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Old 09-13-2008, 03:34 PM   #1
dvu
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Default HPI R40 - Need Help

Hello,

I've started building my R40 over 2 yrs ago, but could never get the engine to work. I've finally got it working, but am now habing problems with the clutch. When I go half way on the throttle, the clucthbell engages, but when I seem to go full throttle at times the bell will spin and at time sit won't do anyting. Seems as though the clutch is slipping. Any ideas on the best way to fix it.

Also, can someone explain to me how the 2 speed clutch in the gear works.

Thanks, Duc
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Old 09-13-2008, 06:06 PM   #2
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What engine do you have?

This may be a general rule below but it all depends on engines as they all have slightly different crank shafts.

I would say take the clutch bell out, and make sure you tighten the spring tensioner so that you pass one threading and you begin to see the next ( approx .2 mm). Then, put shims in front of the clutch spring tensioner before you insert the clutch bell and the inside bearing.. I'd say use Kyosho shims. and you can get a bag of it which contains a whole bunch of sizes, .1 .2 and .3 mm thick. I add about three or four of the .2 or match it with a combination of .2 and .3 mm to allow the clutch bell to spin freely on top of the clutch. Make sure you add .3 mm worth of shims after the clutch bell starts to spin freely. You do nto want too much gap there. Then, assemble the thrust bearing adding the copper and silver shims from the KIT.
To get it right I just add say one silver and two copper. I tighten the screw and if the clutch bell does not move, I remove one copper shim. If the frees it up I would remove one silver and replace the copper and call it the day. This gives me around .3 or .4 end play. You don't want the clutch bell to be too lose.

Once set, then make sure you back the screw out again and add some threadlock, re-tighten and then install engine.

I'm out of breath, good luck
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Old 09-13-2008, 06:30 PM   #3
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Right now I've got the sprind tension nut just onto the threading thinking that the less tension would allow be to engage the clucth easier. If it's not tight enough, would that cause my clutch to slip?

Thanks
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Old 09-13-2008, 07:58 PM   #4
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An easy non technical way of setting your clutch. Turn the nut down until two threads show above the top of the nut.
I do have to agree that the clutch bell needs to be shimmed correctly. Check your owners manual for the correct washer width and bell clearence. It should not be tight without being able to spin nor should it not be loose so that it can move from side to side.
Before anything, check the SG shaft nut. Make sure you tighten the nut and locktite it to the crank shaft. If you don't, the clutch spring will slip and tighten down. Your throttle setting will be messed up.

The two speed works by centrifical force. When the two through out weights (half moon things) spin at a spacific RPM they will engage the inner walls of the 2nd gear housing. After that 2nd gear is engaged.
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Old 09-13-2008, 09:25 PM   #5
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So on the 2 speed clutch, do I want that tight i.e shift latter or loose (shift earlier.) Also, thanks for the info.

Duc
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Old 09-13-2008, 10:38 PM   #6
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Yes, the looser the two screws are, the earlier the shift.
a good starting point is turn both screws all the way down until you can't turn any more, then back both of them out 4 1/2 turns. Normally that will get you to shift at a light RPM. After that, adjust accordingly.
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Old 09-14-2008, 08:26 AM   #7
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Hopefully, last question about the flywheel. I've read in previous post about how the spikes (for lack of a better word) on the flywheel can stick out above the clutch shoe just a bit. My barely stick out, but enough to leave a ring on the the clutchbell. Should I sand those down? If so how do I go about doing that?

Thanks again, Duc
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Old 09-15-2008, 02:17 AM   #8
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Quote:
Originally Posted by dvu View Post
Hopefully, last question about the flywheel. I've read in previous post about how the spikes (for lack of a better word) on the flywheel can stick out above the clutch shoe just a bit. My barely stick out, but enough to leave a ring on the the clutchbell. Should I sand those down? If so how do I go about doing that?

Thanks again, Duc
The R40's flywheel pins don't sit in the flywheel properly. You can hit them in with a hammer (take the flywheel off to do this), but you'll probably have to cut them down. I used a dremel with a cutwheel to cut mine down. The R40s clutch is a piece of crap, I'm not surprised you're having issues. If you can afford an mtx3 clutch its a good upgrade, you need to open up the holes in the chassis a little (dremel again), if not you can use the mugen grey clutch shoe and a kyosho spring (search the r40 thread for the part number)
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Old 09-15-2008, 05:34 AM   #9
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What CraigM said is correct. You can hit the pins in deaper with a hammer, or us a dremmel to lower them. I used the MTX-4 grey clutch shoe on my R40.(Just need to ream the holes out a bit).

Go and have a look at the R40 Thread. There are many posts about how to get the R40 clutch to work.
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Old 09-15-2008, 06:21 AM   #10
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Thanks for the advice. If I do get the MTX-4 clutch, which hole would I need to widen (the flywheel hole)?

Thanks
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Old 09-15-2008, 08:06 AM   #11
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When you use the MTX clutch set, you don't need to widen any clutch shoes. But, if you use the HPI flywheel, and just use the clutch shoe, then you need to widen the holes in the clutch shoe that slip right into the fly wheel pins. Makre sure you do two holes and do it slowly until the shoe can slide in and out easy.

So try one thign at a time first and go from there.

Start with the spring tightened to two threads, then shim the inside of the flywheel like mentioned. then go from there. I use the Kyosho shim set. They are the right size for all crakshafts.

You need good clutch engagement before you play with the two speed.
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Old 09-15-2008, 11:33 AM   #12
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So if I'm reading you right, if I use the MTX set in it's entirety then I should just be able to set it up, put it in the R40 and I'm good to go. Found this at tower hobbies

http://www3.towerhobbies.com/cgi-bin...?&I=LXVCK5&P=7

Is this all I need to buy, and I'm good to go?

Thanks, Duc

Last edited by dvu; 09-15-2008 at 11:41 AM. Reason: change
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Old 09-15-2008, 11:56 AM   #13
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I would go for the MTX-4 shoe over the MTX-3 kit. The MTX-4 shoe is cheaper, and easier to find than the MTX-3 clutch kit. If you go for the MTX-3 kit you will have to buy more MTX-3 Pinions as well if you want to change the gearing. (Don't know about availability of those)
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Old 09-15-2008, 02:05 PM   #14
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the mtx-3 clutch asy is no longer around so i used the mtx4 clutch asy and all is goo and much cheaper then the ofna one go to nitro house web site they are the cheapest around for it
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Old 09-15-2008, 02:41 PM   #15
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Thanks for the info. So this should include everything i need right?

I couldn't tell if it included the clutch shoe, spring etc.

http://www.nitrohouse.com/catalog/pr...ducts_id=17074

Also I appreciate all the input from you guys. I've posted at other sites, and this is by far the most helpful.

Thanks again, Duc

Last edited by dvu; 09-15-2008 at 02:44 PM. Reason: clarify
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