my new project 1997 m3 sedan with s54 swap

[bmwstephen]

What DEI insulation product you used? do you have any pics of how it looks like leading up to the firewall/above where the headers enter the transmission tunnel? So far it looks like a nice solution to the degrading ones on our aged stock ones

Update to my transmission saga. I swapped a ZF5 speed for what I was told was a GS6-37bz out of a ZHP. The guy I got it from had it from someone else and never owned the car it came out of. I got it really nicely cleaned up. New clutch installed, happy days. I went to install it yesterday and discovered I have what I believe is the GS6-37BZ — TJEP out of a n52 car. The bellhousing bolts don't all align, im missing the starter dowel, and the bellhousing part stamping 1069 401 065


I'm having a hard time finding a good gs6 that will work. Car-part.com has a few in the southeast no pictures or condition details and several of the transmissions on there that do have pictures are the same wrong gearbox labeled for the wrong year car.

Attachment 733108



I redid my tunnel insulation with DEI trans tunnel 2 in black:


Attachment 733109Attachment 733110

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Also I 3d scanned this transmission:
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I had an emergency bench press rep trying to install the gearbox using the HF floor jack so I modified it to bolt into the transmission. I also swapped out the casters and got it low enough I can roll it right under the engine without it touch while keeping it all bolted down and level. A huge quality of life improvement doing the trans install by myself:
Attachment 733112 Attachment 733113

Also in preparation for installing the upper bolts I printed a little magnetic e14 socket insert

Attachment 733114

[triplessafebest]

It's this product. A smaller piece would have been fine but I also didn't cover as much as I could have: https://www.amazon.com/Design-Engine.../dp/B08778H4MC

[bmwstephen]

It's this product. A smaller piece would have been fine but I also didn't cover as much as I could have: https://www.amazon.com/Design-Engine.../dp/B08778H4MC

interesting. did you actually use the adhesive backing or did you secure it with some other fastners onto the tunnel?

[triplessafebest]

It's a good adhesive. DEI stuff has never failed me but I haven't used this product before. I prepped the tunnel with a wash, followed by a isopropyl wipe down and a full drying. I used their seam tape on the edges to cover the white fiberglass edge but that's just cosmetic .The foil face is relatively stiff since it is aluminum. The piece can't drape or droop easily and would need to come off as a unit. You could also use some of the factory retainers if you wanted a fail safe.

[triplessafebest]

Picked up a new gs6-37bz last night. Drained it today and its more glittery than I had hoped with some bigger chunks. It needs at least a selector rod seal but probably an output shaft seal and overall looks a little more haggard than I had hopes. Does anyone know if the gearbox side of the internals are the same and I could swap bellhousings between a gs6-37bz THEG and a gs6-37bz TJEP (n52 version)?

[golgo13]

Jeez dude, seems like a challenge finding the right transmission for your needs

[triplessafebest]

Hah its been a pain. I have the new one cleaned up just waiting for seals to come this week.

I'm looking around for a service manual for this transmission or possibly its in a ZHP/late 330i repair manual. Anyone know the torque spec on the big nut that hold the output flange? Is there a specific torquing procedure like some of the other BMW boxes?

[blckstrm]

Hah its been a pain. I have the new one cleaned up just waiting for seals to come this week.

I'm looking around for a service manual for this transmission or possibly its in a ZHP/late 330i repair manual. Anyone know the torque spec on the big nut that hold the output flange? Is there a specific torquing procedure like some of the other BMW boxes?

I haven't had to redo mine yet, but those specs are hard to find (recalling doing it on the 5 speed).

And you're right - they're super hard to find for anything like a reasonable price. I blew my diff on Thursday night, but until I got it home and up in the air I thought it was the trans (the LSD didn't fail, just either the ring gear or the pinion, so my roadside diagnosis was off). Anyway, in that couple hour interim I couldn't find hardly anything that wasn't $1500+shipping. I did find a good one from a local shop here in Austin for $1300, but it was gone by the next morning. So that does seem to be the going rate for them. And yeah, the N52 issue popped up several times in that search.

[triplessafebest]

Correct torque process from ISTA for the tailshaft flange:
torque.jpg

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Also glad that the selector rod seal was easy to remove. The first time attempting a very small seal on an expensive part always stresses me out a little. Tapped a small screwdriver into one side which pushed the other side of the seal up. Then grabbed that with another small screwdriver.

Twins:

tranimsssions.jpg

[triplessafebest]

Intake prototype parts for section 1 and section 2. This feeds my AFE intake nicely. The plan is to have section 3 be CSL box specific. The print failed near the top but still usable to test fitting. It was never going to be an end use part since its just printed in petg-gf

One challenge I need to solve: The engine will move and there isn't a ton of ability for all of this to flex. I'm trying to figure out the best way to get some flexibility into the design without having to resort to anything that flows really badly like a corrugated hose. Open to a few ideas including wrapping and forming a custom shaped silicone hose/coupler, making longer slip fit joints between each piece, and keeping the middle section printed or made out of something with more ability to deform (polypropylene is a bitch to print but would work).

prototype2.jpgprototype1.jpg

[bmwstephen]

Have you consider the euro s50 snorkel? It feeds from brake duct and nose panel. You won’t connect directly to the csl airbox since it was designed to mate to the stock m50/s50 airbox but at the very least you would have a path of cold air into the area of the csl box inlet.

[triplessafebest]

I would rather have an efficient duct flowing directly into the engine. There is room (just barely) for well designed inlet duct to pull air cleanly from outside the car. No mixing with engine bay air, no turbulent flow from sharp turns, quick transitions, or corrugated hose. Also if you squish a round hose into an ellipse you haven't maintained even cross section and there is not an open 120mm circle of space available through this area. 120mm circular area is what I'm trying to stay as close to as possible. It's slightly more area than all 6 throttle bodies added together.

[triplessafebest]

I made a gs6-37bz output shaft seal installer in case anyone else finds this useful:
sealtool_revised1.jpg
https://makerworld.com/en/models/1368925-output-shaft-seal-tool-for-bmw-zf-6-speed-gs6-37bz#profileId-1415126

[triplessafebest]

There a few small improvements to make in the transitions (especially one obvious spot after it enters the engine bay) but this is about as close to perfect as I can get the flow cross sections while still supporting Depos. I haven't scanned a bosch unit yet but my understanding is that they are little more compact. I'll settle for ending up 1.9% under sized in exchange for compatibility.
Screenshot 2025-05-04 162517.png

[Braymond141]

Ummm. The headlight in your photos and the scan is Bosch, not Depo. To further expand upon that, it is an early Bosch with the vent on the high beam rear cover and different shaped low beam cover. You'll have slightly more room with the high beam cover 99% people have on their Bosch (no vent tube). The low beam is similar between old and new, nothing worth noting.


You really need to account for the static rod being in place too. https://www.msportparts.com/collecti...eveling-delete

[triplessafebest]

Yeah I looked more closely at it when I pulled it out to scan it yesterday and saw it was a Bosch unit. My recollection was that the PO said it was a depo and I never look that closely until I was cleaning it up for scan. Saved me time and money shopping for a bosch unit to scan. The static rod is in place. I cut mine flush and sanded it smooth. I think it is pictured earlier in the thread.

USDM vs Bosch scan comparisons:
headlightscompared.jpg

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I guess I never posted a picture of that but this is what I did to the rod a while back:
leveler.jpg

[triplessafebest]

This is close to the final design. I don't have the exact location of the inlet for the CSL opening so that is approximated right now. Once i get a CSL box I can scan that in the car and get that location exactly. I also need to make a redesigned brake duct to fit this version.


The fit is about perfect with the Bosch light installed and I got the cross section areas about as good as I think they can get.
area.jpganotherfitup.jpg

I also got to use a grinder on this car for the fist time removing the horn bracket:
sparks.jpgchassis_cut.jpg