Another F81 Build Thread

[attbimmer]

Originally Posted by TouringM3

Important heads up here - the M4 flares and rear bumper are vastly different than the M3 (which you'll need to do this right). You'll want to be on the lookout for a wrecking yard with M3 quarter panels and rear bumper.

See here that the rear bumper isn't shared M3 v M4:
https://www.realoem.com/bmw/enUS/part?id=8M93-USA-07-2017-F80N-BMW-M3&mg=51&sg=17&diagId=51_3007&q=51128055991

Yes also the M4/M3 front fenders are also different at the a pillar base. There was a YouTube channel that did did this and highlights most of the things that do and don't work. I think it was car cartel or something like that.

[attbimmer]

First parts painted. Very exciting. I'm already thinking about what I will cover everything with while I am reassembling to keep it all safe.

[attbimmer]

I got a bunch of misc parts late last week that included most of the parts needed to repair the broken front end parts, so today I replaced them all and just slide the coolers back on the old body just to confirm things were aligned ok. There is lots of wiggle room in all these parts that support the coolers and front crash bars, so I could see it being tricky to get them all to line up properly. At this point it seems fine, but will see once the outer body works is going on. I found one other broken part for the plastic shroud on the left side cooler. Unfortunately BMW doesn't sell it separate. The cooler it self also had a pretty good impact at some point. I'm surprised it didn't spring a leak. I ended up just finding a nice condition one on eBay with plastic in good shape as well and will swap that in.




Also body shop was busy today.

[attbimmer]

I also ended up not replacing the clutch at this time. I stopped by a local indy shop (Bullet Performance) and they agreed it wasn't worth replacing it and will be fine for quite a while unless tuning it significantly. We reset the self adjust there with their tool and I reinstalled it today (with blue loctite on the pressure plate bolts) and got the transmission reinstalled and torqued. Also replaced the trans mounts since one was completely torn apart and the other was cracked.

[NWH83]

Not sure how I missed this thread. Looks like a great job so far, and such a thorough write-up documenting the journey. Interesting to see some of the differences (as well as the similarities) with regards to the different chassis. Really looking forward to future updates!

[jagus]

Wow, looking forwards to seeing how it ends!! Bravo!

[attbimmer]

Only things left to paint are the front fenders. Will be getting the doors, rear hatch and hood mounted back on the body tomorrow to get ready to bring it home Friday afternoon. Very much looking forward to that.



Once the body is home will kick into high gear hopefully if I can find the time and start getting a lot of parts cleaned and moved over to start building up the wagon.

[attbimmer]

Picked up the body and most of the other parts that got painted yesterday and got it all home safely. Overall it looks great and can start on about a 1000 small tasks to get things back together.




They did a nice job on the trans tunnel and front seat mount.



After thinking about where the heck to get started I decided to do just a few small things before it got too late. I installed the rear hatch struts so that I can easily open it securely and also installed the sunroof seal as the sunroof has to go in before most of the riveted brackets for the curtain airbags can go in.

[attbimmer]

Continued with finishing off the moon roof since that needs to go in before curtain airbags. Also I can then cover the roof and use it for temporary storage. I also installed all the rivet brackets and airbags. Somehow I ordered the wrong number of rivets, so for some just got them in place with 1 or 2 and made sure I can still access to add them in later.



Next I turned my attention back to the wiring harness on the donor car. I was able to get what was left disconnected in the engine bay and everything pushed through the firewall. I also removed everything else from the inside on the firewall and got the large sections of insulation off in one piece.

It's funny, between the 2 cars different things are in better or worse shape on each. On the wagon the insulation just disintegrated when you touched it and crumbled to pieces. On the M3 it is perfect. Various bolts on though are cleaner and in nicer shape on the wagon. Same with various clips. The foam on the rear carpet on the M3 was also oddly crumbling apart, but was fine on the wagon. The end build will really be a best of both mix.

[jaylazy2020]

F81 with a pan roof! Epic

[attbimmer]

Originally Posted by jaylazy2020

F81 with a pan roof! Epic

Funny you say that as I always prefer a slik top. I was considering wrapping the rest of the top black so the moon roof doesn't stick out as bad. What do you guys think of that? Will probably leave it is for a bit at least.

[jaylazy2020]

Originally Posted by attbimmer

Funny you say that as I always prefer a slik top. I was considering wrapping the rest of the top black so the moon roof doesn't stick out as bad. What do you guys think of that? Will probably leave it is for a bit at least.

Has to be pan roof.

The current G81 missed a trick by not offering one.

Any Rs wagon with pan roof is just perfect.

While you have all the a b c and headliner out getting it trimmed in Alcantara 9002 which is the charcoal grey would be the icing on the cake

[attbimmer]

Originally Posted by jaylazy2020

Has to be pan roof.

The current G81 missed a trick by not offering one.

Any Rs wagon with pan roof is just perfect.

While you have all the a b c and headliner out getting it trimmed in Alcantara 9002 which is the charcoal grey would be the icing on the cake

I considered that and may do. I have some left over from a previous project, but not quite enough.

[attbimmer]

Spent some time yesterday finishing removing the wiring harness from the M3 and got it pretty well installed into the wagon. I wanted to get everything into the car in the right locations so that I can start to assess the changes that will be needed to support the new rear end.

Went from this rats nest to nicely placed for most it. It is nice having the extra headroom in the back vs crawling in a trunk.




There are 2 harnesses that go into the tail gate. One that is integrated with the main harness and another that has a disconnect at the rear electronic module. I started by separating the portion that is integrated with the wagons original harness first. 2 things connect on that harness (left side of the car). The radio antenna and the rear glass defrost. The radio antenna were easy to remove since they are single wire runs that have connectors going straight to the head unit. The defroster has disconnects at the back of the car, so the below is what is left.



The other items wired on the left side are rear speakers, 3 other antenna wires for the shark fin and the left curtain airbag. These items look like they may reach ok using the M3 harness, but I'll look more closely. It would mean running the wires in a slightly different way as was done by the factory.

The rear defrost on the wagon has both wires on the left vs 1 on the left and 1 on the right in the sedan, so those will definitely need to be modified. They run all the way back to the right front of the car, so that will be fun. On the wagon there are also 3 other wires going to the small box that the defrost wires go to. Not sure what they are for since the sedan didn't have them on either side. Will have to see where they go. Most likely I will try to build the new harness in a way that it can plug into or add onto the original M3 harness. That way it is easy to see what is changed. Will see though, in same spots that may be hard.

[attbimmer]

Have alternated between wiring work and some simple part installs the last few nights. Got the abs, clutch slave and brake/clutch pedals installed and the front seat belts. Going through the wiring that needs to be extracted from the wagon harness. A lot of things are fairly straightforward and just take some time. The rear electronics module from the wagon has more pins in it than the one from the M3, so would need to use the wagons. When looking at part numbers for that module there are about 15 different ones that all supersede each other and claim to be interchangeable so I guess that will work but likely need some coding. There aren't any details on differences between each and a single VIN lists several part numbers possible. Although there have been a few of these conversions done I haven't found a detailed write up on the wiring changes made. I'm starting to take notes on it and will publish specifics.

[attbimmer]

The last few nights were all wiring. I finished extracting all the wiring from the wagon harness for the rear of the car and have connected it all into the M3s harness. Was certainly a bit tedious, but not that bad. Was able to depin everything and connect it in place as is without having to cut anything. Most things are the same wires between M3 and wagon, but the wagons are usually longer or route to different locations. Also the wagon has a few extra things for the hatch, including a wire for the opener on the glass for the top part of the hatch, some extra lights and the control module for the auto open/close of the hatch. I still need to do the wiring of the right side of the hatch itself and wire up the rear windshield washer pump. There is still clean up and wrapping up the wires more, but I will wait until I can test things out before I do that.




Tonight I completed moving over everything else that was in the engine bay, so that it is ready for the drive train to move over. That will be the project for this weekend.





One of the things I love about a project like this is since everything comes apart it is also easy to clean things up along the way, so everything going back together is in great shape and overall it looks great.

[attbimmer]

Very successful day today working on the rear of the car. Removed the rear subframe/suspension, fuel tank, heat shields, main battery cable and brake/fuel lines from the donor and then got them all installed into the wagon. Fairly straightforward, but need to do everything in that specific order. I waited to do this on a day of have a good chunk of time since it is a lot of parts you have to take off before you can start putting anything back on.

Everything was just bolt on as is for the most part. Since the M3 has electric rear diff, there is a grounding wire on the diff the bolts to the body. That wasn't on the wagon, so I had to add that. Otherwise everything for the rear suspension and brakes are on and everything is connected. I left the wheel well liners off for the moment as there are still a few plastic clips to replace and figure I'll still need to get at things still. I also wanted to check the torque on some of the suspension parts and will do that before everything is finished.







The front end is a little light at the moment, so I put the front wheels on the nose where my handy dolly frame works great as a tire holder.



Tomorrow will work on swapping over the front subframe and suspension.

[attbimmer]

Got the front suspension and brakes transferred over this morning. Not much fabrication needed other than drilling one extra hole in the strut towers for an extra bolt that goes into the top hat. Also had to drill a hole in the small plastic parts that supports the wheel well liners along the lower part of the body.

Got a rolling body now. Ready for the engine and trans to go back in next weekend. In the mean time will continue on wiring.

[attbimmer]

Back to some smaller tasks. Now that all the brake and clutch lines are connected I went ahead and bled them. Before I actually put it in the ground would prefer the brakes work. Will also connect the parking brake arm.

To support the rear glass washer there is a single wire that goes through the giant firewall grommet along with the water line. It took about an hour to cut apart the molded grommet on the wagon harness to get that wire out. Getting it out in one piece was really just lucky based on where it was among all the other wires and how much goo was all over it. I fortunately the water line came apart while trying to remove it, so I will need to repair it. I've ordered some extra line and repair kits for that. A lot of work for 1 wire.



I also went ahead and reinstalled the battery terminal and the distribution block that goes in the engine bay now that the main battery cable that runs under the car is in. Since the M3 has a lithium battery it has a different larger air vent rather than small water overflow line. Had to drill a larger hole and then plug the small one to match the M3 body.

[attbimmer]

A bit more wiring work during the week. Turned out that the most time consuming part was removing the wiring for the overhead lights. With the panoramic moon roof there are no lights in the center for the back seats like in a normal sedan, so the lights are on each side in the back. The left side runs to the back, down to to the middle, across to right and then some wires join to the right that also runs back, down, and up and then many run to the front right where they go up the right a pillar to the center roof. 6 wires on each side and about half of each run up to the front. Was quite tedious to depin all and pull them through and put back together into a new mini harness that could be moved over and connected into the M3s connector up front. Was a few 100 ft of wire. I think that is now the last of the major wiring work on the main harness and will just be small things and tidying up.



Doesn't look so bad when it is all out and neatly wound up.



Got it all installed and looped in well.

I also had the roof bars stripped and powder coated and installed them. They had a few chips in the paint and on one front side about a 3" section had peeled all the way off. Hopefully the powder coat will hold up better.



I'm about to the point I can start clearing out the refugees from the guest room and returning them to their home.

[NYBulldog]

damn this stuff gets me excited. Amazing work so far.

[0NIN]

Keep up the good work, you make it look so easy