Adjusting the rear dampers on an M030 968
THE 968 M030 Sport Chassis option brought a set of suspension, brake and wheel changes to the car, well detailed on 968register.org/optionalequipment/m030/. Front and rear dampers were changed to Koni adjustables, with the rears also carrying an additional coilover spring. My car has the M030 option and has always been a really comfortable ride, the previous owner assuring me he believed the suspension was set to the most mild setting. I wanted to firm up the dampers and try the car at DE.
Given that the “dampers are adjustable”, you might think the adjustment would be something the owner/driver could do without heroic measures. The fronts are a piece of cake – lift the hood, twiddle a knob and you’re done. The rears are the complete opposite of that.
Adjusting the rear dampers:
You can maybe do this job from the side of the car, wrestling around the wheel hub, but I don’t think so. Bottom line this job needs a lift of some sort, or at least some major jacking and support. The dampers are adjusted by fully compressing, feeling some mechanism engage, then rotating. I have seen it written that you can do this with the dampers still attached to the car at the top but that’s got to be a real struggle – easier to get over it and accept that they have to come off.
The rear shocks are bolted to the car at the top and to the rear suspension arm at the bottom. On my car, with the car in the air and the wheels or hubs hanging down, both dampers were still under pressure from the coilover spring, so I compressed each spring just enough to release the pressure before undoing the bolts.
Driver side first. The lower bolt is easy. A long bar was needed to break it free but the bolt is accessible and easy to remove. The top bolt is difficult. The bolt head is in the wheel arch, easy to see and access once you know where you are looking. It’s a bit easier if you remove the wheel. The nut and washer are way up in a little crevice, deep inside the car underbody, hard to see and harder to get to. The good news is that a box ended wrench will sit over the nut and once the bolt head is turned the wrench rotates and jams against something not sure what, and the bolt can be undone by turning the bolt head. Pull or just keep turning and it comes out. The damper is now free top and bottom and can be pulled down from the top mounting. It’s a real jam in there with the spring compressors on but the whole assembly can be wiggled down between the drive shaft, the trailing arm and the exhaust system. Finally, we have the ‘adjustable’ damper available for adjustment.
The passenger side brings an additional challenge; the crevice that the top nut is in does not give space for the box ended wrench to go over the nut – it has to be an open ended wrench. Top nut circled in red in the first pic.
This is all upwards, and the open ended wrench just drops off the nut. Luckily I have 2 hands. One hand has to turn the bolt head, which is easily accessible from outside the side of the car, while the other holds the wrench up, which is easily accessible from under the car. Once you’ve worked out how to do that, rock and roll.
The springs have to come off, which is a bit tricky. They have to be really compressed, to give room for the top mount to be lowered and wiggled off. Then the damper bump stop has to be extracted from the top cover, and that’s not so simple, especially if it has sat there undisturbed since installation in 1995. Now finally we have the clean damper, ready for adjustment.
Fully compress, feel the engagement inside the damper, rotate. I made a tool – circled in red in the third pic. I tried it a few times without a tool, way difficult. With the custom-designed tool it’s so much easier, and the tool has special provisions; first, places for your feet to hold it still, and second, a place for mounting instructions in an easy-to-read spot. Porsche should license this tool design. From me.
The damper turns about 1.5 turns end to end. Turning the piston rod, clockwise is firmer. Once you have picked a spot on this rotation range and set both dampers to the same spot, then you check both dampers are roughly giving the same rebound speed by timing the return of the rod to fully extended. If they are different (mine were) then you adjust the rotation setting of one to get them matched. This all takes quite a while, and a lot of damper compressing.
Now everything in reverse. Bump stop back in, springs lowered on, compressed, top mount back on, relax the springs so they locate themselves but not so much that they will make it difficult to mount the damper back on the bolts. Wiggle the damper assembly back into position on the car, bottom bolt loosely in, line up the top bolt hole then push/screw the upper bolt in, tighten, remove the spring compressors.
Road test, enjoy the ride. </>