changing gear ratio

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Thread: changing gear ratio

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    Cool changing gear ratio

    Hey,

    I'm looking to switch my gears to compensate for my 35" rubber. Who would do this and how much would it cost? would gear ratio go higher or lower to give faster accel?

    thanks,
    Sean

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    Default Re: changing gear ratio

    I want to do this sometime too, but no money or tires yet... I think you gear ratio goes down? well, I don't know the terminology, but if you are running the 4.11 gears now, you'll probably go to 4.88 or 5.29's for better accel and milage (got those numbers out of a NWOR cat)
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    Default Re: changing gear ratio

    Shawn,<br /> You would need lower gears which are higher numbers like jwitz said. Im going to install my coilovers and bodylift and am going to run 35's too. Ive got 3.909 and i do believe with the v-6, you do have 4.10. The gears will give you better acceleration and the lower you go, the better- except you start to loose top speed. 4 wheel wholesalers has a gear ratio chart that can give you an idea of what you need according to rpms. The gears will cost somewhere around $150 and a install kit for about $40. You can install yourself.

    hope this helps

    Dean
    7"Front lift 295/7-18 Nitto Terra Grapplers on 18x9 Black KMC Montsers with TC lift, Team West Coilovers, Deaver 3 leaf spring pack on 4" block with Bilstein 5100's in rear; Volant Intake; Spin-Tech Muff

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    Default Re: changing gear ratio

    For bigger tires, which increase your overall gear ratio, the desire would be to install gears with a lower gear ratio. A lower gear ratio equates with a higher numerical number, i.e. 4.10 is a lower gear ratio than a 3.91 set. This is because you divide your engine RPMS by the overall gear ratio to get your wheel RPM - the bigger the number in the gear ratio, the slower the wheels will be spinning for a given engine RPM. You also have to figure in your transmission gear ratio to determine the overall drivetrain gear ratio. In overdrive with the torque converter locked up, the ratio will be less than 1.00, probably close to 0.80. Third or drive (with OD locked out) with the torque converter locked up is usually a 1.00 ratio in most transmissions. By the way, this is why most dyno runs are done in third w/OD off because there are fewer mechanical losses with a 1:1 ratio in the tranny. With a 5 speed manual, 4th is usually your 1.00 ratio gear.

    If you are upgrading to 285/75-16 tires, this will result in an overall gear ratio increase of approximately 7.5% over the standard Tundra LTD/TRD 265/70-16 tires (30.6"dia). Changing to 4.10 gears would result in a 5% lowering of gear ratio over the standard 3.91 gears. Changing to 4.30 gears would result in a 10% lower gear ratio than the 3.91 gears. The 4.30 gears would probably be the best option with 285/75-16 tires (32.8" diameter) since you would end up with a slightly lower overall gear ratio which would help overcome the increased rolling resistance and weight of the bigger tires.

    The Tundra/Sequioa shares the same rear end as the later model (&gt;97) V6 Tacomas and T100. It utilizes a 210mm (8.25") diameter ring gear.

    I believe at this time about the only optional rear gear ratios available for the Tundra are 3.91 (standard on the V8 models), 4.10 (standard on the V6 5 speed models), 4.30 (standard on the V6 auto 4x4 models), and 4.88 and 5.29 (optional aftermarket - see drivetrain.com link below).

    If you have a 4x4 and desire to retain the 4x4 function, you will also need to change the front differential gears to match the rear differential gears. The Tundra 4x4 uses a high-pinion 7.5" IFS front differential with reverse cut gears - a rather unique bird. This means replacement gear sets are rather limited. You may be stuck with the 3.91 to 4.30 ratio gears available on the various Tundra models. This link provides quite a bit of useful information on Toyota differentials http://home.off-road.com/~bibelheime...diff_info.html

    Changing a set of ring and pinion gears in a differential is not just a drop in and go proposition. Setting proper bearing preload, pinion depth, and backlash is critical for reliable operation. This isn't a task for your average weekend mechanic. Read through the links on this site including the ring and pinion gear installation instructions to get an idea of what is involved www.drivetrain.com

    Alan

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    Joe
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    Default Re: changing gear ratio

    Last time I checked the gears available for the Tundra 4X4 were 410, 430, 456, 470, 488 and 529. The 470 comes from the Taco which I think will work. Finding the reverse cut gears for the front differential is the catch. I ordered the 456 and will put them in when I get the RD90 locker. If they won't fit I'll post the problem. I think their just the ticket for 33"s with a V8.

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    Hey, Joe what ever happened with changing the r&p on the front dif. I'm interested in running a 33" tire but want to be sure I can change r&p if the tires kill the power and mileage. Please post any details, warnings, or lessons. Thanks

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    Default Ring & Pinion

    Now you have me confused - which doesn't take much I might add. Changing gears is just a little more than swapping parts. For mechanics that perform this type of work all the time they will simplify the process when they talk to someone by saying "a gear change is nothing more than swapping out the R&P." They don't bother telling you the details such as pressing a bearing onto the pinion and that Ole Man Murphy may destroy the carrier bearing and you have to press a new one on etc etc etc. (That's why they charge you for a gear install kit for each axle) I'm running 33" M/T's and the power is just fine in town, highway and mild off-road. Mileage hasn't suffered either. However, the Tundra's transmission won't handle stiff wind conditions, as it will kick in & out of OD constantly on very slight +grades. I don't possess any knowledge as what you can do to effectively correct that except to change gears. My Tonka is raised a bit. It's probably raised a total of 3 7/8 inches up front that doesn't help when bucking the wind. I've got my rear end up a little over 6, which I will correct next week, as I can't get a good tire alignment. My max caster setting is .6!!!! which makes the Tonka a real darter on the road. It also puts quite a strain on the rear universal plus I can't make the proper adjustment for my rear brakes. I'm sending the spring packs back for re-adjustment to a 2" lift.

    Regular driving with 33's you will notice the power loss but it's not that bad. If you drive in traffic a lot I would think your mileage would suffer quite a bit as you'll have to get into it a lot more than you did in stock form. Off-road in mud or swamp conditions I would think you would have to operate mainly in the 4L mode.

    430 gears are closest to a factory match up with 33's but the 456's will give you a little more power to navigate at slower speed in bad-a*s places. Just depends on your needs. When you start changing tires, gears, spring rates, shocks etc. you're giving up the supreme ride qualities that separates the Tundra from all others.
    youvebeenkumped likes this.

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