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      06-23-2018, 07:26 PM   #1
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Swift Spec R springs with Koni Yellows - Long term review

Just figured I'd post a long term review of the Swift Spec R & koni yellow combo, which is highly regarded on here.
The idea behind this post is to document my impressions, thoughts, problems and solutions to these problems.

Car is a 09 E82 135i with stock 261m wheels running 225 tyres up front and 255 tyres in the rear, shocks are stock koni yellows up front and TCK line externally adjustable rear shock with a 1" shorter shock body (more on this later).

Immediately apparent when sitting in the car after install was the reduction in ride height. Also immediately apparent to me was what felt like there wasn't enough shock travel up front (FWIW I am running stock bump stops up front). Even from day 1 I never considered myself entirely happy with the setup, but it was still an improvement over 90k km old OEM dampers.

Also worth noting is that the softer spring rate of the front Spec Rs results in a tendency for understeer - This was drastically improved by adding in a m3 front sway bar.

After 12 months or so the I began to notice the rear ride height had been visibly reduced from the initially installed height. After digging up some old measurements I discovered that that rear had lost about 15-20mm of ride height on top of the 25mm or so drop from stock.

This presented 2 issues :
1) I wasn't able to achieve suitable rear camber settings (adjuster became maxed out).
2) On a spirited drive I ended up wearing a hole through the fuel filler neck from the tyre rubbing on it - Only an issue on fast big bumps, normal street driving for over a year and the issue never presented itself.

Problem number 1 - I had two options to rectify either raise the rear ride height or install adjustable control arms

Problem number 2 was cured by replacing the dinan rear shock mounts with monroe shock mounts and installing 8.5mm of bump stock packers to lengthen the shock body and limit how much the suspension can compress (note this is in addition to the 1 x 2.5mm bump stop packer that comes with the TCK koni shocks).

The solution to 2 resulted in a noticeable deterioration of ride quality but resolved the fuel filler neck rubbing issue.

In order to address the main issue (rear ride height) I reached out to Swift and they assisted by sending out a replacement set of rear springs at no cost to me. . Unfortunately this was short lived as within 6 months the new springs had begun to sag once again. . Fortunately for me I discovered that BMW made a kit known as the rough road kit which is basically a 5mm spacer for the spring (increasing the ride height by approx 9mm or 5mm divided by the rear motion ratio). I persisted with this setup for another 3 months or so but the ride height was still too low for my liking and the rear noticeably crashed on sharp bumps - something I had previously attributed to the firmer rear subframe bushes installed.

Now on to the front.... After 2.5 years or so and something which I had not realised was that the front springs had also sagged (although to a lesser extent - 10mm or so compared to measurements from 3 months after install). Upon looking at the front springs in situ there is clear evidence of binding marks on the springs as well as markings on the lower spring mount on the shock.

FWIW measurements measured from bottom of the rim to the body were as follows (after 2.5 years of service):
Front - 565mm with dinan camber plates
Rear - 570mm with rough road kit

Remove the rough road kit and the dinan camber plates and clearance would be a huge issue making the car virtually undrivable on anything but smooth roads.

Photos to follow.
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      06-23-2018, 08:26 PM   #2
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After extensive research (special thanks to fe1rx for his epic Ohlins write up and to vtl and PeterY for the extensive conversations we've have had) I decided to do the koni coilover conversion.

This basically replaces the swift spec Rs with linear springs where I am able to specify the rate and length of the springs. Which then leaves the question of how to select the "correct" springs....

In order to determine this it is important to set requirements:

1) Approximately 20mm increase in ride height front and rear compared to the current swift Spec Rs
2) Springs must be preloaded such that they are not loose at full droop.
3) The setup should limit spring travel to the springs usable stroke and prevent any coil bind.
4) Allow for 235 tyres to be fit up front in the future.

Rear Springs

The biggest issue for the rear was finding a suitable lower spring mount for flat bottom springs - I wasn't comfortable leaving the rear spring unsecured. Due to the shape of the camber arm it was difficult to find and off the shelf part. Fortunately I discovered that ohlins will sell the part from their kit so i decided to go with that. (wasn't cheap).

Rear spring rate and length was pretty straightforward to determine - Look at what others have done and ensure that there is good adjustment range (i.e. suitable position on the upper perches). I settled on a 10.6kg (600lb/in) 10" rear spring this puts the adjuster 35mm from the body for my desired ride height, perfect ! A 9" spring would have also worked just would have been mounted 1" lower on the perch and by virtue of a shorter spring would have had less usable travel.

As for brand i decided to go with Hypercoil - Mainly because i could bundle the spring with other stuff i was ordering from summit racing. Ride height was spot on where I wanted it to be based on the calculated perch location suggesting the advertised spring rate is accurate

Initial impressions with just the rear springs

-Huge improvement in ride quality - which i assume is attributed to the increased suspension travel. No longer does the rear crash over bumps (the crashing from the front is now much more apparent).
-Significant increase in rear end grip especially over rough surfaces - Can feel the dampers working hard to ensure that the wheels are constantly in contact with the ground.
-Car balance - Unfortunately with the increase in rear grip the car has a tendency to understeer far more... The car also tends to snap quite hard if the front is loaded up and you go near the throttle. I anticipate this will be cured with when the front springs go in.

Front Springs (have not been fitted yet)

On the e82 front springs are a little tricky to get right and ultimately depend on your goals for the car. As my intention is to fit 235 tyres to the front in the future, spring length is a huge consideration. This steers you towards a 7" spring which due to its shorter length has less usable travel than an equivalent longer spring.

First step was to take some approximate shock measurements (only suitable for shocks which mimic stock shocks exactly):

Top spring perch to top of knuckle attachment - 385mm (extended length)
Top of knuckle attachment to top of shock body - 240mm
From body to bottom of rim (extended length i.e. full droop) - 640mm

Spring data Z65-178-060 178mm length 6kg/mm

Usable stroke 107mm
Maximum Stroke 117mm

Shock travel = 385-240 = 145mm

Clearly this is more than the springs maximum stroke however this doesn't account for the space occupied by the bump stop. The beauty of the Konis is they have an external bumpstop giving me the freedom to choose any length I like and also alter the point where it engages.

I have decided to go with the bumpstop that comes with the externally adjustable konis on the rear (to keep things consistent). This is a 55mm bumpstop with a soft linear progressive characteristic, that when fully compressed is approximately 22mm in length. Removing this length from the shock travel results in 123mm of total shock travel still more then the maximum available from the swift springs. In order to ensure the spring is never coil bound I will be using a 12mm slice of HDPE to engage the bumpstop 12mm earlier, this ensures that the spring can never be coil bound, with the last few mm past the usable spring stroke having significant bumpstop resistance.

The last point, ride height! the 6kg springs will compress approximately 60-62mm from their free length due to the weight of the body. Full droop length minus this compression results in an approximate ride height of approximately (640mm - 60mm) 580mm satisfying criteria 1 (assuming minimal preload).
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      06-23-2018, 11:26 PM   #3
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Quote:
Originally Posted by titium View Post
The biggest issue for the rear was finding a suitable lower spring mount for flat bottom springs - I wasn't comfortable leaving the rear spring unsecured. Due to the shape of the camber arm it was difficult to find and off the shelf part. Fortunately I discovered that ohlins will sell the part from their kit so i decided to go with that. (wasn't cheap).
Can you provide a link to a pic of the lower spring mount. I didn't know that Ohlins included this component in the kits.
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      06-24-2018, 12:09 AM   #4
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Quote:
Originally Posted by John_01 View Post
Quote:
Originally Posted by titium View Post
The biggest issue for the rear was finding a suitable lower spring mount for flat bottom springs - I wasn't comfortable leaving the rear spring unsecured. Due to the shape of the camber arm it was difficult to find and off the shelf part. Fortunately I discovered that ohlins will sell the part from their kit so i decided to go with that. (wasn't cheap).
Can you provide a link to a pic of the lower spring mount. I didn't know that Ohlins included this component in the kits.
Don't have a link. It's in the ohlins manual for their kit for the e92.

I've attached a photo I took before install, not pictured is a rubber washer which sits underneath the mount.
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      10-06-2018, 10:34 PM   #5
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Quote:
Originally Posted by titium View Post
Remove the rough road kit and the dinan camber plates and clearance would be a huge issue making the car virtually undrivable on anything but smooth roads.

Photos to follow.
Interesting comments on Swift Spec R for 135i sagging.
Do you think this would impact a 128i which has a bit less weight? or was your case caused from track event use.

Do you think the e9x Swift Sec R's would be a better buy with anticipation that they sag. in my research here the e9x lowering springs typically raise ride height in the rear for a e82. While the front leave a gap that's not desired.

In my case on I use 135i 2011 springs & 335iS e92 shocks on the 128i. Here the rear is in a good spot while the front is raised higher gap then than rears. Not really a desired result by most even with a SP lowering perch and 2-3 years on the set up. My goals at the time was cost and function to get the rear linear 2011 springs.
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In-progress: //M front arm, M3 rack, e36M lip Wishlist: Coils, n55 mnts, headers, LSD, e60 finn diff


"The 1-series is the last car that BMW engineered before the Germans, as a car-making culture, fell out of love with driving." - R&T 2013 135is

Last edited by andrey_gta; 10-06-2018 at 10:40 PM..
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      10-07-2018, 12:17 AM   #6
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Quote:
Originally Posted by andrey_gta View Post
Quote:
Originally Posted by titium View Post
Remove the rough road kit and the dinan camber plates and clearance would be a huge issue making the car virtually undrivable on anything but smooth roads.

Photos to follow.
Interesting comments on Swift Spec R for 135i sagging.
Do you think this would impact a 128i which has a bit less weight? or was your case caused from track event use.

Do you think the e9x Swift Sec R's would be a better buy with anticipation that they sag. in my research here the e9x lowering springs typically raise ride height in the rear for a e82. While the front leave a gap that's not desired.

In my case on I use 135i 2011 springs & 335iS e92 shocks on the 128i. Here the rear is in a good spot while the front is raised higher gap then than rears. Not really a desired result by most even with a SP lowering perch and 2-3 years on the set up. My goals at the time was cost and function to get the rear linear 2011 springs.
I need to update this thread with some more details and findings.

To answer your question you're best of getting linear race springs with an adjustable top perch for the rear. Hypercoil or swift (hyperco are cheaper).

Fronts your limited to a coilover or konis with threaded sleeves.

I wouldn't bother with lowering springs none of them are great imo.
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      10-07-2018, 09:19 PM   #7
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How many options exist for threaded sleeves for the Koni
Does Koni sell for the e8x e9x diameter
http://www.koni-na.com/en-US/NorthAm...eaded-sleeves/
https://frsport.com/koni-80-0000-2-t...rch-sleeve-kit
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In-progress: //M front arm, M3 rack, e36M lip Wishlist: Coils, n55 mnts, headers, LSD, e60 finn diff


"The 1-series is the last car that BMW engineered before the Germans, as a car-making culture, fell out of love with driving." - R&T 2013 135is
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      10-07-2018, 11:09 PM   #8
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Quote:
Originally Posted by andrey_gta View Post
How many options exist for threaded sleeves for the Koni
Does Koni sell for the e8x e9x diameter
http://www.koni-na.com/en-US/NorthAm...eaded-sleeves/
https://frsport.com/koni-80-0000-2-t...rch-sleeve-kit
Nope koni sleeves are 50mm ID these struts are 52mm
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      10-20-2018, 02:37 PM   #9
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Quote:
Originally Posted by andrey_gta View Post
How many options exist for threaded sleeves for the Koni
Does Koni sell for the e8x e9x diameter
http://www.koni-na.com/en-US/NorthAm...eaded-sleeves/
https://frsport.com/koni-80-0000-2-t...rch-sleeve-kit
https://www.hpashop.com/Koni-Coilove...on-e82-e9x.htm
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      03-21-2021, 07:53 AM   #10
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I am just wondering how things have progressed longterm on this setup. I have just purchased a "new to me" 135 that is unfortunately riding on Swift R Springs and with Koni STR.T (Orange) which seems to be horrible, mated to horrible, resulting in "more horrible-er". The car seems to be riding very low, which is keeping with your findings, and the the rear of the car on high amplitude compressions seems to get upset dramatically, and go straight to bump stop on a slight compression at highway speed. Seems to make sense looking at your findings.
Typically I would just bite the bullet and go Ohlins Road & Track, however I was thinking something more "cup-kit" like Bilstein B12, I am not sure that this car will see any lapping days in the next 24 months, but this setup is too low and understeers, and then the rear end "jumps" up. (All the M3 arms are in there and tight.).
Any thoughts?
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      03-21-2021, 06:06 PM   #11
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I don't know these Konis very well and if they are meant to work with lowering springs. The Spec R are quite low - my guess is you're basically riding on the bumpstops in the rear.

A B12 kit isn't quite as low, and if you grab some Dinan fixed camber plates up front you can gain an additional 5mm of height (and the camber of course).

Alternatively, BMW PS springs are a nice compromise if you can find them.
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