Bilstein HD shocks impressions
03-20-2007, 08:35 PM
#1
I miss my 'Bu
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Bilstein HD shocks impressions
A couple of weeks ago I replaced my 50,000+ miles old OEM shocks with the Bilstein HD shocks. I have had RB springs on my car since it was around 2000 miles old. Needless to say the OEM shocks were getting tired. I never really felt like the OEM shocks were no good either. In fact, I liked the handling of my car and felt it was comfortable yet sporty. I have been tracking my car since it had about 2000 miles on it as well and last year alone I did 12 track weekends.
So, I had Mazcare in Marietta, GA (plug for a good friend and fellow RX8 owner) install my Bilsteins that I got from TorqueAholic (a plug for another good friend).
On the street - city speeds - ride is still very comfortable but firmer than before. On very slow speed pavement ripples, you can definitely feel a noticeable difference. While cruising down the street the ride has no harshness or crashing over any bumps.
On the street - highway speeds - awesome! The car feels solid. Comparing how it feels now to how it felt before, I can only describe the before ride as "floaty". I would have never said the RX8 is floaty until I tried the Bilsteins out. When going over expansion joints, the shocks keep the car from oscillating on its suspension (if that even makes sense). You go over the bump, it gets soaked up, and there is no unsettling after shock. Just a supple ride. In fact, at speed I would say it is more comfortable than stock was.
On the track - everything is better. The car is significantly more stable under extreme braking (the rear doesn't wiggle as much as it used to). In steady state cornering, any bumps are perfectly dispatched with no skating across the track from excessive stiffness or bounciness. In quick left right transitions (like s curves) the car remains more stable and less prone to wagging its tail allowing more freedom to apply power or trail brake as needed. I had a 3 day weekend and a 2 day weekend at Road Atlanta these past 2 weekends and I felt that I had made a huge improvement in how my car feels. The track had recently been repaved and in the process there were some new ripples in some pretty fast turns. No bump ever upset my car. It was stupendous! The rear felt planted and the car was totally connected to the track. In very high speed corners it remained balanced and drifted predictably.
I don't know much about shock technology but I do know that Bilstein has an outstanding reputation as a high quality shock. I have heard that adjustable shocks (aka "the ****") can vary significantly between left and right shocks and through the range of adjust-ability. I know that I am more of a set it and forget it kind of person so the HDs sounded like the best solution for me. I would recommend them to someone looking for a track-able solution or just a street solution. IMHO they pair very well with the RB springs and sway bars.
So, I had Mazcare in Marietta, GA (plug for a good friend and fellow RX8 owner) install my Bilsteins that I got from TorqueAholic (a plug for another good friend).
On the street - city speeds - ride is still very comfortable but firmer than before. On very slow speed pavement ripples, you can definitely feel a noticeable difference. While cruising down the street the ride has no harshness or crashing over any bumps.
On the street - highway speeds - awesome! The car feels solid. Comparing how it feels now to how it felt before, I can only describe the before ride as "floaty". I would have never said the RX8 is floaty until I tried the Bilsteins out. When going over expansion joints, the shocks keep the car from oscillating on its suspension (if that even makes sense). You go over the bump, it gets soaked up, and there is no unsettling after shock. Just a supple ride. In fact, at speed I would say it is more comfortable than stock was.
On the track - everything is better. The car is significantly more stable under extreme braking (the rear doesn't wiggle as much as it used to). In steady state cornering, any bumps are perfectly dispatched with no skating across the track from excessive stiffness or bounciness. In quick left right transitions (like s curves) the car remains more stable and less prone to wagging its tail allowing more freedom to apply power or trail brake as needed. I had a 3 day weekend and a 2 day weekend at Road Atlanta these past 2 weekends and I felt that I had made a huge improvement in how my car feels. The track had recently been repaved and in the process there were some new ripples in some pretty fast turns. No bump ever upset my car. It was stupendous! The rear felt planted and the car was totally connected to the track. In very high speed corners it remained balanced and drifted predictably.
I don't know much about shock technology but I do know that Bilstein has an outstanding reputation as a high quality shock. I have heard that adjustable shocks (aka "the ****") can vary significantly between left and right shocks and through the range of adjust-ability. I know that I am more of a set it and forget it kind of person so the HDs sounded like the best solution for me. I would recommend them to someone looking for a track-able solution or just a street solution. IMHO they pair very well with the RB springs and sway bars.
03-20-2007, 09:33 PM
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Excellent information... and proof of what I felt that I experienced with Bilstein shocks on my 944 long ago.
FYI... Bilstein uses a "self adjusting piston" which directly varies how far its valve opens based on force. If you grab one by the shaft and shake it downward, it'll immediately drop to full extention. If you were to try the same motion slowly, the shock will barely move. It's this ability to control all types of motion (hard hits, soft dips, quick ripples) which make these really great shocks.
I was thinking of getting two of these to run on the rear, with my Eibach Pro-Kit springs, while running my K-Sport coil over shocks and springs on the front. Bilstein didn't recommend running them with lowering springs though. How far do the RB springs lower your RX-8?
FYI... Bilstein uses a "self adjusting piston" which directly varies how far its valve opens based on force. If you grab one by the shaft and shake it downward, it'll immediately drop to full extention. If you were to try the same motion slowly, the shock will barely move. It's this ability to control all types of motion (hard hits, soft dips, quick ripples) which make these really great shocks.
I was thinking of getting two of these to run on the rear, with my Eibach Pro-Kit springs, while running my K-Sport coil over shocks and springs on the front. Bilstein didn't recommend running them with lowering springs though. How far do the RB springs lower your RX-8?
03-21-2007, 01:38 PM
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Some online retailers sell them with the Eibach springs. You could try calling Bilstein up directly and speaking to their technical support. I have a friend that runs them on a Mustang with Ford Racing springs that lower the car and they are a great match.
03-21-2007, 02:50 PM
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Yes, but they make two versions. HD is "Heavy Duty" but stock length. "Sport" are their "lowered" shocks, which have a shorter stroke. For Mustangs they make both. For RX-8s they only make the "HD" version, or their uber-expensive PSS9 coil-over package. I have already called Bilstein, which is how I know this information. This is why I'm wondering, because my Eibachs WILL work with the OEM shocks (full length stroke of course)
03-21-2007, 03:27 PM
#6
lol, uber-expensive 
the drop will be a lot less with a high gas pressure monotube shock such as the Bilstein than it will be with a low/no pressure shock such as Koni
shock extension force = gas pressure x shaft area
a shock with 300 psig pressure acting on a 1/2 sq in shaft area will have a 150 lb extension force per shock, this force counteracts the car weight on the spring
the drop will be a lot less with a high gas pressure monotube shock such as the Bilstein than it will be with a low/no pressure shock such as Koni
shock extension force = gas pressure x shaft area
a shock with 300 psig pressure acting on a 1/2 sq in shaft area will have a 150 lb extension force per shock, this force counteracts the car weight on the spring
03-21-2007, 05:37 PM
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Hmmm, that didn't seem to be the case with my Porsche 944 shocks, which allowed every bit of the drop that the lowering springs claimed. I think the floating piston which separates the nitrogen gas from the oil also compresses slightly as the shaft moves in and out, keeping pressure on the shaft fairly uniform.
I think your formula for shock extension force is a bit simplified as shaft area for a 1/2 shaft would not only depend on the diameter, but the length of that shaft within the pressurized housing, right?
"Uber-expensive" is a highly technical term which shouldn't be bantered about lightly! LOL It's also relative to one's income, so a PSS9 for one person might be a child's toy iin comparative pricing for another. For me, since I've already spent half a grand on my setup, looking at the PSS9 setup is out of the question right now. Hence the "uber-expensive" descriptor.
I seem to recall tha tthe RB springs only advertise a 3/4" drop. Someone correct me if I'm wrong here.
I think your formula for shock extension force is a bit simplified as shaft area for a 1/2 shaft would not only depend on the diameter, but the length of that shaft within the pressurized housing, right?
"Uber-expensive" is a highly technical term which shouldn't be bantered about lightly! LOL It's also relative to one's income, so a PSS9 for one person might be a child's toy iin comparative pricing for another. For me, since I've already spent half a grand on my setup, looking at the PSS9 setup is out of the question right now. Hence the "uber-expensive" descriptor.
I seem to recall tha tthe RB springs only advertise a 3/4" drop. Someone correct me if I'm wrong here.
03-21-2007, 08:00 PM
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If the shock provides more "upward force" then it counteracts the lowering of the spring.
Oh, I looked up the Racing Beat springs and found they only advertise a 1/2 in drop front and rear and a 20% increase in spring rate.
I wish there was someone out in LA running the Bilsteins so I could try them out before splurging and getting an entire set. Anyone want to loan me a set to try on my car? :D
Oh, I looked up the Racing Beat springs and found they only advertise a 1/2 in drop front and rear and a 20% increase in spring rate.
I wish there was someone out in LA running the Bilsteins so I could try them out before splurging and getting an entire set. Anyone want to loan me a set to try on my car? :D
03-22-2007, 12:35 PM
#9
Got Another Rotary
Originally Posted by TeamRX8
lol, uber-expensive
http://www.shockwarehouse.com/site/i...cted_year=2006
Pretty Good deal considering Koni's and Tokico D-Specs go from $550-600.
03-22-2007, 01:32 PM
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D-Specs and Konis are short-travel shocks, meant for lowered cars. They're not a direct apples-to-apples comparison.
When my next batch of payments arrives I might just order two rear Bilstein HDs and see if they'll work well on the rear of my car.
When my next batch of payments arrives I might just order two rear Bilstein HDs and see if they'll work well on the rear of my car.
03-22-2007, 03:08 PM
#11
1935 lbs. FTW!
Originally Posted by PhotoMunkey
D-Specs and Konis are short-travel shocks, meant for lowered cars. They're not a direct apples-to-apples comparison.
When my next batch of payments arrives I might just order two rear Bilstein HDs and see if they'll work well on the rear of my car.
When my next batch of payments arrives I might just order two rear Bilstein HDs and see if they'll work well on the rear of my car.
Last edited by CosmosMpower; 03-22-2007 at 03:13 PM.
03-22-2007, 03:22 PM
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I had Koni Sport Single-Adjustables on my Mustang. They'd be fine for the track, but were far too stiff for the street! Compression was just horrible.
The point is that I'd rather not have to adjust the rears ever again. If the Bilsteins can offer that, and still work with lowering springs, I'll probably get two and try them. It's an expensive experiment if I ruin a set of shocks though.
The point is that I'd rather not have to adjust the rears ever again. If the Bilsteins can offer that, and still work with lowering springs, I'll probably get two and try them. It's an expensive experiment if I ruin a set of shocks though.
03-22-2007, 06:14 PM
#13
Originally Posted by PhotoMunkey
D-Specs and Konis are short-travel shocks, meant for lowered cars. They're not a direct apples-to-apples comparison.
03-23-2007, 03:06 PM
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Originally Posted by ULLLOSE
Not sure where you got that info. Both the Koni Sport and D Specs are direct fit replacement shocks that can be used with stock springs. The Koni length and perch location are the same as the stock shocks, they have to be for us to use them in stock class SCCA solo.
03-25-2007, 03:28 PM
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Originally Posted by TrackAddict
It doesn't sit like that. Those pics are of the car turning right thus compressing the left side suspension.
How fast was that corner?
03-26-2007, 10:44 AM
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The issue with spring rate is, if you hit a mid-corner bump while that close to being out of remaining free travel, the effective wheel rate will jump to infinite, and the tires on the outside edge of the car could break traction suddenly and dramatically. The rear suspension has a ton of travel, so I don't think the back would come around. The front, however, could "wash out" on a mid-corner bump, as low as that car is sitting compressed. Bump stops are supposed to provide a soft transition when the car runs out of spring travel, but again, the Bilsteins use an internal bump stop which is much shorter.
Just be careful, that's all I'm saying...
Just be careful, that's all I'm saying...
03-02-2009, 04:59 PM
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07-29-2009, 09:40 PM
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PhotoMunkey has said elsewhere that he didn't like that combo at all, HD's are meant to work with near-stock height springs.
I traded my Bilstein HDs to MazdaManiac for his Tokico D-specs though. I wanted adjustability and he wanted my Bilstein's ride height bump for his too-low AutoEXE springs. Perfect trade!
