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It's a lot easier to say that the structural failure is from abuse and there hasn't been a high enough percentage of failures for any real intervention. Any lawsuit would instantly put the burden on the owners to prove that the failure happened under normal conditions. Driving over potholes, curbs, off-track, etc. is not normal use and would fall under a standard insurance claim...same as bending suspension components on your daily driver. Unless 991/981 towers fail en-masse, we'll never hear a peep from Porsche.
Over 2 years ago a friend in his GT4 had a high speed impact at a road works ditch, equivalent to a large deep pot hole.
He said it was quite a significant impact and scared the living daylights out of him, to this day his car is in perfect condition with no signs of any damage and he drives his car very hard.
I'd say you'd be in the clear and not worry.
Originally Posted by jmartpr
Maybe...just maybe....since we are talking about aluminum the failure will happen without any kind of notice after X amount of stress to the part. If we go with your case that would mean this failure only affects some cars...we really don't know or have a clue why it's happening to some cars others, like yours and mine, are OK after many miles of use and the occasional track use. I personally find all of this a bit worrisome as I don't know what causes it, what to avoid or what to look for in case of an imminent failure....guess I'll just keep using it as intended and cross my fingers.
Hmmm... I guess this means I can be optimistic, but this situation ultimately falls under the "serenity to accept the things that I cannot change" classification, heh.
I have whacked my share of curbs at the track... and in one shining moment of my life, I perpendicularly slammed all four wheels over a 4ish-inch curb on the street that I couldn't see at night at a good 30ish mph (I would guess) over a year ago. I cannot tell you how hard my heart sank contemplating my own stupidity in that moment, but I was very impressed with the outcome. I've found no discernable damage from any of this to date.
... Does this mean I'm probably in the clear as far as the strut tower failure is concerned? Or not out of the woods yet?
^^ I think it's safe to say, your car had real litmus test & is solid. It's possible some of these strut towers failed b/c their parts had inherent defective material. Many of these cars have been driven very hard & competitively with no issue. Transmission failures have been somewhat limited to certain build months.
I own a 991 gt3 clubsport that I use often on the track and it was also setted with aggressive camber at Manthey Racing
I saw in a trackday in Spain one GT4 strut tower failure caused by some wide exit over a straight kurb and maybe getting over it back on track but nothing that should cause this kind of damage on most of other cars
Just a few observations
As already suggested any bump stop in an inverted monotube shock absorber inside and you have to dissassemble it to see it. I do not know anything about Porsche specific oem shocks especially if equipped with pasm system but if it was on a regular inverted monotube biltein shock it would be suiet easy
to disassemble as it s inverted in the shock strut so in fact the shock itself stay assembled you do not open the hydraulic part.
I know that rally suspension specialist sometimes use the bump stop in different lengths and material stiffness to make it work in different situations. Of course as a different spring rate it can change the reactions of the car but still depending on how is done I think that some suspension specialist could compare it to the standard part and change it for a slightly longer or slightly stiffer one.
It was mentioned about the shape of the shock top mount that is smaller and with more square edges compared to non gt models... What about replacing it with some aftermarket ones that might have a slightly more round design or are slightly bigger?
In some pictures from underside you can notice that the top mont is not centered compared to the casted printed area that is supposed to be in contact with... Of course the slotted holes are made to make some camber adjustment but could it be that centering it would be slightly better and then just use shims for camber?
The motorsport tower plates will probably not do much for the main problem but as already mentioned could be slightly better to keep the shock not going out and control the car not damaging the hood etc.
The modification of them to have some bolt down points is also I think an improvement but don t think is really enough.
If Porsche doesn't engineer some solution or some aftermarket vendor make something really good I think you can only do small things to make it better.
But probably porsche won t do anything and if no vendor seem too interested is probably because in case their solution do not work someone could claim it made thinks worse etc.
I think that the same king of inner plate as the oem rear ones would be a slight improvement.
The other improvement I think could be worth even if I agree would not solve completely the problem is some strut brace as posted at the beginning of the topic.
After all even if not perfect it s a solution that was always used on older cars and especially an adjustable one with some preload might spread the forces to the other suspension tower and more importantly makes it more difficult for the metal to flex.
Just not sure if that there could be any problems using them on aluminium cast struts anyone could think of?
I think it would at least do all that the motorsport plates do but maybe also spread load
Maybe in the case of the gt3 and gt4 where the strut failure weak point is in the inside it could make sense to adjust the strut bar as to shorten it (opposite as normal instructions) so it would create some force in the inner direction?
I don t know if you see what I mean but imagine fitting an adjustable strut bar to a gt4 where both strut towers are already damaged on the inside.... then adjust the bar to extend..... would make the damage worst right?
I own a 991 gt3 clubsport that I use often on the track and it was also setted with aggressive camber at Manthey Racing
I saw in a trackday in Spain one GT4 strut tower failure caused by some wide exit over a straight kurb and maybe getting over it back on track but nothing that should cause this kind of damage on most of other cars
Just a few observations
As already suggested any bump stop in an inverted monotube shock absorber inside and you have to dissassemble it to see it. I do not know anything about Porsche specific oem shocks especially if equipped with pasm system but if it was on a regular inverted monotube biltein shock it would be suiet easy
to disassemble as it s inverted in the shock strut so in fact the shock itself stay assembled you do not open the hydraulic part.
I know that rally suspension specialist sometimes use the bump stop in different lengths and material stiffness to make it work in different situations. Of course as a different spring rate it can change the reactions of the car but still depending on how is done I think that some suspension specialist could compare it to the standard part and change it for a slightly longer or slightly stiffer one.
It was mentioned about the shape of the shock top mount that is smaller and with more square edges compared to non gt models... What about replacing it with some aftermarket ones that might have a slightly more round design or are slightly bigger?
In some pictures from underside you can notice that the top mont is not centered compared to the casted printed area that is supposed to be in contact with... Of course the slotted holes are made to make some camber adjustment but could it be that centering it would be slightly better and then just use shims for camber?
The motorsport tower plates will probably not do much for the main problem but as already mentioned could be slightly better to keep the shock not going out and control the car not damaging the hood etc.
The modification of them to have some bolt down points is also I think an improvement but don t think is really enough.
If Porsche doesn't engineer some solution or some aftermarket vendor make something really good I think you can only do small things to make it better.
But probably porsche won t do anything and if no vendor seem too interested is probably because in case their solution do not work someone could claim it made thinks worse etc.
I think that the same king of inner plate as the oem rear ones would be a slight improvement.
The other improvement I think could be worth even if I agree would not solve completely the problem is some strut brace as posted at the beginning of the topic.
After all even if not perfect it s a solution that was always used on older cars and especially an adjustable one with some preload might spread the forces to the other suspension tower and more importantly makes it more difficult for the metal to flex.
Just not sure if that there could be any problems using them on aluminium cast struts anyone could think of?
I think it would at least do all that the motorsport plates do but maybe also spread load
The strut brace wont limit the vertical movement or deformation of the strut tower top, which is what we are looking for.....they have joints at the end which allow free vertical movement. Now it should add horizontal rigidity to the body.
I think that what we are looking for isn’t to limit the upward movement, it’s to decrease the power of that movement either by reducing its force (hard given that the impact will be the impact) or by lengthening it’s duration. Barring that, improving the actual durability of the tower is ultimately the best, but most difficult approach.
I think that what we are looking for isn’t to limit the upward movement, it’s to decrease the power of that movement either by reducing its force (hard given that the impact will be the impact) or by lengthening it’s duration. Barring that, improving the actual durability of the tower is ultimately the best, but most difficult approach.
How about spreading the force of the impact over a wider area?
I own a 991 gt3 clubsport that I use often on the track and it was also setted with aggressive camber at Manthey Racing
I saw in a trackday in Spain one GT4 strut tower failure caused by some wide exit over a straight kurb and maybe getting over it back on track but nothing that should cause this kind of damage on most of other cars
What you saw was most likely the "straw that broke the camel's back". The actual cause for the cracks might have happened way before and probably in a more violent scenario.
The strut brace wont limit the vertical movement or deformation of the strut tower top, which is what we are looking for.....they have joints at the end which allow free vertical movement. Now it should add horizontal rigidity to the body.
I also tought that it was far from ideal at first and thought that a one piece non adjustable strut brace would be better...
But then I read al the topic and I see that many think that there is a slight benefit from just the Porsche motorsport plates that after all are just a not so rigid piece of metal and are not even attached as they are on the clubsport or cup cars...
And there is not any other solution available...
So at the end I looked again at the strut brace and I would say that compared to the motorsport plates the strut brace plates should be a more solid part (even if you would fit them without the bar itself) and that the two chassis struts seem to be at an angle and not completely vertical so I would say that
during the use the force that is applyed when one wheel is compressing on a kurb should also be spread on the bar and the other strut at least slightly?
And at worst it should make at least the same work as just the motorsport plates and help the shock not to go completely trough in case of a failure?
Also theorically on other cars the strut brace is mainly there to not let the body flex too much between the struts but I would think that on the gt3 and gt4 it s not really necessary for that but eventually (if it would work but we don t know) to make a slight reinforcement for the struts.
That s why I wounder theorically what happen if you install that strut brace and once bolted you adjust it s tension by shortening it (as opposite as recommended)?
Anyone tried to email any of the main vendors and porsche tuners about what they would recommend?
With all the cars prepared for track they make I would think that they should at least have some advice on that? I think about GMG, BBI, Tarett, Elephant and all the others?
I did something similar with a Scirocco after the lower control arm attachment structure separated from the unibody after running up against a curb.
This was before VWs had a separate bolted on subframe for that.
After it let loose again because of bad welding at Kertzman's, then rewelded, I installed a cross brace so if it failed again the next owner would be able to maintain control.
I also tought that it was far from ideal at first and thought that a one piece non adjustable strut brace would be better...
But then I read al the topic and I see that many think that there is a slight benefit from just the Porsche motorsport plates that after all are just a not so rigid piece of metal and are not even attached as they are on the clubsport or cup cars...
And there is not any other solution available...
So at the end I looked again at the strut brace and I would say that compared to the motorsport plates the strut brace plates should be a more solid part (even if you would fit them without the bar itself) and that the two chassis struts seem to be at an angle and not completely vertical so I would say that
during the use the force that is applyed when one wheel is compressing on a kurb should also be spread on the bar and the other strut at least slightly?
And at worst it should make at least the same work as just the motorsport plates and help the shock not to go completely trough in case of a failure?
Also theorically on other cars the strut brace is mainly there to not let the body flex too much between the struts but I would think that on the gt3 and gt4 it s not really necessary for that but eventually (if it would work but we don t know) to make a slight reinforcement for the struts.
That s why I wounder theorically what happen if you install that strut brace and once bolted you adjust it s tension by shortening it (as opposite as recommended)?
Keep in mind, that while not optimal, the Motorsport plates do bolt down to the body on the back of the strut tower besides the 3 strut attachment points. The brace is just bolted to the top of the tower, youneed to add more attachment point to the body in order to spread the force of impact.
If someone wants to get ahold of Schnell Motorsports, he could probably adjust the CNC machining of those brace hats to pick up a two more bolt holes to attach to the frame. It is not a fix, but it could accomplish what the modified cup plates are doing and put some tension between the left and right struts to help share cornering loads.
If the lateral loads generated by these cars in excess of 1.5 Gs can be shared by both towers more evenly, then there might be a little less metal fatigue on the vulnerable parts of the strut tower. Also, most of the tower failures have been on the right side of the car, and most of the tracks we might run on are counter clockwise yielding more left had turns. Does more stress on the right side from cornering = more failures???? Probably not the whole answer to the problem, but a likely contributor. At any rate, another person's 2 cents on the matter. If this thread keeps going, we will one day have a dollar in the kitty.
06-07-2019, 09:48 AM
