strut tower failure
#1096
Some people on this thread are stating the front struts have no bump-stops. If true, this would be 1) really dumb, and 2) present an easy fix for this problem.
Bump-stops in inverted struts are usually internal. Has anyone disassembled a factory strut to see if it has a bump stop?
Bump-stops in inverted struts are usually internal. Has anyone disassembled a factory strut to see if it has a bump stop?
I think stiffer sprigs are very necessary... and don't freakin lower the car.
#1097
Great info, thanks. Does the front suffer from a lack of bump travel? This is, does the shock bottom out a long time before the tire or wheel would hit anything? On race cars with steel strut mounts, I usually remove the string and modify or re-position the upper mount so the strut bottoms just before the tire starts to dig into anything.
#1098
Great info, thanks. Does the front suffer from a lack of bump travel? This is, does the shock bottom out a long time before the tire or wheel would hit anything? On race cars with steel strut mounts, I usually remove the string and modify or re-position the upper mount so the strut bottoms just before the tire starts to dig into anything.
I was spit-wadding ides, and a top hat with an extra inch or half of travel would be helpful as well, along with a longer bump stop.
#1099
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^^ Thanks for doing that & sharing the info. I'd like to get some idea as to how much the Swift springs alter ride quality. I could see a real advantage of switching them for track purposes, & if the ride isn't bad with them to use for street as well for added protection.
#1100
Burning Brakes
Regardless of how pervasive this failure might be, wouldn't stiffer springs only exacerbate the issue? By nature, wouldn't a progressive spring help alleviate the initial transferring jolt?
#1101
Rennlist Member
I think the goal is that the stiffer spring won't bottom out as easily and will avoid the big shocks to the tower.
#1102
The bump stop does the same, but in a less progressive space (distance).
#1103
Rennlist Member
Is this the actual cause? The shock bottoming out. Has anyone identified this?
#1104
Rennlist Member
I think a reasonable assumption is that big impacts bottoms out the shock, from there that force travels directly through the top mount into the aluminum strut tower.
The GT strut mounts don't have the rubber isolation that base cars do and thus lack additional absorption that mitigates this. Base cars have both longer bump stops (I assume?) and rubber isolated top mounts to absorb and spread out the impact jolt which seems to keep everything under that critical force value that causes failure. This is in addition to the extra ride height on base cars that gives the suspension more time and space to decelerate and absorb impacts. That's my guess as to why you don't see it on anything but GT cars.
The lingering question that I have is, is this a cumulative fatigue problem or a catastrophic failure from a single impact? Or both?
I think some people said theirs failed on smaller impacts that likely didn't bottom out the suspension so that would lend credibility to the fatigue idea.
If the bottoming out hypothesis is right then stiffer springs should help. If it's a issue of fatigue failure due to a series of smaller impacts then they probably won't.
I think the best thing you can do is run some lightweight 18s to add some impact absorption back in until some vendor comes out with a good reinforcement solution.
The following 2 users liked this post by chapmans:
bertram928 (07-07-2019),
unclemat (08-18-2021)
#1105
Strut tower failure
I have a deposit on a GT4 and after seeing this am thinking of cancelling purchase for safety reasons related to this failure Porsche does not seem to stand by this and repair under warranty any thoughts?
#1106
Immediate thought is that your concern is overrated and an incident is highly unlikely. GT4s have driven hundreds of thousands, if not millions, of track miles and the number of incidents is very small as well as being unconfirmed in many cases if there was damage prior to entering the track. YMMV.
The following users liked this post:
Diablo Dude (07-30-2019)
#1109
I may not have been clear, my deposit is on a 981 GT 4 with 12,000 miles. Very concerned about the shock tower failure and assume it is s stress related issue so the older the car the greater the chance of failure. I understand that one failure was on the freeway with no track use ever.
#1110
Rennlist Member
I may not have been clear, my deposit is on a 981 GT 4 with 12,000 miles. Very concerned about the shock tower failure and assume it is s stress related issue so the older the car the greater the chance of failure. I understand that one failure was on the freeway with no track use ever.