heinzboehmer's 2002 Topaz 6MT Coupe

[heinzboehmer]

Looking at my car as I get in to drive home, the Nogaro is in contact with the center console when the seat is forward enough to access the rear bolts. Don’t think there’s much inward to be had.

Hmm, on my car I can max out the forward travel on the sliders before I get any significant interference between the seat and the transmission tunnel. Difference might be down to where we placed our seats vertically on the brackets?




Seems to me like I can still push them inward a bit with my seating position

I don't know if you considered these, but I have them on my car with the PP ABE and I've been really happy with them. I used OEM manual sedan sliders.

https://www.speedengineering.de/en/S...r-s-side/16963

Woah! Thanks for bringing those to my attention, hadn't seen them before.

They honestly look pretty much exactly like what I had in mind. The TUV approval and certificates are very appealing. I like their slider release handle better than the Brey Krause one too.

One thing I don't love about their design is how they incorporated the sub strap mount. I get that it's made to be universal, but I think I can simplify it greatly.

I think I'm still gonna go ahead with my own version, just because I think it'll be fun to understand and work around all the constrains, but this will be an awesome reference to have and I might decided at some point in the process that it makes more sense to just buy this product.

How is the steering wheel alignment with these brackets? Think you could measure the offset of the seat centerline to the sliders centerline?

Even just the offset of the two parallel faces on the outboard bracket (the face that bolts to the rail and the face that bolts to the seat) would be useful. Can backcalculate the centerline offset with the seat and slider width.

[0-60motorsports]

I don't know if you considered these, but I have them on my car with the PP ABE and I've been really happy with them. I used OEM manual sedan sliders.

https://www.speedengineering.de/en/S...r-s-side/16963

Very Nice. Who is the M texture fabric from?

[Obioban]

God damn it. Was never bothered by my seats being off center till I saw that picture from above, and now not only is that bothering me, but I noticed the stock seats in my e82 are off center, too.

[bigjae46]

God damn it. Was never bothered by my seats being off center till I saw that picture from above, and now not only is that bothering me, but I noticed the stock seats in my e82 are off center, too.

🤣🤣🤣

[heinzboehmer]

God damn it. Was never bothered by my seats being off center till I saw that picture from above, and now not only is that bothering me, but I noticed the stock seats in my e82 are off center, too.

Lol, my bad!

I'll be scanning a bunch of stuff (brey krause brackets included) and I'll post my final CAD work on here. Should be super straightforward to adapt the PP brackets to work with the Nogaros, if you want to move your seat further inboard.

[PipeUy]

heinzboehmer yeah I can measure, I'll try to do it ASAP but having a newborn is taking most of my time.

0-60motorsports it's from https://www.ascfabrics.com/product-page/mtexture, it's pretty good but it's not a 1:1 match with the OEM stuff, the pattern doesn't fully match the rest of my interior which is OEM.

[heinzboehmer]

heinzboehmer yeah I can measure, I'll try to do it ASAP but having a newborn is taking most of my time.

No rush! Will be a couple months until my seats arrive, so I have time to design the brackets. Appreciate the help!

[heinzboehmer]

I've done a pretty terrible job of documenting the seat bracket design process, so gonna try to bring this thread up to speed. Prepare for a long post.

Always good to start with constraints. The parts I design must do the following:

1. Attach to the stock sliders and bolt to the stock bosses on the sliders. The sliders cannot be modified in any way.
2. Locate the seats (correctly!). Three point receiver must be in the correct spot. I don't want it floating over my hips or digging into my stomach. I also want the seats to end up as inline as possible with the steering wheel.
3. Have some adjustability. A couple height positions and slotted holes to allow for tilt adjustment.
4. Reuse the stock slider release mechanism. The Brey Krause solution is bulky and I prefer having the adjustment on the front of the seat vs the side, so that's gonna go.
5. Have provisions to attach a sub strap bar. The bar must be in the correct spot to match Schroth's angle-from-vertical spec.
6. And lastly, be manufacturable in bent sheet metal.

Additionally, I'm planning to make a set of prototype brackets that are both wider and longer than they should be. This will let me shim the seat and confirm the location in space in the real world.

First up is getting some more scans so that we can do (1) and (2). Started by removing the seat from the sliders in the car so I could get a reference of where everything is now. For the bolt by the three point receiver, I had to get creative with a stubby hex key, a couple different types of pliers and tesa tape to not mar the bolt head, but I got it done:





I then covered the geometry I wanted to capture in masking tape and started scanning. Opted for masking tape over the Aesub spray because I didn't want to stink up the interior.



I had partial scans of a PP ABE installed in an M3, but none of the whole seat, which would be super useful to check clearances against the sliders. I was planning on asking around to see if someone had a loose seat that I could scan, but then I found this 3D explorer thing on Recaro's website:



Hmmmm. Some network traffic sniffing, quick download and we have the complete seat in CAD!




The model lines up very well with my scans and matches all the measurements I have, so I think I can trust it.

Cool, we have all the info now, so time to get designing. (3) is easy to build into the design. (4) will be designed later, but I have made one decision as of now. Turns out you can buy the injection molded E9x handles, so I got a set and will be designing the slider release bar so that these can press onto the end of it. Should make it look nice and stock:




And now the hardest thing to package: the sub strap bar. I briefly considered designing my own bar (the load math seems straight forward), but I really don't the idea of wrapping the harnesses around laser cut sheet metal, since the edges will mess the belts up pretty quickly.

Brey Krause sells an adjustable sub strap bar (R-9259) that seems relatively easy to package, but having jam nuts on a safety critical component that's super hard to access and do a torque check on sounds like a bad idea. Their Nogaro specific sub strap bar is well made and even though it will not fit where it's intended to be installed, I think I can get around that. It's super chunky (honestly way more than it needs to be), so we can afford to clearance it a bit if needed.

I did briefly consider designing my own version of the Nogaro bar, but I absolutely do not trust my welds and adapting the part I already have seems easier than trying to find a fabricator that will do a good job.

To properly position the sub strap bar, I first needed to have a reference for the "vertical". For a six point harness, Schroth specs that the sub straps must be positioned 0-20 deg back from vertical. As far as I can tell (and what makes sense to me), this "vertical" refers to a line perpendicular to the car's velocity vector and NOT a line perpendicular to the slider's direction of travel. If you keep the car on four wheels, this velocity vector should always (okay, almost always) be on the same plane as the line that you can draw from the center of one wheel to the center of another.

This plane is not easy to find with the info I have at this point, so I modified some BMW center cap model I found online and printed out some tools:



These replace the center caps and allow you to run a string between them to use as a measurement reference. The tools fit tightly enough on the wheels that you can rotate them to tension the string and minimize drooping.



Grabbed a scan of this to have in CAD and double checked the alignment with an angle finder. Easy peasy.

Okay so, where is the sub strap gonna go? If I'm keeping the Brey Krause Nogaro one, I really only see two options. Regardless of which one I pick, the plan is to add mounting features to the brackets themselves that the bar can bolt to:

1. Keep the bar itself in the same spot, but rotate the entire part so that the mounting tabs are closer to the floor. This gets it out of the way of the brackets, since those have to come down the inside of the sliders to attach to the bosses.
2. Move the bar to the middle-ish of the sliders. This gets it out of the way of the slider release mechanism and puts it in a spot that looks more like 20 deg back from vertical to me.

Alright, let's do some measuring. This is the angle of the sub strap in the forward location with where I sit in the Nogaros:



Wait, 15 deg **forward**? Looking at this from the side makes the angle more obvious:




Greeeat. Good to know the Brey Krause brackets do not locate the sub strap correctly.

Whatever, back to the PPs.

I messed around with the seat position and found that I could get the angle pretty much spot on if I offset the seat backwards a bit and use the middle position for the sub strap bar. Bonus points is that this puts the three point receiver in what looks like the correct spot. Hard to tell because the scan is static, but I'll double check in real life. No hard measurements for this yet, since I need the seat in hand to finalize the location, but I'll grab those later.

One thing to note is that, while the angle from vertical is correct if you draw the line from where the belt is going to contact my legs, it is absolutely not correct if you draw the line from the opening in the seat. You can see this here:



The belt isn't going to magically clip through the seat, so that means it'll be riding against the rearward edge of the hole. Unfortunately, I don't think there's too much I can do about this, since the geometry of both my body and the seat are pretty fixed...

I honestly don't know what to make of this. The seat will be seeing rearward forces from these sub straps, but I can't imagine they're anything compared to the forces it sees from the hip belts. I'm tempted to just leave as is? The resultant force vector is still going to be in the correct direction for my body, so maybe it's fine? Curious to hear if others have solved for similar issues.

I also can't help but notice that emulating the 15 deg forward Brey Krause position lets the sub strap run directly through the hole in the seat. And while this is entirely wrong for six point harnesses, it actually falls right within spec for five point. I can't decide if I should abandon the six point compatibility and switch to five point?

I think I'm leaning towards living with the suboptimal belt routing through the hole in the seat, mostly because I would much rather run a six point harness than a five point, but I need to give this more thought.

Anyway, here's the prototype bracket I've come up with. Outer bracket not shown since it gets in the way of the screenshot, but it's essentially the same thing. I've designed it so that it's pushed as far inward (towards the center console) as possible. Final part will likely end up less inward, but it seems useful to have this amount of clearance for testing. Plan is to shim the seat anyway, so I'm gonna give myself as much room to play with as I can.




And yes, I know the amount of adjustability is ridiculous. This is just for prototyping and testing, the final design will be much cleaner.

I think the next step is to find myself a second set of manual sedan seat rails. With those in hand, I can 3D print the brackets and double check all clearances before sending them out to get made of metal.

[heinzboehmer]

Okay, Recaro lists the PP ABE as both five and six point compatible. I don't really understand how that works, since the passthrough in the seat bottom is small. It sure looks to me like it was designed for five point, but what do I know.

The Nogaro does a much better job of this, since the hole is way bigger.

[bigjae46]

That's insane dude. Awesome work!

These replace the center caps and allow you to run a string between them to use as a measurement reference. The tools fit tightly enough on the wheels that you can rotate them to tension the string and minimize drooping.

DUDE! Possible you could design these to stick out about 5" and a flat stem instead of round. The top of the flat stem is centered on the part and angled downward at 4.25, 4, 3.75, 3.5, 3.25, and 3 degrees.

What takes the longest when I do my string alignments is getting the strings centered on the wheels top to bottom and left to right. I was about to make something not too different but I was trying to figure out how to account for the negative camber. I also lack the CAD skills.

I found a 3D printing service. If you can do this, let me know how much to send for the STL files.

[Bry5on]

Save some weight, this section is doing nothing for you structurally. There are other places you can eliminate but this is the easy most effective one. While you're in there, you can also make sure you have some extra bend relief in there to prevent distortion during the brake form operation.



If you find that you have left-to-right motion, you'll want to add a gusset to the outer seat support. I did it differently in mine, but you get the idea:

[heinzboehmer]

DUDE! Possible you could design these to stick out about 5" and a flat stem instead of round. The top of the flat stem is centered on the part and angled downward at 4.25, 4, 3.75, 3.5, 3.25, and 3 degrees.

What takes the longest when I do my string alignments is getting the strings centered on the wheels top to bottom and left to right. I was about to make something not too different but I was trying to figure out how to account for the negative camber. I also lack the CAD skills.

I found a 3D printing service. If you can do this, let me know how much to send for the STL files.

Yep! String alignments came to mind as soon as I set that up. The way the tool is currently designed isn't ideal, though. The tabs that snap into the wheel are super fragile, but I didn't bother attempting to make that better since I don't really expect to use this tool all that much.

I do worry about stiffness as well with the geometry you describe, especially if you're gonna be resting a level or similar on the flat parts. Could always add a bore for a carbon rod or a bolt to keep things from flexing.

But yeah, shouldn't be too hard to adapt this concept for alignments.

Save some weight, this section is doing nothing for you structurally. There are other places you can eliminate but this is the easy most effective one. While you're in there, you can also make sure you have some extra bend relief in there to prevent distortion during the brake form operation.

For sure, but that's coming later. I tried to make the CAD as parametric as possible so that all I have to do is go in and change the values of some variables after I test fit the seat. To do this, I constructed an exclusion volume that represents the spaces the brackets absolutely cannot be in.

So what you're seeing above is just a boolean operation on the rough bracket shape (derived from the variables) and the exclusion volume.



Once I figure out where the mounting tabs for the sub strap bar are gonna go, I'll go and clean up all the extra material.

If you find that you have left-to-right motion, you'll want to add a gusset to the outer seat support. I did it differently in mine, but you get the idea:

This has been in the back of my mind and I've largely been ignoring it for now

I can't imagine there won't be any left/right movement with a bracket of this geometry, but I haven't figured out how to incorporate the gusset cleverly. I say cleverly cause it would be nice to avoid post-bend welding, so that the fab house can take care of powder coating too.

Might go with a bolt in gusset on the bracket itself or tie something into the sub strap mount, we'll see.

[Bry5on]

Yep! String alignments came to mind as soon as I set that up. The way the tool is currently designed isn't ideal, though. The tabs that snap into the wheel are super fragile, but I didn't bother attempting to make that better since I don't really expect to use this tool all that much.

I do worry about stiffness as well with the geometry you describe, especially if you're gonna be resting a level or similar on the flat parts. Could always add a bore for a carbon rod or a bolt to keep things from flexing.

But yeah, shouldn't be too hard to adapt this concept for alignments.



For sure, but that's coming later. I tried to make the CAD as parametric as possible so that all I have to do is go in and change the values of some variables after I test fit the seat. To do this, I constructed an exclusion volume that represents the spaces the brackets absolutely cannot be in.

So what you're seeing above is just a boolean operation on the rough bracket shape (derived from the variables) and the exclusion volume.



Once I figure out where the mounting tabs for the sub strap bar are gonna go, I'll go and clean up all the extra material.



This has been in the back of my mind and I've largely been ignoring it for now

I can't imagine there won't be any left/right movement with a bracket of this geometry, but I haven't figured out how to incorporate the gusset cleverly. I say cleverly cause it would be nice to avoid post-bend welding, so that the fab house can take care of powder coating too.

Might go with a bolt in gusset on the bracket itself or tie something into the sub strap mount, we'll see.

Bolt in. Double up on the lower fastener of the seat rail would be my vote. A simple part with two break operations should do just fine.

[heinzboehmer]

Bolt in. Double up on the lower fastener of the seat rail would be my vote. A simple part with two break operations should do just fine.

Oh yeah! Great idea. Have to make a spacer for the seat rail nuts to bottom out on anyway, so might as well make the extra part do some work.

[bigjae46]

Yep! String alignments came to mind as soon as I set that up. The way the tool is currently designed isn't ideal, though. The tabs that snap into the wheel are super fragile, but I didn't bother attempting to make that better since I don't really expect to use this tool all that much.

I do worry about stiffness as well with the geometry you describe, especially if you're gonna be resting a level or similar on the flat parts. Could always add a bore for a carbon rod or a bolt to keep things from flexing.

But yeah, shouldn't be too hard to adapt this concept for alignments.

I use a string alignment kit so there's not much weight to support. One alternative is to allow space to stick a bubble
level on and make the base able to move a little bit.