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YOUR RESEARCHAdvice on Adjustable front lower control arms
Reported or suspected cause
overtorque of the nut creating a crack
Reported cause
No successful repair reported for this finding.
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Reported cause
Even so I am almost certain that the failure was due to overtorque of the nut creating a crack, which propagated to failure.
Leading evidence: 'overtorque of the nut creating a crack' (1 discussions report identifying this cause; no attributable repair resolution). Across 1 matching discussions, the most frequently mentioned possible cause is 'overtorque of the nut creating a crack' (1 discussions; 1 report identifying it and 0 suggest it). The most frequently discussed action is 'Inspect entire suspension' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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Performed · outcome unconfirmed
944 guys see this all the time with 944's that are tracked using Porsche lower control arms that have been installed for years on cars in service.
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I was stating based on the normal that are used for our applications.
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Aurora bearings are used by most of the smaller tube-chassis race car builders, and are used by companies like Piper and Cessna for their aircraft bearings.
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A torque wrench cannot be used on this nut unless an adapter is used, and then the torque wrench needs to be set to a specific fraction of the desired torque.
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Rennlist: 1 discussions
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Looking to replace the lower control arms in the front on a 996.2 NB and so far i thought about oem gt3 style, elephant racing, SPC, etc..
What are you running and what do you like?
What r u doing with the car? I had stock gt3 arms in the front and it felt fine for street driving and a few track days. My new to me gt3 parts have the elephant monoballs and the rears have solid inserts for the forks. Not sure how that gonna ride yet but i can always switch it back to stock parts if i dont like thw street manners. Im sure they will be nice on the track.
Similar to you .. few track days and street driving.. NVH is a concern but is it a lot is the question.. Finding OEM GT3 lower arms is impossible right now as most are out of stock
I have the ones from RSS. Got them at a black friday price of $1000
dporto has mentioned he has the SPC. If you buy them from FCP they are guaranteed for life.
any more info on these.. I have seen on here someone had an Elephant LCA break the ball joint while driving at track .. kinda scary thought...lucky he was not at high speed. Tarret, Elephant racing, and OEM Forged GT3 arms seem to be the only options that make sense...
OEM GT3 arms are cast, not forged. The forged arms are 996 Cup parts.
I am VERY interested in the Elephant failure, please provide the link. Jason
@zbomb
and I are running these - and probably many others.
sure thing
https://rennlist.com/forums/996-turb...rs-beware.html
yes i know the cup parts are forged.. Demonspeed sells them
https://www.demonspeedmotorsports.co...ry-LCA-997.htm
That thread got a bit acrimonious, no?
Anyway the OP of that thread is respected by me and many others for his depth of knowledge. I called him a few days ago with a question. I do disagree on a few statements. The spherical bearings used by Elephant, Tarett, and everyone else indeed are not Hirschmann. They are made by Aurora Bearing. They're not low-cost junk, they are actually very good quality. Aurora bearings are used by most of the smaller tube-chassis race car builders, and are used by companies like Piper and Cessna for their aircraft bearings. Pegasus Auto Racing wouldn't sell them if they were junk.
The actual failure shown in that thread is almost certainly related to undertorque or overtorque of the ball joint nut. A torque wrench cannot be used on this nut unless an adapter is used, and then the torque wrench needs to be set to a specific fraction of the desired torque.
I am not going to worry about that part on my car for two reasons. One, I have the adapter for my torque wrench and can torque the nut correctly. Two, I replace the ball joint assembly every 2 years, which ends up being about 60 track hours and about 6000 miles.
This brings up several good points. Routine parts replacement is one. I change some parts on a regular schedule much like oil changes. For example I replace the wheel bolts once a year. Failure of the wheel bolts is Not A Good Thing. I replace the front wheel hubs every two years, and so on. I also inspect the entire suspension after every event.
The other is risk exposure. Running the car exclusively on the street I would not bother replacing any of these parts. For what I do which is 20 to 30 HPDE events a year, I feel comfortable with my schedule. If I ran wheel to wheel racing I would change the parts even more frequently.
I agree with what you are saying here including what you are saying here about Hirschmann. We have looked at them and compared them to others in the market including Aurora. They are the same. Well, maybe Hirschmann is made to some higher precision standard, but that does not necessarily translate to better performance in our applications. Every measurable characteristic is the same. Let me add an asterisk to that.
We measured material, hardness, thread and hole dimensions. They were all the same between manufacturers. As long as you are comparing the same grade of product.
There are two 'strengths' of rod ends. The standard and the high strength. Even Hirschmann has a high and low strength model. The rod ends that Porsche uses from Hirschmann for the Cup and RSR cars is the higher strength, which cost about twice as much. The rod ends used in most of the aftermarket suspension parts are the standard strength. Does this mean they are not strong enough ? Absolutely not. Based on calculations we did, the standard strength ones have a strength far beyond what you will ever need in our applications.
The difference is wear. The standard strength ones will wear out faster than the high strength ones. This is why that we always use the high strength ones in our suspension products. Cost is twice as much, but worth it for the longer lasting product. If you are not sure which you have, just read your rod ends. Aurora has a xm series that has the body made from low carbon steel and an xam series that the body is made from alloy steel. The alloy steel is the stronger, longer lasting ones.
We do have some new Hirschmann in stock too, if you want the real deal.
And, as was stated in this thread. We do not make our own lower control arms. We sell the Porsche Motorsports arms sourced directly from Germany. These are the 997 based forged arms, not the 996 or TRW arms that were cast (and are unavailable). They go in and out of stock for us as it is difficult to get them in volume, but we do have some in stock right now.
Thanks
Ed
I agree with that, except it's even more complex. There are numerous different grades of the spherical bearings on top of the different grades of rod ends. You can have carbon steel, tool steel, or stainless steel inner *****; HDPE, sintered bronze, or teflon bearing inserts, and tool steel or stainless steel outer races. Sealed or unsealed, greasable or not, decisions to be made. The rod ends are similar, steel, stainless, etc. All depends on the use case. The spherical bearings should be inspected and replaced when they start to wear, regardless of the manufacturer.
The Aurora Bearing parts are made in Illinois to ISO 9001 quality standards. These aren't being made in kitchen in Saigon.
Also the broken part in that thread is not even related to the spherical bearings. That was a tensile failure of what amounts to a bolt, in a location where it is subjected to simple tension. It's not possible to produce shear or repetitive bending on that part with proper installation. The fracture surfaces were not made available to me so I cannot comment on the precise mode of failure. Even so I am almost certain that the failure was due to overtorque of the nut creating a crack, which propagated to failure. Was there a manufacturing defect creating an additional stress riser, a damaged part during shipping/installation, the thread was not concentric to the bolt, or some other reason for excessive stress concentration? I cannot say.
Yes, of course. I was stating based on the normal that are used for our applications. I had not opened the other post, I was just adding more to your post based on our experience.
Now that I have looked at the post, I agree with you that it is not a rod end failure. It is obviously under some cyclical tension when on the track, otherwise it would have just as likely failed at the point of installation or sitting static. 944 guys see this all the time with 944's that are tracked using Porsche lower control arms that have been installed for years on cars in service.
Thanks
Ed
@Ed@Demonspeed
are the ball joints on the forged outers rebuildable?
also I believe the 997.1 Motorsports cup version you have in stock work on 996. Am I correct on that?
No, they are not rebuildable. The RSR is the only one that is rebuildable. Even the 991 Cup are not rebuildable.
Yes, the 997 Cup arms are compatible with pretty much everything up to a 991. Even the Boxster / Cayman.
FYI, we also have the rubber centered inner arms as well. Great workmanship and a gloss finish to keep them looking great and clean.
LCA Rubber End GT3 Style Control Arm Inner Section | DSM (demonspeedmotorsports.com)
This is a source reference. Confirm exact model applicability in the original material.
