Before you leave for the dealership, take a moment to think about how youre going to use the truck. How does gear ratio affect mileage and performance. How to determine what gear ratios you actually have nasa. How to choose the right axle ratio for your pickup.
The vehicle identification number vin is a 17digit code that is used to identify and track every automobile produced. The rear axle gear ratio is the number of turns that the input of the differential at the driveshaft makes in relation to its output at the rear wheels. Diy ford ford axle ring and pinion assembly how to guide. Easiest way to determine rear end gear ratio on a open differential. A more powerful engine can use a higher rear end to give relaxed cruising and a.
Direct direct rear axle ratios were variable, but usual were 3. All you need is a jack, some jackstands, and knowing how to count helps too. Feb 24, 2008 my rear end went out in my 88 chevy 4x4 half ton, and i am tring to buy a new rear end online. The real key to optimum performance is to take the engine torque curve, the transmission gear ratios, rear axle ratio and tire diameters into. At the hit, youve got a transmission gear as a multiplier and also.
Dec 27, 2008 what is the formula to determine the gear ratio when counting the ring and pinion teeth. This chart applies to all ford nonoverdirve transmissions, manual and automatic. Each number and letter contained within a vin reveals information about the vehicle, such as the make, model, production year and engine size. A smaller engine will need a lower rear end to give adequate acceleration. Apr 23, 2003 for example, if we divide a ring gear with 41 teeth by a pinion gear with 10 teeth we find that the gear ratio is 4.
Ring and pinion ratio calculator by number of teeth crawlpedia. If you take a few moments to study the gear chart for your transmission and rear end ratio combination you will see why this product is so popular. It is also the same letter that volkswagen uses on the end of. It is also important to know the ratio as well as tire size to determine which speedometer gear you need so your speedometer reads accurately. Determining rear gear ratio without removing cover youtube. Enter the tire size diameter and the target vehicle speed in mph. Nov 08, 2007 gear ratio, or in a car, final drive ratio is basically the number of times the tires rotate in relation to the number of times the drive shaft or axles rotate. How to select gear ratio combos for better performance part 2 december 8, 2016 wayne scraba howto. When upgrading your gear ratio, youll usually want to move up within the same series of carrier but you can also use a ring spacer in some applications to move up from one series to the. A quick easy way to determine axle ratio ericthecarguy. Ford axle ring and pinion assembly how to guide many parts compose a rear axle and its most important function is to provide torque multiplication and speed reduction. A lower gear ratio can affect fuel mileage by decreasing engine rpm at highway speeds.
If however you have a posi traction rear end like i do, youre good to. How to figure out the gear ratio of your car by robert tomashek on may 16, 2016. When you talk about gear ratio, you are talking about the gears ring and pinion, in the rear end. How to calculate your rear gear ratio without taking anything apart. We provide a gear ratio guide to show you how to go through the selection process and properly evaluate and choose the right gear for your race car. In the end, its easy to see that mistakes in gearing can craft a truck load of trouble. May 03, 2005 the ring gear is prepped for attachment to the differential by scuffing the mating surface with 80grit emery cloth to remove any rust preventative or burrs thatd interfere with a perfect mating. Count the number of teeth on the pinion gear and count the number of teeth on the ring gear. If you have ever wondered what the gear ratio is in your rear wheel drive vehicle and. How to calculate the rear axle gear ratio it still runs. The term describes similar devices, even when the gear ratio is continuous rather than. If interested post them and i will see if my book has the codes listed.
Tire diameter, transmission choice with or without overdrive and desired highway cruising speed. Gear ratio, or in a car, final drive ratio is basically the number of times the tires rotate in relation to the number of times the drive shaft or axles rotate. I dont recall ever seeing a 37 tooth ring gear but we counted three times. Oct 16, 2019 to determine gear ratio of a gear train with 2 gears, start by identifying your gears. Identify the ring and pinion gear ratio you currently have by counting the teeth on the ring and pinion gears. Choosing new rearend gears is as easy as 1, 2, 3, 4. Technical banjo rearend gear ratio counting teeth the. Churn out all the asphaltchewing, roadgrating horsepower you want with our massive selection of rotating assemblies. As the rear end gear is a multiplier of torque relative to whats delivered to the rear wheels, some interesting calculations can come into play. You should be able to find your gear ratio listed on the axle tag, however, if that has gone missing, you can simply count the number of teeth on each gear and divide the number of ring gear teeth by the number of pinion gear teeth. Selecting the best gear ratio mark williams enterprises, inc.
This utility calculates the rear end gear or front end in the case of a front wheel drive ratio of the current ring gear and pinion, for automotive applications. When in doubt, default to a higher numerical axle ratio. If you cant read the numbers, simply count the teeth and use the following formula. The value will be returned in estimated differential gear ratio, based on the entered values. How to find out the gear ratio with the vin number by jesse dempsen. This gear ratio formula works even for complex gear systems with one or more idlers. The chart below may be of some help in deciding what rear end ratio is right for you. The rearend gear ratio refers to the relationship between the driven gear ring and the drive gear pinion, and is easily calculated by dividing the ring gear tooth count by the drive gear tooth count. Different gear ratios can have different effects in the way a vehicle performs.
Enter the number of teeth on your ring and pinion gear set in the calculator below to find the gear ratio, or simply divide ring gear tooth count by pinion gear tooth count example. Sep 09, 2012 how to find your differential gear ratio without stamps, tags, or tear down sometimes stamps are covered in rust. If the cover is off the differential, count the number of teeth on the ring gear and the pinion gear. I need information about teeth count on ring and pinion on banjo rear end gear sets. Understanding axle ratios medium duty work truck info. After you count the teeth on the gears in the rear. Regards, john elmgreen the rear axle ratio is indeed stamped on the case, actually it is the number of teeth in the crown and the pinion. For example, a ring gear with 39 teeth and a pinion gear. Jun 22, 2014 this feature is not available right now. How to select gear ratio combos for better performance. You can find your gear ratio easily with this method. There were other ratios offered, but i dont have the tooth counts at hand. What rear end gear ratio do i have in my chevrolet or gmc. To determine gear ratio of a gear train with 2 gears, start by identifying your gears.
You find it by dividing the number of teeth on the driver gear into the number of teeth on the driven gear. How to rebuild gears in chevy and gm differentials. Divide the ring gear teeth number by the number of teeth on the pinion. Listed are the expected rpms at 60 mph with a given rear end ratio and tire height. Therefore, for a known imld to be transmitted, the pitch is chosen which in turn determines the number of teeth to suit the desired ratio and size of gear. Rob krider is a nasa national champion and author of the novel cadet blues.
The input gear in this gear train has teeth and the idler gear has 21 teeth. How to find out the gear ratio with the vin number it. The rear axle ratio of your car is instrumental in determining which transmission gear set is best suited for your car. Ring and pinion ratio calculator by number of teeth. If your vehicle is a 4x4, you will need to change the gears in both front and rear axles. A contact ratio between 1 and 2 means that part of the time two pairs of teeth are in contact and during the remaining time one pair is in contact. Jack up the rear end of the truck so that both rear tires are off the. If you are going to buy one used anyway might want to hold out for a 3. Youre going to have to put the car in nuetral or out of gear, so safety first. Im trying to understand rear end gear ratios and ring gears. The gear ratio is the difference in the size of the pinion gear, or input gear, and the ring gear, or output gear. How to determining rear gear ratio without removing cover. Counting cover bolts and cover shapes is a common method to determine which ring gear diameter and differential you have in your rear wheel drive rwd vehicle. Jul 24, 20 if you dont know your gear ratio, you can calculate it by taking the number of rear gear teeth in your rearend divided by the number of pinion gear teeth.
One thing to keep in mind is that the carrier will be different with a 2. You can either disassemble the transmission and start counting gear teeth. Standard rear ends as delivered from the factory 19691989. In order to calculate axle ratio, you would count the number of teeth. Contact ratio of gears, tooth modifications, and the.
This is probably the easiest way to measure your rearend ratio, as it doesnt require removing the differential cover. In other words, the gear ratio is the ratio between the number of teeth on two gears that are meshed together, or two sprockets connected with a common roller chain, or the circumferences of two pulleys connected with a drive belt. This is accomplished with a rightangle drive gear arrangement called a hypoid gear set. With the rear axle removed, you can see the ring gear and count the. That way when you put on the 35s your effective axle ratio will be around 3. If you have ever wondered what the gear ratio is in your rearwheel drive vehicle and. Otherwise, youll either have a slug of a pickup after the tire upgrade or youll end up having a gear shop put in 4. Save yourself the headache and let us figure out your ringandpinion gear ratio. I would like to verify the gear ratio before i complete my rear end swap. So, if the ring gear has 37 teeth and the pinion has 9 teeth, the ratio is 4. Is there an easy way to determine the gear ratio by counting the teeth on the ring gear. Tall gear ratios have low drive shaft rotations and short gear. There are several ways to determine the gear ratio on your vehicle.
To do another, click the clear values button and then enter a new set of values. If you dont know your gear ratio, you can calculate it by taking the number of rear gear teeth in your rearend divided by the number of pinion gear teeth. From jim schilds book restorers model a shop manual, here is a table. Differential repair shop, differential san antonio tx, rear end repair shop, texas, san antonio, tx. The gear attached to the motor shaft is considered the first gear, or the drive gear, and the other gear, whose teeth are meshed with the drive gear, is considered the second gear, or driven gear. The ratio is the number of teeth on the driven gear ring divided by the number of teeth on the drive gear pinion. The ringandpinion gear determines the gear ratio of the rear axle assembly, and therefore the gear ratio directly impacts vehicle acceleration and fuel economy. Three questions sometimes arise when considering a change in rear end ratio. Do this on level ground, and be sure and chock the front wheels so the car cant move. A gear or cog is a rotating machine part having cut teeth or, in the case of a cogwheel, inserted. Power is transmitted from the transmission to rear end 1. Rear end gear ratios or final drive ratio refers to the number of revolutions the drive shaft turns compared to one full revolution of rear wheels. There is a code of 2 letters on the right front of the pumpkin which tells you what the original ratio of that pumpkin would be.
Gearing is what you are buying when you purchase a gear vendors underoverdrive. For road racing, gear ratios are just as important as they are in drag racing. Gear ratio and tire size chart next page this gear ratio and tire diameter chart is meant to give you an approximation of ideal rpms at highway speed 65 mph for three situations. While it may be possible to derive information about an. If it is a dana 41 there should be a metal tag on one of the cover bolts that will say something like w 4111 divide the top number by the bottom number to get your gear ratio. A ratio between 2 and 3 means 2 or 3 pairs of teeth are always in contact. For example, a ring gear with 39 teeth and a pinion gear with 11 teeth.
Low gears give fast acceleration, high gears give better cruising. Does anyone know what the stock rear end ratio for a 55 chevy sedan, 6 cyl, 3 spd manual, no overdrive. Oct 09, 2003 but i dont think you should divide the numbers to find their ratio. What is the rear end gear ratio and how does it affect. How to figure out the gear ratio of your car yourmechanic. Axle ratio is the driveshaft or output shaft revolutions needed to spin the axle one complete turn.
Such a high ratio is generally not obtained with external spur gears, but can be developed in the meshing of internal gears. The rear end axle is responsible for transmitting power to the rear wheels in a rear wheel drive vehicle. If you need a more precise indication of the gear ratio, open the housing and read the numbers stamped into the each gear. Gear ratio guide how to choose the right ratio circle. Choosing new rearend gears is as easy as 1, 2, 3, 4 street. The gear ratio is the ratio of the number of turns the output shaft makes when the input shaft turns once. The gear ratio when counting the ring and pinion teeth. Rear end gear ratios have a significant impact on how your car performs. The calculation uses the number of teeth in the ring gear and divides it by the number of teeth in the pinion gear, to provide you with a result to 1 ratio. Considering only these gears, the gear ratio between the idler and the input gear can be calculated as if the idler gear was the output gear.
Gear ratio is calculated by dividing the number of teeth on the ring gear by the number of teeth on the pinion gear. Divide the number of ring gear teeth by the number of pinion gear teeth. May 16, 2016 a higher gear ratio can give your vehicle better acceleration. Jan 23, 2018 as for stock gear ratios, there is a 58 or so wide web under the housing that runs from the outside of the housing down to the torque tube flange. Determining rear gear ratio without removing cover. Hypoid gear ratios must be determined by tooth combination and not by. Speedmastertm kits bring together everything you need. We will try to include both transmission and rear end gear ratios fyi. For example, a vehicle with 39 ring teeth and 11 pinion teeth has a 3. Switching your rear end gear ratio helps your gas mileage or improves your power. The number of gear teeth and the diametral pitch regulate the size of the gear. A high numerical gear ratio is called a low gear or low rear end, and vice versa. How to find out the gear ratio with the vin number it still. Each number and letter contained within a vin reveals information.
This is a 1968 chevy c10 answered by a verified chevy mechanic. Your entire mustangs rear consists of your axles, the gear housing, a power transfer device ie a spool, lsd, posiunit, etc. As most pontiac fans realize, changing rear gear ratios can yield a tremendous performance increase. Gear ratios can be changed to compensate for changes in tire size.
How to find your differential gear ratio without stamps, tags. Gear ratio tells you how fast the driven gear in a gear system will spin relative the driver gear. For example, if the ring gear has 41 teeth and the drive gear has. Lets say in a rear wheel drive car you have a rear end gear of 3. Crawlpedias gear ratio calculator will find the ratio of your ring and pinion. Gears can be a pretty general term but in this case, they refer to the ring and pinion gears residing in the rear differential. Tire diameter will also have an effect on a vehicles final. The gear ratios can remain as is for most of the other adaptions.
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