RCScrewz Kit

[Jtroutt19]

So I am doing the stainless screw swap on my wraith. The one question I have is that there are no coarse thread screws. So do I just replace the coarse thread with the fine thread or what?

[Sevastra]

You can, yes. It works fairly well too.

Buying an after market screw kit is one of the best upgrades you can do.

[Jtroutt19]

Ok then that is what I will do. Why do you say it is one of the best upgrades you can do? Just curious. I bought them cause I hate rust something horrible and also because the stock heads would strip out really easy. I figured stainless steel would be harder to strip. But let me know. And I also am under the impression that they do not include coarse thread screws in the kit because they want you to use all fine thread

[allanon1965]

the fine threads will grip better and not loosen up as easily as the course threads

[Eric0424]

Stainless steel screws are actually softer than the 12.9 black oxide in our kits, they'll strip easier if the black oxide are not cheaply made, loose tolerance screws with out of spec socket heads and/or if you're using cheap, loose fitting hex drivers. If you want strength and corrosion resistance you need titanium alloy screws, for low stress areas and corrosion resistance the stainless will be fine. No matter what screw you use, a good hex driver and identifying the occasional poorly manufactured screw are your best weapons to fend off stripped heads in screws.

Black oxide 12.9 - tensile strength of 170,000 psi, min. Rockwell hardness of C37
Stainless, 316 and 18-8 (most common stainless screws) - tensile strength of 70,000 psi, min. Rockwell hardness of B70

A stainless screw kit is not a "best upgrade", it's simply a cosmetic upgrade. Not performance or durability based, unless you leave your crawler wet or cover with snow to air dry (promotes rust) or if you have no idea how to install, remove and reinstall the plastic thread screws. Most just cram the plastic screws back in without bothering to find the original threads that were cut during the first installation, cutting new threads each time they have to remove/reinstall something. Then, of course, they blame the screws or the parts for the damage to the plastic threads when they eventually strip.

Axial screws have threads specifically designed for plastics and are better at holding the parts together and apply more torque than the machine thread screws sold in the aftermarket kits. These plastic thread screws are similar to wood screws, but have deeper threads with a sharper angle to grip the plastic better than the more shallow shallow wood, sheet metal and machine threaded screws.

Part of the problem with Axial plastic parts and screws are screw holes that are not always the correct size and some of the button head screws have shallow and/or loose fitting sockets. I bought extras from Axial and replaced all the loose fitting or out of specs screws as I was building my SCX10 and Wraith (about 6-7 screws total for both kits). If they didn't fit right on my hex drivers they got tossed in the trash and replaced with a better fitting Axial screw. If the plastic is right and the screws are decent quality, then the screws specifically designed for plastic hold more torque than the shallow machine thread screws or the wood screw thread.

[allanon1965]

so you expect me to believe that the crappy course screws in the axial rigs are stronger than stainless steel? these same axial screws that the heads pop off of with no warning? I find that very hard to believe. the stock course screws were constantly loosening up, since switching to the stainless steel fine thread screws, no more loose screws, but hey, what do I know?

[Sevastra]

I say getting one of the various RC screw kits is one of the best upgrades you can do simply for the variety of length they offer. I'm always changing and modifying this or that on my wraith, and constantly in need of different length screws for this and that. It's nice having them at hand whenever desired.

[Eric0424]

So you're referring to general screw assortments and not Wraith or SCX10 specific, screw-for-screw kits that replace the stock screws with screws of the same length and diameter but in a different material (stainless, titanium, aluminum). Not really an upgrade, that's just keeping assorted hardware on hand. It is handy to have an assortment of screws around though. Especially if you plan on making frequent changes that require different lengths. I usually measure the screws I need then order them in 100 piece lots depending on price and how many I may need.

[Jtroutt19]

Thanks for all the info guys. I will say this, the stainless screw head feel stronger than the black ones. It does make since about the coarse thread holding better. It does seem like I can get the black ones tighter. But I guess in the end we will see right. I do wish they would include coarse thread screws in the kit thought. Just makes since to me to replace coarse thread with coarse thread.

[Revoasian]

Eric0424- Thanks for the heads up. I too thought the stainless screws were stronger than the factory black oxide screws. I was going to pull the trigger and purchase a set of KNK stainless hardware for the wraith this week because of that reasoning. I don't go in water with my rig there fore rust isn't a concern, but I do use wd40 on the heads applied with a cotton swab if I am playing in snow or a quick rinse afterwards.

[ribaja]

I'm new to the scale/crawler side of rc's but coming from 1/5 scale I never used stainless screws they would stripe so ez the go to screws were tonys screws grade 8 screws black oxide.

[Slaughter]

Fine threads and no rust are the reasons to use stainless. Course threads back out much easier and quicker. You're more likely to catch a fine thread screw backing out before you lose it.

[Eric0424]

Originally Posted by Slaughter

Fine threads and no rust are the reasons to use stainless. Course threads back out much easier and quicker. You're more likely to catch a fine thread screw backing out before you lose it.

If we're talking fine thread and coarse thread machine screws threaded into metal parts, then yes. Fine thread screws can take longer to back out compared to the same size screw in coarse thread.

Screws threaded into plastic are a different story, them randomly backing out of plastic in not a common problem unless the screw and/or part is damaged or the assembly is poorly designed. It's usually just never fully tightened to begin with or someone has destroyed the hole/threads and the part is just no longer holding onto the screw. This worn-out threaded hole will not hold a machine screw of the same diameter either. But if everything is as it should be then they shouldn't back out on their own.

There's a reason we have screws specifically designed for plastics, wood, sheet metal, dry-wall, etc., etc. and it's not because fine thread machine screws are better for these applications. Unlike machine screws in metal that are held in place by the threads alone, plastic screws are also held by the pressure on the screw center shaft (shank) from the plastic hole. These holes are generally slightly smaller than the shank of the screws being used and plastic specific screws have what's known as tri-lobular shank. This tri-lobular shank along with the thread design and spacing is why they hold better and can apply more torque than the machine screws when threaded into plastic.

And according to my calipers the Axial screws seem to have the tri-lobular shanks.

Fine thread machine screws tend to cut/damage more plastic with the narrow spacing between the threads and don't grip as well with the shallow thread depth. Machine screw shanks are also generally round, but there are some exceptions.

Very little chance of rust/corrosion is the only non-cosmetic reason to use stainless hardware, and there's no logical reason to use fine thread machine screws in plastic. Despite popular belief, 316 and 18-8 (as well as other) grades of stainless will rust/corrode and stain in the right environment. Stainless alloys with lower chromium content are more likely to rust than grades with a higher chromium content. Of course all stainless grades will resist rust better than zinc plated and black oxide screws.

[o0wiz0o]

I'll simplify for y'all.

Stock screws = BAD (Self tappers that destroy the plastic and work loose - You can see/feel how sharp they are)
SS Fine Thread = GOOD (No Rust and no damage to plastic parts due to removal)

Doubters want proof? Leave the self tappers in one C-hub and try a fine thread in the other. See which backs out first.

[meatmonkey]

The real reason the Axial uses those damned coarse thread screws is: it allows for quicker assembly time on their RTR's, and they are cheaper since they don't have to be made to the same tolerances of machine thread screws.

While it is true that a 12.9 grade bolt is always stronger than a stainless steel bolt, you will never convince me that Axial bolts are grade 12.9. If they were, it would be marked on the head like many of HPI's, and aftermarket, bolts. I doubt the Axial bolts even reach grade 8.8 judging by how easily they bend/strip heads. So it could be considered that a stainless bolt kit is a mild upgrade, but a grade 12.9 bolt kit is the real upgrade.

[Eric0424]

I'm not here to convince you of anything and whether you agree with the facts above or not is moot. It's not conjecture or weak excuses for spending money on softer (but pretty) screws, it's just fact. The Axial screws are the right screw for the job and the stainless hardware is softer. Take the information for what it is or ignore it and continue buying weaker machine thread screws that do more damage to the plastic parts.

If you're stripping Axial heads "easily" it's you and/or your tools. Aside from the random loose fitting heads the Axial screws are not the worst I've seen and strength is on par with 10.9 and 12.9 hardware I buy from other manufactures. A good, undamaged hex driver has no problem repeatedly installing/removing them, but just one slip in a screw head can compromise a driver especially with 2.0mm and smaller drivers used on Axial M3 pan heads and smaller screws. Axial might not be high quality hardware and include the occasional duds, but it does the job and is still stronger than the cosmetic stainless. If these were 4.8 or 5.8 as you've implied we would be frequently pulling the heads off the shanks, stretching, bending and shearing them in two.

Yes, buying higher quality hardware with more consistent sockets would be a quality/strength upgrade. But no, not all screws are stamped on the head. You will find 8.8, 10.9, 12.9, and alloy steel screws comparable to 12.9 or grade 8 without the stamp.

I personally prefer stainless hardware for a lot applications and will generally use it on outdoor equipment, automotive trim and other projects if strength isn't going to be an issue. But I'm not deluded into thinking it's better or stronger simply because I prefer the resistance to rust and color over the black oxide and zinc plated hardware.

Doubters want proof? Leave the self tappers in one C-hub and try a fine thread in the other. See which backs out first.

It's only proof of the wrong application of said screws. In this case the machine thread may take longer to back out, but it's not a "fix" for the actual problem and you're still doing more damage to the c-hub with the machine threads. Similar to the screw-pins Traxxas likes to use on their suspension pins, both plastic thread and machine thread screws will back out if/when they're used improperly. The problem is a pivoting part (the knuckle) moving against the head of a stationary screw (tightened to the c-hub). With the Traxxas screw-pins you have a screw tightened against the pivoting suspension arm, but the shaft is pivoting in/on the stationary suspension mount. As with the c-hub and knuckle, these screw-pins like to back out on their own. A drop of CA glue can help keep these screws from backing out as frequently.

[maslin]

Stop reading books and go drive your truck.

The plastic thread screws back out, period. Replaced with a similarly sized machine screw they do not back out.

I did not consult any engineering manuals to determine this. I drove the crap out of my wraith and watched the screws fall out.

And I know how to tighten a screw, master certified mercedes shop foreman and all that stuff.