Tilton 7.25,5.5 User Manual
INSTALLATION INSTRUCTIONS
5.5" (140 mm) and 7.25" (185 mm) Carbon Clutches
Tilton Engineering invented the carbon clutch and patented the drive sys tem in the mid 80’s.
Tilton also holds a patent on its pressure ring locating system, which is unique to Tilton carbon
clutches. Tilton’s carbon clutch was the rst ever to win a Formula One Grand Prix (Ayrton
Senna’s Lotus-Honda at the 1987 US Grand Prix in Detroit). Since that time Tilton has produced
thousands of carbon clutches, with multiple victories in races worldwide, from the
24 Hours of Le Mans to the Baja 1000.
The patented Tilton Carbon (C/C) clutch provides the best combination of light weight, low
moment-of-inertia, smooth engagement, and durability. It is also an excellent value when
properly maintained. Every Tilton carbon clutch follows the same rigorous build, test and
docu mentation process. Each clutch is tested for clamp load, torque capacity, and release
characteristics and every component within an individual clutch is recorded in our database.
Tilton maintains a le on every C/C clutch they build. This le includes all of the original build
and testing information and all service/rebuild history performed by Tilton. Save the build sheet
provided with the clutch. It includes critical maintenance information.
INSTALLATION
1. Proper alignment of the input shaft with the crankshaft is critical for long clutch life. Use the
following procedure if your gearbox uses a separate bell housing. Bolt the housing onto the
engine. Place a magnetic base dial indicator on the end of the crankshaft. Sweep the trans-
mission register diameter on the inside of the back of the bell housing.
Total Indicated Runout (TIR) must not exceed .010". Sweep the back face of the bell housing
at a 6" (152 mm) diameter. The TIR in this position must not exceed .010".
2. Install a new pilot bearing. A prematurely worn pilot bearing indicates a bent input shaft or
an input shaft that is otherwise not properly aligned.
Misalignment can be caused statically (see Step 1) or dynamically, like when the weight of
an unsupported gearbox causes a weak bell housing to ex under racing conditions.
3. The drive hub should slide smoothly on the input shaft. An application of
anti-seize compound is acceptable if very little is used.
4. The drive hub can usually be installed in one of two directions. The clutch will work either
way as long as the hub clears the ywheel bolts and the hub’s splines fully engage the input
shaft splines. The hub will move towards the ywheel as the clutch wears.
5. With the ywheel bolted to the crankshaft, place the clutch on the ywheel. Using an align-
ment tool or spare input shaft, align the hub. Tighten the bolts in a star pattern turning each
one less than one full revolution at a time. 5/16" and 8mm bolts should be torqued to
18 lb -ft with thread locking compound. Threaded aluminum ywheels may require less
torque to prevent stripping the threads. Once the bolts have been tightened, the diaphragm
spring ngers should appear nearly at. If the ngers appear to be inverted, you may not
have the proper pressure plate installed in the clutch or the pressure plate may not be
seated in the top oater plate.
6. Set the bearing clearance. If you are using a Tilton hydraulic release bearing the recom-
mended clearance is .170"–.230" (4.3 mm–5.8 mm). Depending on your particular clutch
conguration, the bearing clearance loss will be four to ve times the amount of the clutch
wear. You need to have enough bearing clearance to allow the full wear range of the clutch.
7. When installing the gearbox, do not allow its weight to be supported by the clutch.
8. The clutch diaphragm spring must not be stroked beyond the maximum amount listed in
Tab le 1. A pedal stop may be required to prevent damaging the clutch (Diagram 1).
Overstroking the clutch during the bleeding process can be prevented by applying a light
force to the pedal and opening the bleed screw before stroking the pedal. Close bleed
screw before pedal is returned to it’s original position. Master cylinder sizing recommenda-
tions are also listed in Tab le 1.
Realease bearing contact diameter
(radius face).
Maximum stroke of clutch
diaphram spring.
Recommended master cylinder
bore* when using Tilton hydraulic
release bearing.
Theoretical maximum master
cylinder stroke** with
recommended master cylinder.
**Assumes .040 " cut-o port travel.
...Tilton’s carbon clutch
was the rst ever to win a
Formula One Grand Prix
(Ayrton Senna’s Lotus-
Honda at the 1987 US
Grand Prix in Detroit).
Carbon Cl utch size: 5.5" 7. 25"
38 mm 44 mm
.200"
(5.1m m)
.840"
(21.3mm)
* Except: spri nt, midget, & silver crown pac kage
98 -13 00
Table 1
.250"
6.4 mm)
5/8" 3/4"
.730"
(18. 5 mm)
FIREWALL
Diagram 1
Diagram 2
Diagram 3
5.5" and 7.25"
9. Set the pedal stop. Tab le 1 lists a theoretical maximum master cylinder stroke. There is
another more preferred method. Place the car on jack stands. With the engine o, and the
transmission in rst gear, slowly depress the clutch pedal while having another person trying
to rotate a drive wheel or driveshaft until the point where the clutch releases. Measured at
the footpad, give the pedal an additional 1/4" (6 mm) of travel and set the pedal stop there
(Diagram 1).
MAINTENANCE
1. Thicker replacement pressure plates, in .010" (.25mm) increments, are available to compen-
sate for clutch wear (5.5" clutch: Table 2, 7.25" clutch: Tabl e 3). Even though the clutch is
usually capable of of withstanding .040" (1.02mm) or more of wear before clutch slippage
will occur, it is recommended that pressure plates be changed at .020" (. 51mm) increments
to keep clutch near peak clamp load and torque capacity. If maintaining consistent pedal
action for the driver is important, it is recommended that pressure plates be changed at
.010" (.25mm) intervals. The most accurate method is to measure the thickness of the
individual plates with a micrometer (Diagram 3), not calipers, to the nearest .0005" (.01mm)
and compare them to the dimensions of the plates listed on the build sheet supplied with
the clutch. Once you determine how much total wear there is in the carbon stack, select
the appropriate pressure plate thickness to install. Do not install a pressure plate that is too
thick. Otherwise, the stack height underneath the clutch cover will be too tall and will cause
release problems and/or damage the clutch.
2. Check the clearance between drive hub ngers and the slots in the driven plates (Diagram 4).
The slots must not be more than .025" (.64 mm) wider than the drive hub’s ngers. This is best
checked with a feeler gauge. Premature wear of the slots is usually an indication of input shaf t
misalignment with respect to the crankshaft.
3. Check hub oat. With the clutch installed on the ywheel the drive hub should be able to
oat at least .010" (.25 mm) on the input shaft. Once the axial oat disappears the clutch will
start to slip.
4. Check for signs of excessive heat. A blue-colored hub is a sign of high temperatures from a
clutch having been slipped excessively. High temperatures can cause the diaphragm spring
to lose clamp load. Send the assembly back to Tilton for inspection if damage is suspected.
5. Increased wear at the release bearing contact area is a sign of a heavy left foot or a bearing
that needs to be replaced. Many clutches have been lost to the failure of an inexpensive
bearing that was run one race too many.
Measure at least three dierent places in the
middle of the wear area, and take the average
of all measurements.
Diagram 4
Diagram 5
Cover Assembly
Pressure Ring/Plate
First Floater [^]
First Drive Plate [X]
Second Floater [^^]
Drive Hub
Second Drive Plate [XX]
Third Floater [
^^^
]
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