GB for SLON Workshop CF Rear bulkhead, which can (optionally) be a back seat delete

[Tonggi]

Im curious how I can grind that down. it will render those rivets up top useless.

[heinzboehmer]

Im curious how I can grind that down. it will render those rivets up top useless.

They aren't doing much now anyway. Their main purpose is to ensure that the adhesive dries in a uniform, thin layer, so that it can achieve its max strength.

[Casa de Mesa]

Talked to Slon about this and was told NOT to cut the wall.

We ended up deciding the best choice is to grind down the reinforcement plates so that the gap between the wall and sheet metal is ~1mm (I measured the thickness of the plates to be 1.5mm).

As for adhesive choice, Sika 7888 is the adhesive BMW uses for their carbon roofs and so seems like a safe pick. I found this publication that explores the mechanical properties of this adhesive in relation to the thickness at which it is applied: https://www.researchgate.net/publica...ckness_on_the_ Mechanical_Behavior_of_a_Structural_Polyurethane_A dhesive

Looks like the lap shear strength goes down from ~23 MPa at 0.2 mm adhesive thickness to ~20 MPa at 1 mm. Don't think the 13% decrease will be much of an issue.

We did consider other alternative adhesives —like Araldite 2014— but ultimately decided that Sika 7888 was the best choice. That conclusion was reached mostly because it's significantly less brittle, with elongation at the breaking point at 0.7% for the Araldite and 40% for the Sika. Araldite will be super hard, but might break under moments of high impact, which this wall will definitely see (e.g. hitting a big kerb on the track, hitting a pot hole, etc.).

So, my plan is to grind down the reinforcement plates so that the gap between the wall and sheet metal is ~1mm and then use Sika 7888 for the install.

Any suggestions on the best place to purchase Sika (SikaForce) 7888 glue?

My Slon roof showed up on my town today. Got a hang tag from USPS saying "too big to deliver" so I'm off to the PO tomorrow

However, even though I thought I already ordered the glue, I opened a box from months ago and apparently I never did... so in a sorta rush to find the best place to source this glue. ECS has it available March 24.

[heinzboehmer]

Any suggestions on the best place to purchase Sika (SikaForce) 7888 glue?

My Slon roof showed up on my town today. Got a hang tag from USPS saying "too big to deliver" so I'm off to the PO tomorrow

However, even though I thought I already ordered the glue, I opened a box from months ago and apparently I never did... so in a sorta rush to find the best place to source this glue. ECS has it available March 24.

I still haven't bought any myself, so sorry, won't be of much help. I was probably going to get it from ECS or similar.

Maybe try calling a local dealership?

[bmwfnatic]

Any suggestions on the best place to purchase Sika (SikaForce) 7888 glue?

My Slon roof showed up on my town today. Got a hang tag from USPS saying "too big to deliver" so I'm off to the PO tomorrow

However, even though I thought I already ordered the glue, I opened a box from months ago and apparently I never did... so in a sorta rush to find the best place to source this glue. ECS has it available March 24.

This stuff has a shelf life of only 6 months, because of it expiring so quick I doubt many places will have it in stock.

[Casa de Mesa]

I still haven't bought any myself, so sorry, won't be of much help. I was probably going to get it from ECS or similar.

Maybe try calling a local dealership?

Yeah that's my next step. Will try that next.

Appreciate the quick reply!

Super stoked this thing showed up tho. Today is day 87 it's been in transit. It finally cleared customs last week. With this Ukraine situation, the Russian Post website is unreachable and has been since last Friday. I got an update on Friday that it was supposed to be arriving at JFK airport, but then got nothing. I thought perhaps the plane with my roof was turned back around! Then today I get a delivery notification from USPS. Sweet.

[Casa de Mesa]

This stuff has a shelf life of only 6 months, because of it expiring so quick I doubt many places will have it in stock.

Oh good to know, thank you for. May just order it and wait...

Thanks!

[EthanolTurbo]

Anyone got one of these for sale?

[heinzboehmer]

Think I'm actually going to install this thing soon. M3 is seeing less and less street time and I don't really have a need for folding back seats with the new daily.

Anyone installed theirs with the vincebar front cups? Would be great to see pictures.


Oh, I also bought a broom yesterday and fit it in the trunk without folding down the seats, in case anyone was still worried about that

[Tonggi]

Think I'm actually going to install this thing soon. M3 is seeing less and less street time and I don't really have a need for folding back seats with the new daily.

Anyone installed theirs with the vincebar front cups? Would be great to see pictures.

The vince bar cups are in the way, I dont know how to feel about cutting those down or the slonik plate so its just there for aesthetics for the moment.

I'm curius how to remove the bonding glue off in the future?

[Obioban]

The VinceBar cups have also prevented me from installing mine. I am debating epoxy/riveting some metal strips the thickness of the vincebar cups to go along the mating surface of the Slonik plate where it meets the floor, to avoid needing to flatten the vincebar cups or cutting the Slonik plate to clear.

[heinzboehmer]

The vince bar cups are in the way, I dont know how to feel about cutting those down or the slonik plate so its just there for aesthetics for the moment.

I'm curius how to remove the bonding glue off in the future?

How did you secure yours? Assuming some sort of temporary adhesive/double side tape kinda deal.

Bonding adhesive gets significantly weaker with high heat, so that's an option. This guy managed to get a cf roof off without any heat by using one of those oscillating saw tools: https://youtu.be/0jdThGJtem0 . Think it might be hard to get one of those in where the slon panel is though.

The VinceBar cups have also prevented me from installing mine. I am debating epoxy/riveting some metal strips the thickness of the vincebar cups to go along the mating surface of the Slonik plate where it meets the floor, to avoid needing to flatten the vincebar cups or cutting the Slonik plate to clear.

You would only need to grind 1/3 of the thickness of the plate down, from 1.5mm to 1mm. Don't think that would impact the function of the plate too much, but have no way to prove that. Hmm, maybe I should ask Vince what he thinks about it.

Edit: Alright, emailed Vince, will report back with the response. Although after thinking about it for some more, I'm kinda liking your idea of bonding some plates in and spacing everything up Obioban

[heinzboehmer]

Alright, heard back from Vince. Here's the response:

The faceplates of the gusset cups are 1.25 mm thick. So there’s not a lot to grind from.
You could probably take that path, or perhaps take some off of the gusset cups and a little off the bulk head.

But I recommend that you bond some metal strips along the the entire top (on the sides of the cups) of the floor. Ideally curved strips that sort of mimic the top portion of the gusset cups.

That way you would also add some rigidity to the very thin and flimsy floor skin that you will be bonding the carbon fiber bulk head to.

So I think I'm going to go that route. When I get a chance, I'll disassemble the back seats and see how the bulkhead fits spaced up 1.25 mm.

[heinzboehmer]

Tonggi, Obioban, I have some excellent news.

Turns out that when the brace is fully seated in place, it just barely sits behind the top edge of the front cups.

I still have most of the sound deadening that's on top of the floor panel. The stuff is decently thick (thicker than the front cups), so it pushes the brace up quite a bit when dry fitting. This causes the brace to interfere with the metal at the top of the rear passthrough opening and doesn't let you push the brace all the way back into place. It mostly interferes in this corner (same thing on the other side):



WIth it interfering, there's a good ~8mm gap between the sides of the brace and the sheet metal behind the bolster panels. Since it's mostly just on those corners, I managed to get one side to fit fairly flush by angling it in. Here's how it sits in relation to the front cups when it's much closer to flush on that same side (left side, so judge clearance by the left side of the cup):



Here's how far the cup extends back, for reference:



Next step is to break out the heat gun and scrape away a strip of sound deadening so that I can actually dry fit this thing, but I'm pretty confident it's going to work with very little —if any— modifications to the front cups.

[Obioban]

That's great news, if it pans out!