Square to round swingarm
Square to round swingarm
There was a post on this but I cant find it on search.
What must be changed out to go from a square SA to a round SA on a frame that came with a square one?
I have a round one Id like to place on my 1975 SA frame
What must be changed out to go from a square SA to a round SA on a frame that came with a square one?
I have a round one Id like to place on my 1975 SA frame
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Re: Square to round swingarm
All you will need are axle adjusters, 13" shocks, and the correct axle to go with your wheel hub....
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Re: Square to round swingarm
Actually a bit more as no round swingarm ever came with other than drum brakes, so depending on the wheel/brake combination you want to run there could be fabrication involved.
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Re: Square to round swingarm
If you have to fabricate something, the torque stay which provides anti-rotation for the backing plate (drum) or caliper (disc) should not anchor to the swing-arm, but run forward in tension and attach to the chassis itself and rotate on the attachment point sufficient to allow free movement throughout the wheel's range of suspension travel .
This prevents brake torque from changing the rear suspension load.
I've written more comments on my site here: http://victorylibrary.com/brit/chassis-2.htm#torque
This prevents brake torque from changing the rear suspension load.
I've written more comments on my site here: http://victorylibrary.com/brit/chassis-2.htm#torque
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Re: Square to round swingarm
Kitabel,
What you say is technically correct, and with proper execution improves swing arm function to the point where it prevents/reduces rear wheel hop under extreme front & rear braking (when a lot of weight comes off rear tyre). Which is a major reason race bike builders invented it and use it
But IMO, on a 65up BT, in the real world, very few riders would ever ride so aggressively as to ever need a rear brake caliper, or drum backing plate floating on axle & anchored by in-tension, rose jointed parallelogram link to frame. Many more riders would simply not want the unused complication, one-off fabrication and increased maintenance. To get a real benefit, everything would also have to be way lighter than H-D parts.
With caveats, sticking with the lighter 73 up swing-arm and stock brake anchor might be slightly more beneficial through the twisties,
A BT is what it is, why go to a lot of trouble to turn it into a dog's breakfast?
But whatever mods float your boat.
If you are going Pan-Shovel Bagger road racing and the rules allow, could give you an edge, until everyone else does it.
Nifty
What you say is technically correct, and with proper execution improves swing arm function to the point where it prevents/reduces rear wheel hop under extreme front & rear braking (when a lot of weight comes off rear tyre). Which is a major reason race bike builders invented it and use it
But IMO, on a 65up BT, in the real world, very few riders would ever ride so aggressively as to ever need a rear brake caliper, or drum backing plate floating on axle & anchored by in-tension, rose jointed parallelogram link to frame. Many more riders would simply not want the unused complication, one-off fabrication and increased maintenance. To get a real benefit, everything would also have to be way lighter than H-D parts.
With caveats, sticking with the lighter 73 up swing-arm and stock brake anchor might be slightly more beneficial through the twisties,
A BT is what it is, why go to a lot of trouble to turn it into a dog's breakfast?
But whatever mods float your boat.
If you are going Pan-Shovel Bagger road racing and the rules allow, could give you an edge, until everyone else does it.
Nifty
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Re: Square to round swingarm
Just want to add: "with no real improvement" after dogs breakfast.
Nifty
Nifty
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Re: Square to round swingarm
Thanks, I'll try not to help in future.
Please: show us something you wrote.
BTW: stock on most British bikes for the last 70 years...
Please: show us something you wrote.
BTW: stock on most British bikes for the last 70 years...