Stock 135i Spring specs

[bp05]

For the life of me, I can't find (or come up with the right search terms) the stock Msport spring specs.

I creating a comparison of the spring rates and ride heights of all the lowering springs available, for me to visually see the differences and pick the best one for my application.

From what I've gathered on 1addicts, all the aftermarket manufacturers base drop from the 128i's ride height. Is this true?

If so, I've also gathered that the Msport springs on the 135i are 0.5" dropped from 128i's height. Is this good info?

So my questions are:

- Do all aftermarket mfgs base drop height from 128i?
- Is the Msport 135i springs 0.5" from from 128i?
- Does the Msport 135i springs lower 0.5" on all four corners?

Info would be great!


Background: Just purchased a 2009 E88. Loving it. Very surprised on how well the steptronic automatic performs!

[bp05]

Bump?

[ShocknAwe]

To answer your questions:

No.
Yes.
Yes.

[bNks334]

Someone please correct me if I am way off base with what I am saying, but...

There aren't really any concrete numbers out there... The only definitive number seems to be that M-sport is 120/350. BMW states that the performance suspension is 48% stiffer than base and 34% stiffer than M-sport. Therefore, you could then deduce the following:

BMW Performance Rates
F: 120*1.34 = 161
R: 350*1.34 = 469

Iv'e read on the forums people quoting BMWPS as 160/420 and 195/505 (I think this is the E90 rate).

Base
F: 161/1.48 = 109
R: 469/1.48 = 317

BMW says their performance suspension provides a 10mm drop vs the M-sport suspension and a 25mm drop vs base. That puts the M-sport suspension at a 15mm drop vs. base (25mm-10mm = 15mm or 0.590551 inches).

Based on the above, the M-sport suspension is 10% stiffer and 15mm lower than base. Take this with a grain of salt as I am pretty sure BMW springs rates vary not only by trim but also by what options the car has. That might change the numbers a bit. This is also assuming that BMW is not factoring in the upgraded sway bars that come with their kit when they say the performance suspension is 34% stiffer than M-sport and 48% stiffer than base. This is also assuming the 120/350 rates are a valid starting point for the M-sport suspension.

Swift Spec-R, KW, and BMWPS have a decent spring rate and drop for street cars, imo.

[asbrr]

Your calculations and assumptions seem correct, based on all I've seen/read as well. Choice on what spring rate to go with will vary on your application but spec-R seems closest to what you want, unless there is a less popular manufacturer or custom application where you can get specific spring rates.

At that point, I would recommend looking at an adjustable dampening coilover set so you can properly match things up....

[bp05]

Thanks for the knowledge bNks334!

To my knowledge, all US market 135i's have the sport springs.

I'm looking into getting B&G springs on stock struts, for now. They were recommended by a friend who bought them for his E90. Then upgrading to Koni Yellows.

According to B&G's website, they lower F 1.2" / R 0.8". I'm waiting for a reply from an email I sent out today regarding heir spring rates.

Not a lot of 1ers seem to use this mfg. any input would be appreciated from anyone who current have them installed, or have used them in the past.

I also have been looking at the swifts. Are they too low for commuting?

Wants (look-wise):

- I want to have at least ~ 1/2" - 1" finger gap (normal sized fingers, no sausages lol) on all 4 corners.

- And no rake like the H&R.

Originally Posted by bNks334

Someone please correct me if I am way off base with what I am saying, but...

There aren't really any concrete numbers out there... The only definitive number seems to be that M-sport is 120/350. BMW states that the performance suspension is 48% stiffer than base and 34% stiffer than M-sport. Therefore, you could then deduce the following:

BMW Performance Rates
F: 120*1.34 = 161
R: 350*1.34 = 469

Iv'e read on the forums people quoting BMWPS as 160/420 and 195/505 (I think this is the E90 rate).

Base
F: 161/1.48 = 109
R: 469/1.48 = 317

BMW says their performance suspension provides a 10mm drop vs the M-sport suspension and a 25mm drop vs base. That puts the M-sport suspension at a 15mm drop vs. base (25mm-10mm = 15mm or 0.590551 inches).

Based on the above, the M-sport suspension is 10% stiffer and 15mm lower than base. Take this with a grain of salt as I am pretty sure BMW springs rates vary not only by trim but also by what options the car has. That might change the numbers a bit. This is also assuming that BMW is not factoring in the upgraded sway bars that come with their kit when they say the performance suspension is 34% stiffer than M-sport and 48% stiffer than base. This is also assuming the 120/350 rates are a valid starting point for the M-sport suspension.

Swift Spec-R, KW, and BMWPS have a decent spring rate and drop for street cars, imo.

[John_01]

Since you own an E88 convertible, the spring rates will be different from the coupe. I recall seeing a pic of someone who put E82 springs on the convertible and the rear dropped too low. At least it would be better to check with the manufacturer if their spring kits are suitable for the E88.

Recently there was another long thread about spring selection for the convertible, titled "Backroads Dancer 135i", or something like that.

[bp05]

I did see that thread but did not fully read each post. I will look into it. Thanks!

Originally Posted by John_01

Since you own an E88 convertible, the spring rates will be different from the coupe. I recall seeing a pic of someone who put E82 springs on the convertible and the rear dropped too low. At least it would be better to check with the manufacturer if their spring kits are suitable for the E88.

Recently there was another long thread about spring selection for the convertible, titled "Backroads Dancer 135i", or something like that.

[HP Autosport]

Stock E82 sport is 120 front and 350 rear.

For comparison Swift is 201 front and 502 rear.

[Motohip]

I put 135i springs on my 128i and it was higher

[bp05]

Originally Posted by Motohip

I put 135i springs on my 128i and it was higher

I would assume that happened because the 128i is lighter.

The spring rates would be different.