dshulik

My local private Porsche mechanic used to work at Bev Hills Porsche and his father had a 928 for a while, so he's fairly familiar with 928's. He told me after doing some work alligning the car (hallelujah! Someone that knows how to do it properly before I had to quiz them with the info I've learned on this site!) that the front end seemed sort of "bouncy" and that my front struts/shocks (whatever) seemed like they might be bad. Here's a list of what has been done in the past 18-24 months. Was wondering if anyone has some insight into why it seems a bit bouncy and also a bit harsh despite fairly new shocks/springs.

Had the following done: (1980 model)
-Upper spring seats replaced "s" type - as reccomended by Mark at 928 Intl. (my LA mechanic used to work on his 928 back in the
-Threaded lower spring seat "s" type also? For ride height adjustment. (set to lowest setting)
-Eibach performance springs - from 928 Intl.
-Standard Boge front strut/shock
-18 inch Turbo twists with 40 series 225's

My new mechanic was the one who originally made the observation about the ride. (The new mechanic was only out of necessity as I moved from LA to San Diego) The new guys deal alot with factory RSR's and alot of other Porsche factory racing cars which they support for racing and they seem to know more about the trick stuff than anyone else I've ever met, so when they suggested perhaps there might have been some mistakes made with the installation of the shocks, I wondered if that is very likely? Something to do with the screws at the top? Second, if it isn't the
shocks wearing out quickly, could the springs have something to do with it? I thought they were more performance oriented and would assume that they would stiffen the ride (they have, to the point of being harsh at times although the tire profile probably is a contributor - my buddies '03 Boxster S doesn't ride this harsh with 18's however) but I went with the standard Boge shocks at my LA mechanic's advice to prevent the ride from being "too harsh." I drive about 12K miles /yr avg. Should shocks go bad this quickly?

Paul D

D - I can only comment about your Eibach springs (I put them on my car). The Eibach spring is a progressive type (vs. linear type) spring, meaning it is softer for the first few mm's of compression and gets stiffer quickly with more compression. Small road irregularities will be smoother, however larger irregularities (like railroad tracks) will feel harsher. Having 18 inch rims with 40 series tires will make the overall ride more harsh since you have less compression in your sidewall. I replaced my factory Bilsteins with the internally adjustable Koni's in their full soft setting. This spring I'm planning on setting them to a slightly stiffer setting.

WallyP

Springs and shocks are - or should be - matched.

You have changed to stiffer springs, but are still using standard shocks. The shocks are a bit too soft to control the stiffer springs, so you will get quicker, harsher rebound. Stiffer shock would probably actually ride better - but not much, because in addition, you have removed much of the spring effect of the tires. Look at the amount of tire sidewall that you now have to cushion road impacts. The tiny sidewalls pop a LOT more impact into the spring/shock combo, which are less capable of dampening it.

Rough ride!

Tommy928

My Boge shocks lasted less than 25K and the car was bouncy even with stock springs.

I have since installed Bilstein and Eibach. I wanted Koni but was swayed by an "928 expert" to go with Bilstein - a mistake. The ride is slightly bouncy and a little harsh. The bounce is due to the monotube design and the harshness is just bad valving for the springs.

I have been using Koni on varies cars for over twenty years and they are always firm but not harsh. I would go with Koni if you replace your shocks.

Tommy

Paul D

Wally makes an excellent point (as usual) the shocks have to be matched to the spring rate. I remember driving my friends 944 S2. It had after market springs with Leida adjustable shocks (for both rebound and compression). When the shocks were in their soft setting that car would bounce badly, However when it was stiffened up for the track it was on rails! Kim Crumb highly recomended the Eibach/Koni setup for all around (street and DE) type driving. Good luck!

dshulik

Thanks guys, perhaps the shocks aren't worn but its just the "mis-match" between spring and shock. I'll be sure to get something adjustable next time round....