Coupe into Speedster Conversion

[Phil Planck]

Justin
Your lucky day - about time.
Phil

[JTR70]

Thanks Phil. I think the difference here is I am building off the original trunk closing walls rather than making entire thing from reproduction panels like I had to at the rear.

10/12/16
Loose ends: T2 to T1 front bumper bracket mount detail. Again pulling double duty of not only converting from coupe into Speedster but also T2 into T1.

T1 bracket mounts run all the way back to the suspension horn where as T2's where stopped well short of it as this one was. Like all the rest of the T1 changes I've made to the tunnel etc. this is another detail that has to be addressed. A remnant section of perimeter repair will work fine.

Begin paper template.

New section folded, trimmed and ready to weld.

Carefully taking and lining it up as best as I could as it went.

Done.

Seam weld and rolled corner details copied from the original.

Thank god for reference cars.

Repeat right side.

Thanks for looking!
Justin

[Phil Planck]

A detail I was not aware of. Nice work Justin , and nice needle bearings in those axle tubes.
Phil

[prea356m]

Hi
Many compliments for this incredible.............. crazy job .
Just one question:
When the roof is cut to create an open version I suppose should be definitely provided some reinforcements in specific points of the structure
I would like to know where they are located and how they are made

ciao Mario da Roma-Italy

[JTR70]

Hello Mario,

Thanks for joining us and Welcome! Crazy is a very accurate term for this project. As for open car Specific chassis reinforcements there were none added by the factory. From coupe, to Cabriolet, to Speedster; a 356 chassis was a 356 chassis. Even with full on competition in mind a '59 GT speedster received no additional chassis specific reinforcements.
As for this project did I learn a thing or two? Yes Would I change a few construction details for added strength and ridgedness? Definitely.

All open car flexion is going to happen between the A and B pillars so the final longitudinal construction is going to be your key. I stayed pretty much stock correct but Looking back at it now I could have/should have tied and triangulated into the heater tube more. Especially toward the back. This tube really amounts to just muffler stock so a conversion to a nice cage building stock would really tighten it all together with the right "webbing" tied to it. I've seen Wilhoits flat plate (probably 16 gauge) modification which goes in place of the heater tube. That mod would certainly help. What that wall creates is two smaller "tubes" instead of just one large "tube" that would normally comprise the longitudinal.

Another change I would go back and make would be at the outer longitudinals. These new covers along with Most vendor offerings including a new pair of Simonsen longs I have sitting in my shop now are made from 20 gauge steel. Again knowing what I do now I feel its too light and would prefer these in 18 gauge. As a matter of fact any chassis structural component from the front torsion housing all the way back to transmission hoop mounts I'd prefer in 18 gauge. Especially on an open car. This car should be fine in the end but it will have the typical open car chassis flex especially approaching a driveway at an angle. I'm just noting what I've learned and a few things I'd do differently since you asked. Welcome once again!
Justin

10/21/16
Work on the front continues.

I had a little detour with the front hinges and new personal discovery which I'll post next.
Justin

[JTR70]

10/24/16
My low slung front hood hinge education from a few weeks ago.

After modifying the hinge bosses way back when I thought I had the speedster/Roadster low resting hood detail resolved. The bolt hole for the trigger lock was lowered as found on my OG speedster reference car.


Mocked up on borrowed hinges from that coupe project pictured in the background I thought I had the resting height dialed in.

Once I had the hinges purchased for this car mounted I'll be god damned if it wasn't resting too high again!

The correct resting detail I'm looking for is something like this.


The old factory photo courtesy of Bruce Baker highlights the difference between coupe and speedster perfectly. Its certainly not a big issue and would slip by most, unless pointed out but it is a detail that I feel completes the illusion. Along with the W/S frame and top its part of what gives a Speedster that low slung cool look at the show.

As I was studying my reference speedster my buddy told me that he always thought that there where specific high and low set hinges. I was kinda thinking he was mistaken as I had found that clear difference in the hinge bosses. I soon realized after all this time that he was right. I went right over to his place to borrow a pair of these "low" hinges for copying. This borrowed red unit was pulled from his '55 coupe years ago as he got very annoyed hitting his head on the hood while trying to fill it with gas. Its aligned on its stop with my coupe hinge and sure enough the resting angle difference is notable. My education in the subtle differences of these hinges began. That's up next.
Thanks for looking!
Justin

[Phil Planck]

Justin
What might be neat is a 2 position hinge setting. One for service and one for show. But, admire your attention to details that most of us are oblivious of.

Phil

[Drew.s]

Hi Justin
I just love learning from your build.
So are you saying that both the hinge boss and the hinge need adapting?

Drew

[admin]

What a great job!
I pull my hat!

[roy mawbey]

Justin,

I never knew the speedster lid was so much lower. Just keep on finding more and more details from you and your great thread.

Roy

[JTR70]

Hey Phil, That's an interesting idea. The only way you might be able to accomplish something like that would be to add material to the tip of one spur. Roughly the 5MM you must grind away from the lock lever where the spur tip engages to reach "speedster resting level". If one was really ambitious you could have up to three hood resting height settings I suppose.

I appreciate that Drew, I'm certainly on the learning curve right along with you. If you're shooting for the correct resting height you will need to modify both. You'll notice I moved the lock lever down the width of the bolt on the hinge boss; with the roughly 5mm I had to remove from the lock lever(posting that next) there is simply not enough shoulder left to compensate for that boss modification.

Thank you very much Torsten and Welcome along here!

Roy, there is a practical reason the factory lowered these hoods. They found out early on with them standing up tall and proud on those first few '54 Cabriolet conversion cars that when it came time to lift the hood higher to disengage the locks the back edge of the hood was getting into the windshield wipers. The easy solution was to of course lower the resting height so the locks would release much sooner.

Not strictly just a Speedster thing either as Dick's Roadster above shows a similar resting angle. So I assume all 356 models with a removable windshield frame???
My thanks to all you guys once again!
Justin

High and low hinge locks


Its the depth of this vertical facet that the tip of the spur engages into that dictates the hinges resting angle.

Direct comparison. Borrowed (red) low hinge on the right and high standard coupe/Cabriolet version on the left. The "speedster" version is cut deeper by about 5mm or damn near the thickness of my poker there.

Another detail of note is that "sharks tooth" profile. (I'd later realize its importance.) Notice too they went with thinner gauge stock on the lever.

At this point I was thinking, Okay, coupe/cabriolet hinge "flat" & fat locker lever profile and Speedster/Roadster hinge "shark tooth" profile with thinner stock lever. (& Spur)

Not necessarily I have a '59 coupe here so I went and looked at its original hinges to see what they where; Pictured above. Thin with that Shark toothed profile yes but with coupe/cabriolet locking position. Its mate is bolted to my original early coupe hinge for comparison. They lock out at the exact same angle. So much for that theory. I also found this lock lever profile on decklid hinges as well so its nothing too uniquely special.

With this picture now forming I thought, what the hell let me put it to the test. These black hinges are the originals from my coupster project so I decided to begin this modification experiment with one of them. A note to the Doc: this next sequence was for my car and its hinges so none of this discovery work was done on your time.

Playing it safe by taking out 3mm initially.

My stock coupe "base" hinge was marked with tape to note the angled profile comparison of that "speedster" hinge I borrowed from my buddy.

Before too long I had its mate now resting and locked in the desired angle. I was half way to a pair of speedster hinges for my project.

Both hinges now lined back up to highlight how much I had to remove to achieve that lower resting angle. Again Drew, not enough shoulder left to go the distance of a bolt width more to compensate for the hinge boss modification.

Could it be just that easy? Of course not. The spur is indexed ever so slightly now that forward tang can no longer make contact to advance and cycle the spur through.

I initially thought it was those hammer head tips that came into contact with the spur to knock it forward but after some study it became clear that they never touch the spur. It is the forward center profile section that makes contact and does the pushing.

Here is a comparison shot to highlight the change in the spur position. I mean the difference is ever so slight but it was just enough to reposition it disabling the whole mechanism.

I'm thinking the shark tooth profile was added to give it that additional reach to compensate for the problem I just ran into. So to recap that "toothed" profile locker can be either coupe or Speedster from factory but its the version that lends itself easily for the conversion. Early flat profile units like my black one can be converted but will require the extra step of welding on that tooth to get the mechanism operational again.

I found this hinge version readily available so I returned the initial "coupe" pair we bought and took delivery of a pair with the tooth. They turned out to be coupe version but a careful grinding and filing quickly made them into low slung speedster hinges.

New hinge converted and bolted to that borrowed sample for comparison. Its there and again the mechanism operates fine after the change because that profile extension.

Hood mounted with new hinges. At long last I had the lid height I needed!
Onto the next deal.
Thanks for reading all of this!
Justin

[Drew.s]

OK Justin
I have read once, twice and one last time and I am still a little confused.
I completely understand that I need to modify the hinge body boss, it's on my to do list.
But these modifications to the hinge locking mechanism are stretching me too far.
I think I need to draw this out showing all the modifications you have made on paper and then get you to sense check (if that's OK) the procedure and dimensions.
Could you get your metric steel rule out one more time and photograph/measure this dimension for me?



With this I should be able to create an accurate 'how too' guide for anyone wanting to follow in your footsteps.

Cheers
Drew

[JTR70]

Sorry if that last post confused you Drew. In reality its simple:

The taped hinge is just my bench mark start to finish. Once I'm done filing the top hinge being modified needs to line up with the leading edge on the tape line fully locked and resting on the spur.

To achieve this roughly 5MM needs to be removed from the vertical face of the lock to allow the hinge to travel down a touch more.

These where a matched pair from my coupe. The top one is now a "speedster" version.

The index on the spur has now changed rendering the "release" and advance cycle disabled. If these locks had the "tooth" profile it would be fine but I'll have to weld on that profile to make this pair functional again.

Distance from the forward hood mounting holes center to center is 35MM.
10/28/16

Last Saturday my buddy Rick and his electrical guru stopped by the shop and got my TIG up and running again. I spent a while getting reacquainted with it and going over the joints on the rear skin. So glad to have it back!

Last weekend I also got the front dismounted from the rotisserie for a clear shot at the front end.

Afterwards began trimming and centering the new forward closing wall.


Flange runs pretty much consistent with the hood throughout.

On this side it seems to turn a little too quick as it approaches the corner. This is all that micro adjustment that's required as it goes. Par for the course..... of course.

A little too soon to tell just yet but I have a feeling that center lower lip of this panel might come up short. Will know here in a bit.
Thanks for looking!
Justin

[JTR70]

10/30/16

I was able to perform a more accurate nose mock up with the hoist out of the way about a week ago.

So far its lining up a lot quicker than the rear did but its early.

trough profiles are close.

The right seems to swing wide but can't make the exact determination until the hood is mounted back on. Seems wide though..




I can tell already that the inner closing wall is going to be a bit involved before everything fits snuggly and in the correct spot.

Tops of the fender profile seems to transition nicely into the nose so far.

Fun and encouraging but it soon dawned on me that until the hood is set and latched there is really nothing more to be planned as far as the skins go but I did want to see what awaits down the road.

Thanks for looking!
Justin

[JOP]

Moin Justin,
Is the fenders really at its correct position?
It just seems so off with the new nose on.....
I know it is handmade Porsche and Part but it looks so much to adjust.

It sure starts to look like a real Speedster and I would have a hard time to have to give it back to its owner..... I would be so "bonded" to it
The Doc is lucky to have you Tinman Rio