Suspension upgrade question...

[aboyandhisdog]

I have replaced all of the front control arms and links and have replaced the OE struts with the Bilstein B6 front and rear. Still using the factory springs, however. The front strut mount bearings are also new. On roads where the concrete joints are raised and the streets are just plain crummy with holes and bumps, the ride of the car is absolutely punishing. I'm more concerned with punishing the car than myself, and so my question: What, if anything, can be done to smooth out the ride a bit? I heard somewhere that coil-overs can provide a better ride for the car but I know nothing about them or how they can achieve this over the stock suspension.

If anybody has experience with a tried and true mod for this condition, I would love to hear it! 80% of the time the car ride is just fine, but bad roads really bug me, thinking I am harming my car. I don't ever track this car or drive aggressively so if the performance is diminished a bit, no problem. I was even thinking a tall sidewall would be ideal, but that doesn't appear to be an option that is ever going to be available. Thanks very much, guys! -Tom

[John17]

I know what you mean. I have a 997.2 and a 986 Boxster. The Boxster on 17s is much more compliant than the 18s on the 911. It's so much better we prefer it for trips.

[aboyandhisdog]

Thanks, John! I would like to try the 17's so I put them in a "tire calculator" to compare to my 18's. The fronts on the 17's would give me .3" more sidewall (8% more), but the rears would give me .2" less (5% less) on the 17's.

It is a tad confusing, but the rears on the 18's are a full 1.3" longer in diameter than the 17's but have less sidewall, while the fronts are only .3" longer in diameter than the 17's and have more sidewall.

I'm not seeing enough difference here on paper too justify rolling the dice on a switch to 17" wheels, but thanks a lot for the input on the Boxster wheels.

What tires do you run on each car? I have the Conti Ex Con Plus on currently but was thinking to try the Michelin next time around. But then I read somewhere that the Conti is actually a better riding tire. What do you think???

[ROB III]

Tire Rack rates tires on various parameters, including ride. You might look at their site, pull up the tires you have, than compare to another brand to get some input.
Different car (951) but I went from Bridgestone run-flat Pole Positions to Michelin Pilot Sport 4 S, and found the ride improved. If you are running on run-flat tires, that will also increase impact harshness.
A taller sidewall should improve ride quality. As you go down in sidewall aspect ration the sidewalls get stiffer to help responsiveness but also transmits more impact shock to the suspension and you. I run 18's on my 951 which came on 16's. When i put the 16's back on with stock aspect ratio sidewalls (55 front, 45 rear), the ride improved dramatically. The aspect ration of the 18's I have are 40 front and 35 rear.

[John17]

The 911 has Michelin 4S and the Boxster Firestone 500s, all stock sizes except the Boxster fronts are slightly wider than stock. I can't directly compare them, but on the Cayenne, which came to me with Michelin run-flats, I replaced with standard Michelins and found a dramatically better ride. Handling is certainly not impaired.

[aboyandhisdog]

Good to know! I've always been happy with Michelins, but as mentioned, I did read that my Continentals are slightly a less harsh ride than the Michelins that are available for my car. At the end of the day, probably a distinction without a difference between the two. I really wish I could find a taller sidewall available on a smaller wheel that would give me roughly the same diameter as what I have. Might be a impossible quest! I'll keep looking. Thanks, John!

[cikasfm]

I’ve had a 986 Boxster and now replaced it with a 997.2

On the Boxster I had Bilstein PSS9 coilovers installed & I loved them!

Tuned to “euro spec” height age middle as suspension stiffness, it completely transformed the car & I loved it! But I never adjusted them

Now after buying the 997 with a lot of miles - the first thing I wanted to tackle was the suspension.

I thought I never adjusted my PSS9 coilovers, so just put non-adjustable B12 pro kit (aka B6/B8 with lowering springs) and…I absolutely hate it.

It just made the car undriveable for the streets.

Not only its way too low that I’m scraping everything, even during cornering but also it’s so bumpy that every single spot on the road hits my back over the seat.

I’m about to get rid of them and replace with proper Ohlins coilovers set with DFV (dual-flow valves) to hopefully restore the ride quality

[blueline]

I’ve had a 986 Boxster and now replaced it with a 997.2

On the Boxster I had Bilstein PSS9 coilovers installed & I loved them!

Tuned to “euro spec” height age middle as suspension stiffness, it completely transformed the car & I loved it! But I never adjusted them

Now after buying the 997 with a lot of miles - the first thing I wanted to tackle was the suspension.

I thought I never adjusted my PSS9 coilovers, so just put non-adjustable B12 pro kit (aka B6/B8 with lowering springs) and…I absolutely hate it.

It just made the car undriveable for the streets.

Not only its way too low that I’m scraping everything, even during cornering but also it’s so bumpy that every single spot on the road hits my back over the seat.

I’m about to get rid of them and replace with proper Ohlins coilovers set with DFV (dual-flow valves) to hopefully restore the ride quality

Thanks for that input. Let us know how things turn out once the changes are done and all is sorted.

By the way, welcome to Carpokes!

[aboyandhisdog]

I’m about to get rid of them and replace with proper Ohlins coilovers set with DFV (dual-flow valves) to hopefully restore the ride quality

Please do let me know where you land. Some of what you mentioned is Greek to me, but I am very interested to learn what struts / shocks make the car most compliant. I have no interest in lowering the car from stock, as that is already too low for the reasons you mentioned. I would have never guessed that the Bilstein B6 would be so rough, I just thought that it would be a tad stiffer than the stock B4 setup. I don't have PASM so just need a good, basic suspension that absorbs the road better than what I have now. Thanks...I appreciate your input! -Tom

[aboyandhisdog]

I called Bilstein and explained the issues I was having with a horrible ride from the B6 dampers. They were of no help other than to say I should have bought the B4's which are the stock OE replacement. I've also read and viewed on YT quite a lot about suspensions, and have gleaned a bit of knowledge on dampers. The only coil-overs that were reported with a good ride on streets and even a possibly better ride than stock was the Ohlins R&T. But, the consensus is that unless you need to change the ride height or stiffness on a regular basis, then better to stick with the stock dampers and springs (B4's). And at $3300 for the set, the Ohlins are pricey and (to me) not worth the cost. I think the next time I need to buy new, I'll just go back to the stock B4's.