This isn't a question, just a log of something I did and how it turned out so that other people can find the info (most 405 stuff you Google search goes to missing AussieFrogs pages from before the forum deletion). Getting parts for a 405 is getting a little tricky, so hopefully this can help keep some on the road.
When I had a drum brake cylinder fail, I discovered that my 405 had a Berlingo rear axle swapped in by a previous owner (a Peugeot dealer mechanic in Bundaberg I believe). I had already planned to do this, as it gives it much stiffer antiroll and torsion bars. So I decided to upgrade the front suspension too.
I already had a pair of 206 GTi 180 front shocks and springs in the garage that never made it into my GTi, so I measured everything and it seemed like a good idea. Thicker on each coil, and the curb weight of the 206 GTi 180 is about the same as the 405 (never believe compliance plates on PSA cars btw). The shocks are the same top thread/nut, and the same bottom diameter (51mm) and clamped length. The difference is the 206 GTi 180 shocks are about 40mm shorter at full extension. However since the 405 springs are so soft, they sag more, resulting in less than 40mm change in ride height. I didn't bother measuring before since the ride height of 25 year old springs is not going to be consistent anyway. The 405 springs have a huge amount of preload compared to the GTi 180 springs (see picture 1). My spring compressors were barely long enough to safely unwind after taking them out. One other difference that's not important is that the 206 GTi 180 shocks have a mount for the antiroll bar. Since the 405's ARB is mounted elsewhere these aren't needed, but they don't foul the inner arches so there's no need to cut them off.
The car corners so much better that it feels like a different car. I've taken it on some drives through the parts of town with worn out roads and it's not jiggly, just firm. I've contended with a university and an IKEA carpark and both small/sharp and large speedbumps have been fine. No scrapes on driveways (even industrial zoned ones). For reference, I've got 205/55R15 tyres. Overall I'm really happy with how this turned out.
Fiddling with the splines to match the rear ride height to the front is a job for next weekend.
When I had a drum brake cylinder fail, I discovered that my 405 had a Berlingo rear axle swapped in by a previous owner (a Peugeot dealer mechanic in Bundaberg I believe). I had already planned to do this, as it gives it much stiffer antiroll and torsion bars. So I decided to upgrade the front suspension too.
I already had a pair of 206 GTi 180 front shocks and springs in the garage that never made it into my GTi, so I measured everything and it seemed like a good idea. Thicker on each coil, and the curb weight of the 206 GTi 180 is about the same as the 405 (never believe compliance plates on PSA cars btw). The shocks are the same top thread/nut, and the same bottom diameter (51mm) and clamped length. The difference is the 206 GTi 180 shocks are about 40mm shorter at full extension. However since the 405 springs are so soft, they sag more, resulting in less than 40mm change in ride height. I didn't bother measuring before since the ride height of 25 year old springs is not going to be consistent anyway. The 405 springs have a huge amount of preload compared to the GTi 180 springs (see picture 1). My spring compressors were barely long enough to safely unwind after taking them out. One other difference that's not important is that the 206 GTi 180 shocks have a mount for the antiroll bar. Since the 405's ARB is mounted elsewhere these aren't needed, but they don't foul the inner arches so there's no need to cut them off.
The car corners so much better that it feels like a different car. I've taken it on some drives through the parts of town with worn out roads and it's not jiggly, just firm. I've contended with a university and an IKEA carpark and both small/sharp and large speedbumps have been fine. No scrapes on driveways (even industrial zoned ones). For reference, I've got 205/55R15 tyres. Overall I'm really happy with how this turned out.
Fiddling with the splines to match the rear ride height to the front is a job for next weekend.
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