> News
Centax Clutch Adjustment (29/03/2004)
- By:
- Glenn M. Cauley
When building a Centax clutch, it is very important to shim it properly for proper operation and long life. An improperly built Centax clutch may result in excessive slip, too early or too late engagement, engine bogging, and premature thrustbearing failure.
Borrowing from the advise of Julius Kolff (Team Serpent), he says that thrustbearing failure is almost every time due to the following:
* Non-regular greasing
The thrustbearing should be re-greased once every 30 minutes at least or more often if you run on dirty tracks or your car sees grass often.
Use a thick, sticky grease like graphite grease.
* Improper installation
The thrustbearing has two rings… one with a large inner diameter, and one with a small inner diameter. The ring with large inner diameter MUST go towards the flywheel.
* Bad setup of end play
The clutch gap (0.4~0.7mm) does not have a lot to do with this, but the end play of the clutch housing DOES have a lot to do with this. After everything is assembled, the clutch housing should have minimal end play (0.05~0.15mm) (movement of the clutch housing along the crankshaft).
* Clutch weight modification
Modifying the clutch weights can cause problems, especially if the weights are not all exactly the same. This leads to improper engagement and wobbling of the clutch shoe, and eventually bearing failure.
You shim the Centax clutch in two different ways. There are shims to adjust the clutch gap, and shims to adjust the end play. Each of these is adjusted independently of the other.
This article describes how to shim a Serpent Centax II or III clutch. The original Centax clutch is adjusted in a different manner.
Clutch Gap
Clutch gap is the amount that the clutch shoe moves before it contacts the clutch housing; this affects the WAY that the clutch engages more than WHEN it engages.
Clutch gap is the FIRST thing you should adjust on the Centax clutch, and is done with the bearings NOT installed. For more information, refer to your Serpent car or clutch manual or the appropriate i-manual at www.myTSN.com.
When building the Centax clutch, you must first place a large diameter shim (typically 0.5mm thick) behind the flywheel cone. This is explained in the instructions.
In the images shown here, clutch gap is the difference between values A and B. You adjust clutch gap by placing shims (medium size) on the thrustbearing holder, in front of the thrustbearing assembly.
When properly shimmed, there should be approximately 0.4~0.7mm of clutch gap.
Larger clutch gap:
Causes a harder, more sudden engagement. Better on a wider track or a track with high traction. A larger clutch gap puts excess stress on the clutch components, especially the thrustbearing.
Smaller clutch gap:
Gives a softer engagement, and smoother acceleration. Better on a tighter track or a track with low traction. A smaller clutch gap may result in engine bogging and premature clutch shoe wear.
If you change the clutch gap to a larger or smaller value (by adjusting the shimming), you must compensate by adjusting the tension on the main clutch tension spring.
End Play
Clutch housing end play is the amount that the clutch housing moves along the crankshaft. End play is the LAST thing you should adjust on the Centax clutch, and this is done with the clutch fully assembled with all bearings. For more information, refer to your Serpent car manual or the appropriate i-manual at www.myTSN.com.
You adjust end play by placing shims (small size) in front of the clutchnut that holds the flywheel to the crankshaft.
When properly shimmed, there should be minimal end play (0.05~0.15mm).
Too much endplay will cause more wear on the thrustbearing. When the clutch is not engaged, the plates of the thrustbearing are further apart. When the clutch engages, the thrustbearing plates travel further before they are 'sandwiched' together... by traveling further more force is built up so when the clutch engages, the thrustbearing has more force applied to it. This causes premature thrustbearing wear and leads to failure.
RcTek Website
The RcTek website contains some very good information about Centax clutches, as well as the effects of their mis-adjustment. See the following sites:
http://www.rctek.com/info_centax_clutch.html
http://www.rctek.com/info_centax_clutch_2.html
http://www.rctek.com/info_centax_clutch_3.html
http://www.rctek.com/info_bearings_thrust_race.html
CLUTCH GAP
END PLAY
News