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      03-24-2019, 04:58 PM   #271
vtl
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Drives: 2008 BMW 135i MT
Join Date: Apr 2015
Location: Melbourne, Australia

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With the current suspension setup I was feeling the roll stiffness has improved from when I had the KW V2 setup, but still tended to roll around in low speed corners, resulting in the rear wheel unloading a bit. Not as bad as before but still there. I also found in high speed corners at Phillip island the car really would benefit from more roll stiffness as the weight transfer feels a bit slow and was getting understeer in the high speed corners.


Decided I wanted to try out different sway bars again. I would like to run the E93 M3 front sway bar but previously having tried this resulted in a lot of understeer in low speed corners, unloading the front inside wheel. I decided that to upgrade run this E93 convertible bar I would need to upgrade the rear bar to match, so the car doesn't feel too unbalanced. Previously had upgraded to a 15mm rear sway bar from an E9X XI (AWD model, also same as E93 Msport rear sway).

The 22.5mm rear sway from an M3 was an option but didn't want to go up that far, ideally looking for something like an 18mm but couldnt find one off the shelf. Ended up settling for the Whiteline 20mm rear bar as it has been used by many people with no issues.

Turns out the Whiteline sway bar is already a tight fit with stock axles (but doesn't touch anything), but with my M3 axles (I've done an M3 diff swap into my 135i) this was a problem and when the car is at ride height, the CV joint boots rub on the sway bar. If you compare the sway bar design to the M3 one, you can see that the M3 one is bent significantly differently to allow better clearance with these parts. Annoying.

I decided to keep the 20mm sway bar as it is the specification I wanted, and figured I could solve it with adjustable end links. Unfortunately it looks like the available solutions for this platform are limited, and expensive. My particular problem means I need to extend the end links at least 20mm from stock, which the aftermarket options don't cater for anyway.

Found a good seller on ebay uk selling decent looking adjustable turnbuckle rod joints, and I figure its worth a shot making my own. Ended up having to machine up a few spacer bushes to get the universal parts to work. The stock endlink is an M10 thread on the sway bar side and M8 thread on the knuckle side.

Installation was not fun, due to the larger M3 axles in the 135i, I could not remove the bolts holding the sway bar end link on. This means going through the trouble of removing the axle, which requires a special tool to press them out, and another tool to pull them back into the hub. I had the tools from when I did the swap in the first place, and since I put antisieze on the splines it all came out nice and easy.

Installed the new sway end links, plenty of clearance to the axle, but ended up adjusting them too long. So the sway bar hit the upper control arm haha. Shortened them up now to allow adequate clearance and project done. I can also install M3 upper control arms which are a curved design which gives a bit more clearance to the sway bar as well.


Here is a link to the turnbuckles if someone has the same unique problem I did with the M3 axles and whiteline sway bar (mcgillmotorsport on ebay):

https://www.ebay.com.au/itm/M10-Turn...53.m2749.l2649
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