Non lowering Spring rate Upgrade

[Jackal]

I have been doing some research into non-lowering springs for my 135i. I currently have the M option for my Biene, but with me doing more AutoX, I'm looking at increasing my spring rates, along with dampers and subframe bushings.

I don't want to lower Biene by too much as I drive her daily and like the usability of the current ride height. I am also currently having some rubbing issues with the rears (very minor), and would like to not make the situation worse (Rolling fenders is next up for me). I am looking for options in an increased rate all around... 300/500 and the minimal amount of drop.

My question is, what performance spring sets have the least amount of drop on them, and what are the increased rates like?

Here's what she looks like stance wise currently.





Edit

So that it may help, I'll add the drop and rates here as I go.

M-sport 120/350 N/A
BMW Performance 160/470 10-15mm drop
Dinan ? 10-15mm drop
Swift Spec R 200/500 25mm drop
Eibach Pro kit 148/457 28mm drop

[Dackelone]

I would go with BMW Performance springs. 10 to 15mm drop on a 135i.

[Jackal]

Originally Posted by Dackelone

I would go with BMW Performance springs. 10 to 15mm drop on a 135i.

I had a look at these on the BMWUSA site, and read;

"This new aggressive package lowers the vehicle by 25 mm compared to the standard suspension and by 10mm when compared to the sport suspension. Spring rates are increased 48% compared to standard suspension and 34% compared to the sports suspension"

http://www.bmwusa.com/Standard/Conte...ensionKit.aspx

The M-package on my 135i should have the sport Springs in them currently as I understand it. So I'll be looking at a spring rate of around 160/469?


M-package being 120/350
BMW Performance at 160/469 ?

[MightyMouseTech]

The Dinan springs are supposed to be about 0.5" and be a little stiffer than the BMW Perf ones. Swift springs are about a 1" drop, fair bit stiffer than either of those, and IMHO are the best compromise.

[Jackal]

Originally Posted by MightyMouseTech

The Dinan springs are supposed to be about 0.5" and be a little stiffer than the BMW Perf ones. Swift springs are about a 1" drop, fair bit stiffer than either of those, and IMHO are the best compromise.

Dinan doesn't have a reference value to the percent of increased stiffness on the page;

"The increase in stiffness (20% Front, 40% Rear) will reduce the rear suspension compression under acceleration and front suspension compression (or dive) under braking, giving your car a more controlled feel."

http://www.dinancars.com/product/d10...e-2011-2013-2/

With no reference to what package they are comparing to, I can't determine the value.

I have looked at the Swift springs as well but the 1" drop is too much for me I fear.

[Dackelone]

Originally Posted by Jackal

I had a look at these on the BMWUSA site, and read;

"This new aggressive package lowers the vehicle by 25 mm compared to the standard suspension and by 10mm when compared to the sport suspension. Spring rates are increased 48% compared to standard suspension and 34% compared to the sports suspension"

http://www.bmwusa.com/Standard/Conte...ensionKit.aspx

The M-package on my 135i should have the sport Springs in them currently as I understand it. So I'll be looking at a spring rate of around 160/469?


M-package being 120/350
BMW Performance at 160/469 ?

Yes. The 135i's have the "sport" suspension. The 128i's do not, unless optioned so.

I have no idea what the spring rates are for the Perf springs. I just know the drop is really minimum.

I agree with what MightyMouseTech said above.

Dackel

[ShocknAwe]

Pics of the swift spec r springs in my build thread. Sig link. It's about perfect for DD I think. Certainly the best compromise as long as coilovers aren't on the menu.

[Chris S.]

Had the same plan and reasons. Went with swift spec-r and was not happy with the front. 25mm seems right, but only for the front. Rear drop was minimal, had to tell. Forgot to measure before and after.

Spring Rates felt good but way too soft in front for the limited travel. I put coil boosters in (the H shaped one's from auto parts store) to help.

Still didn't like it. Went back to factory for now. Will probably just spend proper money on AST 5100s and springs.

[MightyMouseTech]

Originally Posted by Jackal

I had a look at these on the BMWUSA site, and read;

"This new aggressive package lowers the vehicle by 25 mm compared to the standard suspension and by 10mm when compared to the sport suspension. Spring rates are increased 48% compared to standard suspension and 34% compared to the sports suspension"

http://www.bmwusa.com/Standard/Conte...ensionKit.aspx

The M-package on my 135i should have the sport Springs in them currently as I understand it. So I'll be looking at a spring rate of around 160/469?


M-package being 120/350
BMW Performance at 160/469 ?

You have the M Sport springs, not the performance springs, so you will be at 120/350. Those are the springs that come standard on the 135.

Going by what Dinan says, I guess their springs are around 145/420!??! Appears they are actually softer than the Performance springs.

[tracer bullet]

FWIW, after going into this kind of thing at great length for my previous car, I will mention you should take all info from the MFR's with the so-called "grain of salt". All too often the #'s cited are generalizations as they don't know what set up you have, be it M Sport or not, 128i or 135i, automatic or manual, etc. It is a safe bet that a MFR saying 1" isn't going to be 1.000" but a decent range beyond that in either direction.

BMW stating a 48% rate change makes me think that's really what it is. The 25mm seems rounded off but perhaps not. The other manufacturers... who knows.

Have you looked into coilovers? You may have to do so to get the combination of spring rate and ride height you want.

[850tgul]

Swift spec r paired with Bilstein HD dampers and Dinan fixed camber plates in front gave me an even, modest drop front and rear. About 0.25" lower than my stock sport suspension. I love the setup but no matter the springs or dampers you will need to upgrade the rear subframe bushings. And go full replacement, the inserts aren't enough imo.

[Jackal]

I have gone with a set of Whiteline subframe bushings and hope to see them before the end of the week. I'm very familiar with Whiteline from my Subaru days and have loved the results.

http://www.whitelinesuspensionparts.com/kdt917

The car is an STU build for autoX, but need to retain daily driver ability (sleeping policeman).

[HP Autosport]

Originally Posted by 850tgul

Swift spec r paired with Bilstein HD dampers and Dinan fixed camber plates in front gave me an even, modest drop front and rear. About 0.25" lower than my stock sport suspension. I love the setup but no matter the springs or dampers you will need to upgrade the rear subframe bushings. And go full replacement, the inserts aren't enough imo.

I agree. The inserts are okay, but not the most ideal set-up if you are looking for the full benefit from the subframe bushings. It's certainly okay for the budget minded.

[Jackal]

Bumping this up for any more input.

I have been looking at ST coils with progressive springs. I'm not liking the statement of 1.4 inches of drop minimum though. I'd really rather keep the ride height as close to my current height as possible.

The rubbing on my wheel wells isn't severe, but I'd like to eliminate it through a combination of stiffer setup, rolled fenders and maintaining stock height.

Inside the drivers wheel well facing forward.