Shearing Bell Crank Screws

[RanchoJim]

I never had a chance to upload a pic of my car. So this is my Worlds RE RE. It's a very stock and meant to be a car to race here and there and drive laps at the track. So after driving at the track 5 times I have managed to shear the left bell crank screw off due to some crashing and what not. I would not say that things have been significantly over tightened, and I have noticed the screw coming loose a bit after about 4 runs on the track. I was thinking of upgrading these screws to steel or titanium to gain some more strength.

I'm curious if you guys have experienced this problem and have a solutions to offer.

[GodSpeed]

The manual calls for Loctite on them so that should resolve any backing out, bad as far as snapping them, I don't know.

[woodall01]

I have had the same problem with shearing off of the screws, a good hit to either wheel while the servo is moving and it's over. I tried some Loctite and it worked a little while, btw how much play do you have in your steering?

[GoMachV]

As soon as they loosen up they are prone to shearing. The loctite should help keep them planted. Make sure you are using all three screws and check them after a few runs

[jwscab]

i suspect since you are running aluminum bell cranks and likely a strong servo, with no servo saver, any impact will definitely increase the chances of damaging the screws. You can exchange them for steel screws, but be aware the damage will travel downstream, to either the servo horn, gears, or mounting tabs.

[teman]

^agreed... put a servo saver on the servo.

[RC10th]

I don't think these screws are terribly strong, I managed to pop the head off of one tightening it in the noseplate on another project. I don't remember the old greenish/gold screws being as brittle, but you can definately tell the new screws are of lesser quality. The heads on many are stamped off center and some have what seems like flashing on them.

[orangemazda]

I found some nice stainless 8-32 (allen head) screws at the local hardware store. I was thinking about using them in the front end of my OIN racer to increase nose weight so maybe I wont have to use so many stick on weights. They are quite a bit heavier (and obviously stronger) then the aluminum ones.

[GoMachV]

The stainless won't fit the hole very well. For the chassis you want 100 degree heads and usually you'll find 82 degree. It's difficult finding 100 degree outside of aluminum (aircraft screws)

[RanchoJim]

Thanks guys. When I was a teenager I never owned loctite nor applied to to any of the screws. All the green screws seemed to have more "bite" when tightening. A loose screw is definitely going to under go some fatigue loading real quick and with the combo stated it will quickly fail. I will put a servo saver on it for now to try and mitigate this issue and some loctite on the screw as well.

[orangemazda]

Hmmm, that's good to know. I'll have to bring an aluminum one with me to the hardware store for a comparison before I buy any of them.

The stainless won't fit the hole very well. For the chassis you want 100 degree heads and usually you'll find 82 degree. It's difficult finding 100 degree outside of aluminum (aircraft screws)

[RanchoJim]

Maybe these will help this issue as well. http://www.chiefaircraft.com/hd-ms24693c8x.html

100 degree 8/32 phillips stainless steel.

[GoMachV]

We have the absolute best hardware store around as well as two specific fastener places and none carry aircraft hardware. I'd save your gas and order up some online. If your not happy with Associated, try fastener express. In my shopping their site some colors were cheaper than others btw.

http://www.fastener-express.com/search.aspx?find=8-32&category=425

[GoMachV]

Maybe these will help this issue as well. http://www.chiefaircraft.com/hd-ms24693c8x.html

100 degree 8/32 phillips stainless steel.

Nice! The price isn't bad either. I may have to order a few!

[RanchoJim]

I ordered my $20 minimum of the standard length and some of the longer ones typically used. I will let you guys know how they work out.