Front Lower Ball Joint Taper

Jeff Lange

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Have a project I've been working on but I've been stuck a bit on the front lower ball joint taper, and I'm wondering if anyone else has come across a similar issue.

I've measured what appears to be an untouched front knuckle to have a lower ball joint taper of approximately 7° (1:8). This matches some various low-res drawings I have from Toyota.

I've also measured what may or may not (I suspect not) be an OEM lower ball joint and it has a taper of approximately 10° (1:6). This matches what some aftermarket companies list their lower ball joints at for taper, and some random forum posts from a decade or so back.

I'm likely going to order myself an original Toyota lower ball joint to measure the taper on it. In the meantime I thought I'd see if anyone had looked into this before.

Jeff
 

Jeff Lange

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I came across this thread a few times in my searching, but it hasn't been extremely helpful because I'm not sure if he was measuring the knuckle or the ball joint.

I measure the knuckle at ~7° (1:8) and the (potentially aftermarket) ball joint at ~10° (1:6).

71767548_10220014045802969_2317918047773392896_o.jpg Based on the relatively low resolution drawings I have from Toyota, it seems that ~7° is correct for the knuckle, but are the aftermarket ball joints actually using the wrong taper, or is that what Toyota intended? The large end of the taper is basically the same between them, but the small end is smaller on the ball joint stud. Also interesting is that the Toyota drawing I have shows a different taper for the upper and lower. (7° lower, 10° upper), this also matches my measurements of the knuckle.

Front Hub w(Angle Lines).png

Jeff
 

Piratetip

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Hmm.
Interesting.

I would take some measurements for you but I don't have any of these spare parts lying around anymore.

It wouldn't surprise me if aftermarket companies are screwing up the taper for the lower balljoint.
Especially if they are assuming both upper and lower balljoints are the same taper, as your drawing there is showing they might not be.

A new OEM part *Should* match, though I am interested to hear what you find.

Another option that could be used if no 7° part is available:
A 10° Taper Reamer.

Though I would avoid that since its not easy to go backwards unless some kind of sleeve is used.

Another thread:
https://www.supraforums.com/threads/lower-ball-joint-taper-degree.1112333/
 

Jeff Lange

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Yeah, I won't be changing the tapers of any components at this point. In fact this is all heading in a developing new components direction, but if I do that (various plans in progress), I want to make sure each component is as factory-interchangeable as possible, and that is definitely the case for something like the taper of the ball joints.

That thread is the one I referenced in my second post. I spoke with the OP on Facebook and he confirmed that he was measuring the ball joint itself, which definitely suggests that aftermarket manufacturers are building these joints with varying tapers. I will see what the Toyota joint measures at, but I fully expect it to be ~7°.

Jeff
 

Jeff Lange

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Got a chance to measure a Toyota genuine 43330-19057 ball joint today and the taper comes in at around 9.4-9.5° which is the same as what I had and also 1:6 taper.

So that's an interesting development.

Factory ball joint with a different taper than the factory knuckle.

Jeff
 

Jeff Lange

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Is anyone able to measure the dimensions of a factory knuckle lower ball joint and post them up to compare? I just want to verify these findings before moving forward.

Jeff