Want to change 4 high to 1.1:1
 

Is this possible or just dumb? Right now i have 4.10 diffs running 35" tires and I like the acceleration I get but have no top end (5th gear is useless unless going downhill on the freeway) and starting from a stop I have to wind the engine up pretty good and slip the clutch finely.

I'd like to run 4.56 or 4.88 gears on the street with the option of a 1.1 or 1.2:1 4 high gear and a 4.7 gear for 4 low

The truck is my daily driver. I would probably also use a twin stick to engage the 1.1:1, 2 high in 2WD for towing and hauling heavy loads

Is this possible with the design of the reduction box or is it physically linked 1:1? or would this effect my everyday driving without the transfer case?

Thanks

http://i40.photobucket.com/albums/e2...9/DSC00180.jpg

cool truck.
there is to my knowledge no kit (unless someone has done a custom machine set of gears) no alternative for high range on a toyota transfer case as a direct gear replacement like a rocklobster kit for a samurai.
there might be an under/over drive unit that could be used...

Why not just run 5.29's?

There's no such thing as a transfer case that has a different gear reduction between 2-hi and 4-hi, so your options would be either dual cases or some sort of reduction unit like a Klune-V. 1.1:1 reduction is not low enough to be useful IMO, so you're better off just going with lower gears and using dual toyota x-cases. This would give you the option of 1:1, 2.28:1, or 5.19:1.

The truck is my daily driver and sole vehicle. I think 5.29's will be too low for the street driving. Using my calculations from my odometer vs GPS, 4.88 will be the closest match to stock power although they will be slightly undergeared but that is what I am wanting. I might even try 4.56 gears if I can get ahold a a complete third from Pull-A-Part

I want a truck with three "sets of gears" I want to be able to drive defensively on the street, have power on forest service roads/towing/hauling and crawl slowly over trail obstacles

I dont know anything about how a transfer case is designed so I was hoping someone had an idea about how this could be accomplished

Can't re-gear the 1:1 high range because there are no gears there, it is just a direct shaft to shaft coupler in high range.

5.29's won't be too much, trust me. You'll really enjoy 5.29's.

4.88's will not be stock powered, your 35's are a lot heavier and have a lot more drag then your stock lil pizza cutters. it's just 200 more rpm from 4.88 to 5.29

I'm going 5.29's and 33's and i have at least 50 more hp than you, and i'm not complaining about high rev's.

Can you even use 5th gear anywhere? Do you get on the interstate? What's your top speed?

As 4crawler stated. transfer case high (weather it 2 hi or 4 hi) is a dirrect connection. meaning the gear ratio is 1:1. same as 4th gear in a manual. direct connection from input shaft to output shaft. Personally i plan on 5.29 and i daily my rig.

On a personal wander, that i feel might be another couple steps from where your at. if you were to run duals (double tranfercase). scratch that, lest start with info.

stock tranfer case high 1:1, stock transfer case low 2.28:1 (on gear drivin cases, newer runners and v6 are slightly different).

taking my 4runner with 4.10 diffs, adding a dual case, front case with like a 1.2:1 ratio (not currently produced), rear case with a 2.28:1 or 4.7:1, or maybe even a third case with how ever low you wanna go. now highway driving would run stock 2wd high. FSR (fire service road) could go front case low. (the math isn't correct but a front case low that would simulate like a 5.71:1 diff). and then doucle front and rear or just run rear.

The similar thought would be to run yours diff's at 5.29 or 5.71 and make a tcase low range that was actually 1:1.2. as in over drive your low gear in the front case for highway driving. i think my other option is prolly more doable using a stock case. The reverse gear would make fitment an issue i believe.

This would all only be accomplished by a complete custom set of gears for your case. this is a far fetched idea and i don't see it coming to reality. Its from college dorm room days.

sorry for the rant but i always wanted to share that idea with some folk. Back on subject, my plan is 5.29, cause i drive at 60 down the highway at 3000rpm (22re) in 4th gear with 4.10 diffs and 34/9.5 tires. i belive 5.29 would allow me to use 5th gear while keeping my top speed. (assuming my top speed is limited by the brick of a front end that my 4runner has)

I do get on the freeway, I use 3rd for accelerating/hills and 4th for cruising. I shift at 3500 rpm usually cruise at 2000. Not sure of top speed but certain I could go 80+. I wouldn't want to because of braking limitations tho

The last post suggested I use 5.29s but you dont have them installed in your rig. I was planning on using a 4.88 diff out of a 3.0 auto to "test" it out if I can find one at a pull a part junk yard or craigslist

Anyone ever heard of someone using an overdrive on a truck? My understanding of an overdrive is its a separate reduction box mated to the transmission like a transfer case but with a different gear ratios. Seems like it could be done?

no one makes an overdrive for our trucks you'd have to run a different trans or tcase to do that.

Well you can buy loaded 5.29 diffs, they come up all the time on pirate. I bought my rear 5.29 elocker on pirate and its current in transit to me.

I'd say give the 4.88s a try. I have recently finished with a build up that includes 35s and 5.29s. "Everyone" said that is the magic combo but now that I have it, I think it is too much. Driving around town it always seems whiny. Compared to my GPS my speedo runs about 5mph slow (i.e. speedo 50mph and actual speed 45mph). After the fact, I found these calculators:
http://www.4x4offroads.com/gear-ratio-chart.html

According to the first one I should gear to 4.94 based on current 35 inch tires and 235/75/15 from the factory. That is a lot closer to 4.88 than 5.29. Looking at some of the other calculators on that page it appears I could go to a 37-38 inch tire on my set up. Still thinking about that.

All that said, I just got back from a longish highway trip in the truck and there was still quite a bit of shifting to 4th and 3rd on the long steep uphill grades. Fortunately for me, it is mostly a weekend warrior and I don't have to drive it all day every day.

Give the 4.88s a try if you want to. Then report back to us with some real world results. Could be interesting. Good luck.

I think this is perhaps the ultimate contradiction ever. How can you have good acceleration with having to start like that?

The reason you can't hold 5th is because your truck is geared too high.

Note that 99% of these charts and calculators are designed around V8 trucks with A LOT more torque than we have.

I run 4.88's with 33's, and wish I had done 5.29. That extra couple hundred RPM would be REALLY nice. These engines like to be tached A LOT more than they will stand being lugged. The powerband starts at 3000 RPM - anything below that and you are seriously wasting gas because you are applying A LOT more throttle than necessary on a properly geared vehicle. You get used to the RPM sound pretty quick - if you can't handle it, you need to sell your Yota and buy something else.

I have tons of acceleration in first after I get started moving, 2nd and third are fantastic as well. Essentially what I have is a 4 speed with a broken 1st gear.

I understand that my truck is geared too high, I am not an idiot. I will not be selling my "Yota" anytime soon either, bra. It will be buried with me.

My current thoughts are to run 4.7 gears in the X-fer case with 4.88 (or 4.56 gears) and buying another set of 31" or 32" tires for towing hauling


Has anyone ever tried to modify the high gear (straight shaft) in the transfer case to anything but 1:1 or is there no room for actual gears?

You actually have a 3 speed.... or a 5 speed with a broken 1st and failing 5th.

Don't call people "bra". We are not fabric that holds up breasts in cups. We are mostly men who hold up breasts with our hands. :gijoe:

Your best bet Bob is a Chevy V6. You would get the same or maybe a little better gas mileage than you do now and more horsepower and torque.

I do not wish for petty bickering, insults or word picking. Please limit any posts to helpful advice or constructive criticism. Assume I have an IQ over 125

Not to my knowledge. Most people just gear their trucks correctly and move on with life.

Guys with really big tires, where 5.71's won't cut it, have been known to use an arrangement like described in post 7 above, running around in stock low as high and then running a 4.7 case, or even a triple setup, for their low range.

If we assumed that you had an IQ of 125, we would have left your thread alone and let you figure it out yourself.

You posted here, you asked questions which can only be answered by telling you to get custom gears made for your t-case.

You then decided on 4.88's with 31" tires. Decent, but you're going to lose top end and highway driving.

Are you asking questions or just looking for a place to bounce ideas?

Best response yet :horse:

your use of the term "correctly" is subjective. Your opinion that 4.88 is too high (numerically low) of a gear for 33" tires is noted.

I cannot afford just to buy new 5.29 gears and hope that you are not just perpetuating De facto standard advice. I am very weary of your advice, tc because of your eagerness to insult me. My main use of the vehicle is transportation on surface streets and freeways.

I can easily afford to take a chance on the 4.56 and 4.88 gears because I can get them used from a junkyard

You can also get used 5.29's off the net. I run 4.88's and 33's, and I kind of wish I had 5.29's. I only say that, however, because I'd prefer them off road. If you are just driving on the street then go ahead with the 4.88's (if you want). I think the 4.56 will still be too tall for your application. If I were in your shoes, I wouldn't even consider less than 5.29's with 35's. All this speaking from personal experience with the following setups: 4.88/33, 4.56/33, 5.29/33 and 5.29/35.

Right now I have 4.88's with 35's. Starts are sketchy and I can use 5 gear, not enough power to maintain unless it's on flat ground. I'm going to 5.29's or 5.71's and 38's or 40's.

I wouldn't get 4.56's if i was you, i don't see them making any real difference with 35's. Personally i run 35's with 4.88's. With 4.88's you will have very good acceleration in 1st - 3rd gears (you'll notice a huge difference starting off in 1st) but top speed isn't great, you won't be winning any races. I do have to shift between 4th an 5th but that doesn't bug me, an there is one long steep grade around here where i have to shift into 3rd, but thats still doin like 50mph. Still i can cruise at 70 if i want, but i usaully keep it at 60-65 just to save gas. I wouldn't run 5.29's because i prefer to get my low gearing in the transfer case and keep my axle gearing as close to stock as possible.

I disagree. The pre-figured tables maybe. The equations are just that, mathematical equations. There are variables and constants. Speed and engine torque are constant. The tire size and gearing can be varied. The equation allows you to determine the appropriate gear change for the tire size change that has or will be made. (or vice versa - gears for existing tires or tires for existing gears)

Ex.
Stock Toyota 65mph x 4.10 x 336 / 29 = 3087

Altered Toyota 65mph x 4.88 x 336 / 35 = 3045

Or 65mph x 5.29 x 336 / 35 = 3300

So which is closer to stock as designed by the Toyota engineers? It has nothing to do with V8 or I4 or V6 or any of that. Now those examples I have given are based on the equation in the link I posted earlier. From what I can gather that is the figure for 4th gear in a 5 speed transmission. I base that on info found in this link from Randy's Ring and Pinion.
http://www.ringpinion.com/Calc_RPM.aspx
The above results coincide exactly with the 4th gear results in the calculator found there. Unfortunately the 5th gear #s will be off because Randy's assumes a 0.80 5th gear and (at least for me with a W56 the figure is actually 0.85) Also note that the Randy's site shows recommended RPMs for a 4 cylinder engine in the 2200-3200 rpm range so...

I'd like to see this statement backed up with some documentation.

I'll go along with that. Pretty much true of any engine.

As requested by the OP, please keep it on the subject at hand. He is trying to solve a problem, not just accept the status quo or give up.


To the OP, it looks like you got the info you needed from 4crawler in a concise and straightforward manner. The rest of it is just opinions, mine included, and you will have to sift through them and decide which you agree with and why. If you decide to buck the trend of the majority, good for you, but expect a certain amount of backlash for doing so. Again, good luck and let us know what you do and how it works out for you.

Ok, so I crunched some numbers today and had an epiphany after I noticed similarities between my truck and what "theAuthority" had said about his on post #21 . I am going to risk exposing myself as a DB but will do so in hopes of helping someone else.

I am now very confident that I have 4.88 gears in my truck. I was assuming my gears were stock since the truck is undergeared but now I suspect that the person (kid) I bought the truck from upgraded from 33" to 35" without changing the drivetrain.

I will be looking to swap my tires for some 33s asap and will likely get some 31 or 32" tires for towing and 4.7 gears in the transfer case for wheeling.

Id like to thank everyone who posted in the thread, you helped me realize what I think is the best options for my truck

How did you determine this? Just curious.

i used this equation knowing that my truck odo read about 16% different (less) than the odo on my gps

.84x=4.10

x = what gears I have in my truck
.84 = 100%-16%
4.10 is the stock gears that my truck odo is calibrated to


solve for x
x=4.10/.84
x=4.880952....
YAY math class!:banger:

Jack it up and count the rotations to be sure. One full rotation of the tire will equal your gear ratio in turns of the drive line (4.88 turns). If you are locked it's easy. If you are open, leave one rear tire on the ground and do the same, but rotate the tire two full turns. Good luck.

Chock your tires and put the tranny in neutral with the parking brake off.

will do, thanks

Did Toyota engineers design for this 100hp engine to have 35's on it? No the did not you have the extra rotational weight, and extra width of the tire all causing drag on the drivetrain......

I'd also like to know how you have 4.88's?, jack it up and rotate and see how many rotations it takes.

You can't use how far off your speedometer is to determine your axle ratio, the speedometers are always off (even from the factory) and you don't know where it started. For example, my 4Runner's stock tire size is around 30", and I'm running 33" tires now. That's a tire size increase of 10%, but my speedometer only reads 3% slow, because it read incorrectly from the factory.

If you're too lazy to jack up your truck, you can record your RPM's at 60mph (on your GPS) in 4th gear (we will assume your tach is reading correctly). Using this number you can calculate your axle ratio since you know (approximately) your tire diameter, you can calculate the number of tire rotations per minute at 60mph, and the 4th gear ratio is 1:1. For example, if your tires are exactly 35" in diameter, and you have 4.88's, you should be around 2812 rpm at 60mph in 4th. If you have 4.56's, 2628rpm. If you have 4.10's, 2363rpm. For reference, 5.29's would be 3048rpm.

I didn't use the speedo. I used the odometer difference after a full tank (over 230 miles). I am confident my math is correct but I am not lazy, I will jack up my rig today

Haha, the odometer uses the same input as the speedometer (it's just a summation over time of the speedometer). Using one is the same as using the other.

The only way to get an accurate measurement is my method which assumes the tachometer and GPS are accurate (probably a good assumption), or jacking up the vehicle and measuring the ratio directly. Keep in mind that you'll want to spin the wheel several times and watch how many times the driveshaft rotates, the higher the number of times you spin the wheel the more acurate your measurment will be (around 10 times is probably best, where the driveshaft should rotate around 41-48 times depending on your gear ratio).

my FSM says the speedo is within factory specs while being up to like 5mph off...

Yep, speedo and odo can read differently, odo is most "accurate" in that is is 100% gear driven off the cable and simply counts revolutions. Of course it can be off with gearing/tire size mismatches, since it in effect counts drive shaft revolutions and not tire revs. The speedo is more prone to being off as it relies on a spinning magnet and a spring (in a mechanical speedo) to register a speed. On my '85 with 4.88 gears, I find the odometer is within 1% error with 33" tires but the speedo is off, have to drive nearly 70 on the speedo to go 65 MPH. But with 35s, the speedo is almost dead on and the odo is off (due to the larger tire diameter).

This is what I have found with my 35/5.29 combo. Speedo 70mph - Actual 65mph (per a gps unit) I lose about 1 mile for every 20 travelled on the odo.

OK, now I am officially confused. I rotated the tire twice and the driveshaft moved just over 4 times. Is this odd that I can drive around even on the steepest hills in Seattle in first gear with the truck undergeared so much. Albeit its not fun to do but i can do it

Spin it 10 times and watch the driveshaft, it will give you an accurate estimate of the ratio. Twice isn't really enough, but it sounds like you definitely don't have 4.88's, maybe 4.10's.

Keep in mind, were both tires spinning, or was one stationary? That will throw a factor of 2 in your result. So say you spin the tire twice and the driveshaft spins 4 times, if both tires were spinnning together the d-shaft would have spun 8 times.

Several ways to determine differential gear ratio:
- http://www.4crawler.com/4x4/4R_TechI...oDetermination

Sounds like you have a 4.10 then. Toyota's have low first gearing traditionally.

One tire was still on the ground, I will have to wait for my roommate to get home to rotate the tire that much