Repair And Fix it

The exhaust pipes on your car, truck or motorcycle carry the gasses expelled from the engine during the combustion process safely to the rear of the vehicle. This is usually accomplished with pieces of steel tubing that are suspended to the underside of the vehicle. Since the exhaust usually has to wind over, under or around the vehicle undercarriage to get to the rearmost part of the vehicle, it is manufactured in several different pieces and either welded, bolted or clamped together to form a continuous flow. Each manufacturer may have different names for the various exhaust pieces, but may include the header pipe, front pipe, exhaust pipe, catalytic converter, muffler, resonator and tailpipe.

Exhaust Manifold

Converting the exhaust from each cylinder on your engine to a single outlet is usually accomplished with an exhaust manifold. An exhaust manifold is usually constructed of cast iron and is bolted to the cylinder head. V-type or boxer engines have two banks of cylinders -- one on each side of the block. In these cases, there should be an exhaust manifold bolted to each cylinder head. The exhaust manifold is usually not considered part of the exhaust system, but it gives the exhaust pipe a place to attach to.

Header Pipe

When referring to exhaust pipes, the header pipe sometimes refers to the part of the exhaust system that attaches directly to the exhaust manifold of the engine. If your vehicle is a single cylinder motorcycle or a vehicle that has an inline engine, a single header pipe would connect directly to the exhaust manifold or engine. Header pipes used on V-type or boxer engines can sometimes be referred to as a Y pipe, as it connects to both sides of the engine and comes together to form one pipe. Some vehicles use a dual exhaust system. These types of vehicles may a have a separate, single header pipe for each exhaust header.

Headers

Some vehicles may use factory or aftermarket exhaust headers in place of a cast iron exhaust manifold and header pipe. Headers are usually constructed of several pipes welded together and take the place of both the exhaust manifold and the header pipe. Headers are usually tuned, meaning the length of the tube that attaches to each exhaust port on the engine is engineered in such a way to extract maximum power and efficiency from the engine. Headers are factory-installed on some performance engines, but are usually an aftermarket accessory that is owner-installed.

Front Pipe

Depending on the manufacturer, the front pipe on an exhaust system can refer to pipe that bolts to the engine -- the header pipe -- or the pipe that connects the header pipe to the remainder of the exhaust system. The exhaust system on vehicles that have transverse-mounted engines may need to compensate for the back-and-forth rocking motion of the engine when accelerating or decelerating. Whereas the header pipe may be a solid, fixed pipe, a flexible pipe -- sometimes referred to as the front pipe -- connects the header pipe to the rear of the exhaust system. On some vehicles, the exhaust pipe that connects to the rear of the flexible pipe may be referred to as the front pipe.

The Dana 44 and the Dana 60 are both automotive axles manufactured by the Dana Corporation. Axles are a standard component of any automobile. Axles used in a live-axle suspension system work to transmit driving torque to the wheel and to maintain the position of the wheels relative to each other.

Dana Axles

The Dana Corporation was incorporated in 1916 as Spicer Manufacturing Company. In the 1960s, Dana became one of the worlds largest independent suppliers of automotive components. It has manufactured axles for more than 50 years. The axles can be divided into three categories: light vehicle, commercial and off-highway. The company offers front and rear axles for cars and trucks, as well as four-wheel drive axles. Two of the companys most popular axles are the Dana 44 and the Dana 60.

The Dana 44

This axle has been used by automobile manufacturers and in the automotive aftermarket. It was first manufactured in the 1940s and is still manufactured today in both front and rear axle models. It has been manufactured as both an independent suspension and beam axle for both front and rear setups.

More than a dozen auto manufacturers have had vehicles with Dana 44 axles, including Jeep, which today manufactures four-wheel drive vehicles with both front and rear Dana 44 axles. The axle has a gross weight rating up to 3,500 pounds and is a semi-floating type in that it has one bearing at the end of the axle shaft that carries the vehicles weight on the axle and that also allows the axle to rotate.

The Dana 44 independent rear suspension, or IRS, axle has been used in Chevrolet Corvettes and Dodge Vipers. It is referred to as the Dana 44 ICA or Dana 44 IRS. Some of the 1985 to 1996 Corvette C4s had this axle, and the Dodge Viper has always had a Dana 44 IRS setup.

The Dana 60

These axles are used primarily in OEM, or original equipment manufacturer, heavy-duty pickup applications by Ford, Dodge, Chrysler and Chevrolet. There are four-wheel drive front steering versions and front and rear axle versions. In fact, Ford still uses the front axle Dana 60. The Dana 60 rear axle generally weighs 500 pounds and is manufactured in both semi-float and full-float versions. The semi-float axles were often rated up to 5,500 pounds and the full-float versions were rated up to 6,500 pounds.

The Dana 60 is manufactured in both Ball join and Kingpin variations, "standard" and "reverse cut" rotation variations and as limited-slip and open variations. The housing material is ductile iron. The Dana 60 axles used by GM and Ford have locking hubs. Dana 60 axles also have a good deal of third-party/aftermarket support that includes many upgrades. It is available with stronger axle shafts, ball joints and universal joints, along with a wide selection of traction control devices such as limited slip differentials and locking differentials.

Primary Differences Between the Dana 44 and the Dana 60

Dana 44 front axles have been used primarily in lighter vehicles, including Jeeps. They have also been used in Dodge trucks, Ford trucks, the Nissan Titan and the Isuzu Rodeo. Dana 44 axles are know for utilizing locking hubs or a center axle disconnect system. In comparison, the Dana 60 front axle has been used principally in vehicles such as Dodge 1-ton pickups and Ford F250, 350 and 450 pickups. However, the rear axle Dana 60 was used in Dodge Coronets and Chargers, Plymouth Belvedere and Road Runners, Ford 3/4-ton trucks and Chevrolet and GMX 3/4- and 1-ton pickups and vans. Additionally, the Dana 60 has been sold in large numbers as an aftermarket or third-party product.

Propeller size is referenced as to diameter and pitch. The diameter of a propeller is twice the distance from the hub to the tip of a blade. The larger the diameter, the more power necessary to turn the prop. Most small recreational boats are limited to a specific diameter because of engine design, weight and hull design.

Pitch and Effects of Pitch

Pitch is the main concern from a performance perspective. Pitch is defined as the distance a prop travels through the water in inches per one single revolution. A good illustration of pitch can be made with a wood screw. A wood screw with its threads far apart, or coarse threads, threads quickly into the wood but takes considerable effort to turn the screw. Conversely, a screw with the threads closer together or fine threads takes many more turns to install but with much less effort.

The propellers pitch has a direct effect on the performance of the boat. The original prop generally is the most efficient for overall performance if the engine came with the boat. An engine replacement may need a prop evaluation. Engine horsepower and rpm, the weight of the boat, hull design and intended usage determine prop pitch.

Pitch and RPM

Outboard engines run between 5,000 and 5,500 rpm at wide-open throttle, whereas inboard or IOs run in the 4,500 too 4,800 rpm range. This is the range where maximum horsepower is made. Horsepower is a product of rpm. A 100 hp motor produces much less at low rpm. The best performance possible is achieved when the engine reaches its wide-open throttle limit rpm but does not exceed it. A prop with too low a pitch generates great acceleration but allows the engine to over-rev, which easily can cause damage. The top speed also suffers. A pitch that is too high causes the acceleration to suffer and create undue manifold pressure within the engine, which also can be damaging.

Choosing the Correct Propeller Pitch

The diameter and pitch is embossed on the propeller hub for identification. A common pitch for most small boats is in the 28- to 19-inch pitch range. If your engine rpm is too high at wide-open throttle, the pitch must be increased. Conversely, if the rpm is too low, the pitch should be decreased. One inch of pitch change is equal to 200 engine rpm. If your engine wide-open throttle rpm is 5,500 according to the tachometer or owners manual, and it currently is operating at 5,100 rpm, the rpm needs to be increased by 400. Reducing the pitch by two sizes brings the rpm up to its limit. This increases the top end speed and pulling power for skiers. The opposite is true for an engine running higher than recommended.

Considerations

If pulling skiers is the major concern, a lower pitch prop may be used as long as the rpm is monitored and kept within limits. This brings the skiers up much faster. If speed is the main concern and the boat is not heavily loaded, a higher pitch increases the speed but slows down acceleration and upper rpm. Remember that the higher the pitch, the more load on the engine.

Tips

Propellers are constructed in three types of material. Composite props are the lightest, offer some flex, and are the cheapest. They are not repairable should the prop strike anything. Aluminum props are the most common. The are heavier than composite, offer some flex, and are a little more expensive and can be repaired cheaply. Stainless steel props are the most expensive and hardest to destroy. They are very difficult to repair. Props are offered that consist of a separate hub with replaceable blades. These are perfect for pitch changes as needed or repair.