Wow, those original shocks are only about a year older than me.
I like to think I've held up a little better.
Update by David S. Wallens to the
Porsche 911 Carrera project car
Feb 6, 2024
|
Porsche,
911,
KW Suspension
Photography by David S. Wallens
Perhaps it was time for new shocks on our Porsche 911: The fronts leaked fluid, while someone had inscribed the rears with April 18, 1995. That was a while ago.
On April 18, 1995, Joe Montana announced his retirement. On or around that same day, our Porsche got new dampers.
Even from behind the wheel, we could tell that our 911 long needed fresh dampers: The car floated about at highway speeds as weight seemed to move from corner to corner, while every impact with a roadway reflector sent a jolt through the cabin.
Shock absorbers aren’t solely about comfort, though, as they help keep a car’s tires planted on the road.
And what happens to a tire that’s not properly gripping the road? That’s right, a loss of traction. Now cut to scenes of bad things happening involving you, your favorite classic and, perhaps, innocent bystanders.
We’ve run absolutely destroyed shock absorbers on cars before–not by choice but just how some cars have fallen into our laps. When pushed to the limit, the dead shocks cause a loss of traction when accelerating, turning and braking. So basically, those dead shock absorbers not only cost us time on track but have also presented a fairly major safety hazard. (The things we do for science.)
The shocks on our old Civic Si were blown, relieving each corner of proper control. (TL;DR: Thanks to tired dampers, the car was a hot mess on track.)
Maybe we should start at the beginning: Exactly what do shock absorbers do?
They do not, as the name suggests, absorb shocks.
Let’s use the proper term here: Technically they’re called dampers because they damp the springs.
Picture a bobblehead.
What causes the head to bobble without restraint?
Answer: that undamped spring that just bounces about.
What if we could control the rate of that spring and slow it down as necessary?
That’s where a damper comes into play.
Think of shock absorbers as timing devices in that they control the movements of the spring.
So instead of that bobblehead bouncing to and fro without restriction, it would experience controlled movement before returning to center.
How do shock absorbers control all that energy? Magic!
Or, more specifically, they do so via the movement of oil through various orifices and passages found inside the unit.
[How shocks work–and how to make them work for you]
Image Courtesy KW Suspensions
As units age, though, things wear out. Seals allow fluid to leak out. The springs that operate the internal valves get weak. In short, those aged shock absorbers can simply no longer mechanically control the springs they’re paired with.
How can the health of a shock absorber be tested? Via a shock dyno, a piece of equipment that measures force against the velocity of the shock absorber’s shaft.
Don’t have access to a shock dyno? Don’t worry, it’s a fairly specialized piece of equipment. We don’t have one either.
Simply based on our experience and visual inspection, the shocks on our 1984 Porsche 911 Carrera were dead. Like, D-E-A-D.
About that experience: When talking shocks, people will often discuss both the high- and low-speed damping. Those two terms refer to the speed of the shock absorber’s shaft as it moves in and out of the unit’s body.
For low-speed damping, picture a car’s body slowly taking a set as it rounds a steady-state corner.
For high-speed damping, picture a tire encountering a sharp bump in the road.
Our Porsche failed in both instances.
A few options here for shock absorber replacement. The easy button would be OE replacements, as 911 owners have used for decades.
Could we take advantage of modern development work, we wondered, especially on a car that’s a keeper?
That question had us heading to the KW Suspensions catalog. This German company enjoys a very favorable reputation for building motorsports-grade dampers–you’ll spot lots of purple and yellow KW logos at the Nürburgring–and we found the company’s coil-overs to be both fast and comfortable on our Grassroots Motorsports Toyota MR2 project car.
[What happens to roll centers when you lower a Toyota MR2 Turbo]
But KW offers something rather special for the Porsche 911 market: the necessary front spindles to easily swap brands. More about that in a second.
The rear shock absorbers on an air-cooled Porsche 911 simply bolt into place. Easy.
Things get trickier up front, however. First, the 911 uses a strut setup, in that the damper also serves as a load-bearing device. The standard operation is to simply replace the insert, the part of the damper containing the fluid, the piston and all the related parts.
Thanks to the different strut designs between Porsche’s different factory suppliers, some inserts often cannot be paired with some housings. For cars originally fitted with Bilsteins, like ours, a Bilstein insert is required. To change insert brands, we’d have to change strut assemblies, including the spindle. (Related note: Our particular factory spindles are NLA, with various aftermarket options costing about a grand per corner.)
KW Suspensions, however, offers the entire replacement assembly, complete with new forged spindles, removing any compatibility issues. The company offers several setups for our G-body Porsche 911: race, street, track and somewhere in between.
All the options for this application are based around the brand’s popular KW V3 damping package, which features black powder-coated steel bodies along with independently adjustable damping for rebound and compression for full setup control: 16 clicks for rebound along with 12 steps for compression.
For more about compression, rebound and you, take a few to read this Grassroots Motorsports article: "How shocks work–and how to make them work for you."
KW’s “mildest” package for the G-body 911 is intended for standard ride heights. At the other end of the spectrum, the track-ready V3 Clubsport Kits replace the factory torsion bars with coil springs paired with threaded adjusters for easy ride height adjustment–especially helpful for corner weighting. (To dive deeper into corner weights, check out this Grassroots Motorsports article: “Understanding corner weights.”)
We went with the setup that’s a bit in the middle. It retains the stock torsion bars but raises the spindles by 19mm, offering suitable shock travel for lowered cars like ours. The part number for the KW V3 Damper Kit for our G-body Porsche 911 is 35271064, and at least 16-inch wheels are required for spindle clearance. Retail price: Figure a little north of $4000 complete.
This is an off-the-shelf setup available right from the manufacturer as well as several major suppliers. The box includes bump stops, necessary hardware and even a tool kit.
(Visit the KW Suspensions catalog for applications covering the E30-chassis BMW 3 Series, Mercedes-Benz 190 E, VW Rabbit, Fox-body Ford Mustang, Morgan Plus 8 and more classics plus a slew of Porsches, including the 356, 928, 964, 993 and F-body 911.)
We ordered our KW V3 suspension package, and it recently landed.
Installation will soon take place, and then we can tell you how it went together and how the car drives. More to come.
Wow, those original shocks are only about a year older than me.
I like to think I've held up a little better.
Colin Wood said:Wow, those original shocks are only about a year older than me.
I like to think I've held up a little better.
Oh, definitely. For one, you’re not covered with your inner fluids.
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