Replacing the 2014 BEV engine bracket + mount myself

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Well-known member
Apr 25, 2015
For anyone interested I own a 2014 i3 BEV still going strong at 78k miles.
Range is still the same i.e 100 miles give or take and everything works fine except the engine mount which was leaking and broken..
This is actually subject to several recalls in the world i.e EU etc,.. but not in the US.
Dealer quoted me a cool 2.7k since the only replacement mount that exists is for a new bracket made out of cast aluminium vs. plastic for the old one. And the only way to put that together is put the new bracket in and that implies literally dropping the whole engine out for the task.
I refused to pay for it arguing it was an original and flimsy design flaw acknowledged by BMW through their subsequent replacement of said bracket by a metallic one with a reinforced bolt and contacted customer service at BMW regarding the matter. But they argued they have no obligation since my car is out of warranty. They suck and I will consider further options.
Meanwhile me and a friend IA (Inspection Authorization mechanic for Airplanes, the highest ranking certification for airplane mechanics) decided to look at the issue and after I ordered the new bracket, mount and new bolt for the setup (Thanks!!!) we realized the bracket could potentially be removed from the top of the engine and holes drilled in the frame at strategic locations to access the 2 bolts unreachable by design.
This was all risky and a jump into the unknown of course as I had no clue if the bracket had other hidden attachments and the IA had no experience working on a BEV and could only count on his aeronautical instincts.
There's a lot of craftsmanship and creativity that goes into plane maintenance and it definitely came in handy here.
To drill the 2 holes we inferred the location assuming some movement of the engine would be possible after the mount was removed through the weakest spots in the frame on the left and used a 1 in drill bit for the feat.
After removing all the bolts and supporting the engine using its own jack besides the one allowing for tires and cover removal the old plastic bracket slid right out. We used a wooden stake to adjust the position of the engine to remove the bolts after alignment with the holes.
The holes themselves are very small i.e 1 in tops and in no way compromise the integrity of the frame, It would have been nice to have BMW actually design access holes in the frame to access those bolts, just like airplanes need inspection/access plates as mandated by CFR 14 part 23, but that wouild be probably too much to ask.
New bracket was easy to install and bolts were screwed in the same way they were screwed out.
Total for the whole operation: 7 hrs and sweat equity + creativity. Probably a good 4 planning and analyzing. So more like 3 of actual work on the car.






Yikes! I wouldn't want to drill rather large 1" holes in the aluminum frame unless doing so was absolutely necessary. Fortunately, it's not. A certified BMW mechanic posted a detail procedure that describes replacing the plastic composite motor mount bracket with the improved aluminum version without dropping the drive motor and rear suspension. One might have to join the Worldwide BMW Group on Facebook to access this write-up. I'll post its link nevertheless:
Why so bad?
The FAA requires access holes drilling for the wing spar inspection of Piper Arrow airplanes through an AD, the equivalent of a recall... one of which crashed a few years ago after the wings separated in flight due to unseen and inaccessible by inspection metal fatigue Scary thought right? Well Piper Aircraft was forced to figure out a way to drill massive inspection plates holes inches in diameter in the aluminium parts holding aircraft wings together and prove the structural integrity to boot after the modification.
Here the holes in a wingless land vehicle were barely an inch in diameter. They do not affect the structural integrity of the frame... which is full of gaps anyways.
And this was assessed not by a BMW certified mechanic but a A&P / IA that needs to put his ass on the line everyday signing off repairs and maintenance on planes which can send him to jail if done improperly and he was quite confident after doing some research. We spent hours preparing this and calculating where to drill.
Sadly BMW in their wisdom never considered making openings right where those bolts were. This is a no brainer. Especially if they put a plastic piece in there with no long term stress knowledge and it proved as expected to be flimsy and a design flaw.
As for the way to remove that piece without holes and dropping the engine I am frankly curious... probably a special tool to remove the bolts from the gap and the wiggle room of the engine being able to move after the mount is removed but the contortions will be epic... and also the bolts are LONG so they would ultimately hit the frame. So probably the supporting metallic frame from the right side would need to be removed.
Keep in mind the BMW personel has their hands tied so they cannot advocate or even consider the shortcut offered here unless BMW steps up and allows drilling access holes.
The Dealers replace the mounts without drilling holes. Has to be a documented procedure somewhere.
i3marc said:
Why so bad?
Because this replacement can be performed without drilling large holes in the weight-bearing frame. Your airplane mechanic has no information about the forces that the section of frame where he drilled holes must endure, so why drill holes when doing so isn't necessary?

i3marc said:
As for the way to remove that piece without holes and dropping the engine I am frankly curious... probably a special tool to remove the bolts from the gap and the wiggle room of the engine being able to move after the mount is removed but the contortions will be epic... and also the bolts are LONG so they would ultimately hit the frame. So probably the supporting metallic frame from the right side would need to be removed.
Several i3 owners have reported their experiences in the Facebook Worldwide i3 Group. One reported taking 3-4 hours. A REx owner reported 8 hours and the need for a helper due to the weight of the REx system. No tools that aren't available at good auto parts or hardware stores were needed. I probably wouldn't have hesitated attempting this repair when I was younger, but I wouldn't want to spend a few hours crawling in and out from under our i3 at this point. I would be very sore the following day :(
I have been driving the car just fine and the hole amount to 0.001% of the structural mass of the entire frame. In fact the frame has tons of gaps in them and those holes were drilled in the thin aluminium covering of the frame not the structual support elements which are those square honeycomb pattern.

In the end I offered a good solution and my ass is in that car and I frankly believe the "certified" mechanics are out to milk you of every $$$ you've got at the dealership.

And trust me an airplane mechanic's knowledge is orders of magnitude superior to the wannabes working on land vehicles. It takes a mere 3000 hrs to get qualified as an A&P or 14 months of gruesome curriculum with 8 hrs a day and 6 days a week.

It is one of the few vocational qualifications that exceed a college degree in its scope. A trained A&P has the ability to overhaul an airplane engine from scratch, or redo avionics, or build harnesses for said avionics. And his name and signature is on the line for posterity.

Car mechanics are amateurs in comparison since planes require orders of magnitudes greater care. In fact can I sue a car mechanic for wrongful negligence if I get into a car crash the same way an A&P is immediately sued if a plane crash happens? Fat chance!

Therein lies the difference in skills and responsibility.
Cool solution Marc but why are you so hung up on the A&P thing? Do you know what happens when A&Ps begin making up procedures? AAL 191. A good A&P follows book procedure. An engineer determines where a hole may be drilled. I doubt there's anything dire in what you did to your i3, but if your A&P randomly made a hole in my wing spar I'd be fuming.
No worries this is all a maintenance item... and WE"RE FIXING A POOR DESIGN ISSUE TO BEGIN WITH!!!

I think whoever keeps that old plastic bracket has more to worry about than TWO 1 inch in diameter holes, the size of one for a bolt, inside the mere covering of the frame.

2 of the bolts retaining the bracket are easily accessible and 2 are a biatch to get to hence the quick and easy fix.
Coming from the collision world, you might think twice before drilling any holes into any structural component of any vehicle. Especially a frame rail.

This might impact the vehicle’s crumple zone performance in the event of a collision. The manufacturer engineers specific kink areas and crumple zones on every vehicle for a reason. Drilling holes or modify any structural zone is a bad idea. Not to mention potential corrosion issues. I believe the area is aluminum, so corrosion might not be an issue.

Are you planning on disclosing this modification to any future owner?

I wouldn’t put my family in your car.
I did consider drilling those holes as you did, but as it turned out I didn't have to. A low profile "through"ratchet wrench and a crescent wrench can access those bolts. the motor needs to be moved around a bit to line the bolts with the gaps between the webbing. The motor does not have to be dropped, it can remain attached on the other side. I think your car will be fine, but I am mentioning an alternative for those who will need to do this job in the near future.