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New in
Clutch University
What's
the best way to drive my manual transmission car?
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| RAM VDS
Clutch System |
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INSTALLATION INSTRUCTIONS AND
GUIDELINES
NOTE: THESE ARE GENERAL
INSTRUCTIONS. PLEASE REFER TO YOUR INDIVIDUAL INSTRUCTION SHEETS FOR
SPECIFICS SUCH AS PRESSURE CURVES AND CORRESPONDING RING HEIGHTS.
INTRODUCTION - WHAT TO EXPECT OF YOUR VDS CLUTCH SYSTEM
In drag racing, the clutch is the traction control device coupling the engine
and transmission/driveline. The clutch system applies energy to the rear wheels
at the launch of the vehicle.
Think of the pressure plate and disc in relation to a braking system. If the
brakes are applied lightly, the vehicle is going to progressively slow down. The
harder the brakes are applied, the more likely traction will be lost and a skid
will occur. With the clutch system, the more pressure the cover assembly applies
to the clutch disc, the more likely the spin will occur. Too little pressure may
cause the clutch to slip excessively, slowing the car's ET's.
To obtain the best clutch performance, you must have enough flywheel mass to get
the vehicle moving and enough clutch pressure to accelerate the car. Too much
flywheel mass and/or clutch pressure will cause an unnecessary loss of traction
at the starting line and/or on the gear changes down the track. Conversely, too
little flywheel mass may cause the engine to 'bog' off the starting line and too
little clutch pressure could cause the clutch to slip off the line or down the
track.
INSTALLING THE CLUTCH SYSTEM
Install the flywheel and torque to 75-90 ft/lbs based on your bolt manufacturers
specs. Do not use star or lock washer on aluminum flywheels or damage will occur
to the mounting flange. Use a high-grade thread sealant such as loctite to
secure the bolts in the crank.
Maximum clamp pressure is obtained by using the factory ring height setting of
XXXX”. Begin with this pressure setting for initial testing.
Install the clutch disc, sprung side facing the transmission, and the pressure
plate. Torque cover nuts to 35-40 lbs.
MAINTAINING CLUTCH PRESSURE USING THE VDS FUNCTION
The static load of the clutch is maintained by varying the ring height (A) of
the pressure plate. This is accomplished by adding or removing shims from the
clutch-mounting studs attached to the flywheel. Adding more shims will increase
the ring height measurement, and DECREASE the static pressure load. Removing
shims will decrease the ring height measurement, and INCREASE the static
pressure load.
To accurately measure the ring height, use a set of dial calipers. You will use
the depth-checking probe of the caliper to check the ring height. In order to
check the ring height, the pressure plate must be bolted down to torque specs of
35ft/lbs. to the flywheel with the disc in place. Insert the probe end of the
caliper through the ring hole (fig. A) and measure straight down to the pressure
ring. The measurement you read on the dial caliper is the current ring height.
To adjust the ring height, shims may be added or removed from the pressure plate
mounting studs. Each shim is approximately .010 inch, and adding or removing one
shim will change the ring height by the same .010 inch amount. Use the chart
below to determine your percentage of maximum pressure at the measured height.
(Make sure your calipers are set at 'zero' before measuring.)
Once the proper quantity of shims is determined, the assembly should be bolted
together one more time and the ring height double-checked. The chart below
displays the percentage of change in pressure based on ring height measurements.
CARE AND MAINTENANCE OF YOUR RAM VDS CLUTCH SYSTEM
Proper maintenance of your new clutch system is critical to consistent
performance. The more you 'work' or slip the clutch on a run, the fewer number
of runs you will be able to make before maintaining the unit. Where a vehicle
using the maximum clamp load may be able to complete X runs before removal, a
unit set up at 75% or less clamp load may require maintenance at XX runs.
Ultimately, how the clutch performs in your vehicle will determine this time
interval.
When the clutch is removed, it should be inspected for signs of warpage of the
friction surfaces on the pressure plate and flywheel by checking them with a
straight edge. If these components are not badly scored or burned, you may be
able to simply block sand them with a 40-60 grit sandpaper to remove the wear
marks on the friction surfaces. The disc should be inspected for glazing and
general wear. The compresses thickness of a new disc is .325"-.330".
This disc can be safely run down to a thickness of .280"-.290",
provided you can achieve the correct ring height setting. If the disc is
severely smeared or worn, replace it.
PRESSURE RING REPLACEMENT
If your pressure plate is severely burned or warped, it may be necessary to
replace the pressure ring. The VDS system makes this easy by allowing you to
replace the plate yourself. Loosen the three retaining nuts holding the pressure
ring to the cover straps, remove the countersunk bolts, and lift the plate out
of the cover.
When installing the new plate, be sure to align the flat spot milled on the
pressure ring with the ring height hole in the cover. Failure to do this will
make for incorrect ring height measurements and corresponding static pressures.
TUNING
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