as well (stock 4.10). Like I said - I'm running 4.56 gears now with tires that measure out to about 32.6 and my 3RZ AT with lift and additional weight is downshifting for moderate rises on highways all the time. I only share this information to add to your consideration, not to be argumentative. I'm struggling with it, too as I only want to pay to do the regear once.

Perhaps you can hook up with a local Tacoma owner who has made the gear change you're looking to do? The Bay area is a rich environment for modified wheeling Tacoma's.

My humble opinion - good luck and whichever way you go - let us know what you learn. I'll probably still be fretting over which way to go by that time...

 

[dustboy]

Thanks for the input Tango, I never would have considered 4.88, but with this kind of modification it's important to weigh all the options. I think I need to actually find out what my overdrive ratio is.
A slower final ratio than stock wouldn't be so bad because I try not to exceed 75 mph anyway--I'd rather get to the trail alive than save 5 minutes. The added torque for towing, load, and crawl would also be good.

 

[Nullifier]

I started with the same drivetrain specs as you with my truck. I am running 255/85 and 4.88. Gearing is dead on. If you had an auto you would want to step up one ration. So if you are tires are 32" then I would go for a 4.56 unless you think you will step up in tire size. Do not waste time with 4.10 if you are going to regear.

I agree with others that this is a good time to toss in an arb rear locker. However I do not believe that you should DIY the gears. To many people try it the first time themselves and do not get it right. There are alot of variables. Setting up the gears properly will have a much bigger durability effect then what brand of gears you toss in. I would tell you that pulling the front and rear third members yourself is fine but take it to a shop to have the gears and possible locker installed. Probably 250 - 300 per axle if you hand them the third members. Some jobs are just better left to professionals.

 

[dustboy]

gear brand?

I'm going to revive this thread since I'm getting serious now about doing the work.

I found a shop an hour away who quoted about $700 to do all the labor. They seem competent and specialize in off-road work on Toyotas. I think the economy is forcing shops to drop their labor rates for such "elective" work.

The shop told me to just buy the parts and bring them to the shop.

Now the question is, what do we know about the brands of gears? Most online shops (marlin, randys) seem to sell Yukon, but there are others like Richmond from Northwest Off Road (made in USA).

 

[dyogim]

I have Precision gears in the rear and yukons in the front. The PG's I've had since 04 with no issues.

Allen at 4WD Specialities in Concord, CA installed it for me for $200. I brought him the third, gears and install kit. Had it back to me the following afternoon. Fair warning though, his demeanor is a hit or miss. Some days he can be an @$$ and others he's the most helpful person in the world. Another shop in the Concord area is ToyotaPro. The owners were/are great guys when they worked at Concord Toyota (delaership).

 

[bjowett]

I have a set of factory front and rear 4.56 axles/differentials from a rare 1997 3RZ Automatic 31" tire package truck. Good shape... any interest?

 

[7wt]

I have a V6 with 4:10s and 235/85s and I wish I had a little more gear sometimes. My truck does just fine on the highways and I get pretty good milage, I just wish there was a little more low range climbing hills and such. Good tire for sure but next time around I am going a little wider.

 

[dustboy]

I have a set of factory front and rear 4.56 axles/differentials from a rare 1997 3RZ Automatic 31" tire package truck. Good shape... any interest?

I'll PM you.