Armac Clutch Lightener Kit
WHAT IS IT AND WHY?
The original clutch on a Tiger Cub was not conceived with modern trials techniques in mind.
Lightening the clutch action means the clutch can be used with one finger, making the action lighter and more intuitive.
The Armac Clutch Lightener achieves this. It also has a number of side benefits:
SHORTER ROUTING:
The clutch cable on a standard Tiger Cub has a very long run, routing around the crankcase, frame and chain. Instead of this, the Armac Clutch Lightener exits the top of the crankcase, so the cable can be shorter.
SEALED MAINSHAFT EXIT:
The conversion kit covers the end of the gearbox mainshaft. This means that when the bike is on its side, the shaft exit is sealed, which stops oil leaking out.
MAINTENANCE:
The Armac Clutch Lightener has an exterior arm. So, if the cable needs to be changed, it can be done without having to remove the crankcase cover.
PRICE: £140
P&P as single item:
£6.50 Special Delivery (inc.insurance)
£5 First Class Recorded (no insurance)
This product is an original design by Armac Design, created in 2005. It is protected by Copyright and Design Rights and no part can be copied without permission.
FITTING THE KIT (also see pictures, below)
If in any doubt, please contact Duncan : 01751 417371, armac.design@virgin.net.
There is the option to send the inner and outer cases to Duncan for machining (£40 + postage)
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*Note: part numbers quoted in these instructions can be identified on the exploded diagram supplied with your kit
* Tolerances are slightly different on all engines. If an Armac Clutch Lightener component doesn’t fit on first offer, don’t force it! See sheet: TOLERANCES: supplied with the Clutch Lightener Kit.
* Instructions updated May 2011
1. REMOVE kickstart and gear lever, then outer and inner case
2. Remove gearbox mainshaft bush from inner case. Place the body of the clutch lightener in place and mark the top edge of the case (with a scriber or tool that can make a small scratch on metal) on both sides of the body.
3. Place the inner case on a vertical mill and index the end of a cutter onto the outer face of the mainshaft boss. Work round this face to completely clean the surface, then traverse out of the top edge of the case to produce the same level between the scribe marks.
4. Before fitting the new ali-bronze mainshaft bush (item 7) into the inner case, check the fit on the mainshaft. Then insert the bush.
5. Check the end float on the mainshaft. There should be between 0.1mm and 0.15mm. Any more than this, and the clutch will not function correctly. You can adjust the play by using shim washers (not supplied) between first gear and the mainshaft bush.
6. Replace the ali-bronze bush in the end of the mainshaft with the new clutch push rod guide (item 8). Re-assemble the inner case onto the engine.
IT IS VITAL to fit the ali-bronze bush inside the mainshaft as it is LONGER than the standard bush and creates a position for the ball bearing (item 10) which would otherwise fall out of the standard bush and jam the push rod. You could also use the ali-bronze bush to drive the old bush further into the shaft.
On versions bought after May 2011, the bush has a stepped outer diameter, because the internal diameter of the shaft varies between engines. Enter the small outer diameter end into the shaft, then tap into place using a drift that will not damage the bush.
On ALL versions, once the bush is firmly fitted, ensure there is AT LEAST 20mm INSIDE the shaft, then any excess can be trimmed off with a junior hacksaw.
7. It is necessary to shorten the clutch pushrod. Normally this is to a length of 150mm. However, if you have new clutch plates or have fitted an extra pair of clutch plates it wll need to be longer. Start off by cutting it to 155mm and do a dry assembly before hardening, then progressively cut it shorter until you get the right length for your clutch. Re-harden by heating with a blowlamp to cherry red, and quenching in oil.
8. Replace the clutch pushrod and place the ball bearing into the clutch push rod guide (item 8), followed by the clutch push rod button (item 4). Hold all of these in place with some grease.
9. Place the clutch housing spacer (item 5) against the mainshaft bush. Set the clutch actuator (item 19) so the cutaway that acts on the clutch push rod button is parallel to the face of the body. Place the O-ring (item 17) over the new mainshaft bush and assemble the body to the case.
10. Adjust the clutch from the clutch centre so there is a small amount of free play.
11. You now need to make the cut-out in the outer case, so that it will fit around the clutch lightener. Using the diagram on the original fitting kit as your template, replicate this shape on the outer case, lining up with the edge of the case and the hole now occupied by the clutch lightener. Cut and file this to match. Start smaller and take your time to achieve a good fit. Replace the case and seal with silicone.
12. Remove the top back crankcase bolt and fit the new 5/16 BSF bolt (item 12), clutch cable anchor guide (item 12) and clutch cable housing spacer (item 2). Make up a clutch cable to suit.
