Spx E92 Track Build Journal

[spxxx]

Originally Posted by roastbeef

i've been thinking up a hand crank solution. the rotating assembly that attaches to the motor is splined. not sure if it is an assembly from an older model that was available with hand cranks that they added a motor too.

i had a little project a while back where i replaced the steel cable of the window regulator with kevlar thread. it saved an ounce per side. i was actually successful in doing so, but i shelved the project for a while and never got back to it.
i also drilled the two rails and wasn't happy with it. the metal is really soft and relatively lightweight anyways. the drill bits rip and grab the softer metals and it just wasn't clean. the trolleys that carry the mounts up and down slightly caught on the distorted rails.

also, you'll lose the little automatic movement that happens when you pull the door handle- the car cracks the window about 1/4" to clear the window trim. you can adjust the height of the windows at their max height stop, but they might make a little wind noise and not seal as good.

Wow kevlar fabric is dedication... Yeah unfortunately there was never an E9x car with hand crank windows unlike the E46 chassis, a few E46 models came with crank windows in Europe. Wonder if they can be adapted for E9x - I'm looking at some random cheap electric window kits on Amazon.

[roastbeef]

part of the reason i shelved the project is i don't know how this kevlar thread is going to stretch over the years. and the only way to get these steel cables out of the mechanism is to cut the tips. this ruins the whole mechanism if it turns out you can't use it.

no, it doesn't look like we can seamlessly Frankenstein a kit together. i looked at oem hand crank assemblies, and they appear they might actually be heavier than the electric motor/trolley rails that our cars have.
hand crank setups are big 1/4 circle metal gears that raise and lower a metal scissor looking mechanism;
https://www.realoem.com/bmw/enUS/sho...diagId=51_2055

https://www.ecstuning.com/b-genuine-...t/51328146801/

this part alone is just a couple ounces lighter than the rail/cable setup we have, and doesn't include the crank and hardware.

we could probably attach a window crank to the trolley mechanism with a custom machined part (see rudimentary sketch below). it would have to be splined to take the window crank and splined on the opposite side to match the window trolley gear. just eyeballing it, they are different sizes.
we would also likely need a flat door card for this, as it won't work right with any kind of curvature.

if i was competent in CAD and had easy access to a machine shop i would be more willing to explore it, but just doing the reading and mental work, this is a big project in time and money that would probably work, but save just a few ounces. you'd be better off investing in some titanium nuts and bolts, and that is not a statement i can say often. lol

how are you planning on rigging a window to that door? i didn't think it had the provisions for it...

[spxxx]

Originally Posted by roastbeef

part of the reason i shelved the project is i don't know how this kevlar thread is going to stretch over the years. and the only way to get these steel cables out of the mechanism is to cut the tips. this ruins the whole mechanism if it turns out you can't use it.

no, it doesn't look like we can seamlessly Frankenstein a kit together. i looked at oem hand crank assemblies, and they appear they might actually be heavier than the electric motor/trolley rails that our cars have.
hand crank setups are big 1/4 circle metal gears that raise and lower a metal scissor looking mechanism;
https://www.realoem.com/bmw/enUS/sho...diagId=51_2055

https://www.ecstuning.com/b-genuine-...t/51328146801/

this part alone is just a couple ounces lighter than the rail/cable setup we have, and doesn't include the crank and hardware.

we could probably attach a window crank to the trolley mechanism with a custom machined part (see rudimentary sketch below). it would have to be splined to take the window crank and splined on the opposite side to match the window trolley gear. just eyeballing it, they are different sizes.
we would also likely need a flat door card for this, as it won't work right with any kind of curvature.

if i was competent in CAD and had easy access to a machine shop i would be more willing to explore it, but just doing the [...]

Yeah I will be running the HGK doors which don't have any attachments for windows of any kind so I would need to cut a slit at the top to even fit a window down into the door when recessed. I'm basically starting with a blank slate and will need to 3D print or fab any mounts or brackets. My main concern is getting the door bars to mount in the OEM locations. Even with lexan windows/regulators/bars I'll still be saving >40lbs per side.

I'll need to use a universal window system most likely. Still waiting on parts to arrive though!

[DRLane]

Originally Posted by spxxx

Yeah I will be running the HGK doors which don't have any attachments for windows of any kind so I would need to cut a slit at the top to even fit a window down into the door when recessed. I'm basically starting with a blank slate and will need to 3D print or fab any mounts or brackets. My main concern is getting the door bars to mount in the OEM locations. Even with lexan windows/regulators/bars I'll still be saving >40lbs per side.

I'll need to use a universal window system most likely. Still waiting on parts to arrive though!

Just out of curiosity, how did you get to > 40lbs each?

Are you caging the car or just dropping door weight?

[roastbeef]

Originally Posted by spxxx

Yeah I will be running the HGK doors which don't have any attachments for windows of any kind so I would need to cut a slit at the top to even fit a window down into the door when recessed. I'm basically starting with a blank slate and will need to 3D print or fab any mounts or brackets. My main concern is getting the door bars to mount in the OEM locations. Even with lexan windows/regulators/bars I'll still be saving >40lbs per side.

I'll need to use a universal window system most likely. Still waiting on parts to arrive though!

i'm not one to snuff out ideas, but you're in for a very tough project. the window angle and movement is very precise and you're basically going to reengineer it from scratch.

why not go with schirmer or karbonius? or just do a fixed window with a slider.

i'm getting p4p 4mm hardcoated windows. they are about half the weight of oem, which are 9lbs, 3.2 ounces each. with the p4p windows weighing about 5lbs, you'd be saving around 39lbs per side, with functioning windows, without door cards.
i don't have functioning interior door handles. i reach out and open the door with the outside handle and then lock the car by holding the handle and the windows roll themselves up. its genious, if i may say so myself.

[spxxx]

Originally Posted by roastbeef

i'm not one to snuff out ideas, but you're in for a very tough project. the window angle and movement is very precise and you're basically going to reengineer it from scratch.

why not go with schirmer or karbonius? or just do a fixed window with a slider.

I don't have high hopes at all, now that I stupidly have 2 track cars... My E92 could be fully gutted and trailered to every event with bolt on lexan for transport. I just like engineering projects and this seems fun (as of now)...

It was a simple cost/benefit analysis, functioning windows are low on my priority list. These were ~$1200 shipped vs $5k for any other decent option with OEM internals. I'd use OEM window regulator / sliders if I wasn't clear on that front.

I want to see your doors though one of these days if you make it Buttonwillow or up North. You must have the lightest E92 on the forum, I want to see what it can do!

[spxxx]

Originally Posted by DRLane

Just out of curiosity, how did you get to > 40lbs each?

Are you caging the car or just dropping door weight?

That's a pretty rough estimate, most folks cut ~100lbs going from OEM to carbon. I'm adding back the ~10lbs per side for the OEM steel door bars that I'm planning to bolt in along with the B pillar door bar "anchor".

I'll probably add a few layers of internal carbon at home too just for rigidity if the strength/quality is subpar.

[roastbeef]

Originally Posted by spxxx

I don't have high hopes at all, now that I stupidly have 2 track cars... My E92 could be fully gutted and trailered to every event with bolt on lexan for transport. I just like engineering projects and this seems fun (as of now)...

It was a simple cost/benefit analysis, functioning windows are low on my priority list. These were ~$1200 shipped vs $5k for any other decent option with OEM internals. I'd use OEM window regulator / sliders if I wasn't clear on that front.

I want to see your doors though one of these days if you make it Buttonwillow or up North. You must have the lightest E92 on the forum, I want to see what it can do!

hard to say if she is the lightest, but its possible or close...

the oem door bars are pinched into the metal molding of the door. i found a few pics... the bottom one is pinched into the door and the bolt you see with the hood on the outside loosely hooks onto a piece on the door jamb. i'd say you would have better luck making your own if that is important to you.

[spxxx]

Originally Posted by roastbeef

hard to say if she is the lightest, but its possible or close...

the oem door bars are pinched into the metal molding of the door. i'll try to find pics. i don't think they'll transfer well.

I'm well aware haha, I already have an extra set of doors stripped down for the project. It's gonna be difficult on the rear side. Plan to use Rivets and epoxy on the rear end of the door and standard bolts (TBD) on the front side. The door bars are designed to cut into the B pillar to hold them in the event of side impact.

Another short term option is adding a more typical door bar setup like you can find for most Miatas, there's several bolt in options for more popular tin-can track cars. I just can't commit to a full cage until I decide on the E46 vs E92 being the full racecar going forward. E46 running costs and initial performance are making it a tough decision.

[roastbeef]

what about this... sandwich a door bar at the hinge bolts and rear latch. the door would open and close, but the bar would stay fixed.

[spxxx]

Originally Posted by roastbeef

what about this... sandwich a door bar at the hinge bolts and rear latch. the door would open and close, but the bar would stay fixed.

That has crossed my mind! I was thinking of using some 1.5"tubing pinched at the door edges and welded in/bolted at the hinge area.

[roastbeef]

Originally Posted by spxxx

That has crossed my mind! I was thinking of using some 1.5"tubing pinched at the door edges and welded in/bolted at the hinge area.

https://carbon-microsystem.com/store...ber-p140285999

this company makes carbon doors with oem style metal crash bars in them.

[wahwill]

Were you able to pass sound with your xpipe and exhaust setup?

[spxxx]

Originally Posted by roastbeef

https://carbon-microsystem.com/store...ber-p140285999

this company makes carbon doors with oem style metal crash bars in them.

I was actually looking at those doors for my E46. Want to lose weight but need full window functions etc since it's street driven to the track. (Trying to actually keep it "clubsport spec" haha).

I'm just looking for reviews in the E46 world, they seem to offer E92 carbon doors as well at a much lower price than other vendors. They're based in Latvia so maybe there's some relation to the other carbon vendors out there.

[spxxx]

Originally Posted by wahwill

Were you able to pass sound with your xpipe and exhaust setup?

My car with a straight piped X and Akra rear is 96.5dB based on Laguna's measuring system.

[DRLane]

Originally Posted by spxxx

That's a pretty rough estimate, most folks cut ~100lbs going from OEM to carbon. I'm adding back the ~10lbs per side for the OEM steel door bars that I'm planning to bolt in along with the B pillar door bar "anchor".

I'll probably add a few layers of internal carbon at home too just for rigidity if the strength/quality is subpar.

Where did you land here?