Big(ger) Brake Swap - Lower Ball Joint Year Interchange

[kishy]

I have a feeling this is a dead horse, perhaps even one I've beaten before, but here it is again:

It's established that you switch to the newer lower ball joints when doing a brake upgrade. What is the specific reason that stock box lower ball joints can't be used with the newer spindles?



Obviously we know they fit into the control arm the same. The stud would appear (in my very unscientific, unmeasured/unscaled comparison image) to be highly similar, with differences in the length of the threaded portion but the profile of the rest of it looks quite similar.

Ideally someone who has tried to fit them together can offer some insight here. I think I have the parts to do this comparison in my garage but rather than mess with greasy old scrap ball joints maybe the answer already is known.

[sly]

the shaft of the ball joint is a different shape IIRC. The idea is to use the one that goes with the spindle that is used.

[86VickyLX]

Different size stud and whatnot if I'm not mistaken. You could maybe in theory have the spindle machined to accept the older style ball joint, assuming that the box ball joint is physically larger than the aero/whale joint. If it's the other way around, won't work.

[gadget73]

yeah, diameter or taper is different. Forget the specifics but going one way is hotdog in a hallway, the other way it stops before the stud gets all the way through.

There would be no good reason to modify the spindle honestly. Yes it could be done, provided the box part is larger, but for the effort you'd gain nothing other than a your-car-only spindle rather than a standard off the shelf item. I personally have an aversion to custom parts if I can avoid them, it makes breakdowns and failures much more expensive and time consuming to fix.

[kishy]

Yeah I'm 100% opposed to customizing the spindle to fit the ball joint if it won't go. Roadside breakdowns are something I always try to keep in mind. A roadside LBJ replacement is possible, but no need to make it more complicated.

I just figured if the ball joint can be used with it (functionally, safely, and reliably), I could do my two brake upgrades then do the joints lower. Since the lowers won't affect geometry an alignment won't be needed after changing them. Both target cars have tight LBJs.

[kishy]

I'm going to bump this with an oddity I found due to the parts interchange Dorman is providing to RockAuto:

Dorman complete lower control arms with ball joints included (520207 and 520208) are listed for 1980-2002 (but not 1979).

Notably, Dorman is specifying that their complete arm with ball joints is a suitable replacement for (among others) E0, F1, F7, and F8 parts.

The arm will fit, as we know, but as discussed in this thread, one cannot (or should not) attempt to use a 94-down lower ball joint with a 95-02 spindle, or vice versa.

Since I happened to use those Dorman arms on my 91, and found within a year the ball joints were making unpleasant noises, I would not exactly recommend them for any purpose as a complete unit without replacing the ball joints.

I never verified exactly what the source of the noise was, assuming it had been a breakdown of the joint in the usual way, but I suppose in retrospect it's possible it could have had something to do with a poorly seated stud moving around.

For Dorman's own individual ball joint 536489, it's listed for 79-94, so they at least recognize the same part does not apply the whole way through. The complete arms just managed to get some bad data assigned to them.

Seemed like this might be worth knowing. Hopefully it helps someone avoid a mistake.

[DerekTheGreat]

Most of the repair videos I watch on YouTube have nothing good to say about Dorman. South Main Auto likes to rip on them a lot, pretty funny.

[kishy]

Well, I never said they were the best choice for any part. Whether they are or not is not really what I was getting at.

If Dorman's application data is screwed up, then it stands to reason that they might not be the only ones. Furthermore someone wanting to replace their LCA and avoid pressing in new LBJs (regardless of the fact I found the LBJs unreliable) needs to be mindful of the fact that the application data is absolutely wrong.

I'm not entirely confident in which direction it is wrong, but it definitely is wrong.

[gadget73]

yeah, dunno whats up with that cross reference. I know the later ball joint fits the early arm, so thats not it. I have 2002 ball joints in my original 1986 lower arms. Without having the two ball joints side by each to look at though, I couldn't tell you more about it. I just don't remember any parts cross-reference saying its the same part from 79-02. I want to say 79-94 and then 95-02 is the split.