Rather extensive drivetrain/suspension refresh

[IamFODI]

This week so far is made almost entirely of bushings!

Everything that goes in the rear subframe is in. Subframe mounts are Bimmerworld solid aluminum; all others are OE.

The subframe mounts were apparently a huge PITA. To be expected I guess.



In other news, when I went to pull the secondary O2 sensors out of my ragged factory X-pipe, the threads were... not happy about it. In theory we could have repaired the threads and gone on with life. But that X-pipe has almost 155k miles on it and has already had to be repaired once (rust crack). Plus, I've had cat efficiency codes here and there. And at this point, the last thing I want to do is add more labor time as we're already way behind schedule. So, after some hand-wringing, I made the call to swap in a much lower-mileage used factory X-pipe. Not happy about the expense but it should get the job done.

[IamFODI]

Steering rack ended up coming in just in time to allow the front end work to get done. And when I say coming in, I mean barely. Looks like it was amateur hour wherever it was packed, because... damn.




Couldn't get a pic of the inside of the box but the rack was just floating in there with nothing but packing paper around it (and not even enough of that). No foam or plastic to hold it in place. Horrible.

If I hadn't been on a deadline, and if the supply of these things didn't seem so short, I 100% would have complained and made them ship me a new one.

Fortunately the rack seems fine. So nice to see it after all this time.

[IamFODI]

One thing I had forgotten to post earlier: at least one of my original >154k mile camber arms (the ones the springs sit on) was starting to crack around the eccentric. I had almost regretted committing to replace these; they don't have bushings or ball joints in them, so the spend-on-parts-save-on-labor argument didn't apply. Guess it was good I did in the end.




Anyway. Back to the more-recent past.

CVs being refreshed with new grease and boots. Apparently the clamps on the outer boots were just a tad too small, so we had to find new ones. Not an expected problem for a refresh kit from GKN (the original manufacturer).




Factory X-pipes: my old one (154k miles) on the left, new-to-me (~50k miles) on the right:

[IamFODI]

Rear subframe with all new bushings and arms, ready to go in:





All bolted in with the heat shields, diff, etc.:

[IamFODI]

Shifter height pics:





Again, this is with a 40mm height extension and a 15% throw length reduction at the new height.


Looks like the stock boot still had some slack, though not much. The 6th gear position leaves the least slack:



So, probably could have gone with a 50mm extension as I had suspected, but probably not much more than that.

I have a new stock knob/boot ready to go on at some point.

[IamFODI]

And she's back on the ground!



The one outstanding issue is that ride heights are no longer quite what they should be; without having touched any height adjusters, the right front is 3mm higher and right rear is 6mm higher vs. before. Not gonna touch any adjustments now though in case things need to settle. Planning to revisit in early spring next year.

Haven't put a lot of miles on her since the work being completed, so I'm not yet ready to post driving impressions. Will do when I'm ready. For what initial impressions are worth, though, they are quite positive. The guy who did the work was so blown away that he said he's gonna do all the same stuff to his own high-mile E90 M3 ASAP.

[Obioban]

Congrats! 🎉

ride height change is strange. I assumed he torqued all bushings fully preloaded?

[IamFODI]

Congrats! 🎉

Thanks!

ride height change is strange. I assumed he torqued all bushings fully preloaded?

As do I. 😬

I wasn't there to see, but from what I've seen he's not the type to screw up something like that (which is why I had him do the work).

Is it really that strange, though, with all the arms being changed? Gotta figure some of them were at least a little out of shape, right?

[IamFODI]

Shifter review is up! https://nam3forum.com/forums/forum/e...ift-kit-review

[IamFODI]

So, uh. The car drives really well now.

Aside from balls-out acceleration and braking performance and maybe steady-state grip on a completely flat surface, everything the car does dynamically is better. Throttle response, steering response, transitions – everything. It's all a lot tighter, sharper, smoother, more linear. Massive upgrade overall, like the car is a generation newer without losing anything. Very different experience from before.

The "smoother" part is perhaps the biggest surprise. I'm not the only one who noticed it; my wife and the guy who did the work both talked about it like it was the main difference from before – even more noticeable to them than the massive step-change in every handling response. I guess it makes sense; everything in the drivetrain and suspension now has the right amount of compliance (from zero to some), except for a few key areas that have been stiffened (rear subframe bushings, front tension arm monoballs, camber plates, springs and dampers).

The exhaust is definitely quieter, presumably because I no longer have a muffler that's rotting internally and at the flanges.

If there's any extra NVH from the solid rear subframe bushings, I can't tell.

The Autosolutions shifter feels perfect for this car. It really contributes to an overall feeling of responsiveness, high levels of feedback, and involvement.

I still wish the front end were more positive-feeling, as I have from the beginning. I guess it makes sense that that aspect hasn't changed much; nothing I've done should have significantly improved mechanical grip or changed handling balance. But, on the plus side, the steering itself feels pin-sharp and almost telepathic, especially just off center – just as it should. This is probably my favorite single thing about this car, and now it's better than it has ever been.

From the moment we bought this car, it was always a reasonable compromise of wants and needs. I liked and appreciated the hell out of it. Now I love it in a way that I don't remember ever having felt before.

And, as a cherry on top... Famous last words maybe, but I shouldn't have to touch any of this stuff again for as long as I own the car.

This was a hell of a process, and my wallet ain't happy, but the results feel so, so good.

[bigjae46]

CVs being refreshed with new grease and boots. Apparently the clamps on the outer boots were just a tad too small, so we had to find new ones. Not an expected problem for a refresh kit from GKN (the original manufacturer).

Nice work! I'm about to do the same. I have a valve cover leak which has made a mess. Going to get the front end done this Dec. Rod bearings, valve cover coating, OFH, new AC compressor, and a bunch of other things. Then the rear end March or April before it gets hot here in TX.

I had the same issue with the GKN kit for my E46. I wonder if GKN assumed the M axles are the same size as the non-M's. It was super maddening because it was off by about 1mm or less. I just bought slightly bigger ones on McMaster Carr.