Ram Clutches Catalogs
Click on the links above(Coming soon) to view entire selection of Ram Clutches, shopHEMI.com caries them all. Below is a basic clutch guide with terms and descriptions, that may be useful when selecting a Ram Clutch kit for your HEMI car or truck.What is a Clutch?
A clutch is the device that couples the engine to the drivetrain. It is designed so that it can be positively disengaged by depressing the clutch pedal. This disconnects the engine and drivetrain. Releasing the clutch pedal engages the clutch, connecting the engine and drive-train. There are several different types of clutches depending on the application or use of the vehicle.Using Your Clutch
When the clutch couples the engine to the drivetrain, it is transmitting the power of the engine to the drivetrain. In a street or a race application, the smoother the clutch applies the power to the driveline, the better the vehicle will perform. Think of your clutch system in terms of the braking system. If you lightly apply the brakes in stopping, the vehicle will stop in a smooth manner. If you stab the brake pedal, the brakes are likely to lock up and a skid will occur. The same principle applies to the clutch. If the clutch is engaged with too much pressure, the tires are likely to spin. When the pressure of the clutch is controlled, the clutch is able to apply the torque of the engine smoothly to the drivetrain without excessive tire spin. Just like your brake system, over time the friction components of the clutch system will wear. The more you use the brakes, the faster they wear. The more the clutch is slipped to provide smooth engagement, the faster it will wear.Clutch System Components
- PRESSURE PLATE – This is the pressure mechanism that clamps the disc to the flywheel to get the vehicle moving. Pressing in the pedal relieves the pressure from the clutch disc to disengage the engine from the drivetrain for shifting or stopping.
- CLUTCH DISC – The clutch disc is a flat plate with friction materials on both sides. As the pressure plate is engaged (pedal let out), the clutch disc is clamped to the flywheel. When the pressure plate is disengaged, (pedal pushed in) the clutch disc is unclamped. The disc is connected to the input shaft of the transmission by the splined hub, causing the input shaft to turn when the clutch is engaged, thus causing the vehicle to move.
- FLYWHEEL – The flywheel is an inertia device that is bolted to the engine crankshaft. It has several functions including carrying the ring gear the starter uses to crank the engine, storing energy to get the vehicle moving from a standing stop, and providing the friction surface for the clutch disc to be clamped to.
- RELEASE BEARING – The release bearing is the actuating device that engages and disengages the pressure plate. When the clutch pedal is depressed, the release bearing applies pressure to the fingers of the pressure plate to disengage the drivetrain. When the clutch pedal is released, the release bearing retracts and allows the pressure plate to apply pressure to clamp the disc against the flywheel.
- RELEASE FORK - The release fork holds the release bearing, and pivots on a ball stud as the pedal is pressed in or let out. Pushing in the pedal pivots the fork towards the pressure plate and forces the release bearing against the clutch fingers, pressing them in to disengage the clutch.
- PILOT BUSHING - The pilot bushing or bearing installs in the end of the crankshaft. When the transmission is installed, the input shaft tip inserts into the pilot bushing, which supports the input in the back of the crankshaft.
The pressure plate applies pressure to the clutch disc to clamp it against the flywheel and engage the clutch. Pressure may be generated by spring (static) pressure or centrifugal pressure. Static pressure is constant, meaning that whether the engine is turned off or spinning 7000 RPM, the pressure never changes. Centrifugal pressure is not constant. It is a function of engine RPM. Centrifugal pressure is generated by the clutch levers and increases to the square of the engine RPM. It is less pronounced at lower engine speeds but very effective in the higher RPM range.Diaphragm Pressure Plates
The diaphragm pressure plate utilizes a Bellville or conical spring to apply pressure to the pressure ring. This type of pressure plate has multiple fingers that the release bearing presses against to disengage the clutch. Diaphragm clutches rely completely on static pressure which is unaffected by engine RPM.The Belleville spring allows the pressure plate to be released and engaged with a relatively light pedal effort compared with coil spring clutches. This design is used almost exclusively in late model vehicles that have hydraulic or cable release mechanisms, due to the lighter effort required to engage and disengage the pressure plate.The diaphragm clutch is excellent for use in street and heavy duty street applications where drivability and pedal effort are a major concern for the user.Borg & Beck Pressure Plates
The Borg & Beck pressure plate uses three levers to engage and disengage the clutch disc. It is a coil spring design, where the pressure of the clutch is applied to the disc using coil springs similar to a valve spring. By combining these springs at a specific installed height, different pressures can be attained for the pressure plate. Borg & Beck clutches rely completely on static pressure which is unaffected by engine RPM.Borg & Beck pressure plates are found in GM, Chrysler, and AMC early model applications with mechanical linkage. Borg & Beck clutches and can be identified by looking at the width of the clutch fingers, which is about one inch. The coil spring design by nature will require more pedal effort to engage and disengage the clutch. Borg and Beck clutches are best suited to street and heavy duty street applications for older muscle cars and trucks.Long Style Clutches
Long style pressure plates are the Ford version of a three lever, coil spring pressure plate. The Long Style is the most popular type of pressure plate for drag racing applications. It's design is the basis for today’s professional drag racing clutches.The inherent advantage of Long Style pressure plates is their ability to apply centrifugal clamping pressure. As engine RPM increases, the levers in the plate pivot against the cover and apply additional clamp load to the clutch disc. This is true in both counterweighted lever Long Style pressure plates and also non-counterweighted designs. (Counterweighted levers have provision for installation of weights to the backside of the levers to further increase the centrifugal clamp effect.)The The Long Style pressure plate is best utilized with mechanical release linkages. Long Style clutches were prevalent in early Ford muscle cars and trucks.Some Long Style clutches feature adjustable static pressure. By turning an allen screw located on top of the spring, the pressure can be increased.Clutch Disc Construction
There are two types of clutch disc construction - solid hub and spring dampened hub. Solid hub discs have the splined hub riveted directly to the disc carrier plate (the circular metal plate that carries the friction material). This construction is typical of all out racing discs.Sprung, or dampened hub discs, do not have the splined hub attached directly to the carrier plate. The hub floats in a spring loaded assembly on the carrier. When the hub is loaded as when the clutch is engaged, the springs help absorb the load rather than transfer it directly to the carrier plate. This arrangement allows shock spikes from aggressive engagement to be dampened out to avoid possible damage to the drivetrain. This type of construction is used in factory replacement discs. Performance discs feature stronger damper springs to absorb higher loads. Most RAM performance discs are equipped with RAM poly-coil springs, which are encapsulated in urethane providing a substantial increase in the spring rate over stock springs. The stronger spring prevents over travel of the hub and subsequent damage to the disc.Selecting the correct disc construction is simple. Stock applications use the dampened hub. From there, as loads increase, the rigidity of the hub should increase right up to solid hubs used for all out racing.Friction Materials
As performance requirements increase, it is necessary to step up the friction characteristics and durability of the clutch facing materials. We will review the full range of friction materials and their features.
- ORGANIC - Organic material is common to all stock clutch discs, and offers the best drivability but has limitations as operating temperatures rise. Under high loads accompanied by slippage, they fade because their coefficient of friction drops off. In addition, at high RPM and high temperature they tend to fail structurally.
- RAM 300 series discs use organic facing material that is bonded to a steel backing plate that increases heat dissipation and provides excellent structural strength that precludes disintegration at high RPM. This structural improvement does not compromise the excellent drivability of 300 series discs.
- KEVLAR COMPOSITES - Kevlar material offers a higher coefficient of friction than organic material, but with some loss in drivability. As the coefficient of friction goes up in the disc material, so will the aggressiveness of the material on engagement. This means that some chatter can be expected with this material in low gear and reverse. Kevlar is compatibile with stock flywheels and pressure plates, making it a good upgrade choice for later model vehicles. We do not recommend Kevlar for competition applications.
- BRONZE METALLIC - Bronze metallic (paddle discs) is the most aggressive materials in terms of engagement. It offers extended life using reduced static pressures, and a quick, clean engagement. Bronze metallic is aggressive on the flywheel surface and should be used only with steel or nodular iron friction surfaces. On the street, this material will cause chatter on engagement.
- SINTERED IRON - Sintered iron is well known for its ability to withstand some slippage and not loose its coefficient of friction. It is the material choice for high horsepower clutch applications for drag racing and truck pulling. A street version of the sintered iron disc is the RAM 900 series, which utilizes a sprung hub. These discs should be used only with RAM steel or aluminum flywheels or excessive wear to the friction surface will occur. A key feature of the competition sintered iron material is that it is maintainable. If the clutch is slipped excessively, the disc can be resurfaced and reused.
Operating a Manual Transmission
Driving a manual performance car can be a challenge if the proper elements do not come together. Proper gearing in the transmission and rear end, matching flywheel weight, and driving style are essential. Extreme street cars will sacrifice some driveability to get the necessary holding capacity in a clutch system, and still work effectively at the race track.Several factors affect the life and durability of the clutch system. The key word is load; specifically the higher the load on the clutch the more likely it is to slip.Chassis Dynos
Most people wouldn't think it, but the chassis dyno provides the single largest load you can place on your clutch system. There is no tire slip during the run and any lugging the engine at all can cause the clutch to slip. Your dyno time is more strenuous on your clutch system than actual passes at the drag strip.Drag Strip
Here are a few suggestions for the drag strip that can greatly improve the life of your clutch system. On the burnout make sure the tires are wet but not in the water, and as the tires start to grab the pavement push the clutch in. Do not attempt to extend the burnout toward the tree. The point that the tires hook puts a heavy load on the clutch, especially in 3rd or 4th gear. Trying to drive on out will place a tremendous and unnecessary load on the clutch system.While it sounds so simple, make sure the car is in first gear before you leave the starting line. Leaving the line in 3rd gear will pretty much wipe out your clutch system. Checking up to be sure your in 1st gear prior to pre-staging can save your clutch system. 'Hot lapping' can put severe heat into the clutch. Some events require this, but try to avoid back to back consecutive runs without allowing the clutch time to cool down. Focus on making quality runs and not quantity.Hard Starts & Downshifting
Hard launches on the street are usually not as hard on the clutch since the tires tend to spin, but still put a good load on the clutch. If you run a sticky tire that will bite on the street, then it is no different than at the race track, the clutch will be loaded harder and wear is going to be accelerated.Many drivers misunderstand downshifting. The clutch is not a brake. However, if you shift to a lower gear and let the pedal back out with no throttle, the resulting 'surge' you feel is loading the clutch braking the engine. This is extremely harmful to your clutch system and will greatly reduce its service life. Under this condition the clutch center hub is loaded very hard and can cause the drive center to break in extreme situations. The straps that retain the pressure ring on diaphragm clutches may also buckle under this severe strain.The proper method is to 'match' engine speeds on a downshift. To do this, add some throttle and raise the rpm's as you engage the clutch so the engine and driveline speeds are closer matched when the clutch engages. Avoid sharp downshifting. Match engine speed when it is appropriate to achieve optimum service life. The result is a smoother transition, which does not load the clutch and disc so hard. If you watch road racers using a clutch, you will see they do this all the time. With some practice you will be able to make the downshift without even feeling it.How Long Should a Clutch Last?
It is nearly impossible to predict clutch life as everything including the driver will affect the service life. In a street vehicle that is raced often, track passes add up quickly. This will reduce the life of your clutch system for street use. To optimize service life it is a good idea to over clutch an application. Using too weak of clutch system will lead to premature clutch failure, whereas, over clutching your vehicle will allow to handle additional load you may want to place on your clutch system in the future. In full race vehicles it is common to see between 75 and 150 passes on a clutch system between rebuilds. An optimally tuned system might only get 30-40 passes between major servicing. Remember, to optimize your clutch system for the fastest run, the clutch operates on the very edge of slippage.Street Driving an Aggressive Clutch System
While not easy, it is possible to master smooth operation on the street with an aggressive clutch setup. The foundation is efficient rear and low gearing and adequate flywheel weight so that the minimal amount of slippage is required on takeoff to make a smooth transition. Experiment with different RPM levels and the amount of 'pedal' you give the clutch on engagement. Get it engaged as quickly as possible to avoid excessive wear.