3-Bolt Ball-Joint Versions and related info... a more definitive guide.

[pfi]

Test-mounted an old guide joint from a 91' ACOQ.
it's clearance, but not much, except for at the "bulge" on the arm shown on the image, guess it won't take long before it'll be a hole in the CV-boot.

bulge-02.jpg

Of course the best would be to get the proper guide joints but it seems to be difficult ...
Anyone knows if the "bulge" have any mission ?
I'm tempted to grind it off, It shouldn't weaken the arm in any way.

[Lago Blue]

@ Rikki Kitto,

Could your issue be in part that the considerable available slack in the joint (when both bolts are loosened) where the strut fastens to the hub-carrier (two large horizontal bolts, #12 in illus, below) is not currently equally positioned on the L and RH struts (and the b-joints are having to be displaced in opposition to compensate)? I set both of mine to 'loose joint pressed fully inboard' prior to tightening, to then always have a easily repeatable go-to position for after any future dis-assemblies (of said joint); to restore alignment.

@ pfi,

Don't know but suspect you are correct about the circled bulge re: arm integrity. Some cars had brake cooling ducts, could it have anything to do with attaching those?

Audi B4 Fr Susp parts illus. Screen Shot 2022-06-12 at 11.14.28.png

[pfi]

@ Rikki Kitto,

Could your issue be in part that the considerable available slack in the joint (when both bolts are loosened) where the strut fastens to the hub-carrier (two large horizontal bolts, #12 in illus, below) is not currently equally positioned on the L and RH struts (and the b-joints are having to be displaced in opposition to compensate)? I set both of mine to 'loose joint pressed fully inboard' prior to tightening, to then always have a easily repeatable go-to position for after any future dis-assemblies (of said joint); to restore alignment.

Or, if having "old" hub-carrier(s) with 12mm bolts and "new" strut-leg(s) with 14mm hole(s) and no spacer to compensate for the difference

[Lago Blue]

In reviewing this thread I thought it may be helpful to here also mention as follows:

Ball-joint application clues via cross-hatch patterns around its stud slots:
Besides using P/Ns, both those one finds listed and those sometimes embossed onto the bottom of the joints, and the physical features of relative ball height, and pin offset to help identify the intended application of particular ball-joints; here's one more theoretical discriminator. Observe the cross-hatching seen on the sometimes slightly raised areas around each of the 3 stud-slots. My theory is that this pattern's presence on both the top and bottom surfaces indicates a joint Audi intended for use sandwiched inside a pressed and welded A-arm, whereas if said pattern is only on the top surface, Audi may have intended such joints for mounting under forged arms.

Which then leads me to...

Purpose of the raised-ball ball-joint for use w/ forged A-arms:
It certainly appears (as pfi has helpfully illustrated above) that the taller buttressed ball joints with the ball position raised from previously and discussed earlier (which appeared with the intro of the Coupe), allow maximum operational and some maintenance work clearance when employed on forged A-arms. This was likely to ensure clearance for the larger OD of the outer CVs and their boots seen on the most powerful turbo and V6 powered cars. The older heavier-looking forged arms (illustrated below) may have posed a similar issue.

A drwg. from the factory service training manual for the 20V Coupe (note early style forged arms and what would be the shorter 20V saloon style A/R bar S-link to the A-arm):


Ball-joint selection and the front fender's arched wheel opening's compatibility:
Beginning with the model year 1990 B3 Coupe, the wheelbase was lengthened 11mm via just the newer increased caster ball joint AFAIK, and the front fender's wheel arch was moved forward.

If one is adapting forged arms to a B3 sedan / saloon, know that the arched opening in that fender is 11mm aft of the Coupes and the B4's. That will require the use of the B3 20v ball-joint that does not increase caster from the 1989 spec, to avoid fender interference.

Confirming the ID of a Ball-Joint:
What is the exact application of this item?:
image_93128.png

By knowing what the physical characteristics are that your (for example) S2 w/ forged A-arms requires of a ball-joint, you can visually assess your theoretical ball-joint in the photo above (even w/o a P/N) as follows:
- P/N was on the box: Yes, but really anything could be written on or physically in the box;
- P/N readable on the joint: No, so no help there either;
- Pin axis is aligned with the stud slot: Yes, correct low offset is for Coupe and B4s;
- Ball is raised and buttressed above the mounting flange: Yes and yes, correct for forged A-arms; and
- Cross-hatching is only on the top of the flange: Yes, correct for forged A-arms.
Therefore, it is the correct item.

Confirming LH and RH ball-joints:
They need to 'point' somewhat aft (towards 04:00 and 08:00 o'clock when viewed from above) when mounted. Your fender's wheel openings are farther forward than the B3 sedans. Theirs point back too, just more.
If you need a visual reference, go back and look at the first numbered paragraph and photo in the first post on the first page of this thread.