What Do I Have to Do to Change 8.5 Ten Bolt Ring Gear and Pinion UPDATED

What Do I Have to Do to Change 8.5 Ten Bolt Ring Gear and Pinion

Selecting the correct hypoid gears for your vehicle and application is essential for attaining maximum performance. The gears are shaped equally a revolved hyperboloid, which ways that the pitch surface of the gear itself is a hyperbolic surface. Hypoid gears are centered off-axis, where the pinion gear sits lower than the centerline of the band gear, allowing the pinion gear to exist larger than it would be if information technology were on-eye. Because of the size and screw angle of the pinion gear, hypoids appoint multiple teeth at once, and then they tin handle higher torque loads.

One of the side effects of the hypoid pattern is a sliding action of the gear teeth every bit they rotate. This is where a lot of issues appear. As the teeth slide along each other, the friction generates heat, which is the enemy of gears. If a differential runs low on gear oil for fifty-fifty a short time information technology results in serious harm then that it is unrepairable; you lot take to replace the gears.

Ring gears convert the engine's rotation into forward motion, but in that location is more than to selecting a gear set up than merely what size you lot remember you demand.

The gears must exist arranged in a very specific position relative to each other, within a couple of thousandths of mesh. This is expressed numerically as .002 inch, which is similar to the bearing clearances in the rotating assembly of an engine. The problem is that while it is easy to mensurate the clearance between a crankshaft periodical and a rod, doing the same on a band gear set is much more difficult. See Chapter 7 for more details.

Make up one's mind Gear Ratio

Determining the ratio of gears installed inside your housing is uncomplicated. You demand to count the rotations of the tires and the driveshaft at the same time. Information technology is easiest with a helper, but you can do it alone with some preparation. First, you need a floor jack, jackstands, tape or a grease marker, as well as newspaper and a pen.

Jack the vehicle up until the wheels are suspended. Secure the jackstands nether the vehicle and balance the weight of the motorcar on the stands. (Never piece of work under a car with just a floor jack. If the floor jack fails, you can be severely injured.) Identify a piece of tape from the fender to the tire or to the ground and to the tire along the sidewall. This is the rotational mark. Place another slice of tape from the driveshaft to the housing. This is the driveshaft marker. If you are working by yourself, you can put the tire marker on the inside of the tire so you tin can come across it from nether the machine.

A sizing code is stamped on every pinion shaft. Gears are congenital as a matched prepare, and they cannot exist interchanged.

The number of teeth is stamped on each gear. The small number is the pinion gear tooth count; the large number is the ring gear molar count. You divide the big number by the piffling number to get the ratio. Here, 40 ÷ 13 = three.076, then these are 3.08:1 gears.

This 3.73:1 band gear fits the GM 12-bolt rider car carrier. The gear measures 8.8 inches, which is noted in the part code: GM8.viii-373.

To change gear ratios, you need different pinion gear sizes. This pinion gear (left) is a 4.eleven, and the gear (right) is a 3.08. This is office of the reason that dissimilar carriers are required for sure gear ranges. The bigger the gear ratio, the further away the pinion gear sits. The carrier repositions the ring gear to compensate.

Put the manual in neutral. Next, rotate the driveshaft and count the number of complete rotations until the tire has made one full revolution. It is unlikely that the drive-shaft rotations will be equal, so y'all tin can approximate the number for a street vehicle. Almost three/4 of a plow gets you close to .73 to .eighty. This is proficient enough for street vehicles.

If you need a more precise indication of the gear ratio, open up the housing and read the numbers stamped into the each gear. If you can't read the numbers, simply count the teeth and employ the following formula:

Gear Ratio = ring teeth ÷ pinion teeth

For example, a vehicle with 39 ring teeth and 11 pinion teeth has a 3.54:1 gear ratio (39 ÷ 11). The gears' purpose is to transfer power from the engine to the wheels, and the differential does this by torque multiplication. If an engine were directly connected to the wheels, the vehicle would struggle to move. The enormous size and resistance of the bicycle would overload the engine and bog it down. The vehicle would accept a long time to actually move.

During acceleration, the engine is spinning from idle (650 to one,000 rpm) to the 5,000-rpm range for normal street driving. Frontwards motion begins nearly instantly without reducing the engine's speed. This is because of torque multiplication: Every bit torque increases, the speed of rotation decreases. The basic formulas are:

Ring Gear Torque =  input torque 10 beam ratio

Ring Gear Speed = input speed ÷ axle ratio

For case, a stock LS1 engine sends 345 ft-lbs of torque to a rear differential with 3.73:i gears at 4,400 rpm. An engine that produces 345 ft-lbs certainly has respectable torque, just it is simply not enough to get a 4,000-pound vehicle moving.

You tin can test this on a vehicle with a manual transmission. Showtime out in first gear, and the vehicle takes off like normal; start off in fourth, and the engine bogs downwardly and dies. This is because it takes tremendous torque to generate forward motility. Using the formulas you go ane,287 ft-lbs of torque (345 x iii.73) and 1,180 rpm (4,400 ÷ 3.73).

Equally a effect of these increases, the mechanical advantage of the drive-railroad train as a whole has increased. How-always, the axle associates is only one component of the drivetrain; and there is ever a second set of gears in the drivetrain: the transmission.

To get the consummate picture, yous need the vehicle's gearing. For example, an LS1 transmission with 350 hp and 345 ft-lbs of torque, is a Tremec T56 6-speed with the following gearing numbers:

First            2.97

Second       two.07

Third          1.43

Fourth        i.00

Fifth           .84

Sixth          .56

Every bit an example, the rear differential is fitted with 3.73:1 gears. Using the formula, the last torque output at superlative RPM in outset gear is 3,822 ft-lbs (345 x 2.97 10 three.73). Full RPM is 397 (4,400 ÷ 2.97 ÷ iii.73).

This means that by the time the engine is spinning at 4,400 rpm, the axles are seeing 3,822 ft-lbs of rotational torque, spinning merely 397 times per minute. This would certainly get a iv,000-pound car moving downward the road.

Shift the transmission into fourth, and the gearing of the manual is 1:1, so the torque and RPM of the transmission is exactly the same as the engine (minus a little bit for parasitic loss). The first adding determines the torque needed from the gears, just i,287 ft-lbs, to motility the automobile.

An object in motion tends to stay in move. One time the vehicle is in motion, the torque required to keep it in motion is drastically reduced, and when the vehicle is in motion, horsepower takes over. Torque gets the vehicle moving and horsepower keeps information technology moving at speed. Consider the example vehicle in sixth gear; plugging the data into the formulas you get 721 ft-lbs of final torque (345 x .56 ten 3.73) at 4,400 rpm and 165 rpm (345 ÷ .56 ÷ 3.73). There is very little output in terms of torque and rotational speed, yet the vehicle would be traveling at a very high rate of speed.

This is of import because there are merchandise-offs for gear ratios and the way they relate to vehicle acceleration (quickness) and overall speed (speed). For a gear to achieve more mechanical reward (numerically college ratio), the pinion gear has to become smaller. Non only does this make the gear weaker, it too limits the summit speed of the vehicle.

Gear Option

A diversity of terms can exist used to draw gear blazon, such as "short," "deep," "tall," or "highway." These terms typically pb to confusion fifty-fifty for an experienced car owner/mechanic. Short gears are numerically higher, such as 3.73:1 or 4.eleven:i ratios. These are the deep gears that become the vehicle moving chop-chop due to their high ratio of input to output rotations.

Tall or highway gears are the depression-number ratios that yield high speed and efficiency, such as 2.fourscore:ane or iii.08:1. These gears do non provide the torque multiplication rates that the larger ratios provide. Once the vehicle is up to speed, they allow the engine to spin more than slowly, which means they are more than efficient for highway utilise.

Finding the ratio is simple. For every rotation of the ring gear, the pinion gear rotates "X.XX" times. For example, a 3.73:1 gear ready requires 3.73 turns of the pinion gear to spin the ring gear one full rotation. This is a directly correlation of the driveshaft rotation to the axle rotation. The lower the number, the faster the axles spin in relation to the engine. This is why lower gears are efficient; the engine doesn't have to spin as fast to go along the car moving and tin can reach higher speed, but it is much harder to go the car going than with larger numerical gears.

Choosing the gear ratio for your vehicle can be difficult. You have to find the balance between top speed and quickness for your application. Specific applications, such as drag racers and off-road stone crawlers demand deep gears to become the vehicle moving quickly or maximize engine torque output at low speeds. High-speed racing, such as with circle runway cars, needs top-end speed, and so the takeoff speed is not much of a cistron.

Street vehicles, however, must strike a fine residuum betwixt the ii, and that ways factoring in several key components such every bit intended use, transmission blazon and gearing, and tires.

Intended Employ

This is the single most important component for gear selection. If yous are building a stoplight-to-stoplight street automobile, higher numerical gears are certainly applicable. If the vehicle sees a lot of highway miles, steep gears drastically reduce the overall speed of the vehicle and make the engine spin much faster.

Manual Type and Gearing

The following gear ratio setup is ane of the greatest upgrades for a transmission overdrive. It does the opposite of the lower gears; it makes the output shaft spin faster than the engine itself. This means that the rear gears have more input speed to work with. A 1:i transmission with output running to a 3.73:1 rear gear yields a 3.73:i final drive; a .68 over-drive yields a 2.54:ane final bulldoze. This is like having 2 sets of rear gears, allowing much better height-end speed while maintaining the quick acceleration of the deeper gears.

All GM not-overdrive (transmission or automated) transmissions somewhen produce a 1:1 gear ratio. Some overdrive transmissions take two overdrives, such every bit the Tremec T-56, allowing fifty-fifty larger gears to be used.

Tires

Tire size is another important cistron in gear pick. Tire sizes vary greatly from vehicle to vehicle, so it is difficult to decide which is best. The formula for comparing tire sizes is as follows:

Effective Gear Ratio = new tire diameter ÷ old tire diameter x old gear ratio

For instance, if you have a automobile with a three.73:one gear gear up and 28-inch-tall tires, and you want to increase the tire size to 30 inches, the final drive is 3.16:1 (28 ÷ 33 ten iii.73), which means less acceleration but higher top-cease speed.

You can also utilise this formula to compare the furnishings of gears and tires for many applications. For case, a vehicle with 4.11 gears and 28-inch tires, moving to thirty-inch tires, has the opposite effect: a 4.40:1 effective ratio (30 ÷ 28 x 4.eleven). This means that the machine accelerates more than quickly, just with less meridian-end speed.

And you can use this formula to extrapolate the effectiveness of your gearing change. With 30-inch tires, the constructive ratio of a iv.eleven gear is the same as a 28-inch tire with iii.73 gears. This makes 4.11 gears with an overdrive transmission and 30-inch tires very effective for street utilize, but requires shorter tires for drag racing.

Diving deeper into the realm of gearing calculations, the post-obit formula helps you brand your gearing decision:

MPH = (RPM 10 tire circumference in feet) ÷ (rear gear ratio ten  manual gear ratio ten 88)

Where:

MPH = desired operating speed

88 = mathematical constant

For this calculation, the formula will be shortened for a 1:1 transmission gear.

This is helpful for calculating the actual (or theoretical) results of a gear or tire modify at a specific RPM or speed. For instance, a vehicle with 30-inch tires, 4.eleven gears spinning at 4,000 rpm travels at 87 mph [(4,000 x 7.85) ÷ (4.xi x 88)].

You can expect up the tire circumference for your specific brand and size or calculate information technology by using the following formula:

Tire Circumference = overall tire diameter x three.14 ÷ 12

Where:

three.14 = mathematical constant (pi)

12 = number of inches in a human foot

For example, the circumference of a xxx-inch tire is 7.85 feet (thirty ten three.xiv ÷ 12).

If yous alter to 3.73 gears, the vehicle travels at 96 mph [(31,400) ÷ (3.73 x 88)].

You can achieve a big difference in overall speed past simply irresolute to a lower numerical gear. If math is non your strong accommodate, many calculators are bachelor online to calculate the gear ratios. Some calculators prove you the top speed for every gear.

Band Gears and Carrier

Equally you know, the pinion gear becomes smaller as the ratio increases numerically, so the band gear mounting depth must be considered. The pinion position is not variable from side to side; it is in a fixed position inside the housing. The ring gear carrier has a small corporeality of aligning from side to side. As the pinion gear changes in size, the position of the band gear to the pinion must modify.

GM differential carriers accommodate a small-scale range of ratios and then the gear mesh is maintained. The consequence is three carrier sizes. All GM x- and 12-commodities variants use similar ranges.

Manufactory Carriers

The factory carriers for the 12-bolt passenger car are available in the following sizes:

ii-Series: Gear ratio is two.56 to 2.73:1. Bearing shoulder-to-ring gear surface is 0.590 inch. This is the smallest of the stock GM carriers. It is weak and not suitable for operation applications.

3-Series: Gear ratio is 3.07 to three.73:i. Begetting shoulder-to-ring gear surface is 1.12 inches.

4-Series: Gear ratio is 4.10 to four.88:i. Bearing shoulder-to-ring gear surface is 1.325 inches.

Aftermarket Carriers

Although most aftermarket carriers provide their own details, they tend to follow these guidelines:

ii-Serial: Gear ratio ii.73:ane and lower.

3-Series: Gear ratio 3.08:1 to 3.90:1.

4-Series: Gear ratio 4.x:1 and higher.

For non-operation applications, a spacer tin can be used to step up a smaller carrier to the next size, such as a ii-Series for a iii-Series gear. These are non for functioning applications, as in that location is a lot more stress put on the longer bolts than they can handle; they eventually fail in spectacular fashion.

Ring Gear Bolts

General Motors used bolts with different sizes and thread pitches for the ring gear. For 10- and 12-bolt units, the band gear bolts are 7/16-inch fine-thread bolts with a large 9/16-inch hex-caput cap. Left-mitt-thread bolts in the band gear were used with some 10-bolt units. "L" is marked on some but not all of these bolts.

The indicate is to be careful and check the bolts before taking them off with an impact wrench. Many front-wheel-drive carriers likewise utilize left-hand threads.

Ring gear bolts are secured with thread locker, which prevents them from loosening considering of the many heat cycles experienced throughout their life. If yous leave the thread locker off during your installation, you will probable find out the hard way.

Bearing Installation

Before installing new gears into the housing, you need to follow a few procedures. All ring-and-pinion gears are forged. In the forging process, they are formed through a series of operations that take a slice of solid billet steel, heat it to red hot, and slam it into a printing to form the bones shape. The next press forms the general band or pinion shape, so the bodily teeth are cutting into the gears during the machining phase.

A damaged pinion shaft wreaks havoc on the remainder of the internals as well. Oil starvation causes this kind of damage. The bearings overheat and seize onto the pinion.

Afterward the automobile work is completed, the gears are heat treated and quenched in oil to induce a difficult outer surface that is mostly .050 inch deep, while maintaining a softer inner core that allows the gears to flex plenty then that they don't break nether farthermost conditions. This is much like a sword wherein the outer surface is very difficult so that the steel tin can agree an edge, merely the inner core of the metal is soft enough to permit information technology to fl ex so it doesn't shatter on affect with an unyielding surface.

Stride i: Remove Pinion Begetting (Special Tool)

A bearing separator, such equally this, can be used in a hydraulic press to remove the pinion bearing. If yous do non own or have admission to a hydraulic press, you need to have a shop remove the bearing. The separator tool simply supports the begetting. Yous want to continue the original bearing intact for setting upwards the new gears if at all possible, otherwise you have to ruin a perfectly expert bearing for the prepare-up phase. It will exist replaced afterwards, but you need one to set the pinion depth.

Step two: Inspect Bearing

Although this inner bearing did non seize, the bluing on the bearing rollers means information technology was shut to declining. If it had failed, it could accept cracked the rear-terminate housing.

Step 3: Inspect Pinion Shim

Under the begetting is the mill shim. You tin can attempt to reuse it, but y'all will likely accept to add together shims or replace it with a thinner shim to get the new gears to mesh correctly.

Step 4: Audit Pinion  Shim (CONTINUED)

Several new shims are included with a rebuild kit. A shim sets the pinion depth; it is not a wear role. Shims come up in varying thicknesses, but it is always a expert idea to start with the original one and go from in that location.

Pace 5: Install Inner Bearing

The inner begetting is a press-on part, and then you need a slip-fit bearing as a stand-in for setting up the gears. Change the original begetting (it will be replaced) for fitment over the pinion gear. Utilise a carbide burr or sanding ringlet with a die grinder to open it up just enough so that it slips on and off the new pinion gear easily.

Pace 6: Install Inner Bearing (Continued)

One time the bearing has been modified, slip the shims over the pinion shaft and place the bearing on elevation of them.

Step seven: Install Pinion Gear in Housing (Professional Mechanic Tip)

You demand to perform an initial fitment so you need to mock up the differential in the housing before you perform the final assembly. Place the pinion in the case and prelube the bearings and so that they don't stick.

Step viii: Install Solid Spacer

All GM 10- and 12-bolt axles use crush sleeves. Do not install the vanquish sleeves yet; you are simply trying to figure out the initial settings. The crush sleeves should only be used for last assembly because in one case they beat out, they tin't be reused.

Pace 9: Install Solid  Spacer (CONTINUED)

A solid spacer is an alternative to a crush sleeve. It does not vanquish; rather, it uses shims to fix the pinion pre-load. It is re-useable and not difficult to ready.

Step 10: Install Solid Spacer (Connected)

Push the beat sleeve in from the forepart of the case. If you are setting up a solid spacer sleeve, wait until the pinion depth is set to do then.

Stride 11: Install New Pinion Begetting

Install the new forepart bearing into the example. On new pinions, the begetting is likely very tight. Y'all may need to use the yoke and pinion nut to pull the pinion into the bearing.

Ring and Pinion Machining

You have a choice between two- and 5-cut machining processes for ring and pinion gears. The backlash must be set differently for each cut mode. The mesh patterns vary as well. The ii-cut gears are the same height from heel to toe. The wearable pattern is biased or angled on the edges (in parallel) in a square course. 5-cutting gears are machined with a shorter toe and taller heel. The habiliment blueprint shows up equally a wide rectangle or oval shape.

Setting up the gears is a complicated process that requires a lot of trial-and-error test fitting. One of the tests is a grease mark that shows the mesh design. This is the proper centering as shown on the ring gear.

When the pinion is as well close to the ring gear, you get a pattern like this.

If the pinion gear is too far away from the ring gear, the result looks similar this.

 Here is what a proper mesh pattern looks like. See Chapter 7 for more than details.

Exist sure to follow the correct backfire spec for the type of gears you have. GM 12-bolt units are all five-cut, but both styles are bachelor for 8.5- and 8.half-dozen-inch ten-bolts. Two-cut gears require a tighter back-lash, between .0030 and .0060 inch, in which v-cutting gears are much wider with a sweetness spot generally between .0060 and .010 inch.

One time completed, each gear set is lapped together to make them a matched set forever. This procedure is essentially a polishing method that ensures the gears mesh together.

Step 1: Press Begetting and Shims onto Pinion Gear

Once the pinion depth is ready, press the new bearing and correct shims onto the pinion gear. This requires a hydraulic press; you can't do it any other manner.

Pace two: Prep Band Gear for Installation.

Inspect the band gear for burrs before installing it on the carrier. Using a flat file removes whatsoever burrs without gouging into the gear.

Stride 3: Install Carrier on Ring Gear (Torque Fasteners)

To attach the carrier to the ring gear y'all thread in two bolts at oppo site ends of the carrier. And so utilize thread lube and thread the rest of the bolts into the ring gear. Using a star torqueing pattern, torque all the bolts to the ring gear. Retrieve that ring gear torque specs are unlike for various differentials. In addition, you must follow your hardware supplier's torque specs. Most ten-bolts are torqued to 65 ft-lbs while 12-bolts (car and truck) are typically 55 ft-lbs.

Each gear is installed into a special machine that puts a slight load onto the gears and spins them while they breast-stroke in silicon-carbide annoying media. This removes any imperfections in the gear teeth besides as corrects any issues with spiral angle, spacing, or eccentricity. Once lapped, the gears are forever a pair and should never be mixed with others gears.

This manufacturing procedure creates a sturdy component that will final for years of service, but the occasional issue may arise, such every bit burrs on the threads of the mating surfaces.

Inspect the gears equally presently every bit y'all open the box. Wait for anything that may snag on the carrier or bearings. If y'all discover a burr, it can be removed carefully with a file.

Speedometers

When the gear ratio is inverse, the speedometer gearing is altered. When you alter gear ratios on vehicles with electronic speedometers, you need to reprogram the computer or follow a calibration process for aftermarket speedos. With mechanical speedometers, yous must calculate the exact transmission ratio for your gears and tires.

About GM transmissions take readily available gear sets to lucifer your application. The driven gear is the gear installed into the removable housing; the drive gear is the gear inside the transmission on the output shaft. Sometimes this gear must be changed to arrange your combination, merely this is not common.

The cablevision drive for the speedometer is located on the driver'southward side of the transmission; a clamp and a bolt usually retain information technology or information technology may be threaded into the housing itself. Remove the threaded cable The cable bulldoze for the speedometer is located on the driver's side of the transmission; a clamp and a commodities usually retain information technology or it may be threaded into the housing itself. Remove the threaded cablevision then remove the speedo drive. Nearly GM transmissions use a nylon gear on the stop that is color coded to match a specific ratio. Typical GM driven-gear housings come in two driven-gear groups: those with 34 to 39 teeth and those with 40 to 45 teeth.

Find Speedometer Gear

To determine what speedometer gear you need, start by measuring the tire bore with the tire on the basis. Measure from the footing to the centerline of the axle and multiply by two.

For a more accurate effect, take into account the flattening of the tire's contact patch. Y'all could use the manufactory tire spec if yous don't accept the actual tires available to measure.

Plug those measurements into the post-obit formulas:

Number of Driven Teeth = (number of drive teeth ten gear ratio ten tire revolutions per mile) ÷ 1,001

Where:

one,001 = mathematical constant

Tire Revolutions per Mile = twenty,168 ÷ tire diameter

Where:

20,168 = mathematical abiding

For example, a GM 700R4 manual with a 15-molar drive gear, 3.73 gears, and 28-inch tires does 720.28 tire revolutions per mile (20,168 ÷ 28) and has twoscore driven teeth (15 10 3.73 x 720.28 ÷ 1,001).

Written past David Vizard and Posted with Permission of CarTechBooks

GET A Bargain ON THIS Book!

If you liked this article you volition LOVE the total book. Click the push below and we volition send y'all an exclusive deal on this book.

DOWNLOAD HERE

What Do I Have to Do to Change 8.5 Ten Bolt Ring Gear and Pinion UPDATED

Posted by: christopherfifeled.blogspot.com