Suspension chatter after full refresh - Koni Special Active and H&R lowering springs

Hi All, This year my 996.1 C2 has presented me with the infamous chassis creak and since I expect it is still on its original suspension and chassis components, I have treated it to a refresh (coffin arms, tuning forks, tie rods, track rods, drop bar links, front top mounts, ...). I have heard praise for a combination of Koni Special Active shocks and H&R lowering springs combination, so included these as well. I presented all parts to my trusted workshop for installation. Whilst installing, I got a call from the workshop to say that they suspected that I may have ordered the wrong parts since in their words, the front springs were rotating / loose when the strut installed in the strut assembly and the car was on a lift (front corner under no load). I am confident in that I have ordered the correct parts and told them that such movement of the spring may be normal when the corner is under no load, given also that they are lowering springs. They checked if the same movement was present on the other side of the car with the original shock and original spring and place, and yes, the original spring can rotate around the shock strut. I told them to check with the vehicle inspection body if this is allowed, and if ok, to proceed with the installation. After installation a four wheel alignment was carried out to factory spec. The mechanic who installed all said that I could expect to hear a "dunk" when going over a pot hole, but that's a symptom of shorter springs floating within the strut assembly, otherwise I should be happy as it feels like a new car... Upon collection of my car, I noticed that it rides and steers without issue. It is very close to the comfort of the previous standard set up (albeit 25 years old with 120k miles), and I don't expect that my wife will complain or even notice . What is noticeable however is that instead of a creak, there is now a constant chattering noise from the front, especially audible at slower speeds and even on a smooth road, sounding like two metal surfaces knocking against each other. I am concerned that the installation was not done correctly (eg. assembling the front strut and spring) and driving it in this state will cause accelerated wear. The mechanic carried over the compensator rings from the old front struts. Maybe these are too short and hence the spinning / loose springs, or something else is loose (top mounts)? Either way, I expect to take it somewhere else with better knowledge for a check. Has anyone with a Koni Special Active and H&R lowering spring (-30mm) combination experienced similar chattering from the front? This all comes at a time when I have been wanting to get some running in miles after a full engine rebuild . I am grateful for any pointers, I would rather go back to the same workshop and have them fix it for free instead of going elsewhere and paying again. Plus, they may learn something .

Are you sure they have fitted everything back in properly? When removing the old bearing, the support ring (part 4) will be stuck fast to it. I have experienced workshops throwing this out with the bearing and then putting the new bearings in with the compensation ring (part 5) sat up against the bearing. Part number 99634351701 if thrown out! You also need the 6.5mm compensation plate for H&R springs with the Konis. Part number 99634351101 I also used the following hose around the first couple of coils top and bottom of each spring so there was no metal on metal.... 14mm interior clear hose on Amazon. Can you get a camera in there and take a photo so we can see what the spring is up against at the top? If you have all the above you will have zero play even with the car jacked up off the ground. No idea if the clear hose is needed, but it was not a risk I was going to take after having to take it all apart again to put the support ring back in.

Hi Gizlaroc and thank you very much for your input. Here are a couple of photos which I hope will indicate or not if the build up is correct: With the corner off the ground, there is no vertical play with the spring between the pan and the bearing. It does however rotate but not totally freely, as did the original springs and struts. I forgot to write in my initial post that I did share a similar picture of the strut build up with the mechanic (it was though for a C4, my mistake - it was very late / early and since I was having a sleepless night due to this). He said that he had transferred over the parts from the original strut not found on the new Koni or supplied by me as new parts. I had only supplied a new conical washer, Lemforder top mount (not sure if it had a bearing but Autodoc states if the top mount is bearingless and those supplied were not indicated as bearingless), bump stops and bellows. Fingers crossed he did transfer over all required parts and build them up correctly. The original front struts were thrown out since they weren't rebounding properly. If any of the parts were still attached, we may never know. I only have the rears and they are clean of any other parts. Hopefully the photos will indicate either way. Thanks again!

Quotes source post: 2694876

I get nothing like that, it sounds like incorrect fitting, have a look at my pics here and see if anything looks wrong/

Thanks Thunderace for sharing, it is encouraging . To my untrained eye, your picture here: and mine taken from the opposite side, do not look too dissimilar in terms of what may be between the spring top and the top mount: Unless Gizlaroc sees anything amiss, I am beginning to hope that the additional cushioning from some PVC tubing around the spring ends may take up any slack and kill the chatter dead.

A very timely thread - about to do a refresh on my 996T with B8s and H&R lowering springs - how do you know which size compensating ring you need for them? Can I use my old standard ones (standard suspension)?

B8's will take either fine, they are shorter dampers for exactly this scenario. I can't tell looking at those pics GBinSWE. The bearing is part 11 in the diagram, it is a plastic cup top and bottom with ball bearings inside. This sits inside the support right to turn it from a plastic base into a metal base so the spring doesn't rip it to pieces. You then have the rubber compensating plate between the top of the spring and this metal support ring/cup. I think you need to put you finger in there, with the car jacked up and see if you can feel the metal between the rubber of the compensating pad and the plastic bearing. If you can't, then I would guess it is still stuck on the old bearing. Or now in their bin. To be honest, the springs are so loosely compressed, you could undo the top strut nut so it is almost off the strut, slowly jack the car up and then feel what parts are there. This won't ruin your geo, and might allow you to feel if the bearing is in the support cup/ring.

Thinking about this a bit more, I don't think you will the support ring from a photo. It will pad things out by 3mm or so though, I drove home with mine missing and it rattled like a bastard. I took it apart to put on the tubing and noticed the support missing.... I then had to go back to the workshop and have a bit of an argument with them that it was not part of the old bearing and was a separate piece. We went through their bins and found the old bearings and then prised the ring off. I then went home and put them back together myself, including the hose, just the bottom actually, where it is spring on metal strut cup. The top is against the rubber compensation pad. It is still under very low compression when the car is not loaded, but the difference is that it no longer spins around, it just means that you can compress the spring a bit by hand, so even if you take off the springs won't rattle.

That bump stop looks to be a different shape to the ones pictured above? It has a wider "ring" on it and isn't as ribbed. Installed in a different orientation?

I think the bump stop has been installed in the correct orientation. The rounded end fits into the bellow at least. Thank you very much Gizlaroc for the further info! I jacked up the front and tried a couple of things this evening. First to compress a spring to create more space between it and the components above, but of course the spring is too short for a spring compressor to get in there. Then I found a 21mm socket and a long wrench and tried to loosen the top nut to separate the components above the spring. Understandably the top nut is well torqued but felt soft / squidgy when forced, and I didn't want to risk rounding it off, so abandoned that. I did rotate the spring so the top end was facing outwards, which made it easier to separate the components above the spring. I established that the top of the spring is against a rubber surface which I assume is the compensating plate. Giving it all a bit of a clean, I can see the build up as follows (my assumption at least): When compared to the fiche below, my greatest concern is that it appears that a stop plate is between the bump stop and what I assume is the bottom of the bearing with housing, and I don't know if a further stop plate (the lower 6 in the fiche) is correctly between the bearing with housing (11 in the fiche). The other stop plate is below the top nut. I assume that the build up is wrong. Components could be missing (conical washer, 2 in the fiche which I supplied 4x) and / or in the wrong order. I will speak with the Mechanic again and tell him that it is rattling like a good 'un with more chatter than Terry Wogan. That will be lost on him since this is in the south of Sweden . If the worst comes to the worst and I get blamed for not providing a full bill of materials, I may order a top mount rebuild kit and go to a workshop who is expert in setting up competition suspension... That said, the workshop I have used this time should be able to do this properly. Another 800 miles to go until my rebuilt engine is run in and I can take it to the party that starts after 4k rpm. Will I get to do that at this rate before putting it away for winter ? Thanks again!

... wrong info

... wrong info

You're forgetting the diameter of the parts are different so some sit inside others. The part you've labelled 'bearing with housing bottom' is the middle of the top mount poking through the other parts, so the large washer (6) is in the right place. Also the no 2 washer won't be visible as it'll be inside the bump stop.

Watching with interest - hope you can get it sorted!

Quotes source post: 2694992

Ignore my bumpstop, mine is cut down slightly and flipped upside down.