New adjustable a A-arm
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From: Montana
New adjustable a A-arm
Here's a sneak peak of my winter mod. I thought some of you might be interested. It's still changing, but the (ME) numbers are sound.
features:
almost identical weight
slightly higher sprung weight
camber scale (to match left right w/o gauges)
max 2 degrees negative camber over stock
3 levels of safety
Four bolts are massive overkill, but I don't ever want it to slip. The final version will be plated, not painted as shown.
prototypes coming.
koryo
features:
almost identical weight
slightly higher sprung weight
camber scale (to match left right w/o gauges)
max 2 degrees negative camber over stock
3 levels of safety
Four bolts are massive overkill, but I don't ever want it to slip. The final version will be plated, not painted as shown.
prototypes coming.
koryo
Last edited by koryo; Feb 7, 2003 at 02:27 PM.
.
Looks GREAT! As to it's adjustability, how much positive camber will it allow? Lowering the Z automatically adds negative camber, so can these arms compensate? Also, will they allow any caster adjustability?
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Joined: Oct 2002
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From: Montana
>how much positive camber will it allow?
stock camber to 2 degrees additional negative camber.
>Lowering the Z automatically adds negative camber, so can
>these arms compensate?
no, but i don't feel that there is enough camber to begin with. lowering the car won't add enough to solve the problem. if it does, i'll change the dimensions to compensate.
>Also, will they allow any caster adjustability?
no plans.
i like the steering feel and feedback, i just want a more balanced cornering setup.
koryo
stock camber to 2 degrees additional negative camber.
>Lowering the Z automatically adds negative camber, so can
>these arms compensate?
no, but i don't feel that there is enough camber to begin with. lowering the car won't add enough to solve the problem. if it does, i'll change the dimensions to compensate.
>Also, will they allow any caster adjustability?
no plans.
i like the steering feel and feedback, i just want a more balanced cornering setup.
koryo
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Sorry, I'll pass......
I've bought arms that allowed both, and this set-up is not for me. I need more.
Being an ***.....bend a ruler both ways, which way is more difficult/stiffer? I'm referring to the bars attached to the bent tube. LOOKS like a weak point.
I've bought arms that allowed both, and this set-up is not for me. I need more.
Being an ***.....bend a ruler both ways, which way is more difficult/stiffer? I'm referring to the bars attached to the bent tube. LOOKS like a weak point.
Are you using the COSMO Lite ver w/ 2003 or the full version?
Just curious how many SWX users we've got here.
Are you going to use a stamped piece to contain the adjuster or planning on a machined piece?
Also what sort of loads have you designed it to handle? FS?
Just curious how many SWX users we've got here.
Are you going to use a stamped piece to contain the adjuster or planning on a machined piece?
Also what sort of loads have you designed it to handle? FS?
Last edited by UnderPressure; Feb 7, 2003 at 06:08 PM.
Thread Starter
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Joined: Oct 2002
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From: Montana
>Being an ***.....bend a ruler both ways, which way is more
>difficult/stiffer? I'm referring to the bars attached to the bent
>tube. LOOKS like a weak point.
True, but in this case it's more like two rulers sandwiching two erasers. it makes for a rather strong assembly. it's weak point is due to buckling (see pic. point b). but this is all moot because an upper a-arm, like this, only needs to resolve loads in two dimensions. it's free to move up and down (z arrows in pic) but is constrained in the x and y axis (parallel to the road).
>Are you using the COSMO Lite ver w/ 2003 or the full version?
both
>Are you going to use a stamped piece to contain the adjuster
>or planning on a machined piece?
the silver part that holds the spherical bearing is machined aluminum and is sandwiched by two symmetrical sheet metal parts.
>Also what sort of loads have you designed it to handle?
we figured that the largest static load would be under full braking. so we used 1g at the wheel. which should be double the possible static load in the first place. we are still debating what the maximum dynamic load would be. i'm comfortable with the design because we matched the area moment of inertia to the Z's forged aluminum upper a-arm.
>FS?
do you mean FOS? (factor of safety) approximately 2.
koryo
>difficult/stiffer? I'm referring to the bars attached to the bent
>tube. LOOKS like a weak point.
True, but in this case it's more like two rulers sandwiching two erasers. it makes for a rather strong assembly. it's weak point is due to buckling (see pic. point b). but this is all moot because an upper a-arm, like this, only needs to resolve loads in two dimensions. it's free to move up and down (z arrows in pic) but is constrained in the x and y axis (parallel to the road).
>Are you using the COSMO Lite ver w/ 2003 or the full version?
both
>Are you going to use a stamped piece to contain the adjuster
>or planning on a machined piece?
the silver part that holds the spherical bearing is machined aluminum and is sandwiched by two symmetrical sheet metal parts.
>Also what sort of loads have you designed it to handle?
we figured that the largest static load would be under full braking. so we used 1g at the wheel. which should be double the possible static load in the first place. we are still debating what the maximum dynamic load would be. i'm comfortable with the design because we matched the area moment of inertia to the Z's forged aluminum upper a-arm.
>FS?
do you mean FOS? (factor of safety) approximately 2.
koryo
Last edited by koryo; Feb 10, 2003 at 02:10 PM.
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From: Wisconsin
Damn...you guys are making someone with a college education wish he had spent more time in class rather than the bars...specifically me! What the hell do you do at work if this is a pastime...build nuclear reactors or something?
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From: Santa Cruz, CA
I'm coming from a robotics and machine design background here, but I've worked on projects where I've done suspension design before, and one thing that we did was design for deflection instead of strength. Typcially the design was required to be much more robust based on its deflection requirements, and by the time we met those goals, the strength was far greater than required.
I was therefore curious if your FEA analysis was deflection based or strength based. Have you measured and modelled the OEM part and run an analysis on it to see how your design compares? What kind of fatique limits are you estimating? (OK, now I'm just throwing out crap that we had to learn in school - just remember that the aluminum will continually weaken...so maybe in the year 30000000 that insert will crack - I have an Aluminum mountain bike so right before a huge downhill my friends (with steel bikes) always tell me that mine may be about to fail.)
Also, have you taken into account the side loads generated during cornering? How about combination cornering and braking (even though that technique is not advisable in racing)? I wouldn't be surprised if a person with race tires was able to break significantly higher than 1G (In my Automobile Magazine, the stock Z brakes @ 1.12G with street tires)
Overall, the design looks pretty cool. Very clean and simple, which is always a plus. I like it.
-D'oh!
I was therefore curious if your FEA analysis was deflection based or strength based. Have you measured and modelled the OEM part and run an analysis on it to see how your design compares? What kind of fatique limits are you estimating? (OK, now I'm just throwing out crap that we had to learn in school - just remember that the aluminum will continually weaken...so maybe in the year 30000000 that insert will crack - I have an Aluminum mountain bike so right before a huge downhill my friends (with steel bikes) always tell me that mine may be about to fail.)
Also, have you taken into account the side loads generated during cornering? How about combination cornering and braking (even though that technique is not advisable in racing)? I wouldn't be surprised if a person with race tires was able to break significantly higher than 1G (In my Automobile Magazine, the stock Z brakes @ 1.12G with street tires)
Overall, the design looks pretty cool. Very clean and simple, which is always a plus. I like it.
-D'oh!
Last edited by D'oh; Feb 10, 2003 at 08:01 PM.
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