strut tower failure
#706
I’m no engineer but it has to be the abruptness of hitting the end of the shock travel that combined with a suboptimal design causes this, possibly with faulty materials in the mix. I would think longer and progressive bump stops would help a lot. You’d lose some travel but the “end of the travel” would be spread out over a longer period of time.
#707
I’m no engineer but it has to be the abruptness of hitting the end of the shock travel that combined with a suboptimal design causes this, possibly with faulty materials in the mix. I would think longer and progressive bump stops would help a lot. You’d lose some travel but the “end of the travel” would be spread out over a longer period of time.
#708
I’m no engineer but it has to be the abruptness of hitting the end of the shock travel that combined with a suboptimal design causes this, possibly with faulty materials in the mix. I would think longer and progressive bump stops would help a lot. You’d lose some travel but the “end of the travel” would be spread out over a longer period of time.
#709
I still haven't seen what bump-stop is supposedly inside the shock. All the normal shocks have an external bump-stop at the top. Thats one reason why you dont see the failure on the reg suspension unless you really run over something like a curb . Ive always wondered if they eliminated the bump-stop it to get the car lowered and still have enough suspension travel?? carl
#710
I agree, to prevent this from happening we need to avoid bottoming the suspension. What about helper springs? I am not an expert on what their purpose is, but based on what I see, it looks to me like they are for just that. They looks stiffer to me and might only come in to effect when the suspension travel is used up.
I'm liking the idea of stiffer springs more and more.....
Last edited by ajw45; 02-26-2019 at 10:06 PM.
#711
The helper springs are fully compressed when the suspension is loaded and they are primarily to keep the main springs seated when the suspensions gets unloaded. Running stiff suspensions with short springs and no helper is fine, you just get the occasional cartoon spring noise when they pop into place. That said, I think I read somewhere that Porsche found on the RS cars the helper spring does does round the the initial spring response curve so maybe during transitions and in that phase from static to dynamic load they add a touch of measurable compliance.
I'm looking the idea of stiffer springs more and more.....
I'm looking the idea of stiffer springs more and more.....
#714
it was suggested to me that a mere 5mm approx. thick layer of high density polyethylene or similar on top of the shock mount would absorb a lot of impact on the aluminium casting, however, you would have to see what that would do to movement and feel of the car, and life span? although its pretty tough stuff
Adding a bump-stop (essentially an extra spring) to the suspension is a good thought however it will threaten to dramatically change the handling. It will need to come into play early due to the short suspension travel, and when it does it will work just like increasing the spring rate or tightening the swaybar- the handling balance will change in significant ways, and you'll likely only find out how mid-corner near the limit right when you hit a bump. So while it's an easy fix on paper it's much more complex than it would first appear.
#715
Adding a clip on style bump stop might help out
https://www.amazon.co.uk/Raid-HP-300.../dp/B003O31UQS
https://www.amazon.co.uk/Raid-HP-300.../dp/B003O31UQS
#716
Adding a bump-stop (essentially an extra spring) to the suspension is a good thought however it will threaten to dramatically change the handling. It will need to come into play early due to the short suspension travel, and when it does it will work just like increasing the spring rate or tightening the swaybar- the handling balance will change in significant ways, and you'll likely only find out how mid-corner near the limit right when you hit a bump. So while it's an easy fix on paper it's much more complex than it would first appear.
#718
#719
There was an update yesterday on youtube's "vehicle villains" channel for that yellow GT4 that had the strut tower fail. The link is easy to find. It was hard to understand the Scottish mechanic through his thick burr but I think he was saying that the first crack started with one of the vertical bolts on the right side of the tower if facing the windshield. The owner said Porsche told him it wasn't covered due to some sort of external forces verbiage. Interestingly, his repair quote was on the order of 5 or 6k pounds. They discussed removing the fender for the repair, plus some of the panels, and pointed out the glue that Porsche uses to secure the strut tower. None of them mentioned using a jig for the frame straightening so who knows. I had a little laugh when the owner wiped off a big deposit from a flying bird off the fender, smeared it onto the tire, then put his hand right into his pocket, then continued to drink his coffee with that hand and the lid off the cup.
#720