As my A3 TDI Sport has passed 130,000miles I thought I'd refresh the suspension and fit some S-Line springs I bought a couple of years(!) ago at the same time. The car has felt a bit bouncy (under damped on rebound) sometimes and loose at the front - I want to keep it stock/oem so I ordered some new bushes and SACHS Advantage dampers; the online place said they didn't have any but offered the BOGE Turbogas instead which is a comparable part number on ZF's webtcat (who also own BOGE). Anyway the dampers turn up in BOGE boxes but are labelled SACHS 400023 and 36F42S!
- Pair of Meyle wishbone bushes (£52)
Pair MEYLE Front Wishbone Bushes & Brackets for VW Mk5 Mk6 Golf, Eos & Audi A3 | eBay
- SACHS Advantage 400023 (aka BOGE Turbogas 36-F42-S) (£115)
- Pair of SKF top mounts including steering bearing (EuroCarParts number 609440810) £32.64 pair
There are other how to's on this forum but I thought more is often better for those attempting the job so thought I'd put my own here.
One thing to note is the use of spline/triple square bolts on the hub to strut bolt and also the droplink. 14mm on the strut and a small 6mm(?) on the droplink.
Once the driveshaft bolt is loosened and the car is raised up, I removed the wishbone, unbolting the 3 16mm nuts at the balljoint and leaving the balljoint itself in the hub. There's 2 16mm long bolts and 1 18mm long bolt on the rear bush bracket. Then there's one 18mm bolt at the front bush which is accessible by removing a couple of undertray torx screws and pushing the arch liner back. Removing the wishbone made it easier and also easier to fit the new bushes on the bench.
Undo the 18mm nut on the strut to drop link. This is a bit of a pain as there are usually flats on the back of the droplink to stop the balljoint turning, but VAG in their wisdom put a small spline in the centre of the thread to counterhold it. If the thread is a bit dry/rusty they are tight to get off and take a while.
Fully undo the large driveshaft bolt and supporting the hub assy withdraw the hub away/push the driveshaft through and support the hub. Undo the strut to hub clamp bolt (18mm nut on the 14mm spline bolt). The bolt had siezed in the strut which made undoing the nut easier as the bolt didn't turn. However I span it free with an air gun to remove it fully from the hub. Use a cold chisel up the back of the hub to spread the hub, and tap down the hub out of the strut.
Then undo the 3 13mm bolts at the topmount (under the scuttle panel). I didn't remove the panel entirely but did have to remove the driver's wiper arm to get access. Once these are undone the strut will fall out so make sure you hold it!
Off the car it was simply a matter of lightly compressing the springs (not much is needed to release tension off the top mount), and undoing the top mount nut. This can be done with an allen key to counterhold whilst using an offset ring spanner. Remove the top mount and bumpstop/dust boot assembly and transfer the boot and bumpstop onto the new top mount (the dust boot kind of clips under the steering bearing. The S-Line springs, being shorter, didn't need compressing at all, just leaning on to get the nut turned a few times.
With the wishbone clamped in a vice, turn the bush bracket round and it will break the "seal" on the wishbone; turn it back and forth whilst pulling and it will work its way off the wishbone. Put some fairy liquid on the wishbone and the new bush should push on without too much trouble! Make sure you note the orientation of the bracket (which sits horizontal with the wishbone). Left and right hand brackets look very similar so make sure you compare with what was taken off!
Refit in reversal, fastening the top mounts first, locate the strut in the hub at the same time as relocating the driveshaft back in the hub. A bit of a jiggle, but worth doing this way. Then lastly fit the wishbone back up.
Removal of the struts isn't too bad although one of the bolts was siezed in a top mount and sheared the captive nut in top mount so I had to grind the head off it. The top mount design is a bit daft having the threads face inside the wheelarch and so are exposed to mud/water etc. It makes much better sense to have the bolt upwards like most other cars IMO!
One good thing compared to other cars I've worked on is that the brake hose, ABS wiring and pad warning wiring is attached to the hub rather than through guides on the strut which makes removal of the strut that bit easier as nothing gets tangled.
Comparing dampers, the SACH Advantage is slightly shorter, perhaps 15mm. Also of surprise is that my old dampers appeared to be good, and interestingly the "bump" is very strong, stronger than the new dampers! They are pretty firm to compress off the car, however the rebound is not as strong as the new dampers (AUDI have never been good at damper tuning, a strong bump and soft rebound just means the car feels firm but doesn't actually handle).
Another thing of note is that there is hardly any rubber in the strut assembly and this leads me to why the A3 suffers so much from road noise and perception of harsh suspension on S-Line. IMO, there should be rubber isolators at the bottom of spring/strut at least, and more in the top mount (there is hardly any rubber there either). On BMWs there are different thickness rubbers, thicker on "rough road" spec suspension. It could be retro fitted with some appropriate rubber to try but it will obviously affect ride height slightly.
Going to do the rears next weekend! btw the rideheight is not odd with S-Line front and Sport rear springs; so far the S-line springs, whilst visibly shorter by 1.5" or so have resulted in the rideheight being about the same. I am assuming this is because they are low mileage springs vs my 130,000mile setup and that things may settle in a few weeks, or maybe the new top mounts stack height is slightly more. I wasn't looking for much of a drop, but just to firm it up a bit in corners.