Help me select/discuss an Upper Front ball joint

So the LMP360 needs upper balljoints.  It's a challenge car so cost is important.  I don't want to mash the easy button and use a 3/4" rod end because they aren't cheap and it's also not the right application.  I am running a 3/4" rod end on the UBJ for the MG Midget however it does not take suspension loads.  For the LMP360  I will be running a pull rod type suspension so I can load the spring loads into the upper A-arm.  

For the lower I'm going to use stock subaru lowers.  These are a clamp in body, tappered stud type ball joint.  The body is mounted to the upright and the stud is mounted to the suspension.  As the Subaru is a strut type suspension they are mounted in an orientation that I do not think is appropriate to take spring loads. 

So my Lower ball joint is settled,  I'll cut the end off the stock A-arm and use the tappered sleeve to weld onto the end of my fabricated A-arm.  

So I'm on the hunt for upper ball joints.    I need something that is realtively easy to mount to a strut conversion adapter so smaller size is important.  It also needs to idealy come from an aplication where the joint takes suspension loads.  

I've considered the following (And have parts on the way for all of them).

Subaru lower Ball joint mounted on top ($4.50).  Pro's, cheap.   Con, Would be loading in compression.

Mazda Miata lower ball joint ($8 ).  Pro's, Designed to take suspension loads.  Con, A-arm mounting is bulky but simple to fabricate.  Not small o/a height is ~4".  Would load in compression.

Honda S2000 Lower ball joint ($12).   Pro's, Designed to take suspension loads.  Con, Would load in compression (May be able to design around this by getting cute with Upright design)

And the last option..  And this is the one that makes me make this post for discussion (well that and the running ball joints in compression question).  

Arctic Cat 0403-483 ball joint ($10).  This is used on the BIG 4 seater side-by-sides as the front upper and lower ball joints.  It is loaded with the suspension loads in compression.   

Pro's: TINY, designed for suspension loads in compression.  Con's: TINY relative to the other stuff.

So I ordered all of these  and they started arriving to day.  The first to arrive was the Arctic Cat ones.  

Here's what they look like relative to the Subaru.  They actually are very nicely constructed.  The fact that the stud is just a clamp vs taper is not really a concern as again, they are loaded in compression and it's the way they are on the Arctic Cat.  I took one appart to measure the stud.  The stud on these is 10.6 mm diameter,  The Subaru is 13mm.  The Arctic Cat Wildcat 1000 4 that these are used on is 1500lbs dry with a 900lb capacity so ~2500lbs.  The LMP360 even with a passenger should be 1700lbs.

They would be mounted 6.5" above the wheel axis (19" above the ground).  The Lower Ball joint is 3.5" bellow the wheel Axis, 9" above the ground.    For cornering the lower A-arm is loaded in compression, the upper in tension.  I believe the highest loading is actually due to Braking.      Also the distance from the spindle is greater so that will reduce shear forces during braking, and the LMP360 is not designed to go off of Sweet Jumps.  

Doing the math it looks like if I assume 2G's of braking 70% supplied by 1 front wheel I would still have a reasonable safety factor for the 10.6mm stud.  In fact it would be loaded to less of it's shear strength then the Lower Subaru joint due to the subaru joint being closer to the spindle axis.  

So which do I use?   Reverse loaded car parts that I 100% know can handle the sear forces?  The Small easy to mount powerports parts that can handle sweet jumps in a 2600lb UTV?  There are uprated 4130 units available for the UTV for $20-40 which is reasonable post challenge life, but I can't put $80 worth or ball joints on my challenge car.    

Does anyone know of another ball joint that would work?  I'd rather not run press in type joints as machining the correct tolerances on the sleeve is a bit beyond my capabilites.  I can get close for clamp in or retained parts.  I thought I was onto something with Nissan Frontier LBJ's as they use a threaded cup with a large nut to retain them until I learned they were almost 6" tall.  

Also while on the subject I have been tempted to run the front uprights upside down.  If I did that I will run pushrods and use either the Miata or S2000 ball joint.   This would restore then to their correct orientation.

If I ran the Uprights inverted, other then ensuring that the brake calipers are oriented such that they will still bleed what would be wrong with this?  

L-R

1. Subaru

2. UTV

3. 1994 S10 Blazer 

4. NA/NB Miata

5. S2000

Turns out the S2000 is just big and heavy.  The lightest automotive one is the Subaru, the 2nd lightest is the S10 and it has a grease nipple.  

I'm leaning towards flipping the uprights and running the GM ones.    But need to fully dimension the upright to see what KPI/Caster/Scrub/trail would be.

In reply to nocones :

I can't answer your question, but I keep seeing a lot of takeoff SxS suspensions on Marketplace & thinking some of them might be useful on a Locost(or similar).

Have you considered future repair/replacement? A Miata BJ should be pretty easy to find darn near anywhere, the Subaru one might be too? Though Subaru's in general don't seem to have an even distribution around the country. I have no clue about SxS parts though, does the FLAPS carry stuff like that yet, or is it dealer/internet only?

Running the uprights upside-down would make it really hard to get the steering axis anywhere near the tire's contact patch.

I based on what little I know of the design differences, I would be inclined to believe that primarily reverse loading a standard automotive ball joint will significantly shortened life and load capacity, although that would at least partially be countered by the lesser weight of the car. To exactly what degree though, I also have no basis for even making a guess.  The catastrophic failure of a tension ball joint loaded in compression should also at least be a 'soft' failure rather than the potential 'hard' failure of a compression ball joint loaded in tension. My gut is that I would be fine running one reverse loaded for the duration of the Challenge, but without knowing the internal joint construction would feel like a gamble beyond that. 

Honestly, even though it's relatively puny looking and the grip forces will be higher, I'm leaning towards the SXS joint for a car like this.  I'm sure that automotive joints have some additional constraints and requirements (long life, severe impact survivability, etc) that increase their size but don't really apply to the same extent here.

Have you not been able to find any other budget friendly automotive compression ball joints?

Intuitively I'd think that flipping the upright might cause more problems than it fixes, but certainly warrants a preliminary investigation to better understand the feasibility.

Bear in mind that "unloaded" ball joints do see regular tension loads if the stabilizer bar connects to the control arm.  The outside upright will be getting pulled down by the ball joint.

It's not ideal but it's also not horrible.

Duhhh, I'm just here to learn. Please continue.

If I recall correctly my Ford Granada I had in high school loaded the upper ball joint in compression. This pic shows the spring perch on the upper control arm (spring already removed).

Not to thread jack, but how do you measure taper on ball joints? I know 7degrees is the most common, but 50+bucks a pop makes me only want to buy one reamer.

No Home, I'm sure you have a plan for this. Please do share once you get there.

Here's some photos of what the upper ball joint looks like for a '77 Granada