Hi World!
Let the games begin!
As the title says, it's a '75 that's getting an LS3 (Cracker's "old" motor - thanks Tony!) and Boxster 6 speed.
Also planned is zippidy doo-dah 911 front suspension with Boxster calipers all around. The rear suspension is getting 911 ebrakes, Tangerine Racing raised pickups and shock towers.
I have plans to stiffen the chassis with a partial cage.

Doesn't that sound like a great plan? I think so, too!

BACKGROUND:
I got this as a roller that was purported to be "dry and accident free". And it was!
Except for all the rust and the place where it was hit. Yeah, yeah... But it's all good. The seller and I worked everything out.

But our little 914s are full of surprises and isn't that half the fun? So, first up is rust repair time!

Let's begin with some pics of what I started with. Wish me luck! Wait, forget the luck, wish me SKILL!!!

Hey, looks pretty good! Let's have a look under the carpet.
This is encouraging...

How about the hell hole? Hmmm.

The outer longs? Pretty nice! No problem! I mean, how much trouble could possibly be caused by those little hell hole perforations?

Remember the Monty Python and the Holy Grail? Where they have to cross that bridge and get asked "what's your favorite color?" and the first guy answers and gets to cross? Remember what the next knight said?

"This is easy!"

Remember what happened to him?

So let's pull the interior out and remove the tar.... "Hello? Restoration Design?"

Forgot the pic of the outer longs...

A real contributing factor to the rust issue was failed window seals and a horrid non-repair that used some odd goo to try and plug the leaks. So at some point, a PO figured that part of the solution was to add drain holes... !

The passenger long rust was exacerbated by water sitting in that area.

I would have thought water and hell would cancel each other out!

So... NOW we'll let the games begin. And I want to start with a disclaimer:

TO EACH, HIS OWN

By this I mean, I'm just a guy with an opinion. Doesn't mean I'm right, just that it's what I believe, think, feel, etc.

My goal with the car is to do as high quality work as I can muster. In my opinion, that means complete panels vs patching. Plus, some of the "interesting" things I want to do as part of this project are more easily accomplished this way. More on that as I get to it.

OK, back to the action. Let's find out where the rust stops and what needs replacing.
Turns out it's:
- back 1/2 of the floor
- seat mount/cross brace
- inner firewal
- outer firewall
- passenger inner long (from a bit ahead of the engine mount to not quite 1/2 way forward)

So out comes the bad!

I was hopeful that the first set of incisions (first pic) would be enough but upon reflection (and given the 400+ hp this chassis is getting) I decided to go all in - or maybe that's "all out"! (2nd pic)

Note that I've started fitting the front sleeve. More on that in a bit.

Good "skill" Chris...do that motor proud! I know you do really nice work and I will continue to look forward to the progress posts!

PS: So this means the latest acquisition is on the way out then, correct?

Tony

Tony - I'll do my best! The latest acquisition ('74 1.8) arrived today!

http://www.914world.com/bbs2/index.php?showtopic=296591

I'm not sure what I may or may not do to it. For now, the focus will be to get it road-worthy and drive it!

Whoa, that is going to be a little bit of work!

Nice sized shop so at least you are not hindered by lack of space.

Those Enkie wheels look to be in great shape, at least you'll be able to get a few bucks out of those.

In planning the fabrication of the sleeves needed for the long repair, I noticed I was going to have to deal with a bit of a structural raised section in the bottom of the forward area.
I recently treated myself to a bead roller and was able to put it to good use.
Gotta say, having the right tools almost feels like cheating. Nowhere near as much

I used it to form a nice, tight fit around that raised section then roll over the 90 degree bends to complete the sleeve.
Turned out pretty well.

I sliced the longitudinal repair section out of my parts car. That was a fair bit of work, in and of itself!

And here's the first goof of documenting my build:
I fabbed up the sleeve for the rear part of the long repair. It was FAR more complicated as I had to deal with the raised reinforcement "ribs" that are part of the doubler that runs up the inside of the long, past the engine and inner suspension mount.
I was so impressed with myself and how well everything fit that I immediately forgot to take any pics and commenced with tacking things into place...

Anyway, here it's trimmed and fit. Also gives a view of what these look like with no inner or outer firewall or back half of the floor!
Note the double/triple-up on the door brace. I'm super paranoid about keeping the very nice door gaps this chassis has.

I'm using Tangerine Racing's door brace kit.

*** Unabashed promotion***
If you need 914 stuff and Tangerine Racing makes it, save yourself a ton of time and just buy it! Chris Foley and his team (and products!) are the best.

Back to the build:
I used the door brace kit as provided plus added another diagonal from the upper seat belt mount to a plate/bolt that I welded just inside the front of the door opening. This means I have a brace in place but can mount the doors and check gaps!

Thanks Chris!
I actually have a door brace kit update planned that uses a system much like you described - a welded nut plate inside the A pillar, so the doors can be installed while the chassis is braced.

Mr. Foley! Always a pleasure...
Here's my super high-tech design. No doubt yours will be a bit more professional but this worked just fine.

Hell hole/long repair welding nearly completed! I opened up holes in the outer skin that allowed me to drill then plug weld the sleeve to the inner reinforcement panel.
A couple of those holes are yet to be closed up.

You may have noticed I've eliminated the heater tubes. V8 means no need. This opens the door to some custom fab I want to do:

I'm doing an inner long stiffener kit but because the firewalls are out, I can run them from the front of the long all the way to, and a bit past, the suspension console.
And I'm planning a center mount ebrake handle so these stiffeners will have no cut outs or heater inspection holes.

More as I get to that.

My paranoia paid off and another Tangerine product performs as advertised!

The door gaps are uber nice, body lines are spot on and the doors close with zero up/down movement as they latch and unlatch. These are early doors off the parts car and they end up with gaps a bit larger at the rear than the front. If I do run these doors, I'll add a small shim behind the hinges to even up the gap.

Also, since the windshield frame can end up tweaked for any number of reasons (being used when entering/exiting the car, etc.), the chassis measurement spec isn't always to be used as gospel. But in combination with other measurements, including door gaps, you can be sure things are where they should be.

That said, looky where mine ended up! This would suggest the windshield frame is straight.

Our welded-in-place nut plate won't need to be removed after the work is done.

CHASSIS STIFFENING: Version 1

LS3 = I need to stiffen this chassis. A lot.
I'll be adding an inner long kit but also need to do more. So, I started to fab a roll cage.
I want this car to retain as much street use ergonomics as possible, plus I want to have a nice interior. To accomplish this, Version 1 of the cage was designed to be a bolt in: A roll hoop with door bars that extended up to just ahead of the door opening and bolt to the top of the long. Something like the one pictured below.

This meant I could tuck it tight to the interior but since it comes in and out, I could install the trim panels, do all the other upholstery then bolt in the cage.

CHASSIS STIFFENING:Version 1
From a design perspective, I'm trying to add little things details that may be unique elements. I figured I see how close I could get the roll cage to match the shape of the car.
So out comes the roll bender!
Once the curve was where I wanted it, it was measure and bend the legs.
I'm happy with how it turned out.

CHASSIS STIFFENING: Version II - Change of Plan

As I've been thinking about the bolt in design, I spoke with a number of experienced folks (Chris Foley, Tony/Cracker) and some race car fab buddies and decided I didn't want to go bolt in. But I also didn't want a race car cage with full front hoop, etc.

What to do....

I understand the targa structure of our cars are pretty strong and since this is a street car that will see the occasional track day, I decided to build what I'll call a "roadster cage".

The main hoop will come up to just below the rear window, it'll have legs back to the top of the long near the suspension consoles. In the cabin, there will be a hoop under the dash and door bars with drops that tie into the tops of the longs. This will all be installed over the inner long stiffener kit.

That said, I also wanted to hide as much of this "cage" as I could. So I'm trying something a bit different. A "through the firewall" design!

Here's the initial rough-in of the rear hoop. It's roll bent to match the curve of the window opening.

The final fit will have the top of the bar just under the window and able to serve as the shoulder harness mount. The window and all stock interior trim can go in/out. I planned to eliminate the back pad so no worries there.

Interesting idea. It should provide some stiffness, without the bulky full overhead cage.

Now that is a very cool way to stiffen the car and do it as low-profile as possible.

Very nice Chris...have it running at WCR!

Tony

I like it a lot, but with my flexible car I get noise as the targa top wiggles against the bar. The main flexure I should think would be a bending of the longs open and shut. Sorta like when they fail and the door gap changes. The more you make the bar fore and aft strong and tied in the better. Also you would want to fight twisting motions between front and rear. Instead of a single bar you might try smaller tubing but more truss work. But maybe not since you want to have it bolt in.

I very much like the ideas you have and also your shop!!!! I like my bead roller too.

Very nice bar tuck. If your not planning on running anything up the logs, cut a slit in the lower rear firewall, and extend stiffing all the way from the front to the rear suspension console.

I would also highly recommend 914 LTD outer log kit. Brad's kit will make your car stiff, runs from the front log all the way back to the rear suspension console. I can jack inside of my car up and the back, and lift three tires off the ground. It also only twists about 1/8" That was with a Roll bar, and petty bar installed. Have not tried it with out the roll bar and petty bar.


You could also go full steel top, or bolt down your fiberglass top, and add re-enforcments to that to to help out.

I checked a 944 out, 18ga metal, and very similar design to the 914 A-pilars. though the Gas had a re-enforcment added to the lower A-pilars.

You can also build a box section going down the center of the chassis. Think Lotus back bone, very strong, and can be made very light.

You are on a very slippery slope.

BTW, LS3 excellent choice

You're stealing my thunder! The plan is to remove the stock tunnel and build a taller tunnel structure. I want to get the Boxster shift lever up nearer the steering wheel so kill two birds...
And I already have the 914 Ltd kit but not sure I'll need it with the inner long stiffening and the stiffening cage. We'll see. I can always add it later.

CHASSIS STIFFENING: Front Hoop/Door Bars

In keeping with the "hide as much as I can" approach, I bent up my front hoop (if something 9" tall qualifies!) and started trial fitting.

No, that isn't the real footing. It's just blocking the heater hole...

Initial fitment suggests I have plenty of foot clearance, can remove/install the steering shaft and even run the stock fuse panel, if I wanted (I don't).

It lines up nicely for a bar that will run from the hoop corner, through the heater hose hole and tie into the front shock tower.

CHASSIS STIFFENING: Con'd

Next, I started on the door bar. I haven't landed on the final height. Taller = stiffer, but again, I want it to be as easy as possible to get in and out.
Comprise is the order of the day on this design.

The pics show an overall height of 5" to the top of the bar. At this point, I think that's as high as I'd want to go.

I'm not final on the design in terms of the drops to the long. It'll be two or three, I'm just not sure. Here's a pic of each. (Note that I hadn't yet coped the drop supports in that 2nd pic.)

One of my race car fab buddies is coming over later to take a look and make recommendations.

I don't think you need three verts. My choice would be the outer spacing, the middle is doing the least. The last pic. Remove the middle.

Chris - You don't need to have your bar that high - consider what I designed for you below (and if followed) - never look back.

The center support is important and I would not eliminate it from the design. The gussets at each end upright are absolutely necessary and should be implemented. Call me if you need to discuss.

I too will be re-configuring my cage in the next year or so - converting it to a more "hot rod" style like your car. I won't go any higher than the 4.5" (and probably even lower) from top of rocker to top of bar I've illustrated below when I do it (JMO).

Keep up the good work.

Tony

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Now that's what I call "Community Support"! Personalized, no less...
Thanks Tony!
And I agree, the height needs to come down. Mostly because at 5", you can't open the door from the inside - the bar interferes with the handle. So that's going to determine the final height. Looks like about 4" to the top of the bar.
And my race car buddy did come by. I believe I now have a final design for the entire cage structure, floor and cross bracing and a cool tunnel!

More soon.

Oh boy. oh boy... is this going to be a full weekend in the shop!
Today, I got the blanks for the inner long stiffener. I got two 10' sections of 16 ga bent with a 7/16" inside radius. This is just a tick tighter than the corner radius of the long itself. I wanted to err on the side of tighter as too big a radius would cause the stiffener to rock on the long.

One leg is 4.5" and other is 7". This will allow me enough material to do the cabin as well as up the long, past the suspension console.

LOTS of , and for the next couple days.
And yep, I'll weld slowly, cooling as I go. But I sure am looking forward to having the floor and firewalls back in!

So, here's what a custom inner long stiffener looks like before the "custom" gets applied. (This has to be in the top 10 for "Most Boring Build-Off Challenge Picture"!)

More pics tomorrow as I start fitting!

I'd throw a seat in there 1st and test how much of a PITA it is going to be getting in and out of the car before settling on the height of the horizontal bar.

Curious what your thoughts are on simply running a tube from the rear shock tower straight to wherever is the best point in the front wheel well inside. One simple tube for maximum triangulation, no need for all the extra bits in the truss design.

I'm pretty sure that angle would make it tough to get in and out. If I remember, I'll mock that up and see how bad it might/might not be. Worth a look. Thanks for the idea!

Great minds... I've been doing just that with my assembled '74. It'll be at least 1-2 inches lower than what's pictured.
And you're in Antioch? I get over that way semi regularly. We'll have to meet up.

Could be. But look at Sir Andy's car. His is easy to get in/out of. More swooped, but reality is, a bar like this doesn't interfere as much as you'd think. Sometimes it's actually easier to get in and out using the bar. And it triangulates the huge miss behind the firewall! That's an important part of this car, especially when you consider the worst rust weakening happens behind the firewall. Could also run an X tube to front suspension points.

Real cages and reinforcements have already been engineered. This is just brainstorming. But I figure this one red tube does more than all the black ones combined with less weight and effort?
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Fantastic fabrication. Way to go Chris. I'm paying attention here:-)

Yep, in Antioch....actually enjoying an IPA from Lagunitas Brewing Co from up in your area

Let me know when around, I'll clear out some space in the garage so you will not trip too badly on all the junk I have !

Interesting... My initial reaction is that this seems worth a much closer look!
I do want to clear up your comment (bolded above) that what Tony's design (and mine) have that isn't shown in his drawing, are tubes that do triangulate from the roll hoop back to the suspension point. Not picking on your perspective at all, just want all facts known.

Something else to consider when designing your structure...Foley was sharing with me recently the importance of designing towards keeping the longs from twisting. However, you have a hot-rod - not a race car. Keep that in mind too so as to not over-build. Clean would be sweet - the less you see and only the necessary installed.

Tony

CHASSIS STIFFENING: Inner Longs

Got started on the inner long stiffener. Since I deleted the heater tubes, I'm going to skin the long "everywhere". And trying to keep it tight. I like the clean look!
Given the way the longs change shape behind the firewall, I'm planning to make each side in two pieces: the part seen here, and the second part for the "up the long" part.

That part will be more complex and I'm going to have to wait til I cut the suspension consoles out to prep for the Tangerine Racing raised pick up kit.

Details, details... trim to fit - even the little weep hole thingy.
Yes, it'll be hidden under carpet but I know it's the way I wanted it.

I too like that clean smooth look.

Fitting the left side... This went way faster as I was able to use the right side as a template. Just laid them back to back, traced then cut. Done and done!

Nice. You don't need a bunch of tubage. This alone is going to make a big difference.

How are you handling the ebrake?

Another. And if you need to make large holes for things like seat belt mount in an inner long stiffener, use a knock out punch! (Crappy pic, in terms of showing that, I know.)
I treated myself to a set of KO punches from Swag Offroad and they're awesome. I use a HF hand hydraulic pump and wow. Super clean, accurate, etc.
I also got their dimple die set which I plan to employ on some of the tunnel and roll cage gussets. Pics as I get to that.

Artsy shot of the day. I just love the smooth, clean look! Now to mess it all up with hole drilling and plug welding. Ah well, it'll get covered up at some point anyway.

I have a ebrake handle from a 993, so it'll be center mount. A couple of us are going this sort of direction - take a look at 914forme's build, post 291.

Nice. That's a mod I've thought a lot about. Keep going man, you have a killer build happening!