4.56 or 4.88 for 34s with Armor

You said you are currently running at 2500 rpm at 80 or whatever your cruise speed is. IF that is the case, the 4.56 gears will bump you up to around 3,000 or just under. That is a better place to be than in 4th. If however you cannot maintain speed at 3,000, you will be truly and profoundly fucked. Going to 4th won't be an option anymore, unless you want to be cruising down the freeway doing over 4,000 rpm. Not a good situation for engine life. Regearing really improves acceleration, and offroad performance but it almost always means a hit on the highway. You have a very narrow window to hit and actually improve your situation. What concerns me is the comment that any little hill drags the truck down even at 3200-3400 rpm. What will happen when you are at 3,000??

 

Truck likes to stay in either fourth gear at 3,200-3,400 rpm to maintain current speeds. If the terrain is fairly level with no hills, it will ocasionally go into 5th and cruise at 2,500-2,800rpm. However, as soon as there is a small hill on the highway for a longer period of time, the truck has to shift back into 4th gear and it will go up to about 4,000rpm to maintain speed up that hill. After the hill, it normally stays in 4th gear and the rpms are again, around 3,200ish. I'm seeing if regearing to back to stockish ratio will help the truck maintain current speeds and stop staying in 4th gear.

I am under the impression regearing to a higher ratio (4.56) will gain the stock ratio back(ish) and pretty much let the engine do less work during daily driving with accelerations, off roading, and maintaining highway speeds. Therefore, with new gears the truck won't have to stay in 4th gear nearly every time I drive it on the highway. Beforehand, the truck use to cruise in 5th gear no problem around 2,500rpm. I'm seeing if, with all the extra weight, lift, tires, etc, and altitude, that regearing the truck will help out getting back to stock driving/wear and tear on the engine.

 

Additionally, using this website http://www.grimmjeeper.com/gears.html

I believe I have a A750F transmission, however, I have no idea how to find out what transfer case I have or what option to select. Stock ratio is 3.73 right?

 

Why are you running that tire size? 33in tires are more than enough to run most trails. That’s just with my experience in SoCal. 4.56 gears should go with 33s, 4.88 with 35s. Regardless of the rpm the load on the engine is what eats fuel. On a separate note, make sure your spare tire matches. I have seen plenty of dealerships put 35s on a truck and leave the stock 31 as a spare.

 

Yup. I'm running true 34 in tires. And yes, I have a full size spare on my swingout bumper. Got rid of the stock spare as soon as I went up in tire size

 

I think you have a common misconception. The regear may get you back to a stockish gear ratio, but it will not get you back to a stock power to weight ratio. If an engine has to overcome more resistance (extra weight, additional rotational mass, additional air resistance, rolling resistance, etc.), then it has to make more power. It does that by running faster. Somewhere between 2500 and 3200 is the absolute minimum engine speed required to sustain highway speeds of 75-80 with your truck. If you regear, the truck will hang in 5th gear longer before downshifting, but not that much longer. Then you will be in your new 4th. You could end up right on the line and the truck starts hunting up and down. You would be much better off with 4.88s. You're still looking at high cruising rpm because the load is close to the limit of the engine.

You could help yourself a great deal by ditching those tires and getting 32s or narrow 33s. You could also regear and just accept a slower highway speed.

 

mhmm maybe I do have a misconception about this

 

I'm not saying that you shouldn't regear. I'm just saying that carrying that much weight, on heavy tall tires, at 5,000+ ft elevation, at 75-80 mph is going to require your engine to turn pretty high RPMs. No amount of gearing is going to change that. The gearing will make the truck feel peppier at lower speeds, help with acceleration, make it crawl better, and take strain off the engine at take off. All good reasons to do it. It is not going to magically drop you back to 2500 to 2800 rpm at 80 too. If your final cruise speed is high on your priority list, you need to be careful not to end up in a hole between gears.

 

regearing to 4.56 with a v6 auto trans will help tremendously with running a 34" tire, and yes you will have a higher rpm on the highway than you do now. the gearing will just help with the sluggishness that comes along with the added weight from armor, etc.

 

So while the engine rpms may go up on the highway speeds, the strain on the engine will decrease? That is my biggest concern is to reduce strain on the engine and transmission when driving and going off road. I was under the assumption higher rpms = higher strain on the engine

 

Following.

I'm in the same boat, just put 34s on with stock gears, and a whole lot of extra weight.

 

So I was on the phone for awhile with Matt from 3D Offroad here in Colorado Springs. (I trust him with my truck 100% - great dude). Regardless, he said the following for my current situation with 34in tires and extra weight:

4.88
2500 rpm = 73mph
3000 rpm = 87mph

4.56
2500 rpm = 80
3000 rpm = 94

So with that, I'm actually leaning towards 4.88 because in the future (year or so) I'll be adding more weight (front bumper) and going to 35s. Potentially if I decide to make this truck a dedicated off road machine with 37s (years and years away), 4.88s will still be able to handle those bigger tire size

 

If you tend to cruise a lot at 75-80mph, go with 4.56s. I run 35s with 4.88s, but I like to cruise at 65-70mph 80% of the time. I avg. somewhere in the 12-13mpg

 

how much weight are you carrying? I’m at an extra 1200lbs with a auto

 

I don't have any current photos, but I don't carry much additional weight besides my armor. I do have a supercharger along with a pedal commander so I tend to be right foot heavy . Personally, I wouldn't have been happy with 4.56s and 35s. With 34s, I would probably be OK for the most part. If MPG was important to me, I definitely would have gone with with 4.56s.

 

Funny that you say that. I took a good thought and realized that power is more important to me in the long run. I’d rather have the power with the room to upgrade to bigger tires in the future. Regardless, the trucks strain will decrease... hopefully... so I went with 4.88s (just bought them at a local shop). We’ll see how that goes and if anything I upgrade to true 35s.

Also, big fan of your wheels

 

Sweet looking Tacoma! I think you made the right choice if power is more important to you. I feel the same way, but prior to choosing I had a chance to test drive a fully armored and loaded Tacoma with 4.56s so I knew right away it wasn't going to cut it for my driving habit. The engine just doesn't have the torque readily available so we have to cheat a little with lower gears. The bonus part is that it'll make you drive a little slower so there's less chance of getting a speeding ticket .

 

This is going to be far out in left field but you should consider boost. When my truck was set up for over landing I pretty much lost 6th gear and that’s with the 4.56 re-gear on 33s. With the TRD supercharger I not only got my 6th back it “feels” like I could have skipped the gears. On a side note, taller gears result in smaller teeth. The problem being wear and strain on the gear set. I broke 2 rings on my rig before I said f it and swapped in a dynatrac. Lesson learned small teeth plus strain = pulling the drive shaft and making it home in front wheel drive

 

You sort of have it right, and the screwy nomenclature we use is tough to keep straight. Just so we are all on the same page:

"Taller" gears = "higher" gears = lower numerical gear ratio. 3.73:1 gears are taller than 4.56:1
"Shorter" gears = "lower" gears = higher numerical gear ratio. 4.56:1 gears are shorter than 3.73:1

Shorter gears (4.56 or 4.88) have fewer larger teeth
Taller gears (3.73) have more and smaller teeth

Having said that, Shorter gears are weaker. There are fewer teeth to share the torque load, so going to shorter gearing in combination with higher engine output is weakening your combination. It surprises me that anyone is able to run a supercharger with these little 8" R&Ps

 

Did someone finally make a 5.29 set for a 2nd gen front clamshell?