In 2005 toyota recalled 750,000 4r's over ball joint failures. The typical 1" uniball that most manufacturers use have a loading strength of nearly 100,000lbs, ball joints don't even come close.
The primary reason for upgrading uca's is to achieve more caster. Jba advertises their arms are capable of getting to 3° whereas conventional wisdom around here is that upwards of 4° may be required to run 285's without doing a BMC. I'm not trying to shit on jba, if I were doing it again I may have gone that route, but I'm super happy with my Total Chaos uppers a d lowers
Ball joints can fail. Those were lower ball joint failures, not upper and they failed as a result of a machining error that scarred the wear surface and over 100+k miles they wore out to the point that some came apart. But it was also a problem in design where the old lower joint was inverted from how the 5th gen is designed so it was pulling apart, not inherently pushing into the socket. The 5th gen LCA/spindle design fixed that even if you were still using the old style ball joints.
You can see why the old style was a big engineering failure.
Old:
New:
The 1" uniball may be stronger in an absolute sense, but the're not stronger in this application because in both cases they'll be mounted in single shear and the through-bolt of the unball is typically weaker than the ball/stud in the balljoint. Given that it will be a pure lateral loading - the weakest point of the ball joint assembly is stronger than the weakest point in the uniball assembly.
The second issue is that uniballs don't last very long. And that's really the issue for me. Both are strong enough for the UCA. But one lasts many times longer. Uniballs are open joints typically with no lubrication other than a small PTFE liner. And they have no internal adjustments for wear - so as soon as they wear even a relatively small amount they become loose, have more dirt intrusion, and accelerated wear. The result is short service life. Ball joints are sealed and lubricated joints that are typically internally spring loaded to adjust for wear as they age without becoming loose. The JBA joints have external threaded adjusters to preload the ball joint as it wears. So they last many times as long in normal use. If Toyota used uniballs in its suspension that need to be replaced every 50k miles - it wouldn't go very well. A uniball on the lower joint might not even last 50k miles. The uniballs in my fox shocks only last about 15-20k miles.
The plus side is that uniballs are cheap, easy to swap, and strong. They usually come with weld-in cups that makes fabrication pretty easy. And they can be mounted in double shear configuration with 360* free rotation. So for a racing application they're great. For a daily driver I wouldn't choose them if I didn't have a specific need for them.
FWIW I've measured dimensions of the JBA arm compared to the stock one and they move the center of the ball joint 22.5mm. That translates to approximately 5-6* of caster. So if you had 0 caster with the OEM arm, you should have 6* caster with the JBA before getting it aligned. It's actually a bit of a problem if you want to run less than 3" lift, you can end up with too much caster. Maybe JBA has backed off a bit on that??
Here's a picture of a JBA ball joint vs a tubular arm with an OEM size ball joint. The JBA joint is stronger than it needs to be. But it is pretty heavily built.
In the pic I plotted the location of each arm. Green is OEM, Blue is Tough Country and Red is JBA. The TC arm adds approximately 5mm of longitudinal adjustment relative to the frame (meaning caster) and adds about 7mm of lateral (camber - moving the point away from the frame). The JBA arms adds 22.5mm of caster and is approximately the same camber. The result on mine was that the TC arm could not get camber into spec and left caster worse than before due to maxing out the cams on camber setting.
I think the JBA arms could - and should be redesigned in a few ways. They should redesign the plate so it clears OEM backspaced wheels. That's an easy fix. They should also double drill the mounting plate so that the ball joints can be installed in 2 different configurations for either extra 2* of caster or extra 6* degrees of caster. Again that would be minimal cost/effort and make them work a lot better for situations like mine where I like to run about 2" lift and I have problems with too much caster. I can easily get a perfect alignment, but if I set it to only 3 or 4* of caster - then I'm rubbing even my 33" tires on the inner fender/firewall area. With 34" tires it's a no-go. So I have to set the wheel more forward (more caster) and then I end up with more like 6* of caster. So it's too much. And OEM arms are too little. Some adjustment would be really useful for me. And it wouldn't cost anything other than a re-design and have all of the plates laser cut with a second hole pattern.
So JBA arms aren't the perfect arm by any measure. They're just pretty okay and reasonably priced.
In a perfect world - I'd just order 500 UCAs from MOOG's china factory and they'd just build OEM style arms for $10 each with my adjusted geometry and they'd use OEM balljoints and just have more caster and be stamped with an additional 15 degree angle on the mounting seat for the joint so they would handle the extended travel without maxing the ball joint motion range. It's a super easy fix if someone wanted to order a bulk set to get them to make some new dies for the stamping.
