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Old 06-20-2014, 01:22 AM   #1
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Default Help with my burnt centax on my 966!!

Hi all,

I have a major problem with my 966 centax. I have a red clutch shoe(??), spring wound in to 1.2mm as per the setup book, clutch gap 0.7. I ran it ok once then second time out it was cooked, baked the bearings but luckily didnt ruin the clutch bell. This is the second time this has happened, ruined the shoe last time as well. I can only think that the gap is too big

What am I doing wrong???

What happens if the 1.2mm was too light pressure, would the motor just slip the clutch whenever the power goes on??. I would have thought that lighter spring pressure would give a stronger clutch pressure so it doesnt slip so much!

Where to start the problem solving? thanks guys
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Old 06-20-2014, 01:52 AM   #2
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It's not the gap. You must have way too much end play. Don't get gap and end play confused. You want very little end play
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Old 06-20-2014, 02:07 AM   #3
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It's not the gap. You must have way too much end play. Don't get gap and end play confused. You want very little end play
end play was spot on, just a tiny bit of end play. Also, I was looking at a video of Micahael salven putting the three clutch pieces onto the flywheel and he had them in the opposite way to what I have in my instruction manual, whats going on there?
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Old 06-20-2014, 03:07 AM   #4
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Originally Posted by Fly'n Fish View Post
end play was spot on, just a tiny bit of end play. Also, I was looking at a video of Micahael salven putting the three clutch pieces onto the flywheel and he had them in the opposite way to what I have in my instruction manual, whats going on there?
check the clutch spring if its straight and sliding well on the retainer. You may have a jamming clutchspring. measure it with so its straight on both sides.
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Old 06-20-2014, 04:59 AM   #5
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There are huge tolerances on the flywheel nut that you can not trust the spring pre-tension setting. Just set the springnut to a feeling of how the clutch engages. If the started setup by numbers is already set to high performance there is a chance that a tiny bit wear on the shoe will create to much gap for the setted spring tension.

And one tip:
If you place a new shoe set the gap to 0.6mm. In the first moments the shoe will have some wear and will deform a tiny bit that it will give a quick result into a 0.7mm gap.
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Old 06-20-2014, 05:08 AM   #6
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There are huge tolerances on the flywheel nut that you can not trust the spring pre-tension setting. Just set the springnut to a feeling of how the clutch engages. If the started setup by numbers is already set to high performance there is a chance that a tiny bit wear on the shoe will create to much gap for the setted spring tension.

And one tip:
If you place a new shoe set the gap to 0.6mm. In the first moments the shoe will have some wear and will deform a tiny bit that it will give a quick result into a 0.7mm gap.
Can you explain 'high performance' as it relates to a clutch? I guess it means high spring preload so that you get more revs before the clutch engages. That could cause the clutch to burn too, to high spring, weak engagement of the clutch and then slipping. How do you set the clutch tension then once you are on the track? or can you do it in the pits ie half throttle gives engagement or some such??? are there any insider secrets to this? thanks guys
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Old 06-20-2014, 05:09 AM   #7
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Originally Posted by Fly'n Fish View Post
Hi all,

I have a major problem with my 966 centax. I have a red clutch shoe(??), spring wound in to 1.2mm as per the setup book, clutch gap 0.7. I ran it ok once then second time out it was cooked, baked the bearings but luckily didnt ruin the clutch bell. This is the second time this has happened, ruined the shoe last time as well. I can only think that the gap is too big

What am I doing wrong???

What happens if the 1.2mm was too light pressure, would the motor just slip the clutch whenever the power goes on??. I would have thought that lighter spring pressure would give a stronger clutch pressure so it doesnt slip so much!

Where to start the problem solving? thanks guys
The video confusion may arise from the fact that there are two types of flywheels - the traditional with the angle in the flywheel and the more recent version with a flat flywheel and the angle in the aluminum disc , follow your instructions for the type you have .
Whenever you fry a clutch disc the Teflon seems to coat the angle surface of the bell , if this happens you will fry disc after disc , clean the surface up with some 320 paper and start over.
Instead of setting the spring using a measurement try the alternate method of running the nut down to coil bind then back in off 1.5 turns , easy and it works.
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Old 06-20-2014, 08:57 AM   #8
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Originally Posted by Fly'n Fish View Post
Can you explain 'high performance' as it relates to a clutch? I guess it means high spring preload so that you get more revs before the clutch engages. That could cause the clutch to burn too, to high spring, weak engagement of the clutch and then slipping. How do you set the clutch tension then once you are on the track? or can you do it in the pits ie half throttle gives engagement or some such??? are there any insider secrets to this? thanks guys
If the gap is right you can hold the car on the ground and give some throttle to feel the clutch. If the spring load is set to high you will feel slip already, to low you notice the engine has some difficulties and when it is right it wants to drag the car out of your hands.
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Old 06-20-2014, 09:01 AM   #9
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Centax Clutch, Like all clutches work is by centrifugal force. Pre-loading the clutch from 9-10mm to end of crankshaft is only a starting point. Most likely it would take 1/4 to 1/3 throttle for it to engage. Your driving style will show you how to adjust. You can watch when the clutch engage by watching clutch plate moves on the test bench. When does it engage? 1/4 of 1/3 throttle? Depending on you, I get it to move when I just crack the throttle. Remember, the higher the RPM, the tighter the clutch engage. You can have full engagement at 1/8 or less, like I said its up to your driving skills. Centax Clutch takes a lot of maintenance, shown on MS Youtube video, 1 hour of running. Use the Scotch Brite of Steel wool the deglaze flywheel, Clutch bell, and clutch materal, composite or Teflon. The way you experiment the more knowledge you acquire. Just have Fun!!
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Old 06-20-2014, 02:43 PM   #10
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thank you everyone for the tips I think I can play around now and get this working. De-glazing is something I didnt do after I cooked the first clutch! also the holding on the ground is probably a good way to get a feel for how it is set, thanks for that!

One more question,which clour shoe would you guys recomend for the 966 and how many should I buy to have in the spare kit? thanks again.
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Old 06-20-2014, 04:11 PM   #11
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thank you everyone for the tips I think I can play around now and get this working. De-glazing is something I didnt do after I cooked the first clutch! also the holding on the ground is probably a good way to get a feel for how it is set, thanks for that!

One more question,which clour shoe would you guys recomend for the 966 and how many should I buy to have in the spare kit? thanks again.
For the steel bell use the yellow shoe ( catalog says brown) , for the aluminum bell use the black shoe.
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