dt930

Has anyone added gussets to the steering knuckles between the pinch bolt area and the main structure? I know the ball joint issue and can take care of that with Fabcar arms, but is the knuckle the next part to break? Or do the failures occur at the spindle?

Any comments are welcome.

Thanks

FrenchToast

The cast AL hubs can fail. The spindles can fail.

As for the knuckle, I've seen pictures of failures at the ball joint clevis (typically when enlarged) and the actual spindle breaking. Breakage isn't limited to the early hollow spindles, although those certainly break more frequently.

Not sure where you would add gussets. Any welding is going to change the molecular structure, areas around the weld could become brittle.

Whatever you do it would essentially be a band-aid to an already archaic design. That bearing technology was old when the 944 debuted. Porsche never updated it, only made it thicker and bigger.

With the decades of fatigue on these components and increased G-load from newer tire technology, the front axle is archaic and really needs to be updated if you're going hard. Otherwise, have the hub and knuckle Magnafluxed regularly.

Would be interesting if Porsche Motorsport has any bulletins about service intervals on these components (regarding the Cup, 968 TRS, etc.)

I don't think any RWD car currently in production uses a spindle on the front. You still see it on the rear of FWD cars.

Droops83

I agree with FrenchToast's comments above. The '87+ 944s have larger, stronger spindles than the '86 cars, but updating to these requires updating at least the hubs/rotors to the late offset parts, and the control arms and tie rods are also needed to be able to achieve a reasonable amount of negative camber for track use.

Check out the thread below, as part of my solution for correcting the front roll center of my '86, I had drop pins TIG-welded into '87+ spindles, which served to reinforce the pinch weld area.

https://rennlist.com/forums/944-turb...-solution.html

This has worked well for almost 5 years now, but as suggested the spindles should be pulled and magna fluxed every season. The hubs are aluminum and as such cannot be magna fluxed but there are crack-checking methods available for AL.

There is a guy from Europe on the Facebook 944 Turbo group named Jan Mertens who is working on manufacturing CNC billet uprights for the 944 which use proper dual-row ball bearing wheel bearings and hubs from the 997. I will probably update to this, because in addition to the obvious safety issues mentioned, I am tired of replacing, re-packing and adjusting the 944's old-fashioned front wheel bearings!

FrenchToast

How does that work? The 997 uses a live spindle. 997 bearing (which isn't the best choice to begin with) would require a bespoke upright.

Not only is the bearing service a PITA, but it also adds more fatigue to the components.

Droops83

I corrected my post above, he is making uprights (I somehow typed "hub") instead. No association with the guy, and I don't know him, but he has been posting stuff on the Facebook group. Would use 997 hubs and bearings, and supposedly there will be 5-lug and center-lock versions, though if we are talking the factory 997 center lock system, I would stay away from that!!

FrenchToast

It's the street 997/991 centerlocks that are garbage. The race CLs are usually okay (the 997 race ones are actually problematic I think).

The race ones are extremely high maintenance but do allow you to use race tools. The street ones are also high maintenance, but require a special operation process and aren't known for their strength.

The street CL system has never been used on a race car. I wonder why..?