On 69-71 ball joints

[Phil Planck]

I just removed the original Koni struts from my 69 912 to remove the guts and install new Koni inserts. I had read some good posts here regarding the design of the ball joint connection to the strut. After careful measuring, I think the original intent was to use a shoulder bolt to help retain the ball joint along with the clamping. After much searching and several phone calls, the only bolt readily available is shown below, along with the original bolt. This shoulder bolt fits snuggly in the too large 11mm opening for the factory 10mm bolt. Although this particular shoulder is too long, it was the only one I could find to test my theory. I also did not have a loose ball joint for a bench test, but measurements indicate the shoulder would fit the round cutout in the ball joint. There are two problems with using a shoulder bolt. First, by strut design, it will only reach the center of the ball pin cut out. Second, and the killer of using it is it is very difficult to get the needed alignment of the pin in the strut. Vertical alignment is not a problem, but rotational, particularly on the car is almost impossible as there is no way to grasp the pin to turn it once aligned vertcally. It may be possible if the strut is on a bench and the ball joint installed there. I think that probably prototype or pilot assembly for the 69 model pointed out the assembly problem so it was decided to use a plain 10mm bolt which could be worked into the cutout. There is a catalog bolt that should work, but would have to be special ordered. I am willing to send this bolt to someone who has a spare strut and ball joint to try to assemble on a bench to confirm my theory. I think that is why the later wedge pin was used, so that it can self align with the ball joint pin. A guide tool with a rounded 11mm nose might work to prealign the 69-71 pin so a shoulder bolt could be used.

[Phil Planck]

Thanks for that input Chris. I will see what I can find.

[Frank Beck]

Amazing.

Those of us in da biz who actually need to make a living replacing Porsche fasteners and don't have time to ponder axial preload, non-linear force, or what was going through the mind of a beer-drinking factory worker in the 60's simply cut a 10.9 partially threaded 10mm bolt to proper length.

For the time it took you to doodle and type out your post you could have had it back together.


Oy Vey... these are just old cars; not spaceships. Let's not make a hobby of overthinking everything. Oh... wait... that's what engineers do for a living.

[Frank Beck]

Frank,

I won't post on this forum again - I really don't need top be insulted.

Whaaa.

Chris,
Typically the only way a person can become “insulted” is if they think too highly of themselves.

Whatever happened to tough-as-a-bulldog British grit? When did you guys become such snowflakes?

[72targa]

I like both perspectives. Hope you hang out.

[Frank Beck]

I like both perspectives. Hope you hang out.

I do too Peter. Come on Chris, PLEASE come back to the sandbox and bring your toys with you. (Raj 2.0?)
Always good to measure the practical against the lofty.

Being a simpleton and salt-of-the-earth kind of guy I would much rather geterdone than self promote and chatter about theory.


Sent you a PM Chris.

[stretch]

Chris, take no notice. There are not many "in the trade" that take the time or have the knowledge that you bring to the Porsche forum's. Most are members of some bullshit secret society and offer no help on the forums. There are plenty in the trade that never bother to answer any technical questions. Maybe there busy counting there money.

[Orbit]

Hello Phil

I have a 1969 912 in Ossi Blue and I would be happy to try your shouldered bolt solution. I have spares and a couple cars we are putting together.

Don't be afraid of Frank, his bark is worse than his bite. Frank is actually a real nice guy despite his biting, but always entertaining, forum posts.

Please contact me at Rodger@orbitracing.com for shipping info.

[Phil Planck]

Roger
Thanks for your interest. I can send you the shoulder bolt I have which is only good for bench experimentation, as the shoulder is too long. It could be shortened to 11mm on a lathe in order to fully seat into the cutout and also start the clamping process, but I think there will not be full thread engagement. But it would help confirm my theory of what was intended but not practical.

Frank, the reason for wasting my time was based on prior discussions on this forum regarding the weakness of the 69-71 design. You your self stated on this forum:

" I use the later Koni wedge style. They're much less prone to problems. "

And what problem were you referring to? I think it was the potential for separation of the ball joint from the strut. I assume you do not whack off 10mm bolts and force them into a wedge ball joint rather than screw around with that crappy wedge thing. Another poster involved in track use stated he would not let a 69-71 on the track with the clamped strut design.

So, that is why I am wasting my time. Just trying to see if an added insurance of safety could be added witout having to find later wedge style struts with 3" caliper bolt holes. Chris has suggested a better bolt solution, which I appreciate.

[71gold]

What happened to Chris’s post ?
I wrote down the volt he reccomended and google searched and found the bolt type.
Then Came back to review his post again for more detail and it’s gone ?
Phil...appreciate your thoughtful approach to address this issue as I am working on 70 & 71 and looking forward to a better solution.
Frank