Black & Tan 332iT

[heinzboehmer]

It’s a bit harder to tell at first blush because you can’t also feel it in your hands.

I think this is what makes the effect of this type of bracing so hard to put into words. I needed ample seat time in my own car after the Slon wall to really understand all the minutia associated with the change.

Best scenario I've found to highlight the improvement is a sudden and fairly large steering input. Not a jerky move, but moreso something that really loads up the outside tires quickly. Without the bracing, you can feel two very distinct "settlings" after turning the wheel. One being the suspension reacting to the change and the other being the chassis "untwisting" after the intial load. Both of these are still present with the bracing, but there's significantly less time elapsed between the two and the chassis settling is less pronounced. I think this also has the effect of making it feel like the suspension is working harder, like you mentioned, cause that's mostly what you're feeling now. Hard feeling to describe for sure. Much easier to understand in the driver's seat.

Also, I think something similar could be replicated for coupes. To make it bolt in, you could piggyback off the rear seat top latches, rear seat bottom pivot point, isofix anchors, front subframe bolts (if you have vincebar style reinforcements) and maybe even the rear window motor mount points. Nutserts make it not a bolt in mod, but allow for easy pick up points along the side of the opening. Now I kinda wish I hadn't bonded the Slon wall into my car, so that I could design something similar to yours, but for coupes...

Attaching a pic of the coupe opening for inspiration

[Bry5on]

M8 version design complete, made a few DFM changes:

• Holes converted to M8 (and M6 for the tie down loop)
• All holes tightened up a little (first rev was deliberately loose fit)
• Slots added to accommodate different car's tolerance stacks (George's touring and mine measure slightly different)
• Eliminated upper bar, now a bow tie shape
• Clevis attachment webbing moved to make separation/cutoff easier, and to make the cuts non-visible after powder coat

Pricing for qty 3 is double the price of qty 1, so I ordered 3 of this set. The cross brace is larger than sendcutsend will powder coat, so that and the spacers will arrive bare finish. That'll allow me to bond the spacers to the brace, then send the bonded assembly out for powder coat. This will simplify installation so that I'm not messing around with floating the spacers in place, but the spacers will need to be bonded to the brace on installation due to the tolerance stackup in the car.

[Bry5on]

More seat time today and I think this is closer to the stiffness increase of the Slon brace than I initially thought, maybe an equal increase. It’s a bit harder to tell at first blush because you can’t also feel it in your hands. Really really great change. No downsides other than there’s more effort involved to drop long things into the rear now. Worth it I think.

Also, I’m going to eliminate that flat top piece in the next rev. It doesn’t really do much. The brace will become sort of a bow tie shape.

[Bry5on]

Cam clamps worked great. These M10 stud versions of the clamps neck down to an M8 fine thread, so the next version of these parts are going to be designed for M8 holes all around. Then I can use M8 cap head bolts on one side and thread the cam lever directly onto the bolt to eliminate a nut. Fewer parts is always better. I’ll also be adding a couple strategically placed slots so that fit up is dead on. Coming along nicely!

[Bry5on]

I recently installed the 6 point RACP brace in my M3, so appreciate not a direct comparison to this but the concept is pretty similar, - I felt exactly the same, you can feel the suspension doing more work in response to the chassis being stiffer and not twisting so much.

Very cool - and I'm impressed that you got it dimensionally so close in a single iteration!.

Also congrats on the house.

Thanks! Yeah it's a very hard feeling to describe in words. Sort of like you can really feel the extra stiffness in the little ripple movements of the rear suspension now. This could honestly be the rear shock mounts displacing a bit before the dampers start doing their job, but it's not something you could feel before. Just lots more 'precise' feeling. All good changes. Did you notice any of this 'ripple' sort of behavior?

Very nice job! I imagine that this about as effective as the SLON product. I'd pick one up if you did one for the coupes.

I'd say that the Slon shear wall is more ideal than my design, but mine should be 90% as effective. The touring just doesn't have the same geometry to run a design like that and I also want it to be quickly removable for fold down seat access. Unfortunately the coupe doesn't have any of the mounting points that I tied into here, so it would be a bit more of an involved job on a coupe, likely involving reinforcing and/or hole drilling in the parcel shelf and rear frame rails. Certainly possible, but not easy bolt in like the wagon!

[YoitsTmac]

Very nice job! I imagine that this about as effective as the SLON product. I'd pick one up if you did one for the coupes.

[karter16]

it's either placebo or I can actually tell that the suspension is articulating more

I recently installed the 6 point RACP brace in my M3, so appreciate not a direct comparison to this but the concept is pretty similar, - I felt exactly the same, you can feel the suspension doing more work in response to the chassis being stiffer and not twisting so much.

Very cool - and I'm impressed that you got it dimensionally so close in a single iteration!.

Also congrats on the house.

[Bry5on]

New house is getting dialed in. These guys were waiting for me upon arrival:


Took a few days to get to car stuff, but the test fit (with 3/8-16 freedom fasteners) went okay. Install is a bit fussy and I missed a couple dimensions by ~2mm but with the undersized fasteners and a couple washers it all went together. Fitment pics:






It's definitely noticeable. Similar to adding the Slon brace, it taughts up the car, especially felt on angled bumps, lumps, dips and step changes in street height. I've only got one run to the hardware store with the wife in it, so not a lot of seat time, but enough to tell a difference right away. I would say it's about 1/3 as drastic a change as the Slon brace, and it's either placebo or I can actually tell that the suspension is articulating more. Not sure yet. For the first time, I felt like the car could use more spring rate (or maybe just stiffer shock mounts), which is honestly not what I expected to think. I really want to A/B an M3 converted wagon without all the bracing back to back with mine now to feel the cumulative change.

Given that the fit went well enough, I went ahead and ordered the M10 quick release clamps. Those should arrive tomorrow, so with any luck I'll have that sorted as well. I'll also likely bond the little 3/8" pucks to the brace itself to make installation a lot less fiddly. It does slide out vertically rather nicely though, which is cool.

[karter16]

It bolts in with 5 fasteners, lifts out upward and I'm ordering cam locks (like a bike seat post) for quick removal. If I do this right, it's a no-tool install/removal for hatch access on the fly.

That is epic! Absolutely best of both worlds!


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[Bry5on]

Excited to see/hear how this goes. Are you planning for this to be removable for when you need the load-thru access? (Looks like you might be but not sure how complex install/uninstall is expected to be?)


Sent from my iPhone using Tapatalk

It bolts in with 5 fasteners, lifts out upward and I'm ordering cam locks (like a bike seat post) for quick removal. If I do this right, it's a no-tool install/removal for hatch access on the fly.

[karter16]

Alright, a few tweaks and I decided to pick up the center isofix mount as well. Parts are ordered, this should be a nice change if the Slon wall in the M3 is any indication.

Excited to see/hear how this goes. Are you planning for this to be removable for when you need the load-thru access? (Looks like you might be but not sure how complex install/uninstall is expected to be?)


Sent from my iPhone using Tapatalk

[Bry5on]

Alright, a few tweaks and I decided to pick up the center isofix mount as well. Parts are ordered, this should be a nice change if the Slon wall in the M3 is any indication.

[Bry5on]

No no no. You used CAD-- cardboard aided design.

Just installed this bracket. Thanks!

I should probably do this next project with said CAD..

So instead of working on any of the projects I've already got in flight, I decided to jump into CAD land to work on a simpler one. Making the touring chassis even more rigid! Still need to design the clevis mounts but this will bolt in using factory mounting points for the seat latches and the gear lashing hooks. Both things that should be able to take some decent loads.

I'm also not set on sheet metal because it would need something to stiffen it up, but it's a start.

[Obioban]

After an iteration of carboard engineering, to borrow a term from Heinz, I designed a three bracket system, laser cut it and bolted it to the transmission.

No no no. You used CAD-- cardboard aided design.

Just installed this bracket. Thanks!

[Bry5on]

Okay, now we're talking. This should work with milled down e39 bushings inserted into the knuckles. The nice thing about that approach is that I don't need to cut or ream a taper myself, just turn or mill the factory e39 bushings.

What remains to be seen is whether the rubber boot can compress an extra millimeter more than stock and, if there is enough thread engagement, if I can increase the depth of the press-in bushing to drop the load on the bottom edge of the knuckle a little bit. As you can see, I've got a safety factor of 2 everywhere, but would really like something around 3 everywhere