Tips on inspecting the multi-disc oval track racing clutch

Tips on inspecting the multi-disc oval track racing clutch

By Jim Mozart, Photos by Moore Good Ink: Commonly, multi-disc racing clutches vary from 4.25in to 7.25in. Racers often favor the smallest diameter clutches available because they believe an advantage can be found in its lighter rotating mass. Yet experience demonstrates that smallness rarely makes an appreciable difference—except in diminishing the clutch’s durability. Some clutch makers fervently believe that the slightly larger diameter clutch with thicker friction materials can withstand much more abuse than its smaller counterpart. Constant racing starts, for example, on a small unit can result in severe wear. Such doctrine is firmly held by Ram, the Columbia, SC long-time racing clutch maker. Monitoring the condition of the multi-plate racing clutch is an essential yet simple operation. When replacing the friction discs during servicing, renew the full pack and ensure the pads are in vertical alignment to apply the clamp load evenly down though the pack. Also, oils and grease cause slippage and damage to clutch components. Always check the oil pan and main seals. Here is how Ram checks their 6.25in Assault Weapon.  Source RAM Clutches 201 Business Park Blvd. Columbia, SC 29203 Telephone (803) 788-6034...
Flatness: How gas ports and flat ring grooves succeed with lightweight racing rings

Flatness: How gas ports and flat ring grooves succeed with lightweight racing rings

By Sam Logan: A great many modern drag racing engines are equipped with lightweight piston rings. These rings require combustion pressures delivered through gas ports to achieve complete ring seal. Horizontal gas ports are used in oval track racing pistons to avoid carbon ingress while vertical gas ports are the preserve of the drag racing engine. In either case, the gas ports direct pressure downward and behind the ring to seal the ring to the bottom surface of the ring groove and also to force it outward and seal its thin outer perimeter face to the cylinder wall. To achieve this, it is essential to decide the correct diameter of gas port and to allocate the correct number of gas ports and to equally space them around the piston. Harnessing gas volume and evenness of pressure to a flat ring groove and flat piston ring accomplishes cylinder seal. “So, the number of gas ports, times their diameter creates a volume number,” explains Gibtec’s Robbie Giebas. “On smaller pistons we reduce the diameter of the gas ports and increase their number. To prevent flutter, pressure must be evenly dispersed around the ring. “Also the advent of flatter rings and ring grooves means you can run tighter ring-to-groove tolerances—often as close as 0.0004in to 0.0005in. A decade ago tolerances were significantly greater, probably twice this amount.” Having functional gas ports and perfectly flat rings and ring grooves—with tolerances of 0.00005in to 0.0001in—promote effective ring sealing. But also this sequence of events relies on the fact that every action is the product of a previous action.   Gibtec Pistons (PRI Booth #501)...
Custom Pistons

Custom Pistons

Any experienced racing man knows that the components of a successful race car should be compatible—all working in concert. But this formula is never more critical than with engine builders. Professional race engine builders are profoundly aware of how engine parts affect one another and have to be developed as an efficient group. For them, the key to successful race engine building lies in maximizing a power plant’s performance by creating a combination of components that complement each other. In most cases, developing complimentary components requires modifying readily available parts or creating custom ones. Off-the-shelf engine components are often acceptable to builders seeking modest performance gains, but they are hopelessly inadequate when summoned to generate significant power. Click here to read the full article as published in Australia’s Street Ford...
First power steering tester reveals more than you might wish to know

First power steering tester reveals more than you might wish to know

By Titus Bloom It’s common knowledge that the entry of one foreign particle in the power steering system can damage the pump. Even if the pump survives the ordeal the refuse will momentarily zap engine power each time it passes through the rotor housing easily consuming 10hp, according to KRC’s new and unique steering pump tester. “This custom-made machine records horsepower, flow and pressure and checks the data every 1,000rpm from 1,000 to 10,000rpm,” says KRC chief Ken Roper. “It even produces graphs and retrieves information we didn’t request! But perhaps its most valuable attribute is that it reveals information we never knew before, like power consumption under load, and it validates everything.” Though the average Sportsman race team may not be too concerned if a steering pump consumes 3hp or 6hp, others like NASCAR teams cannot afford any power-robbing deficiencies and would eagerly welcome even a ½ hp advantage. What caused recent power steering system failures? Recently new short track oval race chassis have suffered a spate of power steering failures. The troubles were traced to the pressure relief valve (spool valve) in the power steering pump. Apparently, galling had caused it to jam in the bore. “For years,” says Roper, “production road car pumps have been modified and offered for use on new race car chassis. As you’d expect, they are inexpensive and most of the time they perform adequately. But they have always been a marginal proposition for race cars as most of their internals are uncoated. Without exception, any friction in the pressure relief valve area slows steering response.” To maintain the valve’s proper function...
Of five major threats to a clutch system, what would you consider the most forbidding?

Of five major threats to a clutch system, what would you consider the most forbidding?

Archie Bosman: As you sit quietly reading these lines, a whirl of activity is taking place in the bell housing. Let’s imagine for a moment the clutch assembly could express its greatest anxiety, what might it be? Might it be the use of excessively harsh friction compounds on the clutch discs or inadequate clamping forces causing slippage? Perhaps, extremely sticky tires are the main threat? Enumerating the cardinal sins: Apparently ‘no’, according to Ram Clutches none of these represent its greatest fear…its principal concern would be mass—that is the weight of the car carried into motion by the clutch. A heavier vehicle imposes a greater load on the clutch system than a lighter one. Further perils include poor gearing, improper flywheel mass and, indeed, sticky tires. A high performance car with an inadvisably high rear-gear requires more manipulating of the clutch pedal to prevent it from slipping than one with a lower gear. A higher first gear (lower numerically) is also problematic as it, too, imposes a greater load on takeoff and, furthermore, can be detrimental to the clutch even when it is fully engaged. Linked closely with high first-gear ratio deficiencies is the flywheel. The purpose of the flywheel is to create inertia, which refers to preserving a state of uniform motion that helps to get the car moving. A heavier flywheel generates more inertia and thus makes it easier to accelerate from standstill. It also reduces clutch slipping on takeoff. On the other hand, with a properly geared vehicle, that is one with an appropriately low gear that invites the use of a light flywheel, it will...
Putting the Squeeze on

Putting the Squeeze on

The Importance of Compression Ratios and How to Measure Them: Since race pistons in domestic V-8 engines move up and down in excess of 100 times per second, replacing them is a normal part of a racer’s routine. NHRA Top Fuel and Funny car teams replace them after every race pass and every second qualifying pass. Pro Stock teams replace them after every 40 passes approximately, and weekend warriors replace them every 12 to 18 months, sooner if their engines are nitrous-assisted. Read the complete story as it appeared in Maximum Drive magazine’s 2015 Sept/Oct...
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