Project Armo "330i" M-tech 1

[Skarpa]

Awesome build!

Thanks! It's been a while since the last update but no worries, the car is coming together slowly and steadily. Here's what I've been working on lately:

Earlier I got the M3 ground effect pieces in the middle mocked up but the end pieces were stille left. Now they are mostly done. In budget models the exhaust tips are slanted towards the corner of the car as in M3 the exhaust points straight out of the back. The leftmost ground effect piece needed some modification. First I cut off the canard next to exhaust tip.


Then I shortened the whole piece and moved it forward so much that it doesn't interfere with the exhaust tips. The front edge aligned nicely with the rear of the wheel well. After this operation there was a strange cavity next to the exhaust tip. I tried closing it up with the canard I cut off earlier and it fit pretty well.


Then I made any other necessary pieces and taped the whole thing together. No I just need to make one piece out of suitaple plastic plate according to the cardboard template and weld it all together.


I came to conclusion the the parts are made of polyethylene. Most likely PE100 or PE300. Here's a list of properties that convinced me.

- Does not turn white under stress
- Does not melt in acetone
- Floats in water
- Sustains burning, burns at slow rate
- The flame is bluish with yellow edges
- Doesn't produce much smoke at all
- Smells like paraffin when burning
- Drops molten drips

https://boedeker.com/Technical-Resources/Technical-Library/Plastic-Identification

The right side end piece was quite a lot easier than the left one. It fit pretty well as is with just a little trimming. I trimmed the bottom edge of the rear valance as well to give a way for air to escape as planned.




In these pics you can see the crooked ground effect piece that I complained about before. Since then I got it fixed by heating it up with a hot air gun and leaving it to straighten under a weight. All in all I'm happy with this little sub-project. One slight blemish comes from the fact that M3 rear valance is much wider than the M-tech 1. The ground effect pieces in the middle fit very well but in the ends the shape of the bottom of valance doesn't match with the lip in the ground effects at all and I had to just overlap the parts.

The ground effects were the last thing before I start to prepare the body for painting. For that I wanted to put the body in rotisserie again. My rotisserie is a budget one made of two engine stands. The last time the body was suspended in it I wasn't quite happy because you could only rotate it to about 45 degrees angle:


Now I decided to fix the issue. I extended the engine stands about 250 mm. At the same time I aligned the stands to vertical stance. There was a few degrees of "preload" or backwards tilt built into the engine stands to prevent the engine from drooping under load but in the rotisserie that is not necessary and just creates unnecessary tension.




Now I'm happy. The body doesn't quite turn all the way upside down but I found no need for that.


As a final thing I drilled 20 mm holes for the rear ABS sensor wires after noticing that I was missing those.

[Rob]

Awesome build!

[Skarpa]

That's interesting that the m3s got a plastic ground effect piece under their bumper. Neat.

Stellar work as always.

Yeah, it was a cool thing to find out. And thanks for the kind words.

[Kershaw]

That's interesting that the m3s got a plastic ground effect piece under their bumper. Neat.

Stellar work as always.

[Skarpa]

The diff is ready. I swapped the pinion shim once more for a slightly thicker one in hope of better tooth contact during actual load. I sanded the right side side bearing shim slightly to get a correct preload for the side bearings. The breakaway torque is 70+ Nm. I had just one M10 screw in an output flange for turning the flange and I didn't want to exceed 70 Nm in fear of breaking the bolt.



I'll be able to fill her with oil once the correct rear cover bolts and oil plugs arrive. Apart from those, all that was left was to make the proper markings for an LSD:

[Skarpa]

A while ago I learned that M3 has plastic plates in front of the rear valance to guide air under the valance rather than forming a huge air wall in front of it. I started pondering if it was possible to incorporate the same parts to M-tech 1 rear valance. After studying photos of rear ends on the internet (and having a look at some car pictures as well) I decided that it would be possible. The bottom edges of M-tech 1 and M3 rear valances seem to be very similar and at similar height. So I ordered the parts.


Of course the fitment is not perfect. The M3 rear arches are so much wider and the exhaust tips are differently positioned. This dry fitting didn't tell me much more than that because there was no way to know exactly where the parts would sit. I mounted the valance on the car and started working on the plastic pieces one by one The spare wheel well defines the location of the center piece so I started with that. The piece actually fit nicely so I drilled holes in the valance and made a tab on the side of the spare wheel well to fix the piece.








I have pretty much no idea of which kind of fastener is used in each location because the spare part view is not very clear on that. I ordered all parts that seemed likely. Mostly the parts seem to have tabs for sheet metal nuts but the holes are also correct size for 6mm plastic rivets. The spare part picture also shows kind of collared sheet metal washers that have something to do with the rear valance but I have no idea what they are for. Perhaps low profile washers to be used with screws and sheet metal nuts.





When mocking up the parts I went with screws all around because they are easy to fix and undo. Next I mocked up the large section on the right side of the spare wheel well. It needed a bit more work because the M-tech 1 valance has a more curving shape than the M3 one. It cut off a thin slice from the valance to match the parts. Then I welded a few more tabs on the spare wheel well.






Damn, that big plastic section is warped on the right edge:evil: I should probably have complained about that. I'll see if it straightens up once I have everything installed and heat it up a little with a hot air gun. Originally the plastic plates are fastened to the valance every 30 cm or so but there are unused blind tabs in between. I drilled and used them as well to have a better fitment. The final fasteners need to be lower profile than these.







Not bad at all. The end pieces will need more modification, though. I'll also need to massage the M-tech 1 valance some. It's kind of warped at the right rear corner after 15 years of various storage.

[Skarpa]

I've worked with the differential from time to time when I've had time. The differential is a 2.65 LSD from an E34 diesel and I swapped 2.93 gears in it. I assembled the LSD unit I think at least a year ago using one extra friction disc but replacing the bearings and especially adjusting the tooth contact has taken me a while. Now we are getting close.

The inner bearing of the pinion was so tight that I had no chance getting it out with a bearing puller.


The bearing puller jaws combined with a hydraulic press did the trick. I think I had 5 ton force before the bearing race moved. The bearing puller jaws were slightly bent but nothing too bad.


After pressing in all new bearings it was time to test assemble the diff with the old shims to get an idea of which direction I need to move. The bearings are precise enough that replacing them did nothing to the preload of the side bearings. The rotating torque was still in spec.




I don't have a rotating torque meter so I used an old school method:

When you know the distance form the shaft center you can calculate the rotating resistance. At first I thought I might need to attach a camera to the tool and take video of the spring scale to be able to read the value but experience showed that it's surprisingly easy to read the value while rotating the shaft and the value stays pretty stable. Not as good as a proper tool would be but sufficient.

The tooth contact was way off. No shim available would have been thick enough for the driver's side and the contact pattern was wrong as well:




The contact is all the way at the root of the tooth meaning that I needed a thinner shim for the pinion. BMW cells the pinion shims in two sets: thinner set and thicker set. The old shim as measured with a caliber was 3,52 mm: thickest one available. I bought the thicker shim set and tried with one from the middle of the range (3,49). There was practically no change. I didn't bother trying the thinnest shim in the thick set, 3.46mm. The difference was just too small to make a change. Replacing the pinion shim is not a quick task: take apart the diff, tap out the outer race of the inner pinion bearing, replace the shim, press in the bearing race, rebuild the diff, adjust the bearing preloads, adjust the backlash and then check the effect of the adjustment.



I bought the thinner shim set for the pinion and both the shim sets for the side bearings. Until now I had just used generic shims for adjusting the backlash to see the effect. As a test I used the absolute thinnest pinion shim available (3,255) to see that the range of adjustment is enough to get the correct tooth contact. That was confirmed. I was able to get the tooth contact off in another direction, meaning that it's too close to the top of the tooth.




Also, the drive side pattern is too far on the heel side. Next I took a shim from halfway of the thinner set. (3,34 mm). The contact is starting to look fairly good:




The contact area is pretty centered heightwise as well as sidewise. The pattern is not quite as clear as before. I may have used wrong amount of marking paste or something. I'll wipe the gears clean and do a new test but unless anyone more experienced has differing opinions, this is what I'm going with. I will probably need to sand the passenger side side bearing shim as even the thinnest one is too thick. I guess my diff cover and the gearset are just on the opposite sides of the manufacturing tolerance area.

[Skarpa]

Progress has been somewhat slow with the overload at work, summer trip and welding the dd but I've managed to do something at least. I cleaned the front frame and laid epoxy primer on all bare areas as well as inside the bottom beam. Then I welded the patch panel in place.

As I said before, this is supposed to be the last rust repair (for now). WOO! As for the engine: Ethanol is confirmed. I'll go with E85 from the get go even though the first setup will be pretty mild and would not require it. I got an ECU with an ethanol tune and 373cc injectors (Volvo 0280155830) for a decent price. Although I need to have the tune modified a bit to fit my cams and ITBs. In Finland at the moment there's a reward of couple hundred euros for doing an E85 conversion to your car so I'll score that when having the engine swap inspected and approved.

[Skarpa]

Edit: Duplicate post

[Skarpa]

I've just spent the last few days reading through your thread. Your work and ideas are really impressive, keep it going that way :D

Thanks! I still have a few tricks up my sleeve...
... Also an awesome idea for a future project once this one is done. Can't live without at least one forever project going on.

[geckster]

I've just spent the last few days reading through your thread. Your work and ideas are really impressive, keep it going that way :D

[Skarpa]

Now that the rear corners of the engine bay are taken care of it was time to move to the front frame. That's hopefully the last area of the body where I need to replace sheet metal because of rust (on this round). On closer inspection it was luckily a lot less rusty than I thought. There was quite a lot of surface rust but not that much deeper corrosion so phosphoric acid will take care of most of the spots.


However, the inner panel of the bottom beam was pretty rusty so I removed it.









Patch panel taking shape:




The old panel had the bottom brackets of the radiator that are now needless. It also had various stiffening ribs. I don't have a bead roller and for a moment I contemplated on making dies for oblong ribs but then I got lazy and decided to do just a pattern of dimpled holes. I used the hole near the hood lock as a guide.




The dies were a pretty fast job on a lathe.



The process worked exactly as planned.




On hindsight the dimples could maybe have been a bit bigger or there could have been four on each side but that's nitpicking considering how happy I am with the dimples and the fact that practically no one will see the panel after the radiator is in place. It will be easy to modify the dies if I want to change the size of the dimple for some possible future job.

[Skarpa]

This project has been going somewhat slow lately what with all the other things in the life getting in the way but now the strut braces are welded in and the the fuse box area repaired.

[Skarpa]

Your Welding is looking much better

Thanks, I've noticed the same and am pleased.

[BUDNUNTA]

Your Welding is looking much better