Greg, heres one...

What is the wall thickness of the side of a OEM VTR swing arm. To mount rear stand spools, will 020~.080" grip length rivet nuts be adequate?

 

Have 'em welded on. Don't weaken the swingarm by drilling into it. Go to PitBull's website and they have 'em for ~$16. I got some and will be installing these when I do the brace upgrade this winter.

 

One thing I know a little bit about is material strengths and applications. A properly drilled .333" diameter hole located near a "corner" of the side of the swingarm box will not "weaken" it. In fact, if you look at the top of the left side of swing arm there is an OEM rivet nut for the chain guard. Stresses imposed by the spools are minimal, and race teams routinely install spools in this manner. I tight fitting rivet nut actually reinforces the hole.

Welding a threaded "boss" to the side or bottom of the swing arm may actually be more risky structurally. The heat affected zone and "thinning" (required to achieve proper weld penetration) of the parent material caused by welding will create localized stress in the aluminum and also change its "condition" (i.e., temper). With the extruded tube (versus cast) used for the VTR swing arm, the "grain" and strength will definately be more affected by welding than a correctly positioned hole. Stress & strain in the top & bottom sides of the swing arm are usually greater than than on the sides (where only lateral forces come into play). The mechanical cleaning necessary to remove the clear coat and underlying oxidation before welding thins the section. Post-weld cleaning (and technically heat treatment), followed by application of a corrosion inhibiting coating is also required. Furthermore, unless the swing arm is removed, welding on the bike poses obvious fire safety hazards.

I actually recommend that you reconsider welding versus installing a rivet nut.

I will report on the wall thickness and rivet nut installation procedures when complete.

 

Skokie... how did this go?

 

Center of hole = 107mm from end of SA & 25mm from bottom. SA wall thkns = +.052". Install cadium plated steel ribbed rivet nut, counterboring bearing side of alum spool for rivet nut clearance & shimming bottom half of where spool bears against SA due to slight radius on sidewall of SA. See photo

 

 

oops

 

I just bought a stand with pads, problem solved.

 

I'll be having the extra swingarm welded with the spool adapters and 900RR brace as soon as I can get up with Hammer7205. He does a lot of high quality professional welding and I don't see this being a problem for him.

I look at it this way: A hole is a stress riser when applying a bending force, especially when there is less material there. It may seem relatively minor but you never know when a crack might propagate from that point. It all depends on the fracture toughness (Kic) of the material. I'd rather have a small section of the swingarm slightly more brittle than the rest than have a hole.

Look at the whole swingarm. There's welds all over it. I don't think one more will hurt. Also, this swingarm will be powdercoated after all is said and done. The baking from this process should relieve a good portion of the residual stresses created by the welding process.

 

Pre-heating and post-annealing (conditioning) are done at the factory, its not easy to find out what alloy was used and its condition (i.e., T6). Some alloys have been developed that "age" condition when they on on the way over on the boat! Careful welding, working both sides, cooling cycles, gas mix, temperature, filler rod, use of a jig, etc all are factors, and its sounds like Hammer7205 has a handle (n0 pun) on this. Believe me when I tell you a properly drilled and sized (reamed or stoned) small hole where it is located will do no harm. There are holes & rivet nuts in the arm already I believe for the brake hose or whatever. I have designed many a structural member with all sorts of much larger holes without needing to reinforce them. Crack propagation is thus highly unlikely, clearance with my 2bros cans has been an issue. I'm not saying NOT to do it, as people successiveyl do so all the time. You can even weld while on the bike but it is not recommended or as you are doing on the bench. You are however making an assumption regarding effect of the powder coat cure heating cycle.

 

380-400°F for 10 minutes will have some minor aging affect on the metal, but not much I agree.

Do you really think that the whole swingarm is welded together and then heat treated as a whole? I think the part would severely deform from the process, don't you? Ever put a brand new piston in an oven and heat it for a few hours? Measurements before and after are drastically different.

Bret, I'm starting to come around a little bit on the hole argument but I still don't think welding will be an issue if done correctly.

 

 

Touche!

 

I am hoping to resurrect this old thread but in English this time. I have no idea what the hell you two are talking about with reference to heat properties and stress points but I really want to add some spools so I can use the shiny new stands I got for my birthday.

Can you please let a retard know the best and easiest way to accomplish this goal? Please keep in mid the work RETARD while explaining the process. Thanks for the help guys….

 

Skokievtr has one solution here for you... https://www.superhawkforum.com/forum...5&postcount=15

 

Thanks for the reply Tweety!! I did read that post but was unsure of what he meant by "Counter Boring" the back of the spools. In the end, I think I an just going to go with a rod through the axle. Not only do I not have the tools like the rivet gun but I am still nervous about the whole concept of drilling into the swing arm.

As for not being able to remove the tire or abjust the chain, I also have a motorcycle lift I can use, much like they do in the shops. I was really only planning on using the stands over the winter for long term storage to take the weight off the tires.

 

Well, counterboring is that you drill a few mm with a larger drill size so that the small metal rim of the rivet nut can slide in and the spool itself is resting on the swingarm, with no gap (if there is a gap it can bend when you lift the bike)...

If you want to I have a OEM swingarm with welded on spool mounts that I'm not going to use now that I have my new swingarm on... The shipping from Sweden might not be too fun though...

 

hawkrider - did you weld the bosses? i hope not.

skokie - you said exactly what my friend larry said. and larry is a solid and crdible source of information - he just retired after 30 years of welding instructing at the local community college. i asked larry about welding bosses on the bottom of the sa but he had concerns regarding cracks adjascent to the welds.

skokie, how are the riv nut spools?

 

While running QC at a metal fab shop we regularly installed rivnuts through the wall of box tubing. When installed per factory recommendations they offer amazing strength. Not sure I'd sit on the bike while it was on the stands with just the rivnut.

As for the effects of welding, jigging the weldment seemed the only way to minimize the degree the tubing "walked" due to the heat from the weld. It seems unlikely the heat generated by welding a rivnut would cause the tubing to walk much but I'm still planning on skipping the welding. Not worth the aggravation if it goes poorly.

 

I actually haven't done anything yet. The project still sits in the garage.

 

Just fine. The other day, I was adjusting my steering head bearings and had the bike on my dolly lift under the engine sump and well as on the rear stand (using the spools of course). For some reason the lift was tipping the bike to the right side so only yhe right spool was engaged (bearing) on the rear stand and the left spool not! The one spool support the back of the bike no problem. I've also sat on the bike when it was on the rear stand (without bouncing), and the spools held up fine. Remember, these are 1/4" (6mm+)bolted spools. I would go to 8mm if I was to do it again though.