Need advice on bracing my swingarm

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mixalive
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Need advice on bracing my swingarm

#1 Post by mixalive » Fri Feb 27, 2015 3:32 pm

I want to have a brace welded onto the FZ600 swingarm on my RZ350 with 1" OD 6061. Should I use .125" or .250" thickness?
RZ350 with FZ600 swingarm, FZR600 wheels, front end and FZR400 bodywork.

hondaror
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Re: Need advice on bracing my swingarm

#2 Post by hondaror » Fri Feb 27, 2015 3:37 pm

It won't really matter much. I'd use square tubing, not round. I'd also go with the lighter. Once the structure is built and welded on the swinger will be much stiffer.
Rory
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Redline Junkie
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Re: Need advice on bracing my swingarm

#3 Post by Redline Junkie » Fri Feb 27, 2015 5:10 pm

Do you really need to brace a FZ swinger on an RZ??
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Re: Need advice on bracing my swingarm

#4 Post by hondaror » Fri Feb 27, 2015 6:11 pm

I'd like to do mine. Stiff is good. After tracking TZ250s, there is a huge appreciation for a stiff bike that handles.
Rory
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Re: Need advice on bracing my swingarm

#5 Post by solo 2 » Fri Feb 27, 2015 8:52 pm

First of all don't worry about wall thickness except for weight, go for the biggest OD that will fit and look right, stiffness has more to do with the tube size. Also if it's not correctly triangulated with at least one brace point somewhere near mid-point of the swinger it's essentially useless. If you're not riding the bike near the edge of it's capabilities stiffness is not really an issue, appearance only(good enough reason).

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Re: Need advice on bracing my swingarm

#6 Post by mountaincycle » Fri Feb 27, 2015 10:12 pm

I can't remember who posted this braced FZ600 swingarm but its does look strong.
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fz600 swingarm.jpg
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hondaror
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Re: Need advice on bracing my swingarm

#7 Post by hondaror » Fri Feb 27, 2015 11:04 pm

No offence to whoever built that one, but it's not pretty.
Rory
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Re: Need advice on bracing my swingarm

#8 Post by JonW » Sat Feb 28, 2015 4:55 am

no Rory, its plain ugly... but I think you meant that really... LOL!

Why do you need to brace that arm in the pic? it would be fine without... since its strong enough you could use anything thinner and prettier and still 'improve' it...
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waltmil
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Re: Need advice on bracing my swingarm

#9 Post by waltmil » Sat Feb 28, 2015 7:26 am

I can think of another reason besides ugly to not do that. If you weld aluminum, you take out any heat treatment so your piece might not be as strong as it was when you started unless you can properly heat treat it after you finish.
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Re: Need advice on bracing my swingarm

#10 Post by hondaror » Sat Feb 28, 2015 12:20 pm

Well someone took the time to construct it. Should have tried to copy a nice looking unit, paid attention to the lines of the bike, with regards to the brake arm length.

Heating hardened alloy anneals, but are they hardened in the first place? Does anyone know?
Rory
2 1984 RZ350s
1985 RZ350
9 1986-1990 RZ350s
2000 ST2
2005 749
2005 749 with 999 engine

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Re: Need advice on bracing my swingarm

#11 Post by solo 2 » Sat Feb 28, 2015 1:20 pm

If you are a competent TIG welder and use the proper filler material there will be some localized loss of strength, but keep in mind the weld itself in aluminum will always be the weak spot. Aluminum will gain back some of it's strength just sitting at room temperature for a few days after welding. I've talked to our welders at length about welding aluminum and none are worried about the after weld strength.

Annealing T6061 aluminum is a very specific process and ends with it being immediately quenched in water at about 1000 degF. Almost all extrusion will be 6061.

With cast aluminum all bets are off unless you know the alloy and have experience though most are weldable.

With this I'll add that many people worry too much about tensile strength, it's the modulus of elasticity that matters in most cases and that does not change much across all types of material groups. All metals of the same group start to deform at the same point only the yield point changes due to tensile strength.

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mixalive
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Re: Need advice on bracing my swingarm

#12 Post by mixalive » Sat Feb 28, 2015 3:09 pm

Thanks for the great info, Guys.
RZ350 with FZ600 swingarm, FZR600 wheels, front end and FZR400 bodywork.

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