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Old 10-02-2010, 05:41 PM   #1
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Default Xray Clutch Help...

I just finished my first Nitro car build; an Xray NT1R with a RB Junior9 .12 engine.

I was just trying to drive it around slowly on my street and it seems like it needs just toooo many r's for the clutch to engage. I am not familiar with .12 engines; the .28 in my Savage would have been doing a wheelie down the street with that many r's. I read through the Xray manual and the setup guide and I can't seem to find what to adjust to make the clutch engage sooner.

Any guidance would be appreciated!!!

FYI: I am very sure I matched all the measurements in the assembly book, save one. I could not seem to get the 'Clutch Gap' bigger than .4mm. The recommendation in the book was .6 -.7 --- could that be my problem??
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Old 10-02-2010, 05:55 PM   #2
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That is quite normal for that type of clutch. You need to break in the engine fully and then get it tuned before you start dialing in clutch engagement. With a centax style clutch it takes a warm engine and some rpms to get proper engagement. The adjustment nut can be tightened to achieve later engagement or loosened for sooner.
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Old 10-02-2010, 06:05 PM   #3
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Bag 08 in manual. 338584,85,86 Shims or 964073,74,75 Washers. the endplay could be adjusted. By Addiing of taken off shims or washers. Shims and washers has different thicknesses. Anything wider than .6-.7, you have too much your thrust bearing could fall apart. Your manual will tell you the thickness of shims and washers.

If you actually want to early shift you have the adjust 2speed tansmission. Rear Tranny Bag03, screw 908262 x 2 CCW ealy, CW Delay. A good starting point, bottom out the two screws, and loosen 4 turns CCW. and go from there.

Good luck!

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Old 10-02-2010, 06:27 PM   #4
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.4 should be fine for breaking in a new motor. Just loosen the adjusting nut on the spring 1/2 turn or so to get it to engage sooner. Once you get the motor broke in and tuned for racing, you can tighten it back up to get the snap off of the corners if you want.
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Old 10-02-2010, 06:46 PM   #5
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Thanks for the quick feedback! I will just continue with the motor break-in process and worry about the 'feel' later.

If it still feels odd, I'll just visit the closest Nitro track I can find and ask for some help.
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Old 10-02-2010, 06:58 PM   #6
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One more question or clarification,,,,I just read the clutch section in the set-up book again (for the 5th time )

When the book says the lighter the the setting (looser collar) on the "Clutch Spring Preload" is for "earlier engagement;better on slippery tracks", is that same thing is how soon the clutch engages at a given rpm?
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Old 10-02-2010, 07:02 PM   #7
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Quote:
Originally Posted by Micro-E View Post
One more question or clarification,,,,I just read the clutch section in the set-up book again (for the 5th time )

When the book says the lighter the the setting (looser collar) on the "Clutch Spring Preload" is for "earlier engagement;better on slippery tracks", is that same thing is how soon the clutch engages at a given rpm?
Yes. Loosen that nut and it will engage at a lower rpm. Tighter it will engage at a higher rpm.
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Old 10-02-2010, 07:21 PM   #8
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THANKS!

You da' man wingracer!!
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Old 10-03-2010, 03:36 AM   #9
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If you have set all messurements (even the spring tension nut) with a gap of.4 then you should have a mild engaging clutch.
Sometimes the term "endplay" is confused with the "gap"

But if you are right and the gap can not be set to something bigger you have to take a look beween the engine front bearing and the flywheel. If there is a lot of space made by the collar on the engine shaft you can remove some material from the collar so the flywheel will be moving up closer to the frontbearing leaving more room for a bigger gap.
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Old 10-03-2010, 02:02 PM   #10
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Roelof,

Good point. Next time I have it apart, I'll re-measure and see why there is not much gap.

For now, I "loosened" the clutch spring preload a turn of the flywheel and now the clutch seems to engage more like I would expect (earlier). A touch high on the rpms until the clutch warms up, but then the engagement seems reasonable.

Unrelated: I really like that RB engine. It is my first .12 and what a good experience! Fires right up, idles so smoothly and consistently I could walk away from it for 5min, come back, and it would still be purring away. NICE.
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Old 10-03-2010, 03:07 PM   #11
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I see you have only experience with a Savage (normal clutch) and a .28 engine.

Do not get fooled about an high rpm. A savage will engage at maybe 10.000~12.000 rpm while with a centax type clutch the NT1 has an engage point of 20.000~22.000rpm. Also the top rpm of a non modified .28 will be somewhere about 36.000~38.000 while your RB can reach with easy 44.000rpm.

But messuring the gap is easy.
- Remove the bearing closest to the spring nut
- mount the hole clutch
- push the clutchbell to the shoe and be sure it is on the shoe
- messure the distance from the top screw to the 1st gear with a caliper, if you have a digital one set the messured distance to zero
- pull off the clutchbell and push it to the thrust bearing and messure it again.
- the difference is the gap, directly shown with the digital caliper

There are tools on the market you can stick between the end tip to determ the space, sadly enough I have seen many which are not acurate or are even complete rubbish. If you have one or get one it is wise to check all steps with a caliper if they are right.

And maybe this will give an extra help:
http://www.youtube.com/watch?v=7wjogF57xpo
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Old 10-03-2010, 04:37 PM   #12
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good vid! Geez, everything is on YouTube...

THanks!
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