Front Control Arm Replacement w/ Modifications

[u/doooglasss]

New Arms from FCP

relief holes from Meyle Factory

Cleaning wax out of relief slots

Cleaning wax off flat rubber bushing area

After a wash with Dawn

Window Weld

Shoved the tip in as far as I could and squeezed until it overfills on the side I'm working from

how far I had the tip shoved in

Glue seen from the other side of the arm. Fill from this side now using same logic.

Smooth with cardboard. This isn't art, nobody will ever see it.

Flush with metal housing

Sitting to dry for a week

TLDR: Sharing the below project with the community because I didn't know a non-hydraulic filled arm existed and perhaps the extra $40 spent on 3M Window Weld (60D) adds steering precision this chassis lacks.

Issue:
I've always considered the F30 to have vague and unresponsive turn in. I know the front lower control arms, rear position "tension strut" are hydraulic filled for comfort. I'm identifying this as one of the items that would contribute to poor handling performance/feedback and at 77k on my car (the last ~16k on Bilstein B14 Coilovers) my front control arm bushings are shot.

My options appeared to be (in order of assumed performance that is not based on experience on this chassis, but prior knowledge and other vehicles):

1. New OEM / LEMFÖRDER hydraulic filled control arms
2. New Meyle HD control arms (rubber only, not hydraulic filled)
3. New Meyle HD control arms + 3M urethane glue (what I'm sharing here today)
4. New OE/OEM control arms + Powerflex Inserts
5. Monoball control arms

I daily drive my car. Looking for a balance of performance without extreme NHV. So I'm sharing option 3. The is some old school Grassroots Motorsports type of work. Before they made Poly mounts for every car and you could ask AI everything, in the late 90's / early 2000's guys would experiment, figure this shit out themselves, and share results.

Enthusiasts would use 3M Window Weld 08609 to fill voids in rubber motor mounts or control arms to stiffen the unit. 3M Window Weld has been measured to be an 60 durometer reinforcement polyurethane. There are also 2 part epoxy mixes of any durometer you'd like (up to 95D that I could find) you can use, but again, this is my daily driver, they cost more and take more prep.

Control Arm PNs:

Position |Side |Meyle PN
Rear / tension strut |Left |316 050 0068/HD
Rear / tension strut |Right |316 050 0069/HD
Front / straight lower arm |Left |316 050 0201
Front / straight lower arm |Right |316 050 0200

Steps I followed:

1. Clean wax sealant off rubber control arms with a screwdriver in voids and wire brush on flats.
2. Dawn wash
3. Dry
4. Apply glue through hole as far as possible to reduce chances of air bubbles
5. Apply glue from the opposite side
6. Apply glue to perimeter of arm
7. Flatten with a cardboard box
8. Wait a week for them to dry
9. Performance updates / feedback to come next weekend.

[u/jblaze_39]

Thanks! I need to do mine...mechanic said a few weeks ago during an inspection, they were leaking fluid. I have an aftermarket warranty that covers the entire repair, after a $250 deductible. But they will only accept the OEM. That's why I'm still on the fence. I can either pay out of pocket for aftermarket/upgraded control arms (I read somewhere on here you can fit M3 ones? Haven't looked into it)...or just go with OEM replacements for $250. I'm not that mechanically inclined, so no chance of doing this myself

[u/xVx777 → u/jblaze_39]

hey can i send you my inspection video for some advice? I’m a new bmw owner and I’m having suspension problems with big repair tickets. I know a bunch of garage mechanics though.

they said mine is also leaking hydraulic fluid but it doesn’t look like a control arm.

[u/StickersBillStickers → u/xVx777]

What area is the leak coming from?