OE Coil spring confusion
 

I’m in the process of completely refurbishing the rear suspension on my 2003 3.0i which I believe to have been equipped with sport suspension from the factory because the VIN crosscheck says “sport suspension settings” and it came with the 18” wheels, sport 3 spoke steering wheel, black headliner, black shadow line, yada yada. Well as part of refurbing all the rear arms, ball joint, and bushings, I also ordered new rear springs, part number (33-53-6-750-351).

As I pulled out the old springs, I noticed the part number was different, (33-53-6-750-352). I measured the old springs at 15.5 mm diameter wire. The new springs measure 16.0mm. So I’m not sure if the factory put in the wrong springs or if I’m attempting to put in wrong springs. The new springs are about 3/8” taller but the old springs have 195,000 miles on them, so I’d expect some fatigue. This got me curious about the rear sway bar and front springs. I measured the rear bar at 23.5mm which I think is consistent with the sport suspension. I measured the front springs at 16.7mm but I don’t know what the official sport front springs should measure. Anybody know?

Where did you get the part number for your new springs? Usually same basic vehicles with sport suspension has 3 separate spring variants depending on other additional equipment altering the weight = axle load. So considering the one digit difference in part numbers likely your new springs are calculated as a different variant and axle load. Though those changes are minor and on E53 heights can usually be neglected. Spring part numbers are on a separate spring table on official TIS and only few have access to it.

I ordered all the parts a few years ago and so I am just now getting to it. I think I used the drop down selections after entering my model and year on bmw of South Atlanta or similar site. Realoem doesn’t list the spring part numbers. The original springs have an S3 designation and the new springs have an S2 designation whatever that means.

Yes, a few years ago in some countries there was access to official ETK and TIS from BMW website and then spring table was available. Same think was briefly in Finland.

I think S1-S3 are the variants of the same specs like I said earlier. At this point I wouldn't worry about it and just install the springs.

In case it helps anyone else I found a site with the spring selections based on options:


https://cats.parts/bmw/E53/47745/L:N...FA13525LY15549

Nice find. Though awkward to use because Google translator doesn't work directly.

I accessed it using Chrome on an IPhone and that seemed to work okay as far as everything being in English.