Koni adjustable vs Bilstein Sports

[wildcat077]

I have to replace my original shocks on my 89 Coupe as they are" tired" and i'm debating between Koni adjustables and Bilstein Sport shocks all around.I've got 245/45/16's in the rear on 9 inch wheels and 225/50/16's in the front on 7 inch wheels.
I would like to lower the car to "euro specs" but at the moment the suspension is too soft and i have to go "easy" on the lowering...
Anybody have any input as to which shocks would be adequate for my application ??? Pros and cons...

Thank you !

[Bill Verburg]

I'm very partial to Bilsteins, they work, they last.

Your lowering issue is related to the front wheel/tire. The 7ET23.3 wheels w/ the 225/50 is going to be real tight. You might want to think about 225/45 for that app. The 245/45 rears on the 9s willl give you plenty of room for lowering.

[wildcat077]

Thank you Bill !
They are also cheaper on Pelican than the Koni's...
The lowest i can go at this time in the front is two fingers between the
tire and the fender without rubbing and the height is just a tad over 26 inches from the ground.Still need that elusive 1/2 inch to get 25 1/2 from the ground.
I have no problems at the rear although my current shocks are like "pogos" in other words
completely toasted... lol
I will be ordering a set of four on Monday from Pelican !
With all your knowledge,is there anything else you would recommend while i'm in there ???
I also have to replace my CV joint boots as both outer boots are cracked.

This is my first Porsche and i've had it for about three weeks now so i'm slowly discovering what the previous owner Didn't fix on the car !!!

Thank you !
Phil

[Bill Verburg]

Originally Posted by wildcat077

Thank you Bill !
They are also cheaper on Pelican than the Koni's...
The lowest i can go at this time in the front is two fingers between the
tire and the fender without rubbing and the height is just a tad over 26 inches from the ground.Still need that elusive 1/2 inch to get 25 1/2 from the ground.
I have no problems at the rear although my current shocks are like "pogos" in other words
completely toasted... lol
I will be ordering a set of four on Monday from Pelican !
With all your knowledge,is there anything else you would recommend while i'm in there ???
I also have to replace my CV joint boots as both outer boots are cracked.

This is my first Porsche and i've had it for about three weeks now so i'm slowly discovering what the previous owner Didn't fix on the car !!!

Thank you !
Phil

Enjoy and learn the car stock before making any big changes. At 26" you don't need a bump steer kit at 25.5 it would be advisable to use a simple washer kit for the steering rack.

Little things like a nice thick steering wheel can make for big leaps in enjoyment

[wildcat077]

Just for your info... i'm not one to leave things stock... lol
Wether it be my snowmobiles,ATV's or boat !!! or the latest toy
I've already changed the steering wheel for a 930 style,replaced the muffler with a Fabspeed one in two out,MK premuffler,Steve Wong chip and K&N air filter assembly from Fabspeed !
The wheel and tire upgrade is done and the next step is lowering after i replace the shocks with something better than the originals !
I stronghly believe they built this car just for me some 20 years ago ... lol
Why did i wait so long ???

I'm a licensed aeronautical technician and pretty handy with tools and whatever manual may contain the pertinent information,i think i will have fun discovering this car !

Thank you !
Phil

[KTL]

Actually the Bilstein HD is said to be a better match for the stock torsion bars/springs of your '89 Carrera. The Sports are a better match for..... well, hard to say. They're just stiffer. The best thing about Bilstein is they have a service that will custom match your shocks to your car's weight and spring rate. Koni actually does this too.

I have the Koni single adjustable shocks and I have to say I don't think they're worth the added cost and trouble of adjusting them. Fronts are easy to adjust. Rears not so much if you've got the stock air cleaner box and heating system plumbing which blocks access to the top of the shock. The adjustment is only rebound, so keep that in mind as well. That being said, they're certainly not a bad shock. My car with 23/31 torsion bars and the Konis handles very nicely at the track. Adjustment of the rebound is a snap and if you do some diligent adjust-test, adjust-test, adjust-test.... iterations at the track, you'll find you can see some benefit from them. But it's really more work than it needs to be. For just playing around at track days, it's kinda overkill in my opinion. I'd much rather be equipped with the custom-valved set it and forget it Bilsteins.

The only reason I got the Konis is because I wanted to put something better than the off the shelf Bilsteins (Sport rear, HD front) with my stiff torsion bars. Why didn't I get the custom valved Bilsteins? I intended to, but decided against it since I plan to switch to Bilstein front strut housings in lieu of the existing Boge struts I have on my car. Since the Bilstein and Boge use different shock inserts, I didn't want to do the revalving twice. So in the interim I went with the Konis to fit my Boge housings.

[RSTarga]

I know I am in the minority but i prefer the Koni gas adjustable shocks. The Bilsteins are an excellent shock but mine always started to clunk after a short period of time. The inner bushings wear out and are a pain to fix. I've had my Konis for about 5 years now and they are still fine. I just upgraded to 21/25 torsion bars and they still provide adequate damping.

[diverdan]

Bilsteins on my P cars are awesome especially the adjustables. Put some adjustable Koni gas adjustable inserts in my Alfa sedan and I rate them right up there with the Bilsteins.

diverdan

[Miguel Antonett]

IMO, Koni (red) adjustable is the way to go.

[vtrich]

Here's another opinion. I have Bilstein Sports with standard bars in an '88 coupe. As others have mentioned, I think the car is over-damped with the sports. It's firm, but not in a totally balanced way. I know, this sounds muddy.
I will most likely swap out the sports for HDs at some point.

I have an Audi S4 with Stasis coilovers, they use Konis matched to appropriately rated springs. I don't really like them. I have found they have softened too much.
OK,...I know,...it's apples to oranges,...and maybe the spring rates are messed up, but I've owned alot of sets of Bilsteins, in alot of different cars, and I've never been dissatisfied.

I do like the Koni sticker better tho.

Rich

[RWebb]

Originally Posted by vtrich

... I think the car is over-damped with the [ Bilstein Sports]. It's firm, but not in a totally balanced way. I know, this sounds muddy.
I will most likely swap out the sports for HDs at some point.

* * *

I do like the Koni sticker better tho.

hahaha - +1 on the great stickers

When the system is over-damped, the initial displacement will be reduced when you hit a bump. BUT, the return movement from the springs will also be reduced and will be slower. That may be what you are feeling.

There may be some curves posted on the Internet - type in: over-damped harmonic driven oscillator in Google and switch to Images
- if that doesn't get it, then drop various terms from the search & lather/rinse/repeat

You could just send them in for a refurb, or sell & replace.

[vtrich]

Randy,...thanks for the hint! Although I haven't plugged in your Google search suggestion, I can expect, intertwined with scientific results, some that may cause me to "lather/rinse/repeat" but with cold water.

I have procrastinated for 2 years,....

Rich

[RSTarga]

The spring (torsion bar) and roll bars, should do the work. All you want the shock to do is stop the car from continuing to bounce on down the road,and keep the tire on the ground, anything more than that and you are over damped. That's why the brits call them dampers, it is a much clearer term. If the shock is stiff enough to not let the spring work then you defeat the purpose. Just look at an F1 car go over a curb in slo mo. they seem to float over the curb, and their suspension travel in comparison to our cars is negligible.
David

[vtrich]

THANKS to both you guys, Randy and RS.

Randy, with your link I found a host of explanations that could/would explain my setup, unfortunately it is written in a language I don't understand.

RS, great explanation. I don't think my setup is horrible,...I just get the sense it is not ideal. I think the sports are just ok with the stock torsion bars.

Great feedback,...for me at least

Rich

[KTL]

Agreed the Bilstein struts are a bit of a pain with respect to maintenance. Not only are the bushings in the housing troublesome, but there's also the loads of grease in the housing, the bump stops (I think the set I dismantled yesterday was missing them- just pieces of rubber in the grease), and also the radial seal atop the strut tube.

The nice thing about the Konis or Boge struts is the top collar nut/gland nut is easy to service and there's no tension pin to deal with, as is the case with the inverted Bilsteins. This is the one thing I like about the Boge struts- I have installed both Bilstein and Koni inserts in them and they're basically a drop-in replacement. The only reason I got the Bilstein struts is due to the ability to raise the spindles and decamber them for additional negative camber, which I plan to do.

[RWebb]

sorry there was nothing helpful - if I run across something, will try to recall this & post

to be honest - the "best" way to understand it is to take a Soph. year physics course...

[Bill Verburg]

The shocks have a huge influence on the ride and handling of your car, you can run extreme spring rates on the street w/ the right shocks but they really need to be adjustable to go back and forth between street and track.

For a mostly street driven 911 Bilstein HD front and Sport rear w/ stock t-bars is a nice dual duty setup, the Bilsteins have less unsprung weight and react well to small street type pavement ripples but can still behave well on track.

Sport f/r is great on track but a bit harsh in street use

having the ability to adjust damping is far more important when you start running very high spring rates for track but also want to use the car on the street.

[wildcat077]

Thank you all for your input

I will follow up on Bill's advice and go with Bilstein HD's in the front and Bilstein Sports
for the rear as i don't plan on doing any torsion bar mods quite yet so this suspension setup will be more than adequate for now.

Next upgrade will most likely be brakes before i start with torsion bars...
Although i might do a day of "mild" track time with the club this summer at Mt Tremblant,Quebec just to get a feel for the car... lol

You've all been very helpful !
Phil

[1980 911 sc]

LOL he said "mild track time with the club". He might as well inject himself with poison and get it over with... welcome to the abyss...

[KTL]

Originally Posted by 1980 911 sc

LOL he said "mild track time with the club". He might as well inject himself with poison and get it over with... welcome to the abyss...

Well said!