Well the job is finally done. Was hard to find time and willpower to finish it. It stopped being fun right after the first seized brake union, but I still have no regrets. It started out as a control arm change due to an advisory on my annual inspection and ended up in £4k of parts.
It took me another 4 days of solid work since my last update, getting free weekends to spend in the garage is tricky.
I wish I had the determination to properly document things, but when you are laying on your back getting rust in your eyes and your hands are covered in blood and grease, you don't really feel like taking photos! It also turned from perfect summer weather, into the non-stop relentless UK winter rain during the course of this project.
The big kick in the balls came just as I started to re-assemble the parking brake shoes on the rear right where I had installed a new knuckle that I purchased on eBay from a very low mileage car. I noticed that the hub on the new knuckle sat way farther out so knew something wasn't right. It turns out that the 135i has a slightly longer wheel hub than every other E8x and E9x cars which meant that I needed to buy another hub and also replace the bearing since removing the hub destroys the outter race. That also gave me the headache of having to press in new bearings and hub which I managed to fuck up on the first try and destroy my nice new FAG bearing.
Around this time I did start to fantasize about buying a nice garage-queen CPO Porsche Cayman. Thinking about it's nice smooth rust free underbody and non-seized bolts. But the Porsche forums are boring and I'd get bored without having something to fix.
It was also incredibly difficult to reassemble and correctly torque down all the new control arms as the upper control arms in the rear are buried so deep in the subframe that it's impossible to get anything other than a spanner on them. So those ones had to be torqued using the double spanner trick and the use of my own poorly calibrated guestimation of torque.
Everything else was fairly trouble-free. The driveshaft puller I purchased was an absolute life-saver and because everything I was putting back on the car was brand new, it just bolted together easily.
After getting everything reinstalled and on the ground, I jumped in the car and headed for an alignment, but as soon as I got the car onto the road, everything just felt completely fucked, there were horrible clunking noises and the car felt like it wanted to flip over when going any faster than about 5mph. I thought I had really messed something up so I cancelled the appointment and went back to the garage to inspect my work. After an hour of checking torques and clearances I decided to do some googling and it turns out that it's all normal because my alignment is way out. After I got the courage to drive it again, I (very slowly) drove to an alignment shop where they got it all back into spec (minus the extra front camber from the M3 arms). They remarked that it was indeed as far off correct alignment as it could possibly be, which is to be expected when you remove and re-attach every single bolt.
So the car is back, from the short drive back from the alignment I can say that it's absolutely perfect now. It feels completely different to drive but I've replaced and upgraded so many parts that I have no idea which things made the big improvement. The diff is certainly doing work though, I disabled the "ediff" and took it for a spin on my local greasy cold wet country roads and it really does feel more stable, it would be hard to compare traction but the rear twitches much less. In fact the entire car feels smaller and tighter which is what every car enthusiast wants
. I suspect the big improvement comes from the front M3 arms and the stiffer subframe bushings but I'll play around with the new diff a little more once I get more miles on it.
I'll trawl through my phone and upload a few photos. I also took the opportunity part way though to fit some new interior trim into the car to replace the basic silver plastic trim with some nice "anthracite maple" BMW individual trim I got for a steal on eBay.
