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Old 04-04-2020, 07:02 AM   #1
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Join Date: Jan 2020
Location: San Francisco, CA
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Smile Just installed BC Racing I-25-BR coilovers!

I just installed BC Racing I-25-BR coilovers on my 1998 318ti.

imgur album

I decided to use them because they're reasonably adjustable, affordable (mine were slightly on sale at ~$950), and completely replace the entire OEM units (no extra disassembly required). I'm not trying to get some crazy stance going or push the car too hard; just some good, usable dailies. I went with the default 6 kg/mm all around, and have the settings at 5 clicks away from the softest.

I bought my 318ti last year at ~215k miles; the shocks I pulled out of it are definitely the original factory ones - completely blown. I can push down the rear struts with one hand, and they don't spring back up at all. I didn't try with the front coilovers because I didn't want to bother disassembling them, but the front-left was definitely leaking hydraulic oil for some time, based on how damp it looked.

I only took it on a short drive so far, but it already feels so much better. I used to get horrible bouncy oscillations going down the freeway, and even a very mild launch would cause the rear end to sag like crazy. Now, the entire car feels much more planted. I will say it feels like there's just a bit more road noise than before, but that could be my imagination.


Thanks to the various contributors to this forum, without whom I definitely couldn't have pulled off this install, or even known where to start on aftermarket coilovers. I also referenced the Bentley manual for torque figures and other installation details. Some lessons learned:


When it comes to removing the camber control pin (horizontal bolt that attaches the strut to the steering knuckle), it REALLY helps to have a second person to hold the hub up. Most guides suggest tying the knuckle to something, but there isn't really any good spot to tie it down without blocking the old strut from being removed or the new strut from going on.

Having a jack to support the bottom of the hub/knuckle assembly is crucial for re-aligning the strut. My scissor jack worked great since it's really easy to adjust up and down in small increments.

Especially if your new coilover kit replaces the sway bar end links, remove them *before* removing anything else. Otherwise, they might interfere with the new parts. In particular, you should remove the nut holding the bottom "U" bracket first (#10 in this diagram). The rest of the end link's bolts are fairly straightforward. You'll also have to push back the rubber around the bolt on the top part of #5 to expose flat surfaces to grip with an open wrench when removing nut #10. You can control the position of the sway bar and its end links by jacking up/letting down the opposite side to get a better angle.

I set my front ride height by measuring the distance from the center of the hub to the top of the fender arch's opening, and then adding (15" wheel size / 2) = 7.5" to get a number I could roughly compare with the ride height numbers BMW/the Bentley manual provides, which are measured from the bottom of the wheel. It's not perfect because the strut will compress further under load, so I just added a few inches and hoped for the best. The end result was 545mm once the car was back on the ground, which is 16mm lower than the 561mm Bentley lists for sport suspension with 15" wheels. I'm quite happy with the end result, but it's really easy to adjust the overall strut length with the BC's, so I might revisit this later.


The trunk lining is quite annoying to remove, but you don't have to remove it completely - just enough to make the bolts accessible. Make sure to remove/push aside all of the plastic trim pieces first, including the tail light covers and the little side pocket buckets.

Although some folks have had luck with pry bars to remove the rear springs without a spring compressing tool, I wasn't so lucky. Even after unbolting the rear sway bar, releasing the parking brake, and putting a good amount of weight on the hub, I couldn't get enough play on the springs to remove them. I ended up buying a set of spring compressors from a local auto store for $40! A bit of a ripoff, but what can you do... plus, it really did make the removal relatively straightforward and safe. Again, to echo other posts on this: be VERY CAREFUL with springs! They store a LOT of energy, especially when they're bound up a few inches by the compressors. Slow and safe is a lot better than fast and dead.

The new springs that came with the BC kit have a height adjuster and small top/bottom spring perches. However, as far as I can tell, the perches seem to be designed to fit over the stock rubber ones, rather than replacing them as I had initially hoped. If I had known this in advance I would have just bought new rubber perches since mine seemed quite hard (although no cracking just yet). I reused the perches and put the BC ones on top of them without issue.

The kit also came with an "SA05-1010 M50 HLK LOWERING RUBBER CUSHION", which appear to be a way to replace the BC springs' standard cushion and locking rings with just a single rubber cushion - minimizing the overall spring length as much as possible, therefore lowering the car even more. But I didn't want a super low ride, so I just set the ride height adjustment rings to the lowest possible setting and went from there.

A jack comes in handy again for correctly setting the ride height and lining up the hole in the hub where the strut bolt attaches. Again, I set my ride height by measuring from the hub center to the wheel arch and adding half the wheel length, but this time there was a considerable difference between unloaded vs loaded lengths. But the end result was 540mm (same measurement as before, bottom of wheel to top of arch). According to this ancient post, the rear is at 509mm with sport suspension, which seems quite low to me. Maybe I measured mine wrong, but I'm happy with the way it looks and feels for now - and it'll be hard to lower it further without removing the entire spring, so I guess I'll probably live with it for a while.


Next up, new tires and an alignment

If I missed something or you want to see pictures of something in particular, just let me know in a reply. Cheers!
aspyrx is offline   Reply With Quote


bcbr , coilovers , mods , suspension

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