Loctite on Wrap Around Handlebar, Stihl 461

[muntiacusmuntjak]

Greetings, I just installed a full wrap on a 461, but out of curiosity I looked up torque specs in the repair manual, as the screws go right into plastic, which seems like a horrible design. Anyway, long story short, the torque wrench you'd need costs like 400 dollars and nowhere I know rents them out, so I scratched that idea and just went with "tight enough"; however, the weird part is that there the loctite recommendation for these screw was 648, a high strength variety I'd never seen before (actually noted as 649 and 648 in the guide I have, but given that only 638 is currently in production, I'm assuming that's what's referred to) rather than the medium blue 242, which has a lot of applications. Given that Stihl's current full wrap now has a plastic joint that is replaceable/breakable, I'm not sure why you'd ever want to permanently lock your screws in there--and given that they're mounted in plastic, using a blow torch to break the seal is out of the question. So I went ahead and used 242, but wondering if anyone could educate me on this and the torque issue--as in, should I keep ignoring this information or is it essential? A tangentially related question too: what the hell is that rubber retainer/support on the handlebar for?

 

[buttercup]

Loctite in plastic? I never heard of that, I would never do that either.

 

[farmer steve]

Look up loctite 425. Pic of the rubber thingy.

 

[muntiacusmuntjak]

Thanks for the quick replies. As a side note, I got the loctite numbers mixed up above and edited them for clarity.

Yeah, so even a little bit of googling backs up that warning about loctite on plastic--says the wrong type can enbrittle/corrode, which doesn't seem worth the risk, especially in this case. Thankfully, the stuff is still more or less removable at this point. I appreciate the recommendation for 425--that looks like it'd be more appropriate. This makes the service manual even more confusing though--the recommended loctite is also a metal to metal, and I had two friends recommend subbing the blue for it, so I guess I figured it must have some utility even in plastic. Below are pictures of the instructions I'm referring to--I've circled the rubber thingy too in the second image. The third image is just what the service manual links to when it indicates applying threadlocker--and here it changes from 649 to 648--like I said, seems weird, maybe I'm missing something