How to Choose The Right Clutch
Once you start modifying your vehicle for more power and performance, your stock clutch will eventually not have enough clamping force causing your clutch to slip. Choosing the correct performance clutch for your combination will ensure you get all that power to the rear wheels. Knowing how you use and drive your vehicle will help point us in the right direction when choosing a clutch. First, to handle more power and performance, clutch manufacturers choose different clutch disc facing materials along with various pressure plate combinations. Some clutch disc materials are more forgiving, engage smoothly while others are able to absorb more heat and live under extreme conditions but can induce chatter on everyday street use. Pressure plates ARE also available with a diaphragm, Borg & Beck, or Long style DEPENDING on the application. Diaphragm style pressure plates typically offer light pedal pressure making them very street friendly while Borg & Beck along with Long style pressure plates have increased pedal effort. Finding the proper balance is key to finding the right clutch for your application. Hays offers a variety of clutch kits to help with this choice. One main factor to consider is Drivability vs Performance. With disc choices ranging from organic to metallic to sintered iron, the type of performance and drivability desired will help us decide which material to use. If on-the-track performance is paramount, select a disc material that is aggressive like sintered iron but REALIZE that making this decision will affect how smoothly the vehicle will operate under normal driving conditions. If drivability and smoothness is whats most important, select a disc towards the organic side. Keep in mind though, under racing conditions, the life of the clutch disc will likely be reduced.
Let’s go through some of the other factors that need to be taken into account when choosing a performance clutch. Load plays a big part in determining clutch selection so let’s take a look at the most important factors affecting load.
Vehicle weight plays a big role when choosing a clutch. Many older cars are very heavy and have engines that produce high torque numbers at lower engine speeds. This creates a high load situation on the clutch that can result in a slipping/overheating clutch if the wrong clutch is selected. The heavier the vehicle, the higher the load on the clutch and the more clamp pressure needed to move the vehicle.
Horsepower and Torque
Knowing how much horsepower and torque will give you a good idea of what clutch is needed for you application. The higher the operating RPM range of an engine, the more centrifugal clamp pressure is applied by the pressure plate. High torque, low RPM applications will require higher clamp pressures while lower torque, higher RPM applications will require lighter clamp pressures.
Rear End Gearing
High rear end gearing puts heavier load on the clutch system as well. If you have ever tried to let out the clutch from a stop in second gear, you likely experienced difficulty getting the vehicle moving without ‘bogging’ the engine. This same effect occurs when too high of rear end gearing is used. This situation also requires the clutch to be slipped more on takeoff to make a smooth transition, resulting in accelerated wear to the clutch.
Tires with more traction, such as drag radials or slicks, allow the vehicle to hook up harder and are less likely to spin than street tires. When a tire spins, the load on the driveline is decreased, but when the tire hooks up, the load on the clutch is increased substantially requiring more clamp pressure.
The intended use of the vehicle when choosing a clutch is the most important consideration. A clutch designed for better performance in your street car will not work overall in terms of longevity if you drive real aggressive. Clutch kits are available for street performance to all out racing and everything in-between so be sure you choose the right clutch for your driving style.
Let’s go through the variety of clutch choices Hays can offer.
Hays Classic Clutch kits are the original Hays clutch. For clutch kits that are street friendly, smooth and reliable, look to Hays Classic line of clutches. Hays Classic Clutch kits feature an organic disc with an upgraded pressure plate for increased holding power over stock. These kits are available with a diaphragm, Borg & Beck, or Long style pressure plates depending on the application. A diaphragm style pressure plate typically offers light pedal pressure making them very street friendly while Borg & Beck along with Long style pressure plates have increased pedal effort for more clamping force. Hays classic line of clutches are designed for stock cars and trucks or ones with minor performance bolt-ons, such as headers, intake and exhaust. They’re a great choice for muscle cars!
Hays Street 450 clutch kits are an excellent performance upgrade from your stock clutch. Engines with mild modifications such as headers, intake manifold, or mild camshaft changes work well with these clutch kits. These clutch kits are designed to handle stock or mildly modified engines up to 450 horsepower. It is a great clutch where drivability is still the most important factor. It features upgraded damper springs which deliver 30% greater clamping force than a stock clutch allowing you to put more power to the ground. The organic/composite disc allows for smooth, no-chatter engagement. The disc friction material is bonded to a steel backing plate that increases heat dissipation and provides excellent structural strength for higher RPM use. For mildly modified vehicles and stock clutch replacements, the Hays Street 450 clutch kits are a great choice!
Hays Street 650 clutch kits are designed handle highly modified engines up to 650 naturally aspirated horsepower. These are true street/strip clutches for spirited high performance driving or frequent track use. The high performance disc utilized in the Street 650 has an 8-spring hub with encapsulated damper springs and a sintered metallic friction surface. This disc does a great job at dissipating heat and fighting the slippage found in organic discs. The encapsulated spring can handle 3 times the shock load versus a standard coil spring. Sintered metallic material provides a degree of slippage on vehicle launch to offer smoother engagement characteristics found in a street-style clutch.
If you visit the track often, The Hays Street 650 clutch kits are for you.
Our top of the line performance clutch is our Hays Dragon Claw Clutches. These Clutch Kits give you race clutch performance with the drivability of a street clutch. They feature lightweight construction – the Pressure plate cover is forged from 7075 T6 aircraft grade aluminum; and the matching lightweight flywheel is forged from 6061 T6 aircraft grade aluminum; The Complete dual disc assembly weighs as little as 35 lbs and single disc assembly weighs 28 lbs, making them quite a bit lighter than most stock and many aftermarket clutch setups. These can withstand the high torque produced from forced induction engines and survive extreme racing use without requiring additional pedal effort. Dual Disc kits can easily handle up to 1100 ft pounds of torque.
Utilizing a diaphragm style pressure plate in combination with a lever assist technology, the diaphragm plate offers street style pedal feel with the holding power of a race clutch. With a unique lever assist design, as rpms increase the centrifugal force swings the levers outwards multiplying the holding pressure applied to the clutch plate, this results in a clamping force that holds under extreme conditions. Dragon Claw clutch kits include matching lightweight aluminum flywheels so you're getting a complete engineered clutch package. These work great on daily driven turbo and supercharged combinations. The Dragon Claw is a great choice if you want stock pedal feel but want upgraded holding power offered with its lever assisted technology. Perfect for the street or track.
General Tips and Suggestions
When replacing a clutch always replace both the pressure plate and disc assembly, never use a new disc with a worn pressure plate.
General installation tips If oil is present on the old clutch assembly, the leak must be corrected before installing a new clutch assembly. More often times than not, it will be your rear main seal.
Be sure to check this as now would be a great time to replace it. If you're not replacing your flywheel it should be resurfaced to the original specifications, this will insure proper, trouble free clutch performance and operation. Before assembly, make sure the flywheel is clean of oil and grease. Brake cleaner works well.
Make sure and replace the throw out bearing and pilot bushing/bearing to ensure trouble free performance of your new clutch. Always use a clutch alignment tool during installation to insure correct positioning of the pressure plate assembly, disc and pilot bushing/bearing.
Torque all pressure plate and flywheel assembly bolts to manufacturers specifications using a progressive crisscross pattern.
If in doubt, you can always call our experienced staff and they will be happy to help you choose the right clutch for your needs.
Make sure you get all the power to the ground with a Hays Clutch Kits.
For more information on Hays Clutches and accessories, visit our website at HaysClutches.com
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