Second new clutch and still slipping - HELP !!!

[virtual120]

After fitting 2 new clutches and one clutch liner my clutch still appears to be slipping at high revs before take off. If i bring the revs up slow it will sometimes hold and i can fly (but nervously). Is there any issues with the OEM clutches I am unaware of and is there a better aftermarket clutch I can buy.

When i fitted the liner, i used epoxy and wrapped 2 layers of insulation tape around the clutch to hold the liner in place (as advised on this forum).

Or, is there anything else I should be looking out for that might be causing this problem.? This is a new Raptor 50SE with standard TT50 motor. Everything else appears to be great.

Thanks for your help.

[vandelescrow]

Did you put the shim under the clutch? with out it, the clutch wont spread out properly to engage the liner.

[virtual120]

Yes. Thats the shim with the 2 holes in it yes !

[vandelescrow]

Yes that is the shim I'm refering too. You are using the clutch bell that came in the kit? You purchased the heli new, not used, And your using TT clutch liners. Sorry that was the only thing I could think of.

[virtual120]

I burned the first clutch out as i had the throttle reversed when it started. I bought another clutch and liner and its slipped ever since :(

Oh well, back to the drawing board.

[MXRACERX43]

Shoes are even and not spread or sprung?

[LAMAR COOLEY]

virtual120,
When you install a new liner USE only ONE WRAP of ELECTRICAL tape.
I'm not sure what " insulation " tape is.
I can speak from having done this on a couple of occasions,
Two wraps causes the gap to be to large.
I believe this is more than likely your problem with the "new liner".
By the way, what color is the liner you are using ?
Another thought; If you're using the original clutch bell ( the one that had it's liner ruined )
It may be possible that the clutch has worn away some or too much bell lip and the gap is now to large when you installed a new liner into it.
If that's the case then one wrap of tape might possibly re-establish the proper clutch to liner clearance.
I hope this is of some small help.
Regards

[virtual120]

Thats a thought. Although, when I wrapped only one layer of tape around the clutch, it sat loose in the bell so wouldnt have held in the liner whilst the glue was drying. So, maybe your thought of the bell being worn may be correct. Ill look into that. Thanks for your help.

Also, is there a specific way the liner has to go in ie. shiney side up and dull side down. One side of the liner is shiney and one side is dull. I was wondering if its the wrong way round wether that could cause the clutch to slip !

Cheers
Tim
ps. Insulation tape is the same as electrical tape.

[virtual120]

Have taken the whole thing apart again and all looks perfect. The gap is good. Could it have been a build up of dust as it was new, and may that have caused the slipping?

[iher]

how many flights have you tried this new lining?
you mentioned a" shinny side" well.... there is a possibility that it behaves like new brake pads on your car. when new, the clutch arm and liner are not perfectly parallel and the new liner has irregularities. it takes a certain amount of wear to make a perfectly parallel contact.
if you also add the fact that it`s smooth it might slip for a while before engaging fully.

I usually roughen the surface with sand paper, ( both sides, one for gluing and the other for fast initial wear) just enough to get fibers exposed.
I use 2 layers of yellow painter`s masking tape ( the one we all know ) the clutch may rub a bit the first 3 flights.
its important before gluing the liner, to check that the clutch arm´s external diameter is perfectly aligned with the fixed part diameter.

[LAMAR COOLEY]

virtual120,
The blue liners usually have some partial printing on one side. This is the side I apply epoxy to. I have never found it necessary to "sand" or "scuff" a new liner.
If the gap is right the clutch will work properly.
I've heard of people using a strip of card board ( same dimension as the liner ) between the liner and the bell to fill the gap between the two.
Quote: " The gap looks good."
I'm not sure I know how to interpret this.
If the gap is to large the clutch arms will not "throw out" enough to properly engage.
And eventually lead to clutch failure ( breaking )
There is a fine line for the proper clutch to liner spacing.
If the clutch contacts the liner when new or after a repair, the only way it's going to
wear-in, seat properly and form a gap ( space ) is if you hold the blades and let the clutch wear the liner. I would not recommend this myself.
When you install the engine and clutch assembly into the bell ( when installed into the frame ). You should be able to spin the bell by hand (finger ) and not feel any drag of the clutch on the bell liner.
Regards

[virtual120]

Great, thanks for all the tips. I decided to fit another liner last night and the clutch fit in nice with just enough clearance to spin freely.

Ill give it another go over the weekend.

Thanks again.

[iher]

One of the most common problems with clutches, is misalignment. Depending on the heli, you have a certain degree of missalignmente between the clucht bell and the shoes.
with a good quality and new sistem, ususally the starter pin ( that fits into the one way bearing in the certer of the clutch shoes) takes care of aligning the 2, and make a continous axel froen starter to engine.
but wear can generate play, and the gear ajustment can push the bell in a slight angle. This wears the linner reaaaaaly fast.
Although rare, another thing to look for is how well aligned are the clutch shoes in relation to the engine axel.
hope this helps