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 Post subject: PooKs trike build
PostPosted: July 5, 2008, 5:59 pm 
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Joined: March 16, 2008, 4:49 pm
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Location: Richmond Kentucky
Well I finaly got back to work on the "V" I started on the side pods that will hold the two 5 gallon cells and located the batteries as far forward as I could.
Cant wait to stop bending and welding and start on the body work! :D
PooK
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PostPosted: July 5, 2008, 8:10 pm 
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Looks great Pook. I can't wait to see what you have planned for the body. I've seen control arms bend when loaded with a swaybar that far inboard, but you may be able to pull it off no lighter than your rig is.

Post a pic or two of how that drivetrain works if you don't mind.

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PostPosted: July 5, 2008, 8:40 pm 
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Location: SoCal
Yeah that makes me nervous, too. What size tubing is the lower control arms made of?

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PostPosted: July 5, 2008, 9:51 pm 
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1.25"od .120 wall DOM, uppers are 1.25"od .095 DOM.
Ill post up some drive pics when the hubs finally get done :cry:
PooK


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PostPosted: July 5, 2008, 11:27 pm 
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Boy that's some beefy stuff, you'll probably be fine.

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PostPosted: July 6, 2008, 10:12 am 
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yeah, I know its overkill. I suspect the down links will fail before the arm bends, but for the slight weight penalty-vs-peace of mind on a three wheeler (that I'm sure will NOT handle well if something should happen to one leg of the tripod) it seemed worth it. :wink:
My bigger concern is that the lower ball joint, due to a error in my design sits on TOP of the lower arm, its a three bolt ford style and I'm using grade 12 10mm fasteners but.....the stress is still there. whats your guys input?
PooK
In the early pic below the joint is under the arm but now needs to sit on top to get the susp correct.
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PostPosted: July 6, 2008, 3:52 pm 
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Location: S. Florida
pook wrote:
[snip]
My bigger concern is that the lower ball joint, due to a error in my design sits on TOP of the lower arm, its a three bolt ford style and I'm using grade 12 10mm fasteners but.....the stress is still there. whats your guys input?
PooK
In the early pic below the joint is under the arm but now needs to sit on top to get the susp correct.

My CMC designed suspension uses a very similar looking ball joint with grade 8.8, 10mm bolts with 17mm hex heads. So far, so good.

7/8/08
I've since discovered the ball joint comes from a ~1983 VW Golf Mk1.
By the way, I -really- like the way your trike is turning out. Good construction etc.


Attachments:
File comment: This joint has a cast iron housing but looks like yours. Otherwise I don't know what car it came from.
ball-joint.jpg
ball-joint.jpg [ 11.13 KiB | Viewed 26264 times ]

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Last edited by olrowdy_01 on July 8, 2008, 2:28 pm, edited 2 times in total.
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PostPosted: July 6, 2008, 4:29 pm 
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cool, thanks! makes me feel a little better.
I finished the pods.....Or as my 6 year old would say "the bat wings" he may be right :cry:
Im gonna have to ponder them a bit more, I wanted the F1 side pod look but not sure I got this one right.
PooK
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PostPosted: July 6, 2008, 6:48 pm 
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Pretty cool! I like the side pods. Usually side pods make it tough to get into the vehicle but you can just enter behind the pods. One of the good things about 3 wheels.

What steering box and what front uprights did you use?


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PostPosted: July 6, 2008, 9:17 pm 
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I was going to run them on back till the same thing dawned on me about climbing over.
The rack is Porsche 911/914/912 they are center steer cars.
The uprights are Ford mustang II's with 2 inch dropped axles.
The rotors and brakes are Chevy, the tie rods are Volvo and Ford, the sway is a Suzuki and on and on......The guys at the shop are scared to leave their cars unlocked at work now!!!!! :roll:
PooK


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PostPosted: July 6, 2008, 9:23 pm 
I love this build, it looks very well thought out. But, I have a question about your swing arm: Are you going to add additional material between the two sides of the swing arm to prevent it from twisting around the cars roll axis (one arm going up, the other arm going down)? Even motorcycles join the two sides of the arm and they don't see that much side loading from the bottom of the wheel (only from bumps while leaned over turning). For example see this picture of a Suzuki GSXR-750 Swing arm:
Image

For more interesting examples of motorcycle swing arms I found this page. They all have lots of additional material to prevent twisting.

You shouldn't count on the ends of the axle to provide the kind of stiffness you will need.

[edit] I have some time now so here is an idea of the loads that swing arm may see:

Assume you finished car weighs 1500lbs in road going trim, with driver. 50/50 weight distribution, and going through a 1G turn. These weights might be high, but the cornering estimate is probably low for modern sticky rubber.

The O.D. of you rear tire is probably close to 24", or 1 ft radius. Around said 1G corner the rear tire will have to provide 750 lbs of lateral force for its share. That lateral force acts at the tire patch, 1ft away from the axle, which is where the side loads get transmitted to the swing arm, and from there to the rest of the car. So your swing arm is going to be twisted with 750ft-lbs of torque. Without any additional torsional stiffness in your swing arm all of that torque will be opposed by the ends of the axle that are bolted through your swing arm. 750ft-lbs is a LOT of torque. You could probably do some serious damage to your swing arm in its current configuration.

Now this line of thinking ignores the dual shocks you are using, which should reduce this effect over what a monoshock sportbike swing arm would see, but it still bears thinking about.


Last edited by enderw88 on July 8, 2008, 2:57 pm, edited 1 time in total.

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PostPosted: July 6, 2008, 11:26 pm 
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Location: Richmond Kentucky
Thanks.
Here is an early pic before the gussets were in on the trailing arms, the tube in front of the tire is 2 inch .125 wall and runs through both arms and welds to both the inner and outer of each side then its is reinforced with 3/8th plate.
the arm swings on 1 inch chromo heims (50k radial and I’m guessing about 5k lb side load) each, they hold a 1 inch axle that holds a 3 bearing roller hub that holds the drive sprockets...(a hay bailers got nothin on me!!) the heims adjust backwards to tension the engine chains and the wheel adjusts to tension the drive chains. the pic above just shows some 1 inch bolts that Im using while the hubs are being finished so its had to see.
but to make sure it doesnt twist I jacked the chassis up with the engine inplace by each arm to check my spring rates (that I totally ordered wrong) and no twist at all was seen.
Thanks for the feed back Ill get some more pics of the rear when All the pieces start showing up.
PooK

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PostPosted: July 8, 2008, 1:54 pm 
Cool. I missed that cross piece in the previous photo. Glad you caught that first.


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PostPosted: July 8, 2008, 2:22 pm 
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No prob, I may look into more bracing, I didnt know the loads were that high, thanks for the numbers though!
PooK


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PostPosted: July 8, 2008, 2:53 pm 
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Joined: April 23, 2006, 8:26 pm
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Location: SoCal
pook wrote:
My bigger concern is that the lower ball joint, due to a error in my design sits on TOP of the lower arm, its a three bolt ford style and I'm using grade 12 10mm fasteners but.....the stress is still there. whats your guys input?

You have it way out near the end of the arm which is the right thing to do. I think you'll be fine.

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Midlana book: Build this mid-engine Locost!, http://www.midlana.com/
Kimini book: Designing mid-engine cars using FWD drivetrains, http://www.kimini.com/book_info/


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