E30 Zone

Hi All

So I would like to upgrade my tired old suspension, springs & shocks. I am going for the Bilstein B12 Prokit that includes shorter shocks & Eibach springs. Giving a possible 40mm front & 30mm lowering from standard.

However, when I looked to purchase there are two sizes listed - 45mm & 51mm which is in relation to the strut diameter. Apparently, the VIN doesnt help as BMW fitted whatever size they had in stock when the car came off the production line?

Does anyone know about this & does this mean I could fit either size? I could obviously wrap a measuring tape & go like for like but I was interested to know thoughts of the gurus on here please.

BMW were very specific when they built the cars ,I`ll stand corrected but the entry models ,316 318 etc had the thinner struts whilst the 320 325 318is and all Tourings had the larger ones on.

Mart.

A lot will depend on the condition of your present struts, if they are 45mm and rotten then it is a no brainer to find a good set of 51mm and fit the 51mm Bilsteins at the same time IMHO. Will add a bit to the cost but probably worth it in the long run.

Good 51mm legs are getting a bit thin on the ground these days but they do come up occasionally

flybynite wrote: ↑

Sat Sep 10, 2022 3:41 pm

A lot will depend on the condition of your present struts, if they are 45mm and rotten then it is a no brainer to find a good set of 51mm and fit the 51mm Bilsteins at the same time IMHO. Will add a bit to the cost but probably worth it in the long run.

Good 51mm legs are getting a bit thin on the ground these days but they do come up occasionally

Just to confirm that 45mm legs only fit 45mm inserts and the same as 51mm ones ? No interchanging of each type ?

Mart.

martauto wrote: ↑

Sat Sep 10, 2022 3:59 pm

Just to confirm that 45mm legs only fit 45mm inserts and the same as 51mm ones ? No interchanging of each type ?

Yep, correct 51mm inserts need 51mm legs, 45mm inserts need 45mm legs, no mixing and matching

Only benefit I have seen for 45mm legs is it allows for a thicker sleeve at the bottom of a coilover if it is the type that welds onto strut leg stubs. However I'm not a fan of that type of coilover I prefer the complete strut type like KW or conventional springs and shocks like the B12.