Alex's Big Block Chevy Locost

[Shevalev]

No this is my final version. These are performance frictionless ball joints and they are not for street applications. These have been used primarily for circle track applications and they run a setup just like this one. Here i made a calculation to find the axial strength of this joint. Strength= .78 [ ( E + .176 T )² - E² ] * X
E is the ball diameter
T is the housing width
X is the allowable stress of mild steel
I plugged in all the values....
Strength= .78 [ ( 1.438 + .176 *1.811 )² - 1.438² ] * 52000 = 41301.33 PSI

41301 PSI is pretty close to the yield strength of steel. In addition, the ball of the stud has a race on the top side and a strength moulded polymer cup on the bottom alongside with a oil impregnated steel spider. I dont see how this could fail under axial loading. Here is a picture of another race car having this type of setup. Let me know your thoughts about this.

[Bent Wrench]

The top is fine, that different joint spreads the upper arm legs and provides more room to stand up the coilover for a better angle.

Not as sexy looking as the joint you pictured but highly functional especially where the coilover is concerned.

The upper joint you pictured would work fine with a cantilevered coilover. (inboard coilover)

The new picture does not show the lower joint, that is the position I was most concerned with originally as the lower joint carries the weight in that type of layout.

[Shevalev]

okay sorry for the wrong image. Here is one more that has the lower joint clearly shown.

[horizenjob]

In that last picture it looks like there is a lot of bending load on the clevis from the coilover. Is that good enough to take a couple of thousand pounds on a bump?

[Shevalev]

Yes, i guess there is quite a bit of load on those clevises. I am currently working on this setup in solidworks to see how this will hold up. Ideally i am aiming for a load of 4000 pounds and a yield strength at 6000 pounds. I talked to QA1 and they said that this setup is used in many circle track cars... I have seen this setup personally in a number of cars. In addition, there isnt much give that the clevis will have which makes it fairly solid item which is made out of chromoly. The threads are 5/8-18 on the stud and the clevis and the circle track cars use half inch on top and 5/8 on the bottom. Those cars weigh around 3500 lbs so it isnt even close to what mine weighs. Are you having any doubts about this?

[a.moore]

The lower arm in your last pick is under constrained. Friction from the bolts is all that prevents the ball joint plate from pivoting around.

[Bent Wrench]

I talked to QA1 and they said that this setup is used in many circle track cars...

For the upper joint only. Never in a weight bearing lower position.

[Shevalev]

Do you think this bottom joint setup would be acceptable for racing?

[Bent Wrench]

okay sorry for the wrong image. Here is one more that has the lower joint clearly shown.

Unsafe at any speed! Please impress on the owner of that car to correct that design before venturing out on the road.

Due to the loads from the shock being inboard of the joint it will try to twist the inside edge of the joint downwards under compression and tip it up on extension.

The clevises were never intended for any lateral, axial, or twisting loads. A clevis is only good for pushing or pulling inline with the rod.

Even though the rear rod is welded to the plate it is not strong enough and out of line with the loads imposed by the shock.

You will find in every joint holder of that style they are used in an upper position
http://www.speedwaymotors.com/Upper-Ball-Joint-Collar-Ring-Speedway-Jet-DW9,3227.html

He needs a lower arm like this design, where the joint shock and arm are all inline so that no twisting forces are applied.
http://www.speedwaymotors.com/AFCO-20026R-1-5-8-Rod-End-Round-Tube-Lower-Arm-16-5-8-Inch-LH-Screw-In,24526.html

[Bent Wrench]

Do you think this bottom joint setup would be acceptable for racing?

Absolutely not.

[Shevalev]

thank you guys for catching me at the the right time before i made any mistakes. So would this setup http://www.speedwaymotors.com/AFCO-2002 ... ,24526.htm have a clevis attach to it also? I see the holes near the ball joint collar ring so i am guessing something should attach to it. This tube would be replacing the lower collar ring and 1 a-arm tube that i have now, but still keeping the clevis and the rear a-arm tube? is that correct?

[Bent Wrench]

Here is a kit to build a custom length arm

http://www.speedwaymotors.com/AFCO-20028RM-1K-Lower-Control-Arm-Kit-3-4-Press-In-Solid-Rod-End,40167.html

or you can buy/make all the pieces to build your own.

And always select a ball joint intended for the lower position (weight bearing)
http://www.speedwaymotors.com/Shop/Suspension-Arms-Bushings-and-Accessories-Ball-Joints/12.html?facet=LA_Location_Type:Lower
I stress this because a lower joint is designed for that type of load and is less likely to pull apart on impact.
You may get away with other designs (heck, Dwarf cars are using steering tie rod ends for ball joints!) but Im not going to recommend that for the street.

I would also add that on your example using the rod end for an upper joint that the shock is laid over at far too steep of an angle.
I would use the 4 bolt upper joint to provide more room to stand the shock up.
Or design an inboard shock setup with a rod from the lower arm to a cantilever attached to the shock.

[Bent Wrench]

thank you guys for catching me at the the right time before i made any mistakes. So would this setup http://www.speedwaymotors.com/AFCO-2002 ... ,24526.htm have a clevis attach to it also? I see the holes near the ball joint collar ring so i am guessing something should attach to it. This tube would be replacing the lower collar ring and 1 a-arm tube that i have now, but still keeping the clevis and the rear a-arm tube? is that correct?

Yes it will use a rod end at the inboard location, the arm installs at a right angle to the thrust line and with the shock inline to the swing axis. A strut rod attaches with a clevis to the tab on the arm and forward to a rod end to the chassis to triangulate the lower arm.

Here is another prefabbed arm
http://www.jegs.com/i/Alston-Race-Cars/064/181423/10002/-1

Here is that arm installed
http://www.jegs.com/i/Alston-Race-Cars/064/102012/10002/-1

Another example
http://www.sterlingkitcars.com/members_n_forums/shocks-suspension/115-pinto-front-end-type-1-chassis.html

Those finished AFCO arms are too long for a Locost.

Or fabricate a lower A arm like shown here
http://www.gwellwood.com/project-cars/the-lethal-locost/lethal-suspension/

[Shevalev]

i am definitely thankful for all of your advice. Is it ok to not have this http://www.jegs.com/i/Alston-Race-Cars/ ... 3/10002/-1 at a right angle to the frame? Can i use my same suspension mounting points and just cut off the shock mounts and reposition them? or would you recommend for me to just redo the mount and make it proper?

[turbo_bird]

i am definitely thankful for all of your advice. Is it ok to not have this http://www.jegs.com/i/Alston-Race-Cars/ ... 3/10002/-1 at a right angle to the frame? Can i use my same suspension mounting points and just cut off the shock mounts and reposition them? or would you recommend for me to just redo the mount and make it proper?

Not without cutting the pivot off the end of the tube and either welding it back on at the correct angle or weld in a bung and use a rod end.
Kristian