heinzboehmer's 2002 Topaz 6MT Coupe

[Casa de Mesa]

Still need to figure out the attachment method. I have an idea that should make install a 10s job, but still need to try it out.

So I have this idea if yours doesn't pan out...

[heinzboehmer]

Practiced my CAD skills today:



Then cut the same shape out of some 3/4" thick plywood:



The point of this thing is to act as an impact barrier for whatever I put in the trunk, especially to/from the track. It's not unlikely that I'll have some bigger/heavier stuff there (i.e. a small jack) and I really don't want that stuff to crack the carbon wall under braking.

Still need to figure out the attachment method. I have an idea that should make install a 10s job, but still need to try it out.

[heinzboehmer]

Continued prototyping today. First I cut/ripped the armrest foam away from the armrest frame. Looks very ugly, but holds it shape surprisingly well. Will probably use this instead of some other foam now that I've seen what it looks like. Updated the weights in the previous post btw.




Then I stuffed the foam back into the armrest:




Pretty much indistinguishable from stock.

After that I reattached the leather onto the small seat back foam. Used zip ties because I didn't feel like messing around with the hog rings:



Then came tensioning the leather onto the foam. For this prototype, I just stuck a bunch of zip ties through the leather and foam. Worked pretty decently, but the shape isn't perfect:




I'll use a different tensioning solution for the final version, which should work better.

This did give me a pretty good idea of how it can be made to look, so I'm happy with that. Parts/tools ordered for V2.

And here's how both those pieces look in the car. Clearly not perfect, but I'm pretty confident that I can get V2 to look pretty much exactly the same as the stock seats.

[heinzboehmer]

Yeah, I actually chatted with SLON about this notion 3 years ago— if you are using the back seat as a seat, this is not a good idea. If you have heavy items in the trunk, not good in a crash.

100% agreed. I wouldn't be considering this if there was any chance of people riding in the back. However, the buckets make it so hard to get back there that the car effectively became a two seater when they got installed. I also made the decision to remove the rear seat belts a while back, which means the rear seats are completely off limits now and I don't expect that to change anytime soon.

Fortunately, this is easily reversible if I do ever change my mind.

Interesting idea.

I've been passively trying to figure out a rear seat delete option that doesn't look like crap. I never use the rear seats and if I had the Slon wall, I'd pull them. But I don't like an unfinished look in a street car, so something would have to go in its place that isn't a piece of plywood covered in carpet.

Yes, exactly! I knew there was a bunch of weight to be saved, but I don't like the look of any of the rear seat deletes.

I think this path is a good compromise between losing weight and keeping the factory looks and sound/heat insulation. I don't plan to touch the bottom section of the seats.

The safety stuff is the only bad part about all this, but I've probably talked about that enough.

[Casa de Mesa]

Interesting idea.

I've been passively trying to figure out a rear seat delete option that doesn't look like crap. I never use the rear seats and if I had the Slon wall, I'd pull them. But I don't like an unfinished look in a street car, so something would have to go in its place that isn't a piece of plywood covered in carpet.

[Obioban]

Yeah, I actually chatted with SLON about this notion 3 years ago— if you are using the back seat as a seat, this is not a good idea. If you have heavy items in the trunk, not good in a crash.

[heinzboehmer]

Speaking of the rear wall, I've had an idea for losing a decent chunk of weight for a while that was infeasible until I finished up that install.

The rear seat backs are pretty heavy due to the metal frames in them and I figured it wouldn't be too hard to make them lighter. However, without the wall, there would be very little to attach the frameless seats to, so I hadn't given this project a shot until now.

I picked up a spare set of seat backs to practice on and took them apart. Haven't gotten past that, but figured I'd document it for when I do this on my actual seats.

Started with the smaller one and removed the top plastic trim by pulling straight out:



Then went around and pried this retainer off of the metal frame. It's stitched onto the leather, so once it's free, the leather is too:



With that all pried up, the leather and foam are almost free. There's one T50 torx bolt at the bottom that needs to come out and then you can separate them:





Leather is held onto the foam with some hog rings:



And that grey carpet material is just glued onto the metal frame. Pretty easy to pull apart:




Disassembly of the larger seat back is mostly the same. First the plastic trim comes off, then the leather is pried away from the metal frame and finally the leather is detached from the foam by removing the hog rings:




Armrest assembly is held in with one T30 bolt:



Couple plastic trim pieces to remove, couple leather flaps to undo and one long plastic "clip" to separate and then the leather can come off:








And once again, that grey stuff is just glued on and easily removed:




With everything apart, I weighed all the individual pieces. Here are the results:

Small Leather	1.3 lbs
Large Leather	2.2 lbs
Armrest Leather	0.9 lbs
Small Foam	1.8 lbs
Large Foam	2.3 lbs
Armrest Foam	1.2 lbs
Small Metal Frame	7.9 lbs
Large Metal Frame	16.3 lbs
Armrest Metal Frame	1.9 lbs

Now comes the question of what I want to remove. I think I've decided that I'm going to keep the leather, foam and grey carpet pieces. Previous experience with folding the seats down tells me that the foam is doing a ton of work to keep cabin noise down, so if I replace it with some lighter stuff, I'll likely need to add some sound deadening in. I doubt that I can get some other foam and sound deadening to weigh less than 4 lbs, so I'll just keep the OEM stuff. Plus, that means the cushions will be stuffed with the factory preformed foam and not something I hacked together in the garage. Should keep them looking exactly the same as before.

Next question is how to mount the seats back in the car with the frame gone. This is where those grey bits come in. I plan to sew some heavy duty velcro strips along the top of them and then glue the carpet + velcro assembly to the foam. Will probably also sew some velcro strips onto the sides of the leather to be able to velcro both seat backs together.

Last thing to consider is the armrest. This will likely need to be stuffed with some other foam. I'll try to separate the armrest foam from the armrest frame, but it didn't seem trivial. No big deal if I have to buy something to stuff it with though, as it's just a rectangular prism.

Final weight savings to be seen, but should be around 26 lbs. Not bad!



Also, felt irresponsible to not give a big disclaimer about this work. I understand that part of the reason the metal frames are so beefy is to prevent stuff that's in the trunk from entering the cabin in the event of a crash. I feel okay removing this safety measure for three reasons:

1. This car is far from a daily now. The most I put in the trunk is some tools that I bring to the track. This trunk will likely never see big, heavy, bulky items again. If it does (e.g. a spare for a roadtrip), it's getting ratchet tied down.
2. The slon wall will help. While the carbon is more brittle in the direction that things would hit it from, it should still absorb some of the kinetic energy of the objects that hit it. With that said, I do understand that the wall stops helping if something hits it and makes a hole through which other objects fly through.
3. I'm already thinking of building a crash/hard braking guard to go in the trunk. Will likely bolt/clip in underneath the parcel shelf and then clip into those cargo net brackets on the chassis rails. This could be a net or a piece of plywood or some sheet metal, I don't know yet. I want to add this because I really don't want to crack that rear wall. It's not inconceivable that a small, pointy object placed in the trunk could fly towards the wall under hard barking and crack the carbon, which would reaaally suck.

[heinzboehmer]

At this point, wouldn't it just be easy to tip the car over on its end and put a bunch of weight on that panel? haha

Lol I feel like that almost would have been easier than what I did

[liam821]

Sounds like a good way to send a car rolling down a driveway. 🫠

hahah!!!!! That might be a hard one to explain to my insurance company on how I lost another M3 down the driveway. "So you see, it happened differently than last time. This time I was trying to install this structure rear brace that stiffens the chassis 30%, so I built this ramp...."

[Obioban]

At this point, wouldn't it just be easy to tip the car over on its end and put a bunch of weight on that panel? haha

Sounds like a good way to send a car rolling down a driveway. 🫠

[liam821]

I want to replicate every single thing about this install!

At this point, wouldn't it just be easy to tip the car over on its end and put a bunch of weight on that panel? haha

[0-60motorsports]

Looks Beautiful.

[heinzboehmer]

Thanks man! I do think the black was the right choice. I'm not very interesting when it comes to colors (in case that wasn't obvious), so I'm really liking the look


Also, found some time to edit pics. Here's another dump:

[Casa de Mesa]

Picked up something yesterday:


Finish is Cerakote Arctic Black P-202. Supposedly designed to help dissipate heat. https://www.cerakote.com/shop/cerako...lack-oven-cure

Now just need to find some time to rebuild them and get them on the car.

LOVE the Cerakote finish!! I regret not doing Cerakote on my 996 calipers.

The car looks really fantastic with these, Heinz. Love the subtle tone rather a punch-me-in-the-face color. It compliments Topaz really nicely.

I think your wife and Casa de Mesa would get along

And I'm 100% sure my wife would be happier if I left my car alone, lol

Your car looks stellar. If any car on this forum makes me second guess my sanity, it's yours.

[heinzboehmer]

Today, I managed to turn a 10 min job into a 2 hour one.
Car was squeaking a bit when turning the engine off, so I decided it was time to swap the belt tensioner. Unfortunately, one of the bolts snapped when I went to remove it:



Ignore the dirtiness. Looked mostly like old oil and grime that hadn't seen the light of day in decades. Cleaned up relatively easily.

Anyway, there was still a bit of the bolt protruding past the oil filter housing, so I decided to try extracting with some vise grips. Sprayed some penetrating fluid then ground a flat into the threads so that there would be something to grab onto (and to get a bit of heat in the bolt).

Fortunately, it worked!



Replaced it with a hardware store bolt for now, but factory part is on order. Also ordered all the surrounding bolts just in case.

Glad it was a easy fix, but also annoying to deal with. At least the belt isn't squeaking anymore!