Neck gussets

[Capslocker]

Hello guys

I Will soon start my first xs650 bobber built.
Today i am looking too cut off and Replace the neck Gussets with Own design.
the stock thickness of the gussets steel plates are approx. 3mm. Should I keep
the same thickness or can i use thinner steel plates?

 

[jd750ace]

I'm sure Yamaha didn't put any thought into how thick the material is.

 

[Capslocker]

Ok. Thanks for your answer. I just don't want to mess up the stifness of the front end!

 

[jd750ace]

I was being sarcastic. Without proofing your thinner metal, you will most assuredly lose stiffness. These bikes don't have the most rigid frame to begin with. Many sawzall types will tell you to just go ahead, but I'm a huge fan of function first.

 

[Capslocker]

Okay.

So you are telling me to, if i change it, to stick with the original thickness?

 

[jd750ace]

I certainly would, even if you incorporate a stiffening feature in your design. I've seen folks make a single out of heavy plate (3/16-1/4" stuff) and it looks good, but you do lose the load bearing stability of the triangulation.

 

[fredintoon]

FWIW, 3mm sheet is near enough to the frame tube thickness that it's easy to set up the welding robot.
You can get the same strength out of thinner material by making flanged holes and edges in it.

 

[wherearewe]

Dunno if this helps, but Hugh's neck gussets are thicker than the factory ones @3.3mm. The ones from monster craftsmen are even thicker. They are both more compact, and more of the gusset sits behind the tank. Hugh does one that is dimpled which looks great and adds strength.

 

[gggGary]

There is some serious engineering in gusset design, really, Hughs look well thought out.
Some basics;
you want two, welded to the sides of the tubes not one welded to the tube center.
Legs should taper out to thin tips, don't use a triangle shaped piece.
About the thickness of the tubing should be good, too thick is as bad or worse than too thin.

While the stock gussets are ugly they use good design, note how they aren't welded at the corners, they use curves and bending to distribute the loads, that's not an accident or cost cutting. The neck WILL flex, the gusset helps control and spread out the forces when it flexs. Concentrate all the flex to one or two areas and those areas will crack. A stiff gusset welded solidly to the tube center will cause the top tube to crack at the back end of the gusset "sooner or later".

 

[retiredgentleman]

"There is some serious engineering in gusset design", I totally agree Gary

The gusset area of the bike is probably the most important, structure safety design in the entire bike. It never ceases to amaze me, that the average chopper/bobber guy thinks he knows more than the manufacturer's engineers know.

I'd say that 95% of the saws-all gang don't even consider safety or handling effects, when they start hacking out factory frame parts. As long as it looks "pretty", they're happy.

 

[hard_y_rd]

I heard if you cut the gussets out and wrap with tinfoil, you're GTG. Lol.

 

[501Spanky]

"There is some serious engineering in gusset design", I totally agree Gary

The gusset area of the bike is probably the most important, structure safety design in the entire bike. It never ceases to amaze me, that the average chopper/bobber guy thinks he knows more than the manufacturer's engineers know.

I'd say that 95% of the saws-all gang don't even consider safety or handling effects, when they start hacking out factory frame parts. As long as it looks "pretty", they're happy.

Some of us have been doing design engineering for 20+ years and consider safety and handling very thoroughly thank you very much! I have designed literally thousands of gussets and you will be happy to know that I left my factory neck gussets alone.

I do not provide guidance on structural issues on a public forum because I can / will be held legally responsible for said advice.

Not everybody that rides a non stock bike is an idiot. Some are, but not all. JMHO.

 

[Capslocker]

I was actually inspired about hugh's gussets. I could go out and buy them but i rather make them myself. I'll be doing something like hughs but with my own drawings.

Thanks all for the reply's. I prefer to ask first and cut later.

 

[hard_y_rd]

As i said before, i'd be more worried about the guys cutting out the top motor mount. Now that sucker holds the neck in place.

 

[650Skull]

As i said before, i'd be more worried about the guys cutting out the top motor mount. Now that sucker holds the neck in place.

On my bike the top motor mount bar helps to stop twist/flex between the 2 vertical frame tubes in the front and the backbone.

The neck is held and braced by the backbone and both front frame tubes, + a shaped plate from both front tubes to the bottom of the neck. This is all strengthened and held by the above and by the gussets and the top motor mount bar.

 

[jd750ace]

Some of us have been doing design engineering for 20+ years and consider safety and handling very thoroughly thank you very much! I have designed literally thousands of gussets and you will be happy to know that I left my factory neck gussets alone.

OK, so that's 1 in a row! I believe ignorance is the fuel here most of the time. Some guys see stuff without gussets and assume they don't need theirs and whittle away. Spanky, you are an exception, as it's your profession.

As my dad told me, "Ignorance is not a sin, son. Ignorance can be cured, but stupid goes to the bone"

 

[retiredgentleman]

Some of us have been doing design engineering for 20+ years and consider safety and handling very thoroughly thank you very much! I have designed literally thousands of gussets and you will be happy to know that I left my factory neck gussets alone.

I do not provide guidance on structural issues on a public forum because I can / will be held legally responsible for said advice.

Not everybody that rides a non stock bike is an idiot. Some are, but not all. JMHO.

Sounds like you're in the 5% group.

 

[eddahenry]

If your modelling off the HHB gussets you should be right I just tacked up a set today , look the goods and the run at the side of the cross tune and at a angle across the down tubes so should spread the load nicely

 

[Nailbomb]

Whenever you get a bunch of people together agreeing on something its often called a echo chamber.

Please allow me to be a dissenting opinion.

No offense guys, but we're talking about a 40 or so year old bike that was 650cc and had 5 engine mounts. Not everything the factory included was necessary.

 

[jd750ace]

Whenever you get a bunch of people together agreeing on something its often called a echo chamber.

Please allow me to be a dissenting opinion.

No offense guys, but we're talking about a 40 or so year old bike that was 650cc and had 5 engine mounts. Not everything the factory included was necessary.

Engine mounts do more than arrest the conter torque of the motor bud. If you are a mechanical design engineer or perhaps racer who has ran one of these for said 40 years after pitching a couple of "extra" engine mounts or other frame features with zero problems, do tell. If it's JUST an opinion, thou hast done told us.