Question on interior stiffening plates

[tdskip]

Good morning - are the interior rocker panel stiffening plates that are commonly used on Targas welded flush against the existing panel or is there an air gap to create another box section. Is there a pro/con to either approach?

It appears that they are welded flush, as are most of the 914 kits I have seen, but there was some discussion of creating a box section.

Example photo from another Pelican attached.

[gtc]

Flush.

[tdskip]

Thanks for the confirmation.

[jpnovak]

Yes. Flush.

BTW, I am working with MadDog Motorsports. We are hoping to have these available soon.

[tdskip]

Very cool Jamie.

BTW - I've read several of your threads on this and related topics. These are excellent resources for the community. Thank you.

[dennisO]

Jamie,

Any idea when these will be available?

[Marwil]

I was going to design and fab these myself but.... if someone else has them in progress then I am willing to wait a bit. What gauge are you planning on using? I was thinking of going with 12 or 13. looking forward to more info on these Jamie.

Mark

[tdskip]

Originally Posted by Marwil

I was going to design and fab these myself but.... if someone else has them in progress then I am willing to wait a bit. What gauge are you planning on using? I was thinking of going with 12 or 13. looking forward to more info on these Jamie.

Mark

Hi Mark - might 18 be a better option? 12 is pretty darn thick and hard to shape, no?

[Marwil]

I think the last time these type of things were available they were 14 or 15 gauge (about 0.070") - this is apparently the thickness that the factory used for the early Carrera race or rally cars. Lots of people here who are way more knowledgeable than me on the details. If correctly preformed I think 13 or 14 are doable and would really strengthen the chassis - 18 or 16 gauge might be too thin and the potential gain might not merit the effort required to prep and weld them into place.

Mark

[tdskip]

Hi Mark - thanks for the note back. Makes sense. Let's dig into this and see what people say and what the factory did.

EDIT - I found one reference to 14 gauge from this thread.

Targa body brace??

[Marwil]

Yeah - that's one of the threads. I have read threads and posts till glassy eyed over the last year. Quick find!

Mark

[tdskip]

Originally Posted by Marwil

Yeah - that's one of the threads. I have read threads and posts till glassy eyed over the last year. Quick find!

Mark

Go Mark, go.

I wonder if he put the new metal, which is a lot easier to work with, could have some additional strength put into it via running a crease/bead down it ?

[Marwil]

I thought about the crease idea too. Could use a beading machine to do it. I think the weak point is where the seat rail mount attaches to the sill. Do you remove the seat rail and reattach? Is the trouble worth the gain in continuity of the new piece? We almost need an engineer's input.

[tdskip]

I am, shhhhh, working on an early-ish 912 so I think I'll be better off for doing it. Later 911 coupes for the street might be more questionable. I am not planning on doing this on my '74 911 coupe.

[jpnovak]

Well.. Kit #1 will be in a 72 coupe... Part of strategic strengthening and stiffening.

These will be announced once available.

[Marwil]

My ride is 78 Targa with no rust but 225 k miles on the chassis - it's softened up a bit.

[tdskip]

Jamie - can we ask what gauge you are planning on using? Having a kit would be nice, I just may need to push ahead this week as part of making sure I don't lose my door gaps / panel fit when I remove the DPO hacked in floors.

[tdskip]

Mark - I found this reference point on an older (but excellent) threads;

When I last spoke with Mark at Eurotek (sill plate reinforcement pieces), he provided me this information :

- Prior to 74, chassis metal is .032", thereafter, .035" (20 gauge)
- RSR used two layers of .070" on the sill plate.
- On the longitudinal pieces, .035" before '85
- After '85 (C2 and C4), went to .080" thickness

Sorry. I forgot who provided the following info., but thanks:

Restoration Design replacement panels:
Inner rockers, 0.059" or 16 gauge
Outer rocker sill, 0.046" or 18 gauge

Link: Added Sheet Metal in Later Coupe bodies

That suggests that even a 18 gauge panel (1.214mm) would make a difference, as that combined with the original 20 gauge (.912mm) would be roughly equivalent to a 13 gauge (round up from 2.216mm combined thickness) panel. That would make it slightly thicker than post 1985 cars.

So the question becomes how much improvement is a worthwhile improvement.

[tdskip]

Anyone else find anything through their research?

[86 911]

Bringing this topic back up. I am very interested in sourcing stiffening plates to install in my 1976 911 that was converted to a cabriolet.

@jpnovak did you get any designed for the 911? Mad Dog Motorsports only has them for the 914.

Would these stiffening plates eliminate as much flex as a roll bar? I like the idea of plates better as my car will remain a street car and having access to the rear seats is nice.