Driveshaft Basics

A driveshaft, also called a propeller shaft, connects a vehicle’s transmission to the differential. As far as propulsion systems go, the driveshaft has a pretty simple purpose: transmit torque between the engine/transmission system and the wheels. Drive shaft rotation energy is transferred to the wheels through a gear system housed in the differential. Barring a catastrophic mechanical failure or excessive vibration, drive shafts require little maintenance or repair.

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Driveshaft Standards

A vehicle’s driving shaft has to be designed to meet high standards for the following performance metrics:

  • Durability
  • Shear Stress and Vibration
  • Warping when Exposed to Temperature Extremes
  • Torque Transmission Efficiency

Usually, joints connect several propeller shaft components when the shaft has to be relatively long.

Driveshaft Joints

There are several prominent joint designs for propeller shafts. The most common are universal and constant-velocity joints. Universal joints have the advantage of allowing two components of a propeller shaft to pivot through a wide angle. This is advantageous in complicated machinery where the line between an engine/transmission and the differential is blocked by other components. Constant-velocity joints are specially designed to maintain constant rotation speed between two components of the driving shaft, even at significant angles. Universal joints generate vibration and angular momentum discrepancies if deviation angle becomes large enough. Joint design can be as important as the driveshaft itself.

Considerations

As with everything, cost/performance tradeoffs are inevitable in drive shaft selection and repair. Constant-velocity joints are more expensive than universal joints but are usually worth the price in efficiency and durability. Drive shafts can be severely degraded by vibrations and improper joint alignment. Sudden braking/acceleration can also reduce driveshaft lifetime since doing so puts stress on the shaft, joint components and differential gears.

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The Transfer Case

This is a vital component commonly found in all wheel drive and four wheel drive vehicles. It is connected to the rear and front axles and the vehicle’s transmission through a drive shaft. Two wheel drive vehicles do not require a transfer case. This is due to the fact that they are equipped with a driveshaft that goes directly from the transmission into the drive wheels.

Types of Transfer Cases

Drive Type

Chain driven

Chain driven cases utilize a chain that usually drives only one axle. However, this type of vehicle component can also drive both axles. These cases are lighter and quieter than gear driven ones. They are commonly used in vehicles such as full size trucks, compact trucks, sports utility vehicles, and Jeeps.

Gear driven

Gear driven transfer cases can utilize sets of gears in order to drive both the rear and front driveshafts, or only the front driveshaft. These are generally heavy and strong units that are commonly used in large trucks. However, there are several gear drive cases that are manufactured for passenger cars.

Shift Types

E.S.O.F.

These cases are equipped with dash mounted buttons or switches that have front sealed automatic locking drive flanges or an axle hub. In order to engage a four wheel system, a car must be moving at very low speeds. The speed that a 4×4 can be engaged at also depends on the vehicle. This is only found with a four wheel drive high option. Additionally, a car must be stopped in order to engage a four wheel drive low option. The transmission should be shifted to neutral. After doing this, the four wheel drive low option can be used.

M.S.O.F

These cases are equipped with a selector lever. This lever is found on the driver’s side floor transmission projection. It also has either a two manual front axle center selection or two sealed auto front axle locking hubs. In order to engage a four wheel drive system, a vehicle must be running at low speeds. To engage a four wheel drive low option, the car must be completely stopped. At the same time, the transmission must be put into neutral. After this, the four wheel drive low option can be selected.

Housing Type

Independent or Divorced

Independent cases are completely separated from a vehicle’s transmission. They are commonly bolted to the car’s gear box output shaft. The very short driveshaft connects the transfer gearbox to the rear and front differential. These transfer gearboxes are commonly utilized on long wheelbase vehicles that include military or commercial trucks.

Married

A married transfer gearbox is bolted directly to a vehicle’s gear box. This transfer gearbox is an integral component of a gearbox. These two components also share the same housing. This transfer gear-case is commonly found in some four wheel drive cars and recent Subaru products.

Rebuilt Cases

Sometimes, these cases can bog down due to excessive use or old age. Buying a brand new case can be financially burdensome. This is the reason why many car owners consider rebuilt cases. Rebuilt cases can be similar or much better than brand new transfer cases. At the same time, only broken parts of a transfer gearbox are replaced.

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Transmission Rebuilds: When & How

Automatic transmissions are delicate mechanisms designed with precise clearances between the moving parts. Rebuilt TransmissionParts that move, of course, wear down. And when the wear gets so bad the gears no longer mesh correctly, the vehicle will no longer shift as it should. Well before this point the transmission should be rebuilt or replaced.

Signs of Trouble

Some initial transmission symptoms may not indicate the need for major work. Replenishing low fluid solves some problems. If topping off does not help; draining the unit, changing the filter and replacing seals and gaskets may coax a tranny back from the edge of failure if it has only minor symptoms like these:

  • Leaks
  • Fluid is dark or smells burnt
  • “Check Engine” light is on

A few more serious trouble indicators almost always indicate the tranny should be replaced or rebuilt:

  • Slow or no response to change in engine speed
  • Resistance to shifting into park or drive
  • Hesitation when gears change on the road
  • Shimmy during gear changes
  • Metal shavings in fluid
  • Tranny-related noise

Rebuilding Procedure

A rebuild begins with jacking up the vehicle or raising it on a rack. The mechanic then drains the transmission, takes it apart and lays it out on a bench. Each part in turn is cleaned and inspected for wear. Professionals will use new replacements for worn parts, but home mechanics may wish to consider carefully selected used parts from local sources, especially for the more expensive components.

Some parts should always be replaced during a rebuild. The clutches and bands, for instance, work by friction and so undergo tremendous wear. Seals and gaskets should also always be changed out. The torque converter, the fluid coupler that transfers rotational energy from the engine to an automatic transmission, is subject to large amounts of stress in operation and is quite susceptible to damage during the removal process. Many mechanics replace the torque converter as a matter of course.

Cautions for Do-It-Yourself-rs

A rebuild can be a challenging proposition. It involves removing several hundred pounds of dead weight containing nasty liquid from a vehicle over the mechanic’s head, and there often is no plug to facilitate drainage. After, all the delicate parts covered in toxic goo must be disassembled in an environment free dust…and the whole put back together with replacement parts as appropriate. Then the rebuilt tranny is put back on the vehicle and filled with fluid. At this point the used fluid must be disposed of properly.

Transmission

Do-It-Yourself mechanics, particularly those with the proper tools and a good deal of experience, can and do rebuild automatic transmissions with entirely satisfactory results, and many do enjoy the process. An owner at a lower skill level, however, or someone who does not have the time or the tools to do the job right, should consider having it done professionally. This usually involves purchasing a new or rebuild transmission built from a reputable specialist like Rocky Mountain Driveline who performs exhaustive test to ensure perfection. You may still do a self-install, though this still means dealing with the weight and proper disposal of the old fluid. As an alternative, the installation can be handled by just about any local shop.

Transmission failure can make a vehicle unusable or worse, lead to an accident. Investment in a rebuild keeps cars running better and longer. Whether a home mechanic rebuilds the tranny out of the vehicle or a shop replaces it with a purchased rebuild, taking care of tranny problems saves time and trouble in the long run.

Rocky Mountain Driveline is your local leader for rebuilt transmissions. Stop by or call today!

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Flywheel Resurfacing, What & How?

The flywheel in a car has several purposes. Its main purpose is to store energy to provide momentum and keep the crankshaft turning. It also helps balance the rotating assemblies and smooth vibrations transmitted to the drivetrain. It transmits energy smoothly to the transmission, providing power to perform its work.

The transmission receives power from the engine through the clutch assembly. The clutch disk is covered in friction material similar to that found on brake shoes. When the disk is pressed against the flywheel by the pressure plate, a high amount of friction allows it to grip the surface, and rotating energy is applied to the transmission to make your car move down the road. When the disk lining begins to wear, it loses this ability to grip.Flywheel Resurface

As a result, it will begin to slip, and over time, it will polish the mating surface, making the slipping worse. The friction from this slippage causes a great deal of heat. There is so much heat produced, in fact, that it will effectively “heat treat” the metal surface. This can damage the surface, causing it to become too hard. In some cases, cracks and blisters can develop in the surface of the flywheel due to this increased hardness. This condition is often referred to as “hot spots” on the surface. Hot spots occur because the heat is applied unevenly. Consequently, the hardened places are not evenly distributed across the surface.

For these reasons, whenever the throwout bearing, pressure plate or disk is replaced, manufacturers also recommend the flywheel undergo a “resurface”. During a resurface, the part is fixed to a machine that cuts a very thin layer of metal off the surface. This process exposes fresh metal to the disk, and provides a slight roughening of the surface. This will improve grip over the previously polished surface. The amount of metal removed during a resurface depends on the depth of the hot spots.

It is a good idea to stop using the vehicle when the clutch starts to slip, and have it repaired immediately. If too much metal has to be removed during the resurface, the part will be too thin, and it will no longer meet manufacturer’s specifications for proper operation, weight and safety.

Some symptoms of problems in the clutch assembly include:

  • A great deal of force is required to engage the clutch pedal.
  • The car is difficult to shift into gear from neutral.
  • A squealing noise is heard while shifting.
  • The engine races when leaving a stop or climbing a hill.
  • The car has sluggish acceleration accompanied by the engine racing.

    Since the flywheel is attached to the engine’s crankshaft, the engine and transmission must be separated to remove the flywheel for a resurface. In many vehicles, this will mean the engine must be removed and reinstalled to perform this work.

    Rocky Mountain Driveline has the machinery and expertise onsite to resurface flywheels. A resurface will help to restore like-new operation to your clutch assembly.

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    A Guide Towards Great Handling

    Installing a new or rebuilt Rack & Pinion system in your car can easily breath new life back into the vehicle. Precise and smooth control of the wheel can be the central part of the driving experience which determines comfort and handling. It may sound like a complicated procedure, but this repair job is one that is actually within the reach of anyone with even minor automotive experience. The process is virtually the same with most vehicles. The only variable may be the method for removing the system from the frame.

    The first replacement step is to remove the old Rack & Pinion system. You will need to adjust the wheel so that the tires are in the forward position, and lock them in place. Once complete, disconnect the positive and negative cables from the car battery. Using a jack, lift the car so that the front wheels can be removed. Continue the repair by draining the power steering fluid and detaching the lower joint of the wheel column.

    Rack & Pinion

    The next step involves the tie rods and engine mounts. Remove all nuts from the inner and outer tie rods. Once free, disconnect the tie rod ends from the steering knuckles. The front exhaust tube must then be detached before removing the center member and all the nuts attached to the engine mounts. Next, you will remove the bulkhead hole cover by, again, removing all nuts.

    Now, to the Rack & Pinion itself. Remove the lower joint and mark the neutral position of the steering for later reference. Also be sure to mark the central housing and the shaft. You then remove the entire system by detaching the power fluid pipes and the mounting bracket bolts.

    Installing the new system is essentially the above process in reverse. The new system should be put in place…the mounting brackets, too. Verify all replaced nuts are properly tightened using a torque wrench. The hoses which supply the system with power steering fluid must now be put back into place. Reconnect both the high-pressure line and the low-pressure line, ensuring they are well secured to prevent future leakage.

    The pinion shaft must be properly aligned when it’s reinstalled. This step takes advantage of the neutral position of the wheel marked earlier. The mark indicates where the component should be attached to the steering joint. Once these items are in place, the bulkhead can be properly put back into place. The front stabilizer is next on our checklist. Gather the nuts and mounting gear for the engine mounting center. Put the component back into its original position. Tighten it securely into place. As the replacement nears an end, tighten the nuts on the tie rod ends, and secure the new cotter pin. All other securing nuts should then be put in place for tightening. The last step in the process is to refill the power steering fluid reservoir. You must then bleed the system to achieve optimal performance. In some cases, the repair process may also call for aligning all of the wheels.

    Rocky Mountain Driveline is your local leader for rebuilt rack & pinion units. Call or stop by today!

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    Differentials…What Are They?

    The term differential refers to a mechanical device that receives energy from a power source and converts the direction of that energy at right angles, left and right, with limited loss of power. While the term, these days, is generally considered a key automotive part, mechanical differentials can be used in any situation where such directional conversion of power is desirable. In automotive uses, wheels are attached at the end of the left and right driven arms extending out of the directional power converter mechanism.

    Differential

    In addition to converting the application of power, this directional power converter has the ability to operate with the left and right converted power arms, called axles, rotating at different speeds. In automotive applications this allows a transference of power even while the two converted power arms, and the attached wheels, rotate at different speeds. Meaning the vehicle is turning. This is accomplished by the use of slip gears that mechanically ensure, even though only one physical power force enters the power conversion mechanism, the operation of the various sized gears results in a mechanical equivalent of two power inputs and two powered outputs. This arrangement of gears is therefore a mechanical equivalent of the mathematical equation that is a proof of this direction of power conversion system.

    In early automotive differentials this caused a loss of traction at the point where the wheels met the road. This, depending on the vehicle weight and amount of applied power, could be a problem. The result was development of a differential that had a limited amount of slip or loss of power to the left and right angle powered arms exiting from the case containing the differential mechanism. In automotive applications the left and right arms are called axles. Since the use of this mechanical principle for automotive purposes the term axle is used for the left and right power converted arms to even non-automotive mechanisms.

    Early Forms of Mechanical Differentials
    The ability to covert the direction of applied power is actually not a modern invention. Ancient devices have been found that also used this manner of converting applied power from one direction and applied that power in one or more different directions.

    In the first quarter of the eighteenth century this mechanical principle was applied to clocks. By the first half of the twentieth century analog computers were using this principle to do simple arithmetic calculations.

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    Troubleshooting Rack & Pinion Steering

    Rack & Pinion Steering

    It is very important to know if something is off with your car before you drive it. After all, you just want a safe and accident free ride. With regard to a rack & pinion steering, it is necessary that any associated problems are quickly identified.

    Determine What’s Wrong With the Rack & Pinion Steering

    So, how can you determine if there is something wrong with the rack & pinion? You can rather simply test this on your own. First, you will need to look for a straight and level road with minimal traffic for a driving test. While testing, you may try to release the wheel to check if the car will drift off course. You can also try turning and releasing to check if the wheel will return to its normal position by itself or does it need to be manually straightened. Moreover, you also need to check if the wheel is stiff when used. If you tested positive with these driving tests, then it is necessary for you to have the rack & pinion steering checked right away for possible repairs.

    Rebuilding the Rack

    Once problems with your rack & pinion steering are noted, you can send then consult a professional mechanic for repair. Or if you prefer to check it out yourself first, you can certainly do so. You have the option to rebuild the rack or change it with a new one. There are replacement racks readily available in the market. Moreover, these racks have two standard variables: short and long. The long racks are assembled and are ready to install. They also come with new tie rods, mounts, and bellows. For high mileage vehicles, this would be the best option to choose…and it saves on install and repair time. On the other hand, a short rack does not include tie rods or bellows. They might cost less, but they take some time to install as you would also need to install the tie rod ends separately.

    Flushing the Wheel

    Once the rack is removed, you will need to flush the steering’s pump as and line to remove the old fluid. This will prevent contaminants of the dirty, old fluid from circulating through your new rack. You can flush it by lifting the front wheels and then pouring fresh fluid into the pump reservoir which allows the fluid to drain through the return line. Whenever the rack is placed on the chassis, be sure to reconnect the return line in the drain pan. Then, add the fluid into the pump reservoir. Next, crank the engine or perhaps turn the pump manually. Then, place two quarts of fluid into the pump reservoir and connect the pressure line towards the pump.

    Removing Trapped Air

    After flushing and filling the system, the final step is bleeding the system of any trapped air. You can do this by lifting the front wheels, then rotating them from one side to another side maybe 10 times at an easy pace while the engine is off. Repeat this steps until you can no longer see bubbles on the fluid reservoir. The levels should remain steady. Then disable the ignition and crank it several times while checking the fluid reservoir. Verify there are no bubbles and the reservoir is full. Providing this checks out, you should be good to go!

    Posted in Driveshaft, Rack & Pinion, Steering Gear Box | Tagged , , |

    Diagnosing Your Differential

    Differential Diagnosis

    Your automobile’s differential and axle system are very important. It works to transmit torque and rotation through the car’s shaft. This gives the wheels the ability to move at different speeds, a feature that is important for traction when driving. A failing differential may cause you to feel vibration, hear strange noises or see fluid leaking from your car, all while negatively impacting your vehicle’s performance.

    The first thing you should do to check for a problem is to listen for noise in your gears. The noise will normally be heard when you first put your car into drive after it has been idle for a period of time. The sound will resemble a rattling or clanking noise and comes from the universal joints. The joints are used to connect the transmission to the differential. Once it is worn down, it will cause it to work harder. Additionally, the gears will wear down. In order to diagnose the problem, you will need to take your automobile to a professional technician, as it requires special equipment.

    The second thing you will need to check into in order to make a proper diagnosis is to listen for grinding gears when you reach high speeds. The noise will sound like humming or the same clanking that was mentioned above. This could mean that the gears are becoming stripped or worn. This will make for things to feel awkward when they are spinning in the drive shaft. The noise may sound worse during a quick acceleration or if you have to brake unexpectedly.

    Differential GearsVibration and fluid leakage are other factors that will need to be looked at. Worn or ripped universal joints could cause vibration that will be felt in the drive shaft and engine block by way of the automobile’s transmission. The vibration will most likely be felt through the vehicle’s floor when driving at high speeds. A leak or crack in the vehicle’s seals may also cause vibration which will cause the differential to fail. Though less noticeable, fluid may pool under the car in the front or rear once it has been sitting overnight.

    If you feel you may have problems with the differential or axle in your vehicle, you will want to seek a professional. Driving with these issues or a bad axle can cause more serious problems or even an accident. And remember, Rocky Mountain Driveline is your local leader for rebuilt differentials. Call or stop in today!

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    When & Why Flywheel Resurfacing Is Necessary

    Resurfaced Flywheel

    A good rule of thumb is to resurface your flywheel every time you have your clutch worked on. Many clutch manufacturers refuse to accept warranty claims if this isn’t done, but this may or may not pertain to your driving habits and needs. There are some signs you and your mechanic should look for to see if the flywheel needs a resurface job or a complete replacement. These signs can help you decide whether resurfacing or replacing the flywheel is appropriate, as worn or badly damaged flywheels can often lead to expensive clutch repairs.

    Is there glazing or discoloration? If so, your flywheel needs to be resurfaced. Glazing and discoloration are signs of wear and can prevent it from meeting the clutch smoothly. A resurface job should never cost more than about $50, and will help keep the clutch from slipping or abnormal wear.

    Are there signs of cracking? This would be bad because it means the part is unsafe for continued use. Cracked flywheels can actually explode while in use, making this a very dangerous situation. Additionally, cracked flywheels also mean that the shift mechanisms could wear out quickly.

    Is the part “cupped” or unevenly worn? “Cupping” is caused by the interior surface of the part being worn down by constant contact with the clutch. Uneven wear indicates another problem, such as a misaligned part or one that has too much “play” between it and the contact point. Your mechanic can tell you if this is a problem that can be solved by a resurface job or if a replacement is more appropriate. A lot depends on how badly worn the part is and how uneven the wear is. Beyond certain factory tolerances, the part has to be replaced for continued safe operation.

    Flywheel Resurfacing

    If you’re a DIY mechanic, be sure you have the right part for the job. Although flywheels on different makes and models of vehicles from every major manufacturer may look the same, they aren’t. The tolerances and “play” profiles are completely different, and using one where you need another can result in improper wear on key components, not to mention expensive repairs and possibly even serious personal injury.

    A trained, reputable mechanic should always be your first stop when you have a vehicle issue of any kind. They know and understand what the factory specifications are and how everything in your vehicle works together to keep you on the road mile after mile. A resurface on this part, while relatively simple, requires special tools that the average DIY mechanic isn’t likely to have. Even more, improper resurfacing can actually do more damage than not resurfacing the part at all. If you have any doubts or are unsure whether you have the right tools, leave it to the professionals. Rocky Mountain Driveline resurfaces flywheels…It’s a whole lot cheaper than a transmission overhaul!

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    Driveshafts 101: What You Need To Know

    Driveshafts

    All automobiles have a driveshaft. This is the piece of equipment that transfers the energy created by the energy into the force that drives the wheels. It’s actually a very simple device.

    The driveshaft looks like a simple cylinder. What it actually is is an outer tube that protects the shaft itself, which is a spinning cylinder. The frequency of the spin depends on the engine. In addition to automobiles, boats and motorcycles also have driveshafts. Some vehicles may, in fact, have more than one. It is important that the driveshaft balance be maintained.

    If your car is rear wheel drive, it will have a long drive shaft that runs the length of the car and then a differential to transfer torque to the wheels, which are connected by short half-shafts. You may sometimes hear a mechanic talk about an automobile’s ‘diff’, shortening the word to something easier to say. A front-wheel drive vehicle has two short shafts, one to each front wheel or, more commonly, a device called a ‘transaxle’, which serves the purpose of the drive shaft, transmission and differential. Obviously, this is reversed in rear-engined vehicles. There are various different arrangements, dependent on the exact configuration. Four wheel drive vehicles have a slightly different configuration again, with front and rear shafts and differentials.

    So, what do you need to know about your driveshaft? It’s a moving part and, as such, can fail. Being relatively simple, it is less likely to fail than your transmission (transaxles, of course, are as vulnerable to failure as standard transmission). The most common problem is with the balance of the shaft. An unbalanced driveshaft causes vibration and a loss of power. Race car drivers spend a lot of time worrying about balance because it can make the difference between winning and losing. For the ordinary person, making sure your driveshaft is balanced can help with both power and fuel efficiency. In some cases the universal joints attached to the shaft have to be repaired or replaced.

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