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

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  • #16
    Originally posted by M2ki View Post
    Okay, maybe these audi wishbones are forged.
    But cast iron wishbones are still used and made every day and they will not snap in 5 minutes like error404 claimed.
    you can ask this company: https://lightweighting.co/market-research/
    and find out about the cast iron LCA
    sigpic

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    • #17
      If you have some info on this topic, you can share it here, others will also appreciate it.
      I'm not gonna bother some company with my stupid questions.
      1989 Audi 80 Quattro
      1994 Audi 80 Quattro Competition

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      • #18
        Common sense of what should I use to translate word 'Gusseisen' to English?

        guss.JPG

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        • #19
          Seriously, you guys are really arguing about this over the wording in ETKA?

          You can see they are forged with your eyes - the big wide flash trim lines down the side give it away. Casting leave a very thin flash trim line.
          Panthero Coupé quattro 20vt
          Indigo ABY coupé
          Imola B6 S4 Avant

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          • #20
            Bingo, thanks for pointing that out (the trim-lines feature) sir. Error is exactly right. For those less familiar, what he is referring to, is that looking at our very likely forged A-arm that is laying flat, all along the sides of the arm one can see and feel how rough finished the steel is, as opposed to the smooth top and bottom surfaces. These side areas appear to have been ground just quickly with a hand-held abrasive wheeled tool. The width of that ground area (or more accurately it's height) is quite wide, wider than what one would find along the part lines of a cast part, as casting moulds are made to meet and mate more perfectly almost everywhere leaving a very narrow flash gap, whereas with forging dies, in order to have an effective hammer-blow, the perhaps only semi-molten metal has to be given a more generous area to be squeezed to, hence the wider areas needing trimming after being die-struck.

            Many other folk have long had this same question: "Is thing X cast or forged?" particularly when one can't have witnessed the original process, but require a definitive answer. Some myths and other determinative methods are discussed here:

            https://forum.millerwelds.com/forum/...way-to-weld-it

            https://weldingweb.com/showthread.ph...-forged-or-not

            Photo below shows in its' center, a cast crank's necessarily narrow mould horizontal part-line lined up against a forged one's wanted wider part-line:

            The tell-tales of two cranks.png

            Quite interesting all of that. However, from my perspective, particularly as there isn't much we can do about how the arms where made, the most significant thing is that, all of the advantages fall in favour of the likely forged arms, and in particular that they allow us to then employ the large diameter OEM bushings they require vs. the earlier small ones. The proper care and feeding of those bigger OEM bushes alone will have as great or greater benefit to your driving pleasure every day; than whatever A-arms you may have. What I consider proper (in terms of cost, durability and steering response) is simply the use of these (link below) along with new OEM bushes:

            Arm-Stops

            All right then, if there are no more questions, eventually this OP would like to next steer the conversation back towards ball-joints if you don't mind?
            Last edited by Lago Blue; 10th June 2019, 16:48.

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            • #21
              A few thoughts and questions I had while writing the above:

              - It appears that the "B4" ball-joints where part of the B3 to B4 wheelbase lengthening component changes that also saw the front fender-arch move forward on the later cars;

              - It may be that the later ball-joints (for forged arms) with the raised ball position, were made simply to maintain the original (with pressed style arms) clearances (under the CV's and A/R bar?) above the arm"s topside (photos below hints at how close ball-joints for pressed arms on forged ones; makes things):

              Forged arms & ball-joints for pressed arms close-up.pngForged arms & ball-joints for pressed arms RH side.pngForged arms & ball-joints for pressed arms LH.pngAndrey Puzakov's photos and interesting bushings

              - It may not be of any immediate consequence if one was to as above, use ball-joints made for welded arms; on the forged arms, simply closer particularly on full extension I'd guess (watch your fingers!), but the reverse (pressed arms with ball-joints for forged arms) may not normally be entirely do-able due to the presence of the buttressing on the later ball-joints, which might interfere with the pressed arms joint receiver plates (however as per photo below, it can be done);

              Pressed arms & ball-joints for forged arms.png NailTim's pressed arm mod photo

              - Question: The spacer-plates (item 5 in the ETKA illustration up-thread and in photos above) "under" the nuts, appear to be specifically for use with the plain lock-nuts (vice the later serrated ones), rather than a particular A-arm or stud, what is their purpose and/or how do they function?


              - Looking at the photo below, one can see how a less offset ball-joint (as ball is moved towards front of the car, towards left in photo) will increase the caster angle, and due to that increased top-mount to ball-joint ball tilt, also increase the mechanical trail distance; ever so slightly;

              S2 hub ball-joint receiver offset.pngG60Rallye's S2 RH hub photo

              - Perhaps counter-intuitively, the analogous bearing to the ball-joint on a bicycle's head-stock would be the bike's more lightly loaded upper bearing, each carrying strictly lateral loads and zero vertical loads (unless one employs the early style A/R bar drop-links which connect to the A-arms*);

              - So the job description for the ball-joints would include, holding the strut base steady in position laterally, allow both suspension and steering to pivot, and transmit mostly horizontal loads*. It will therefore most likely first exhibit play front to rear and/or sideways.

              - Despite that unlike top-mounts, they aren't constantly carrying the vehicle's weight, but by sitting so close to the axle, closest to the cross-roads of braking, cornering and accel. forces (aka the wheel bearing?), they must transmit the largest of the lateral loads to the chassis and also help to precisely define front-end geometry, and being so small, they ought to be the joints that wear out the fastest, not the top-mounts!

              - Question: Is the forward offset of the B3 Coupe hubs' ball-joint receiver (seen in photo above) the same as the B4's?

              - Use of the later less offset ball-joints will also alter the Ackermann slightly (by effectively moving the rack aft), a small increase in its effect;

              - The above to say that, when cornering, the toe-out of an inside wheel increases as the included angle between the steering arm and the track rod is made smaller, as it would be by moving the strut-bases forward;

              see Dale Thompson's remarks re "move the steering rack rearward" on page 9 here:

              https://www.me.ua.edu/me364/PDF/Steering_Ackerman.pdf

              - The sum of these very small changes may help to explain any differences one might feel in steering two cars so equipped;

              - Citing the above possible effects, the obfuscation of various parts listings, and there being two near identical joint types (with both the raised ball position and the buttressing ridges), it would be easy (particularly for a garage!) to miss that your two ball-joints are not of the same offset.


              Audi B3 & 4 ball-joints 2019-05-23 2 at 21.20.58.png

              However, when it comes to achieving most effective ball-joint function, and even including the side discussion which hinted at the possible resilience of different A-arms, knowing all the above is but about half of it.
              Last edited by Lago Blue; 10th June 2019, 11:59.

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              • #22
                Back-stopping your ball-joints.

                No discussion of ball-joints would be complete without an examination of how well they are hinged to the car, which is important because it is only through the A-arms' inner connection that any lateral ball-joint station-holding ability (the steadfastness of which is critical to sending and receiving pure steering signal) can be achieved. That connection needs to be, as far as possible, just as strong and precise as the ball-joints themselves, otherwise the accuracy with which they can guide (or be driven by) the tires' contact patches will only be as tight as the looseness of that total chassis connection. It is precisely because that primary A-arm hinge-line is much more easily degraded than the ball-joint itself, that ball-joint effectiveness while underway; is most often wholly contingent upon the tired condition of that hinge.

                What this will briefly speak to (as I have written of this at length elsewhere) is the A-arms' connection to the sub-frame. The sub-frame's other larger four sub-frame to body bushings which I view as, similar to OEM top-mounts, necessary filters, I will not address here further.

                Because of the inherent vulnerability of the stock installation, new OEM A-arm bushings perish quickly and will allow random lateral ball-joint mobility on a scale nearer to the pin offset difference between the two (of three) ball-joint types seen above (it may approach the thickness of the end of your little finger). This (until addressed) makes much discussion of A-arm construction moot, except to say that forged arms hold paint better and to repeat, require the larger bushings whose increased joint volume contribute greatly to achieving stronger and more durable A-arm hinge-lines. Even poly bushes used here may eventually disappoint. These oft neglected joints will, with simple assembly differences, reward those who choose to not simply dismiss what OEM bushings can provide; and who attend to this deficiency. This mod will subtract slack and random vagueness out of your steering linkage. One of the reasons this mod is so effective is that the two wheels are then made to more closely point in concert and work; as one. This mod is, IMHO often the missing other half of understanding and achieving proper ball-joint function and will do much to both preserve the arms' bushings (otherwise they're sadly replaced for naught) and improve the steering character of your car.

                Link to: Arm-Stops

                On another forum I read that a rally UrQ owner was asked, at perhaps a US event nearer their east coast IIRC, the function of the factory heim-jointed trailing links (photo below) and was told they were to help preserve both the arms and the bushings. Whether it was that arm-trunnion cracking, similar to what one may have heard sometimes occurs to stock pressed-arms (perhaps originally designed to carry the OEM double-ended push-thru type bushings) when used with nylon or similar more rigid bushings, may have been taking place to these also welded tubular arms and/or perhaps bushing/joint damage as axial loading (loads parallel to and felt along their mounting bolts) is their weak flank, no matter. The point being the factory clearly recognized the need to address the cause of this issue, that the stock arm-hinge design was axially weak. On our street cars, we may wish to not have to employ such complex measures, but what is left of your stock bushes restraining your arms from fore-aft movement; if much at all?

                Audi S1 rally subframe with arms & long-links.png

                From under your car, one can get some idea of how far your ball-joints will wander under accel. and braking by levering your A-arms forwards and backwards in their mountings. Underway, your car will move them more, more often, more easily, faster and more violently than you can, but also individually, alternatively and unpredictably as you can well imagine. Each wheels' compass heading is individually changing course with every A-arm fore-aft shift and shuffle. It's quite fixable though.
                Last edited by Lago Blue; 4th June 2019, 16:26.

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                • #23
                  From the Factory Service Training Manual for the early 20v 7A Coupe which lists new caster detail and other changes (including S/S A-arms!) between this car and the earlier 10v 90Q):

                  Audi 7A 20V Fctry. Srvc. Trg. Man. Fr. Susp. detail changes.png
                  Last edited by Lago Blue; 9th June 2019, 03:26.

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                  • #24
                    Stainless steel?? Is this another translation anomoly? Interesting information over the caster change but I'm not sure anyone will ever claim to have rust resistant front wishbones on their car!

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                    • #25
                      Regarding stainless steel, that would be my guess, but you just never know what someone may find. Considering that S/S usually yields to bending more easily, It is perhaps an unlikely choice. However, if such did exist, that there were at least 4 versions of forged A-arms to quickly follow these would have eclipsed that idea in any case.

                      What I think that description corroborates is that both the early (for pressed-arms) and late Coupe ball-joints likely share exactly the same reduced offset for increased caster, mechanical trail and wheelbase, the later (for forged-arms) joints simply being a raised ball version.

                      Perhaps of greater significance for us today is that although the altered ball-joints evidence the importance with which Audi regarded the necessity of this change for "good stability", and the decision was made to nearly double the caster measurement, this is still a very small physical change; and yet, save for the welcome huge net bushing volume increase that finally came with the 2nd forged-arm versions, not enough attention was paid to how axially limp the inner A-arm bushes still quickly became, which undoes much if not all of the increased caster sought by the altered ball-joints in the first place; and further, allows the geometry to be rather random, variable and each side can do its' own thing independent of what the other side is doing! Given OEM bushes, that one may likely have parts effectively in the steering linkage, so worn that their slop is of the same order of magnitude as a factory part who's purpose contributes to the change in the listed wheelbase of the car; has got to be a compelling reason to want to fix it. While one cannot say it was done this way to ensure ample dealer service work, as most folks don't even notice the degradation, however everyone who has done the mod notices after a car has gotten Arm-Stops.
                      Last edited by Lago Blue; 10th June 2019, 12:02.

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