suspension difference between s30i and s35i?

[bucketlover]

I just purchased a new to me manual 2011 Z4 sdrive30 this past week and stumbled across lightly used springs for the s35i for very cheap. the post reads it will ONLY fit the s35 variant but in my minimal research, it seems the only key differences would be in the M sport and non-M sport suspension?

[KennyP]

Originally Posted by bucketlover

I just purchased a new to me manual 2011 Z4 sdrive30 this past week and stumbled across lightly used springs for the s35i for very cheap. the post reads it will ONLY fit the s35 variant but in my minimal research, it seems the only key differences would be in the M sport and non-M sport suspension?

n52b30 engine in 30i weight is 148kg.
n54b30 engine in 35i weight is 195 kg
Also DCT is heavier than regular automatic... manual is the lightest transmission choice.. way lighter than DCT

dct in 35i is 85kg... manual in 35i is 55kg... manual in 30i is 36kg... and the automatic in 30i is 79kg
So your manual transmission is also way lighter than any transmission options in 35i...

So 35i cars have a lot more weight in the front... To deal with the extra weight front dampers are different and im sure front springs are also different...

Rear weight difference isnt that big... and bmw uses same partnumber shocks for both 30i and 35i in the rear... im guessing springs are same aswell...

30i and 28i use same shock partnumber in the front... probaby same springs too... n20 engine is like 10kg lighter than n52 in 30i.... difference between these engines seems so small that bmw didnt bother making separate parts for 28i and just used the same stuff from 30i

So if you put 35i springs on a 30i car your front ride height is going to sit high... as those spings are meant deal with the extra 50-60kg in the 35i car. maybe even more... n52 doesnt have intercooler and its plumming. that weighs something aswell...

So i wouldnt put 35i springs on a 30i... if you find something thats for 28i... then you can probably be sure it also fits 30i...

[bucketlover]

Thank you for the write up, i really appreciate it. I see, so it’s not a fitment issue, but rather a difference in springrates(?)? I forgot to mention that they were H&Rs, so I guess I’d better keep looking around than to try these ones out?

[KennyP]

hmm i checked out H&R kit for e89.
Seems like H&R doesnt differentiate between any models... they offer same product for 23i, 30i and 35i it seems... Wierd...

While oem front springs on FCPEuro are clearly different between models... FCPEuro sells one product for 30i and 28i and has separate front spring for 35i/is...
For rear replacement spring they have one spring that fits both 35i , 30i and 28i...
Just as i said and assumed before...

Its a bit wierd... but if H&R sells them like this... and doesnt care about weight differences.... then i guess its fine to fit... just expect the front to be bit higher than when same kit is fitted on the 35i...
Odd thing... but lowering springs are never meant to be a precision product tbh... coilovers with adjustable ride height are superior that way...can adjust it to a millimeter.

[B21]

The Ohlins R&T setup was listed as just one variant…quite often the caswcwith aftermarket suppliers..after all BMW fitted the same ARBs for the 18i manual through to 35is ��

[KennyP]

yep KW V3 kit is actually also one product code for 28i, 30i, 35i and 35is...
But thats at least adjustable... you can adjust the height to be correct..
and you can adjust the damping settings to fit you and your car...