Tlaloc75

993 suspension upgrades are a perennial subject in this forum and one of particular interest to me since I went through a complete suspension rebuild last winter. For those who haven't done this (yet) it can be grueling. There are a large number of decisions to be made in terms of what your intended purpose is, the components that match that purpose and then the work of actually gathering and installing all the parts necessary to make your dream a reality.

One of the hardest parts for me was deciding what to do with all the rubber parts that needed to be replaced. There were control arm bushings front and rear, sway bar bushings, steering rack bushings, subframe bushings, and shock top mounts to deal with. Each has its own variations from soft to solid and tradeoffs between performance and NVH. What's a guy to do?

I spent months researching, talking to experts, asking questions and pondering what I wanted to do before I could even start to buy parts.

Ultimately I chose to install solid tie-rods, replace the rubber bushings in all of my control arms and in the subframe with RS/Sport versions, stay with stock rubber everywhere else (shock mounts and swaybars), and install PSS 10 coilovers. In my mind this would give me additional cornering precision, a little less KT effect and a more RS-like handling feel without the additional NVH that camber plates and other solid attachment points might cause.

I completed the project and have been very happy with the results. The car is smooth, refined, tenaciously grippy on uneven pavement and an overall joy to drive. Playful, refined, and basically perfect for how I use the car.

While I was happy with what I did, I didn’t know what it would have felt like if I’d made other choices. Would monoballs have given me even more grip? How much would they impact NVH? Would it be noticeable?

Thanks to another forum member Andy Hodapp, I can now answer these questions!

Andy had a similar end-goal in mind when doing his suspension refresh but almost every decision he made was different than mine. Let’s compare:
- Shocks: I chose PSS 10, he chose Koni with H&R springs.
- Front control arms: I chose ER Sport bushings, he chose Walrod Poly.
- Tie-rods: I chose Tarrett RSR solids, he chose ER bump steer reducing solids.
- Shock mounts: I replaced with OEM, he left his alone.
- Steering rack bushings: We both chose to use the blue poly.
- Front ball joints: We both chose to replace with OEM.
- Swaybars: I have M030 with new bushings, he has stock with original bushings.
- Subframe bushings: I chose RS/Sport hardness rubber, he chose ER solids.
- Rear control arms: I chose OEM RS for KT and A-arm and ER RS/Sport bushings in new OEM arms for Camber and Toe with ER lockout plates, he chose to build his own solid arms with monoballs for KT, Toe and Camber and then replaced his A-arm bushings with poly.
- Tires: I have 235/265 RE71r tires on 8.5/10 width 18” wheels, he has 225/255 on 17” wheels with Federal 595 RS-RR tires.
- Alignment: Basically the same, both have 1.2 camber in front, 1.7 in back nearly identical toe and caster. KT is 3.5 for my car and 2.5 for his.
- Body style: I have a coupe, he has a cab.
- Ride height: I’m at RoW Sport, he’s between RoW Sport and RS.
- Clutch: I have RS LWF, he has stock. Not that it impacts handling, but might as well be complete.

Now the important part. How do they each feel? To get the answer to that question we drove both cars on the same stretch of road back to back. Its a road I am very familiar with and it takes about an hour to do the full stretch, so plenty of time to make comparisons.

First surprise was how little NVH his car had. My initial impression was that there was no additional NVH at all. Now granted he has a cab so there is more noise inherent in that body-style but I’ve driven it before and know what it was like on its original suspension. I was expecting a big change. Lots of noise and vibration. Maybe some clunking or clanking noises. But there was none of that. If he hadn’t told me he had replaced all the rubber in his suspension I wouldn’t have known it in the first 10 minutes of our drive. The car felt stiffer but that’s because he turned up the damping on his Konis. He felt the grip was so much better with the new suspension that he was getting too much roll and added some damping to compensate. So I noticed a firmer ride but no additional NVH. Pretty remarkable, especially given that the subframes bushings were now solid!

After pressing on a bit longer and hitting some spirited corners I was able to form a more complete opinion. I was mentally comparing to both how his car felt before and also to how my car feels. For the purpose of this writeup I’ll just focus on how it compared to my car. Steering in his car felt just a bit livelier and also a little lighter. Bumpsteer felt about the same as my car, but since his car is at least 10mm lower on stock wheel carriers that’s impressive. ER tie-rods seemed to be working well.

Rear end felt very planted. Extremely planted. Never felt it wiggle or move in the slightest, it was just plain solid and did exactly as it was asked. I couldn’t feel any KT effect, which made it feel more like a 964 in terms of rear end steer.

I noticed slightly more understeer in some corners and a little less tenaciousness at turn-in. I think this is tires, not suspension. He’s running more stagger and his tires just don’t have as much grip as RE71r, which are spectacularly grippy.

Back to the NVH. Did I ever notice any differences compared to my car? The answer is yes, but I had to look for it. After driving for a while I started to notice that the ‘feel’ of the suspension was different, but in some hard for me to describe ways. Part of this was shock damping. The PSS 10 feels more sophisticated than the Konis, in that they feel more responsive to sharp impact, damp large undulations better and overall keep the car more settled. So there was that. But there was also a feeling of being able to sense sharp impacts more intensely. Some of this was muffled by his taller sidewalls but not all of it. If I paid attention I could sense that there was metal where I had rubber.

Once we moved to my car I was able to complete my impressions and compare the handling and NVH even more. Putting aside grip, which was mostly likely a function of tires, my car felt a little smoother, a little more composed and like it had just a bit more ‘give’ when pressing on. This made it seem a little more forgiving but also just a bit less direct. On an autocross course or smooth track, I would prefer his suspension choices. On a lumpy Montana road I would prefer mine. But just barely. The differences were much smaller than I would have expected and I really had to pay attention to notice them. Its impressive to me that a cab, with all of its open air possibilities, can be tuned to this level of performance. He is going to have so much fun with his new setup!

By the way, did I mention that his choices probably cost 1/3 of my choices? Building your own arms is much more cost effective than buying parts from Porsche. Especially RS parts that need to be shipped from Germany.

So my conclusion is? Both choices are really good and neither is a let down for the street at all. Monoballs, as Andy chose, are completely livable for a street driven car and provide that extra measure of precision. RS bushings, like I chose, are super high performance and give you a little bit more comfort while preserving a touch of KT steer to keep you safe.

I’m happy with my car and Andy is happy with his, they are both spectacular driving machines and so much better than they were before the refresh. Instead of feeling like a classic that needs to be urged through the corners they both feel modern, relevant and eager as can be.

For those of you who are curious, here's what Andy's control arms look like:







Here is what mine look like:

jscott82

Don't forget monoballs wear much much faster and need to be inspected for wear and rust. Rubber you can install and forget bout it.

MarinS4

I have pretty much your setup Tialoc but with solid mounts and front LCA poly bushings.

The solid subframe mounts are frightening on paper but in the wild they don't seem to degrade NVH. They make a big different in stabilizing the rear though. Everything just seems much more predictable with em.

The front LCA poly bushings are another great addition over stock or RS. I just don't think the original design works well with today's tires. When the car was engineered the level of tire grip was nowhere near what it is today.

I could not be happier with the performance and NVH trade offs.

woohoosocal

Nice write-up. Thanks for the info.

Andy Hodapp

I'm not too worried about rust on the monoballs, went with chromoly joints. As for wear they certainly won't last as long as rubber but I did go for oversized joints in hopes they would last longer. They will also be relatively easy to replace as I've already done all the R&D work for them. My impressions were just how great the PSS10's are, before driving the car, I never thought they could be worth three times the price but you can definitely tell they are much better dampened then the Koni's. Same story with the RE71R's, better tire in every way but you definitely pay for that. Amazing how quite they are for how much performance they give. The Federals are extremely noisy but they do seem to have much higher grip levels then my pilot super sports I have on my 18's. Overall the tradeoffs in NVH were well worth it for me but I can see how they would not be for others. I'm young and the added noise and harshness doesn't bother me. Both cars are great and I'm glad I went down the road I did. Thanks so much Tlaloc75 for letting me drive your car. Hope we get a few more days of good driving this year!

MarinS4

Andy, if you install boots on the upper arms like what you have on the toe links they last much longer. ERP sells em separately.

Love the custom KT and Camber arms! The alignment locks look better than others I've seen as well. Props!

mpruden

Great post. That's such an advantage getting to drive two cars back to back. I think I need to move to Montana so we could have a Targa in the picture too.

Tlaloc75

Come on up any time.

Andy Hodapp

The shop that helped me with the control arms wants to see how they hold up without boots. If you read online there are some arguments on whether boots help or just trap in moisture and debris.

trophy

The lack of NVH when I put in the rod ends, monoballs and solid side mounts was surprising.

I have unbooted rod ends on my car for over 5 years now and are checked regularly. No additional noises associated with wear etc.

I am going to pull all of them off this winter and fully inspect and potentially replace as part of the maintenance however, based on how the car feels I don't think they need replacing.

Tlaloc75

Yes, that sounds like a good setup. I'm not sure if I could feel a difference specifically from solid subframe mounts vs my RS rubber mounts. That was what surprised me, how similar the setups felt. The handling and NVH differences were all pretty subtle.

Its good news - a lot of these choices are going to result in a great handling car regardless of which way you go.

Tlaloc75

Are you running solid shock mounts? If so, did you notice much of a change in NVH from those?

Sutton

Great write up! I'm surprised the differences weren't more pronounced given the divergent choices for the components.

​​​​​Of particular interest, is the bump steer kit on Andy's car. I don't believe your car has one? If not, do you think you'd notice much benefit from having it?

I had been on the fence about the solid bushings for the rear sub frame, fearing unacceptable NVH, but will now add that to the list.

Tlaloc75

Yes, I'm surprised too .

My car does not have a bump steer kit, but I'm at a higher ride height than he is. I did notice that when I was experimenting with ride height that going much lower than RoW Sport did result in squirrelly steering. At my height, I don't feel like I need the correction (though it couldn't hurt). At Andy's height (~RS+10), he probably does need the correction and to me his steering felt good, so I think the kit was doing its job. His steering felt alive, direct and solid. No twitchy feelings, no need to correct while driving down a lumpy road.

Knowing what I know now, I'd probably go for solid subframe as well, but I'm also very happy with my RS mounts. Not sure you can go wrong, they are both very good.

trophy

I have camber plates and monoball rear shock mounts. Biggest change in NVH comes from rear shock mounts.