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I'm going with the Eibachs because the feedback in a few different threads is that the ride feel is the same as stock and the drop is fairly modest compared to H&R. That's the combo I want and I think the DSC I have now will continue to keep the ride quality in check.
I'm going with the Eibachs because the feedback in a few different threads is that the ride feel is the same as stock and the drop is fairly modest compared to H&R. That's the combo I want and I think the DSC I have now will continue to keep the ride quality in check.
You will like them. Only real concern I had was the harshness of the H&R, based on what I read. I went with TechArt and have no issues with ride quality. Was planning on DSC, but after driving around for a few days, didn't see the need for it.
I'm going with the Eibachs because the feedback in a few different threads is that the ride feel is the same as stock and the drop is fairly modest compared to H&R. That's the combo I want and I think the DSC I have now will continue to keep the ride quality in check.
So, in the interests of further procrastination this morning...
Here's a picture of "our" front suspension. (It's actually from my 718T but, the architecture is identical to our 991s) This suspension is a MacPherson Strut design whereby the bottom of the damper is rigidity attached to the steering knuckle/hub carrier. The strut must turn in the knuckle to enable steering but doesn't move relative to the carrier in any of the other 5 degrees of freedom. The ball joint on the single lower control arm and the strut-to-tower interface controls movement of the knuckle/carrier.
In the 991/981/718 the strut is not perpendicular to the ground. It attaches to the strut tower and carrier at an angle which is, in part, required to clear the inner wheel barrel.
The lower control arm describes an arc with suspension travel thus moving the bottom of the carrier inward with any deflection up or down from the nominal parallel to the ground. So, in this design, upward suspension travel results in compressing the strut and, because the carrier is moving inward, moving the strut inward toward the inner wheel well. This results in both a camber change and a bending stress on the strut which is transferred to the chassis strut tower. The deflection of the strut during suspension movement can be easily calculated for any lower control arm rotation from nominal. The deflection of the arm and movement of the strut can be seen with your own eyes as you lift the car and allow suspension droop. The deflection of the strut is minimized when the lower control arm movement is within of +/- 5° of parallel to the ground.
Based upon my observations of our "fleet" the lower control arm is (very close to) parallel to the ground with PASM and slightly "angled up" on SPASM. In the latter case this means that the strut is already slightly loading the strut tower and that further suspension travel will put additional bending stress on the strut tower. Further lowering will simply "angle up" the lower control arm more and thus put more preload on the strut tower. This then means that suspension travel is putting more stress on the strut tower than would otherwise occur. Because the strut-to-tower interface is where camber is adjusted and because the strut "controls" the top of the steering knuckle, you can't just put a big rubber buffer on top of the strut to absorb the bending stress without getting more dynamic alignment changes.
Now, in a double A-Arm suspension like the 928 (and.. ahem... the new 992 GT3) the "strut" is independent of the steering knuckle. The movement of the knuckle is controlled by two ball joints and, while the knuckle does move inward with suspension travel there's no strut trying to "bend" it. This means that suspension travel has no effect on camber and that you can have more suspension travel (and thus why the 992 GT3 guys all got stiffies when they finally got the 928's suspension in a 911 )
Furthermore, since the only function of the damper/spring assembly is to be a damper/spring it means that you can put a big-a$$ rubber bushing on top to avoid transferring bending stress to the shock tower and also to absorb vibration and do it all with zero effect on handling.
Short story: if you have strut tower phobia, don't lower the car below factory specs.
You will like them. Only real concern I had was the harshness of the H&R, based on what I read. I went with TechArt and have no issues with ride quality. Was planning on DSC, but after driving around for a few days, didn't see the need for it.
I really cannot comment on any other springs because I have no experience with any of them on a Turbo other than my H&R.
I have had H&R on other cars though and always felt like they gave a very similar ride to stock springs but the stance was just better.
As far as the ride in my Turbo posted in post above...it is a bit rough on crappy roads but then I only drive my Turbo in Sport or Sport Plus and I also have very low profile tires...my rear is a 325/25.
I would think that adds too the roughness??? But on most roads it is not too bad...I mean this is a high performance sports car...not a Lexus...LOL
Oh and I have ZERO rubbing with my setup...over bumps or turning.
You will like them. Only real concern I had was the harshness of the H&R, based on what I read. I went with TechArt and have no issues with ride quality. Was planning on DSC, but after driving around for a few days, didn't see the need for it.
But, I'm trying to round out the power mods first and the only pressing issue I'm focused on is to close the fender gap a little bit. I expect to go with the Bilstein B16's eventually, but after I'm satisfied with a few other things.
So, in the interests of further procrastination this morning...
Dave, your knowledgebase is seriously impressive - thank you so much for sharing it with us! I think I learned more about suspension in 5 minutes than I have in 40 years...
I was just out with him this weekend, but didn't ask or notice how his fix was holding up. Might at least arrest the splits development (no pun intended? )
I probably have one of the higher mileage 991 Turbos around here... ~63K, and definitely used as intended. Plenty of scuffs on the lower lip areas, but thankfully zero splits.
Damn, probably shouldn't have said that, now I'm doomed...
Here's a picture of "our" front suspension. ... This suspension is a MacPherson Strut design...
Nice write-up, thanks!
Porsche really excels at applying engineering to overcome fundamental weakness in base design... The handling refinement they were able to achieve with the (flawed from a performance perspective) MacPherson strut suspension is remarkable. The MacPherson design is so ubiquitous because it is pretty simple, inexpensive, offers some space/packaging advantages, and offers pretty good performance, but was definitely not designed for optimal performance...
Rear engine design is similarly flawed, but again, Porsche has refined the engineering to overcome almost all of the negatives...
I have heard amazing things about the new GT3 double wishbone. I was out with a new 992 GT3 owner this weekend, but alas didn't get a chance to sample it!
I'm ok with the stock ride height on the 991 Turbo S.
Originally Posted by .2PDK
Your 991 looks lowered or am I seeing things?
Stock. DSC controller, but that doesn't affect ride height at all.
Originally Posted by 2fcknfst
With the 991, however, it truly needed to be lowered ...A DSC helped too.
Do you have some before/after side pictures? Were the gaps in your car more obvious than my Turbo above? Perhaps my darker color (Agate Gray) masks the gaps more than silver?
Stock. DSC controller, but that doesn't affect ride height at all.
Do you have some before/after side pictures? Were the gaps in your car more obvious than my Turbo above? Perhaps my darker color (Agate Gray) masks the gaps more than silver?
I sure do...
Before:
And after:
From truck like to stealth like in a matter of a few hours...
11-01-2021, 11:17 AM
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