problem with clutch ... Maybe?

[Diver6127]

Ok the car is a NTC3, kit version, with standard gears and standard clutch mated to an OS .15 CV-R (nonpull).

The situation:

Was out bashing today since it's gonna rain for the rest of the week. Everything was going well. Just finished retuning, temps around 230 F.

After a few high speed passes, the revs would pick up but no movement. After 2-3 short guns of the throttle, revs would drop and clutch would engage normally. Ok thought it was a fluke. Tried to replicate the same problem, but nothing happened. After a few minutes, hit a bump ... car bounced and then it happened again. Can it be the clutch? All gears are fine, no missing teeth or small pebbles in teeth.

The clutch has barely over a gallon of run time. It was originally on my .12 CV-RX (about 3/4 of a gallon) then switched everything as is on to my .15 CV-R.

I am thinking that it may be as simple as a clitch spring or maybe it's the clutch shoes itself or a glaze on my clutchbell. Should I just replace the whole clutch assembly since it might be time?

Has anyone tried using aluminum shoes on their NTC3? Anyone ever do a 3 shoe conversion on their NTC3, and what type/manucaturer?

 

[Candyman]

OK, it could be the clutch. Sounds like it has some miles on it. I would check all the things you said. Make sure the bell isn't too glazed. Grab a Scotch Brite pad and scrub it. Make sure the shoes aren't excessively worn. Definitely check the springs. Make sure they're seated in the shoes correctly. Sounds like they may be binding.
And speaking of binding, check the drivetrain. Roll the car by hand for a bit and see if there's anywhere that it seems to be holding up. While you're doing that, bear down on the suspension a bit to see if it's binding when the suspension is compressing.
Hopefully that will give you food for thought and a few things to look at.

Oh, and I just reread your post. Were you saying that after a few passes the engine would rev high just on it's own? If that's the case, it's a mixture thing. That may be why the car doesn't roll. Because if the engine is revving on it's own, the brakes are still probably engaged and the car won't move.

Of course, I could be wrong...

 

[Diver6127]

Well, I am going to break down the entire assembly. It's about time anyway. I will check the springs, shoes and clutchbell for wear and glazing. Regardless, I am upgrading the cluch to a three speed anyway, got a good deal at the LHS. As far as binding, the car rolls just as easily as the day I put her together. No brake engagement.

My brother reminded me that since I clipped the shaft, I may have some play in the flywheel. Enough play to where the flywheel will spin since there's not enough pressure on the collet. He advised me to use spacer from HPI, Part # A804 (Collet assembly) Couldn't just get the spacer, doesn't matter, only a $2 part anyway. Says the same thing happened to him when he had his shaft clipped for his NTC3.

I will address the problem tonight after work. I will take pics as a reference for myself and also for those that may also encounter the problem.

 

[Diver6127]

Ok, well I took the clutch apart. I found nothing out of the ordinary other than normal wear and tear. I scufd up the clutchbell with some scotchbrite since it was showing some glaze build up. Also upgraded to a three shoe clutch just because I figured, why not? Also changed the springs to a little stiffer springs (gold). Changed the fuel lines also, they were in need of changing anyway.

Since the shaft was clipped in order to fit the NTC3 specs for using a short shaft, I took my brothers advice of putting in a spacer (hpi part #A804) since the same thing happened to his NTC3. I couldn't test the car since it was already dark. If I can make it outside before the rain starts tomorrow, I'll post an update.

Candyman, thanks for your input. I took everything you said into account and checked everything. If anyone else has any other ideas as to what may be wrong, please let me know otherwise I'll just have to give it a test run and see what happens.

Thanks in advance!

 

[shadey26 ntc3]

I had the same problem. on two diffrent ntc3 . no matter how high the engine reved the clutch would not engage, check two see if the shoes are binding. thats what I was told ! hope that works for you.
peace

 

[Diver6127]

Already found the problem. Because the shaft was shortened for the ntc3, the measuremet was off. The shaft was too long not allowing the collet to fully engage the flywheel so there was slop allowing the flywheel to just spin till it caught on something.

Now all I have to do is really put this three shoe hopup & stiffer springs to the test. can't wait but it's raining till the weekend. Oh well. Thanks for the input though.

 

[shadey26 ntc3]

naw man thank you . I would never thought of that being a problem two . I am going to check both of my cars for the same problems . If you ever need help with ur car just pm or e-mail.

 

[Diver6127]

FINALLY got a break in the rain so I could test out if I "fixed " the problem. I ran it around for about 2 tanks of hard driving and high speed passes. Problem never repeated itself. I will test more tomorrow. Smooth pickup throughout the powerband and no slipping of the flywheel.

The threaded shaft was too long after it got clipped and there was not enough pressure on the collet so the flywheel was just spinning. I added a .5 mm spacer from the HPI collet assembly (p/n A804) and all was fine.

As for the clutch spring and 3 shoe upgrade, all I could say was WOW! Hole shot had great pickup and seemed to grab better at the top end. I highly recomend this hop up for the NTC3.

I don't have the part # for the 3 shoe flywheel anymore since I threw away the bags already. I just got the 3 shoe flywheel, 3 shoes (p/n 2310), an gold (p/n 2307) clutch springs. Added note, I had to get 2 packs of clutch shoes since my LHS wasn't sure of the part # for the 3 shoe pack. Wasn't in their parts catalog for some reason. Same went for the springs. Pretty good hopup for less than $20.