Koni Sport Settings for Swift springs

[tjswarbrick]

I'm wondering if anybody here who has experience installing/running Koni Sport dampers with 500lb rear springs can give some advice on setting the rear shocks prior to installation.

I intend to share my configuration/setup, as well as goals for the car, but don't want to clutter things up too much at the outset.

Thanks!

[tjswarbrick]

Current setup:

All (mostly) Stock
E88 Cabrio
N55 Turbo
M-Sport
E-Diff
60,000 miles
215/40F and 245/35R Dunlop RFT;'s
18" 261's - 7.5" F and 8.5" R.

[tjswarbrick]

To be installed:

Koni Sport (Yellow) shocks and struts
Swift Spec-R springs: 200lbs/in front and 500lbs/in rear
M3 front bump stops
Z4 rear bump stops
Dinan non-adjustable camber plates
26.5mm E92 M3 FSB
"Black Race" polyurethane RSFB
335is front shock mounts
Michelin PSS 225/40 F ; 245/35 R
~1.6 degrees negative camber front; 0.0 to -0.2 at the rear.

[tjswarbrick]

Goals for the car:

BMW Traditional Balanced ride/handling compromise (before they went all mainstream appeal and run-flat tires);
No bounce, float, or rear/front delay;
Minimize understeer for neutral on-limit balance;
Responsive turn-in;
Minimize Dive/Squat;
Controlled body roll;
No harshness or crashiness;
Controlled ride motions;
Make it ride and handle like it should have from the factory.

Is that too much to ask?

[tjswarbrick]

Use Cases:

1) Daily Driver - 20 mile highway commute (just don't want to get beat up.);
2) Distance Cruiser - 300 miles each way up or down the length of CA with 1 to 3 passengers on a fairly regular basis;
3) Canyon Carver - I like to take the long way home, as long as it is twisty, scenic and entertaining. The reason I bought a BMW Convertible! Most of those around here tend to have odd camber changes and, shall we say, maintenance issues. I'll typically have one passenger who may or may not be interested in testing their intestinal fortitude and kidney strength.
4) Weekend toy - Same roads as above, but at a higher pace, maybe alone - or with a passenger who will enjoy the ride.
5) Track Toy - Entry-level stuff. Car Control Clinic, HPDE, Autocross. Maybe 2-4 per year.

I'm happy to button up the front dampers a bit for 4 and 5 above, then turn 'em back down for the week, but intend to leave the rears as installed.

[tjswarbrick]

So, where should I realistically target the rear damper settings to get the most out of those springs?

Thanks!

[John_01]

Rear dampers at 0.75 turns from full soft - Based on my experience with the externally adjustable rear Koni dampers from TC Kline, and 500lb rear springs.
BTW, I wonder if the my TCK rear dampers have the same valving as the koni yellow. They may have stiffer valving than the yellow ones.

My rear dampers are now 0.5 turns from full soft, as I have the car setup for comfort and have some OE style floating over bumps. 1.0 turns was an effective track setup for my car, but it was a bit tiring as a daily driver.

I guess for your Koni yellows dampers the rear should be either 0.75 or 1.0 turns from full soft. Front dampers should be set to around 1.25 to 1.5 turns from full soft.

[tjswarbrick]

Originally Posted by John_01

Rear dampers at 0.75 turns from full soft - Based on my experience with the externally adjustable rear Koni dampers from TC Kline, and 500lb rear springs.
BTW, I wonder if the my TCK rear dampers have the same valving as the koni yellow. They may have stiffer valving than the yellow ones.

My rear dampers are now 0.5 turns from full soft, as I have the car setup for comfort and have some OE style floating over bumps. 1.0 turns was an effective track setup for my car, but it was a bit tiring as a daily driver.

I guess for your Koni yellows dampers the rear should be either 0.75 or 1.0 turns from full soft. Front dampers should be set to around 1.25 to 1.5 turns from full soft.

Thank you.
Rears are total 2 turns from full soft to full hard, right?
(I don't have mine in hand yet.)
Making .75 turns just under 40% from full soft?
I THINK TC's are valved a little differently, but he changes 'em based on the spring rate. Koni doesn't say what springs their "Sport Kit" includes, to draw any conclusions about rates.

[tjswarbrick]

I'll use a little math.

From Koni's site:
Koni Sport shocks are designed to work with factory springs, but can be adjusted firmer for higher rates.
Adjustment range is about 100%.
Since the stock springs are 350 lbs/in, range should be 350-700 lbs.
500 lbs = 42.85% higher than 350 lbs.
So turn the knob .85 turns from full soft? (Not very far off from .7 turns anyway.)

Can anyone with the yellows and 500lb/in shocks confirm? Deny? Tell me I'm smokin' crack and what setting might me be a better starting point for my use?

[John_01]

Rears have around 2.0 turns travel and fronts have 2.5 turns. In reality there is a little bit more travel than 2.0 and 2.5 turns in them, so its important to be consistent and always take measurements from the same end.

The trouble with the your interpolation of 42.85% is that there are some non-linear aspects. The required damping depends on the resonance of cars weight and springs, which I recall has a square root calculation in there. Doubling the spring rate doesn't necessarily mean you need to double the damping force. We don't know the damper adjustment is linear either.

[tjswarbrick]

Originally Posted by John_01

Rears have around 2.0 turns travel and fronts have 2.5 turns. In reality there is a little bit more travel than 2.0 and 2.5 turns in them, so its important to be consistent and always take measurements from the same end.

The trouble with the your interpolation of 42.85% is that there are some non-linear aspects. The required damping depends on the resonance of cars weight and springs, which I recall has a square root calculation in there. Doubling the spring rate doesn't necessarily mean you need to double the damping force. We don't know the damper adjustment is linear either.

Very true on all counts. Which is why I'm asking for help from folks with experience.
I appreciate the input.

[titium]

Originally Posted by John_01

Rear dampers at 0.75 turns from full soft - Based on my experience with the externally adjustable rear Koni dampers from TC Kline, and 500lb rear springs.
BTW, I wonder if the my TCK rear dampers have the same valving as the koni yellow. They may have stiffer valving than the yellow ones.

My rear dampers are now 0.5 turns from full soft, as I have the car setup for comfort and have some OE style floating over bumps. 1.0 turns was an effective track setup for my car, but it was a bit tiring as a daily driver.

I guess for your Koni yellows dampers the rear should be either 0.75 or 1.0 turns from full soft. Front dampers should be set to around 1.25 to 1.5 turns from full soft.

+1

fronts 1.5 turns i.e right in the middle - standard koni yellows
rears - 0.75 of a turn from full soft (around 1/3 of the way to firm) tck konis externally adjustable

that's what i run on a e82 coupe with swift spec r springs for daily driving. found the rears to have the biggest impact on ride quality with anymore the 1 turn and it starts getting uncomfortable on the street. I also have upgraded subframe bushes and dinan upper shock mounts

[tjswarbrick]

Originally Posted by titium

+1

fronts 1.5 turns i.e right in the middle - standard koni yellows
rears - 0.75 of a turn from full soft (around 1/3 of the way to firm) tck konis externally adjustable

that's what i run on a e82 coupe with swift spec r springs for daily driving. found the rears to have the biggest impact on ride quality with anymore the 1 turn and it starts getting uncomfortable on the street. I also have upgraded subframe bushes and dinan upper shock mounts

Awesome.
Thanks so much.

[dtla1]

What are the advantages of these "335is front shock mounts" you plan to install? I've been absent for a while, never heard of this mod.

[tjswarbrick]

Originally Posted by dtla1

What are the advantages of these "335is front shock mounts" you plan to install? I've been absent for a while, never heard of this mod.

According to my supplier, they are cast from high-strength steel instead of stamped from mild steel. Look the same, same dimensions, but heavier and much stiffer and stronger.
I haven't received them yet, so cannot confirm.

They were just an incremental cost increase over replacing the mounts with OEM units, so I didn't question it and haven't done my usual research. But I should check in to that...

[Washington335i]

Hi Tom, was on 1addicts and saw your post. The front strut mounts you will be getting are the -5098 BMW part #s, not the stock -0943 that come with your car. The -5098 are stock on all 335 models with sport package. The -0943 are on non-sport models and on all e82/e87/e88. I have both in stock and noticed that the -5098 is about 5oz heavier and has visibly thicker steel. BMW dealer told me it is heavier-duty for sport models. Dimensions are virtually the same. It was a no brainer to use them for your application and virtually all kits I sell. They are more expensive, but worth it in my view.
Best regards, Chris

[tjswarbrick]

Thanks Chris!

Looks like "Heavy Duty" or "Sport" Front Upper Strut Mount is a Strut Mount with Bearing, which BMW calls Guide Support - P/N 31306775098. MSRP 150.35.

Per RealOEM, the factory Guide Support for 2012 135i is P/N 31336760943. MSRP $96.67.
Which is what you said above, isn't it?

Honestly, I think I sent you the Sport ones, too. You can verify today upon arrival.
Procured as P/N 31306775098KT1 and came with a ton of additional stuff.
But this way I don't need to compress the springs and assemble the things!

[John_01]

Have you considered the difficulty of adjusting the front shocks with the OE strut bar in place? Depending on your budget, you could consider to have the 1M front strut bar installed as it makes it a breeze to adjust the front struts. The 1M caps on the top of the front strut adjustment are important to protect against debris getting into the strut mount bearings. With the Koni adjustment points protruding up, its no longer possible to refit the stock plastic caps over the strut tops. I don't know if there may be another solution, but the 1M strut bar is a nice one.

[tjswarbrick]

I'll check in to that bar.
Someone else had mentioned the Mason Engineering strut bar as well. It comes two ways, but the open center version requires new cross braces which makes it kinda pricey.

Interesting. At ECS they have different part numbers for 135i and 1M, but they sure look similar.

[135ivert]

Originally Posted by tjswarbrick

I'll check in to that bar.
Someone else had mentioned the Mason Engineering strut bar as well. It comes two ways, but the open center version requires new cross braces which makes it kinda pricey.

Interesting. At ECS they have different part numbers for 135i and 1M, but they sure look similar.

That was me. I have the Mason Engineering standard center brace which uses the OEM firewall cross braces. It looks like it would be a PITA to adjust shocks with it installed.

[tjswarbrick]

I see the 1M bar is really just cross-braces linked to rings around the towers instead of the post across it. Will help with access, but not really a strut tower brace.

The Mason Engineering one is a brace, and looks awesome, but pricey for the open-ring version.

The AA and Cusco braces leave the stock 135i tower bars in place - thus hindering access to the adjusters.

Has anybody installed or seen the Turner bar in place?
It looks, to me, like it could go either way - but I can't find any pictures of an installed one.

[tjswarbrick]

Looks like Turner also integrates with stock 135i bars.

HPa M3/1M setup for 135i is no longer in the mid-$300 range but now $520. Ouch.
ECS has one without the M3 center support for $250-ish.
All steel Mason unit, which is an actual strut tower brace, is $550 for the open-center unit, when including shorter firewall struts.
ECS one will allow access to adjusters, but not really improve chassis stiffness. (Would probably help with "mushrooming" concerns.)

If I had the scratch for the M3 unit, I'd probably go Mason, but right now none of these are particularly appealing. I wonder if the 1M center caps fit this unit...
Frustrating.
But it does look like the diagonal/firewall bracing is optional with the Mason unit.
So maybe start there, then get the additional braces when money appears if it still feels soft.

Mason unit blocks the airbox!