Porsche 944: Actually there is a substitute

[Zoomin]

Great idea!

Keep up the good work.

[sparkydog]

And from this quick sketch of an exoskeleton to the finished item. This whole thing is probably a huge overkill - I really doubt that the 944 unibody is going to move on me when I start cutting into the rear frame horns - but there ya go! Now I can sawzall away with confidence.

[sparkydog]

And here's the whole enchilada - the exoskeleton along with another stuff of the Mustang frame section. Tomorrow I can begin to use all of it to position the rear axle center line and start planning the surgical cuts! (Sure is a lot of conduit in there.)

[sparkydog]

Tonight I finished the "Mustang Rear Frame Clip Positioning, Leveling and Elevator System". This consists of 4 sets of allthread rods, welded on wingnuts and anchor lugs. Now the rear clip section is hanging under the 944 by the 4 rods and has been through an initial set of yaw, pitch, roll, fore/aft and side/side alignments to within about 1/8" of final. This means I can now start projecting cut markings up onto the bottom of the 944 using the silhouette of the rear clip.

Then I start cutting an opening into the 944, raising the clip, re-align, mark cut locations on the 944 again... repeat.

I'm hoping to get to final position in less than 5 sets of that cycle.

[sparkydog]

Cycle #1 is complete. Marking the edges of the silhouette turned out to be a small challenge but after trying a few techniques I ended up with the funny spray paint stick. Before making the 1st cuts I was 5.5" below finish height and after making the first clearance cuts I only have about 1.75" more to go up.

[sparkydog]

Starting to cut into the actual rear frame horns of the 944 now. Gosh it was "fun" having to sawzall right thru the middle of those shock mount bushings!!. I'm close enough to final height that my brain can begin to visualize how some of the Mustang and 944 are going to fit together. Eventually some of the 944 "floor" and rear bulkhead sheet metal will go away and be replaced by a more simple shape. But for now I am simply whittling away and leaving as much as I can until the structural metal can be joined.

[EZ SPEED]

awesome. keep up the great work!!

[sparkydog]

Over the weekend I did enough trimming/shaving to the 944 that the section of Mustang rear subframe is now at the correct height and fore/aft location. The first picture shows that I have the Mustang frame clamped to the bottom of the 944's structural metal at the bulkhead area. I will now need to figure out how to tie these two worlds together so that the forward thrust from the rear wheels is transferred into the 944 unibody in this area.

The second major area where the Mustang and 944 metal must tie together strongly is where I c-notched the 944 frame horns to clearance for the Mustang's upper coil spring bracket.

[sparkydog]

I have decided NOT to add the Mustang's upper shock mount brackets back into the mix for two reasons: first, it would require cutting clean through the 944's rear frame horns. Second, I keenly observed that the right side upper shock mount would then live directly where the 944's gas fill pipe routes. (Hopefully you can understand from these two pics.) I want to try and leave the exterior of the 944 alone so moving the 944 gas cap and door does not appeal to me. I would rather deviate from the stock Mustang shock location and go with something custom.

[sparkydog]

Some of you might have noticed 2 posts back that I seem to have cut out extra material where the Mustang coil brackets are recessed into the 944 frame horns. The size of the gap happens to match the thickness of the square tubing I was using for height reference - I held it up next to my gap of shame in this picture. This happened because I apparently cannot remember which side of the tube I was measuring from. The correct side was the top but I used the bottom. This added a false 3/4" to my cut heights. Doh!

[sparkydog]

Here's a better illustration of why I'm not adding the stock Mustang upper shock mounts back - in this picture the 944 fuel fill pipe comes down from the gas cap where the opening is with the 2 arrows. The shock mount bracket would be right beneath this on the outboard side of the Mustang frame rails (where the yellow circle is) which is smack inside the 944's frame rails.

[TexasLS1]

I did notice the gap above the Mustang upper spring mount - it makes sense now! I hate it when that happens... Keep the updates coming, I like seeing the details getting worked out on this project. Tons of great progress, and you have already earned your sig line "Balls and a Sawzall" lol

[sparkydog]

Originally Posted by EZ SPEED

awesome. keep up the great work!!

Originally Posted by TexasLS1

I did notice the gap above the Mustang upper spring mount - it makes sense now! I hate it when that happens... Keep the updates coming, I like seeing the details getting worked out on this project. Tons of great progress, and you have already earned your sig line "Balls and a Sawzall" lol

Thanks EZ and Tex!

Well I got an urge to see what the situation looked like with the actual rear axle of the Mustang up in there so... after some sweating, wrestling and swearing I was able to hang it up inside my complicated maze of jigs and galvanized whatnot.

[sparkydog]

Before I commit to shaving any more off the Mustang frame remnant and before I commit to changing where and how the shocks mount - I wanted to check things out. In this picture you can sort of see the stock Mustang lower shock mount in the bottom left corner of the picture and the shock would want to run straight up into the area where that shiny bolt head is. That would be the section of 944 frame horn I'd have to cut out. (The shiny bolt and the square tube are my temporary bracket to hold the frame inside the 944 so it can support the weight of the rear axle.)

[sparkydog]

Yellow things are showing where the stock Mustang shock would route.

[sparkydog]

Cycle #2 is over and now the Mustang axle and subframe are back out of the 944. I decided that the stock upper shock mount locations were just not going to work inside the 944 so I shaved another 10" off the Mustang frame horns because I don't need this metal to mount the shock mount onto. Some of the bracing conduit came off too. Also more 944 rear seat area sheet metal came out.

It's time to come up with the plan for attachment welding and prep all the areas that are about to get hot. The 944 has an awful lot of seam sealer and it really enjoys burning.

[Jim 383]

I hate to say this, and its no reflection on your courage or fab skills-- but didn't this start out as an LS engined 944? It's turned into build a Mustang the hard way. I'd rather see a 283 in an otherwise stock 944. I apologize in advance.

[sparkydog]

Gosh Jim 383 I hope you feel better for getting that off your chest!

Here's a reprint of what I wrote in post #9 of this build:

"So I’m just going to toss the motor, the suspension, the brakes and the transaxle and put stuff in there that will hold up to V8 power, stay reliable and if it breaks cost nothing to repair. An LSX motor is a given. While I’d like to keep a rear transaxle there isn’t anything (that I can find) that meets my three criteria – affordable, 300hp stock, 68-ish wide. A Corvette rear is the obvious 1st choice but it’s out of my budget and too wide without modifications. BMW M3’s rear IRS can take 300hp but are costly also. So along the way I figured I’d bag the rear transaxle and just go conventional motor/trans in the front. There’s the Ford Explorer/Stang IRS but again – a little too rare and costly for my tastes.

If anyone has a suggestion I didn’t consider please let me know! For now I am thinking I will use the front and rear spindles/axle/brakes/suspension etc out of a Mustang GT (late 90’s or younger). I’ll get an aftermarket K member because there are a bunch of Mustangs with LSX conversions and there are bolt on solutions. So bear in mind when I say this I mean I am going to surgically remove the structural metal out of the donor Mustang as well as the suspension, then cut big holes in the poor little Porsche and graft all that s*** right in."

Yes you are correct I did not follow through on the LSX V8 part of my original claims. I learned along the way that I could not afford to use an LS motor and stay in my very modest budget. So I had to adapt and move on.

[grumpyolddog]

Hey sparkydog just keep doin your thing...... lots of junkyard engineering, hotrodding at it's best

[sparkydog]

Here's the plans for most of the brackets/gussets to marry up the 944 and the Mustang rear end.

The plans called for fabricating 4 pieces of .050-ish round disks so out came the cutoff grinder, the flap wheel and the poor man's lathe.

[sparkydog]

I also needed to figure out a way to make symmetrical notches in the frame for these soon to be real brackets. So I fabbed another weird jig thingy that allows me to use a nearby bolt hole on the 944 and then create cut templates out of pizza boxes - then use the template interchangeably from one side to the other.

The last pic shows the outboard side of the passenger side notch pretty much ready for welding. I still have the inboard sections to notch and prep for welding.

[sparkydog]

It was time to make use of my circular disks. First off - choosy mothers choose JIF so the peanut butter jar lid was the perfect size to help me center my disks onto the tops of the coil spring brackets.

Then I was able to use my mighty MIG to weld at full power without fear of burn through! I definitely achieved full weld penetration as you can see on the back sides.

These round pads will be where the force of the springs is transferred into the 944 frame rails. The disks had to be warped in a couple of areas in order to conform to the spring clocking pockets that were part of the Mustang's stamping.

[sparkydog]

Then it was time to use the weird jig thingy one last time to position the cut templates for the inboard sides of the 944 frame rails. As you can see the jig is just a symmetrical bracket with some allthread extending out both sides. Then a wood spacer in order to place the pizza box cardboard about flush with the inner or outer sides of the 944 frame rails. Then I used masking tape to "trace" the profile of the template. Lastly a little squirt with some white spray paint and I had an easy to see shape to follow with the cut wheel and sawzall.

[Mil-Spec]

Amazing work. Keep going!!

[Frizzle Fry]

Still my favorite kind of build. Good thing we don't live near each other