Runout

[gavin673]

Just wondered if anybody here could advise me on runout for the spectra. Specifically if BIGRCR was out there. I seem to be unable to get the runout on the fan to less than .005. I just don't see any way since the taper fits so perfectly on the fan. I tried tapping and turning but it just doesn't make a diff. Once that bolt gets torqued down, back to .005. Is this acceptable? It seems you are entirely at the mercy of the runout of the crank which is bad. I spoke to Toxxic Al once on the subject of crankshaft runout and he told me that it wasn't even worth it to try to pull the crank and bend it in the right way. Since it is in a 'U' shape it is very flexable. He said he observed a motor under strobascopic ligting while running and they saw that the crank actually deflects while running. Any thoughts?

Thanks,
Gavin

[rbort]

Are you saying the runout is 5 thousands by the figure? If so that is way too much. If should be less than 2 thousands on a stock motor. If you send your motor to a balancing shop they true the crank and its generally within 1/2 a thousands -- at least at hanson's, don't know what Al does.

If in fact its that off you may need to send your engine and fan to Al (hanson or Toxic) to have them mount it and true it up for you. I know Al at hanson's does this, he took care of mine at its within 1/2 thousands.

-=>Raja.

[gavin673]

Yes 5 thousants. The crank itself is out 3. I find it funny that a modified motor - specifically one for a ma machine - would not have the crank retrued from the get go. I never seen a stock zenoah with a straight crank. It is very frustrating to buy a modified motor and then have to send it back just to get it right. The purpose of getting a modified motor is that it will be right from the get go.

Gavin

[rbort]

Yes 5 thousants. The crank itself is out 3. I find it funny that a modified motor - specifically one for a ma machine - would not have the crank retrued from the get go. I never seen a stock zenoah with a straight crank. It is very frustrating to buy a modified motor and then have to send it back just to get it right. The purpose of getting a modified motor is that it will be right from the get go.

Gavin

5 thousands is bent. Is that a new engine out of the box or has it been in a crash or something? A stock zenoah new out of box is within 2 thousands and that is considered acceptable. A modified Hanson Zenoah is 1/2 thousands or better. Not sure what Toxic Al specs are...

Another possibility is that you grabbed the front of the crank to tighten the fan or remove the rotor in the back and have twisted the front of the crank to the back of the crank during assembly. This will cause the crank to be off like that as well.

In any case that engine is not usable as is. Send it to one of the Al's and have it trued before you install it in a heli.

-=>Raja.

[gavin673]

Brand new. I did not twist the crank at all. I am sending it back to Al.

Thanks,
Gavin

[rbort]

Good idea!

-=>Raja.