1965 Cabriolet Rejuvenation

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Mark Dionne
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1965 Cabriolet Rejuvenation

#1 Post by Mark Dionne »

My father bought this car in 1972 for $2000. He commuted daily in Boston snow and salt for 8 years and continued driving it until about 1997. In 1976 the first layer of patches in the floor rusted through, so he got a sheet of 14 gauge steel about 4 feet square, bent it into what he called a "bathtub" and screwed it in with dozens of sheet metal screws. It bent up in front of the pedals and around the longitudinals back to about the front seat mounts. Additional patches were screwed in at the closing panels.
Porsche 356 Cabriolet 1965.jpg
In 1984 he restored the outer body and had it painted the same white color. As long as I can remember, he never put the top down--he was afraid that the fabric would crack and start leaking. In 1999 he gave it to me. The mileage was 173980. Right away I put the top down--the car was officially in retirement. I drove it occasionally until 2003 when I decided it was not safe any more.

I fixed a few things since then such as the brakes and a gas tank leak, but the amount of rust was daunting. Pretty much everything in the bottom 2 inches of structural sheet metal in the front half of the car was completely gone. The worst was the bottoms of the pillars at each end of the front torsion bars, not a simple repair.

Finally in December I started working seriously on the car. My working philosophy:
  • 1 - the car will be a Sunday driver
  • 2 - it will stay in the family, so selling is not an issue
  • 3 - with few exceptions, I will do all the work myself (except finish paint work)
  • 4 - Phase I will be repairing structural damage and getting it drivable
  • 5 - repairing a part is generally preferable to buying a new one
These are in line with what Dad would have done, I think.

I'm currently about to button up the driver side longitudinals. I'll add some posts about the things I've done so far that I have not seen in other restoration stories here. Eventually I hope to post about repairing the cabriolet top. I'll bet there are not that many stories about it here.

I am not taking the traditional pictures of piles of rusty German sheet metal that was removed from the car. Most of mine has come out in the vacuum cleaner. :D

Edit 2/29/12 and 9/26/12: List of things to do in Phase I:
- Fix gas tank leak (done with POR-15 kit)
- Rebuild brakes all around (done)
- New leather on seats (done)
- Repair and restore horns and mounting brackets (done--needed for state inspection)
- New floor and longitudinals
- Repair pedal bracket
- Repair bulkhead in front of pedal area
- New door sills
- Repair "closing areas" inside fenders
- New battery box area (spare tire area)
- Repair center tunnel and pedal areas
- Repair front torsion bar supports
- New front diagonal braces, horizontal struts and surrounding areas
- New brake line, fuel line and main battery cable in tunnel
- Repair body rust at fuel filler, replace fuel filler cup
- New battery, tires, shocks
- New carpeting, sound deadening and undercoating
- Update brake master cylinder to dual circuit
- Replace steering wheel coupler, restore tie rods
- Treat surface rust in area under fuel tank with POR-15
- New starter
- Rebuild fuel pump and carbs

For those not familiar with Porsche lingo, the longitudinals are box-like structures, roughy 8 inches square and 3-4 feet long, under the doors, that hold the front and back of the car together and support the sides of the floor. They are especially important in convertible cars since there is no roof to add stiffness. They are very susceptible to rust since they are hollow boxes that were not painted inside during manufacture. Typically the lower half of the inner vertical part must be replaced along with the bottom and outer side, which are actually formed by one large piece known as the outer longitudinal.

NOTE: This narrative continues for 4 or more pages. To get to the additional pages, use the "Go to Page" link way down at the bottom.
Last edited by Mark Dionne on Wed Oct 10, 2012 10:34 am, edited 6 times in total.
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Carl Zapffe
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Re: 1965 Cabriolet Rejuvenation

#2 Post by Carl Zapffe »

Hi, Mark,

Congratulations on your inherited gem! I encourage you to keep the car in the family, so that's nice to hear. This car does, after, all, have great sentimental value.

What I would recommend, however, is to realize that you cannot do everything. Your cab is worth quite a bit of money, and you may want to bring it to a professional to estimate repairs in areas where you may not be proficient, like the engine and the transmission. The last thing you want is for the engine or tranny to fail while you're driving it. Others will recommend other courses of action. I just don't want you to spoil your memories by being in a preventable accident, like if your tires are too old or something like that.

Please post more pictures when you can. Nice car! I'm jealous! I wish my dad had similar tastes to your dad!
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Mark Dionne
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Re: 1965 Cabriolet Rejuvenation

#3 Post by Mark Dionne »

Carl,

In 1956 dad bought a '54 VW. In 1960 he and I rebuilt the engine. I was 10. Below is a picture of another VW engine I rebuilt myself for my "dune buggy" when I was 15. So engines are not a problem. (I promise not to use this paint scheme on the Cab.)

Good point about the tires though. Last time I was driving the Cab, the tires were probably 15 years old, not to mention the body rust, and I was not driving slow.

-Mark
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VW engine.jpg
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George Bryan
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Re: 1965 Cabriolet Rejuvenation

#4 Post by George Bryan »

Mark, great story and welcome to the Registry. It looks like with your background of garage time with your dad, you know your way around an air cooled car. There is a wealth of information on the pull down menus on the site; and of course on talk. There are some great threads on C issues; and in the authenticity section you will find some detailed threads about what fits where, originality pics and data, and such like that.

Great philosophy. I drive my cars all the time. I brought a 65 C cab home that was off the road for 40 years, smoked thru it, put the top down and it hasn't been up since :D

Best of luck and enjoy your car. Hook up with some local 356 guys and join us for the social events during the year. Our East coast holiday is there in Danvers MA this year in Aug...lots of 356 guys up your way.

Thanks for the post. Great story. Consider writing it up and sending it to our magazine.

Regards,
George Bryan

PS In the early years, I did a Super 90 engine in bright orange & chrome... 8)

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Mark Dionne
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Re: 1965 Cabriolet Rejuvenation

#5 Post by Mark Dionne »

A friend who has done a lot of restorations advised me that one of the best places to spend money was on the interior. So one of the first things I did was to put new leather on the seats.

Getting the new leather over the seat back is difficult because it is a tight fit. I learned a trick: before sliding the leather on, cover the seat padding with a thin plastic bag from the dry cleaners to make it slippery.

One of the reasons I needed new seats was that some animal got into my garage and ate holes in the leather. I also had mice making nests in the hollow areas inside the longitudinals, using stuffing from the seats as nesting materials. Worst of all, mice also made a nest in the headlining of the convertible top when it was down.

Here are a few highlight photos of seat internals.
Attachments
This is how the seat back goes together. There is a loop of cord that passes through hems in the burlap back piece. A big pad goes between this layer and the driver's back.
This is how the seat back goes together. There is a loop of cord that passes through hems in the burlap back piece. A big pad goes between this layer and the driver's back.
The new leather needs to be cut like this to fit over the seat back, a nerve-wracking decision. I ended up putting stitches at this point in addition to glue. The cut is covered by the chrome side plate.
The new leather needs to be cut like this to fit over the seat back, a nerve-wracking decision. I ended up putting stitches at this point in addition to glue. The cut is covered by the chrome side plate.
Detail of how the rolled edge of the leather is tacked to the wooden rail at the bottom of the seat back. Do not cut your finger like I did.
Detail of how the rolled edge of the leather is tacked to the wooden rail at the bottom of the seat back. Do not cut your finger like I did.
A "pick up" tool makes a great needle for threading cords though the tangle of springs.
A "pick up" tool makes a great needle for threading cords though the tangle of springs.
You can see the old cords used to pull down the center of the seat bottom where your butt goes. (This photo should go first.)
You can see the old cords used to pull down the center of the seat bottom where your butt goes. (This photo should go first.)
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Re: 1965 Cabriolet Rejuvenation - Stoddard outer longitudina

#6 Post by Mark Dionne »

I've been measuring my replacement outer longitudinals from Stoddard, and I'm not sure I should use them. The width of the flange at the top where it joins the inner longitudinal (at the door sill) is significantly narrower than the original. The original measures 0.685" to 0.720" while the Stoddard is 0.565" to 0.575".

If I install by matching the edges of the metal, then the new sill (and the rubber strip at the door bottom) will be pushed outward by over 1/8 inch making it harder to fit. If I push the Stoddard part inward to the original location, then it will be hard/impossible to edge-weld the sill to the outer longitudinal.

Edit: See my March 26 posting for more.
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Sill Notes.jpg
Last edited by Mark Dionne on Mon Mar 26, 2012 5:46 pm, edited 1 time in total.
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Re: 1965 Cabriolet Rejuvenation - Stoddard outer longitudina

#7 Post by Mark Erbesfield »

Mark Dionne wrote:I've been measuring my replacement outer longitudinals from Stoddard, and I'm not sure I should use them. The width of the flange at the top where it joins the inner longitudinal (at the door sill) is significantly narrower than the original. The original measures 0.685" to 0.720" while the Stoddard is 0.565" to 0.575".

If I install by matching the edges of the metal, then the new sill (and the rubber strip at the door bottom) will be pushed outward by over 1/8 inch making it harder to fit. If I push the Stoddard part inward to the original location, then it will be hard/impossible to edge-weld the sill to the outer longitudinal.

Question: Does anyone have an outer longitudinal from Restoration Design or another manufacturer that they can measure for me?
I would email Mike DeJong at Restoration Design. He has always been very helpful.
Mike@restoration-design.com
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Re: 1965 Cabriolet Rejuvenation

#8 Post by Phil Planck »

And I would call Stoddard to see if they will replace them. I had a problem with one of their floor pans and even though I did not discover the problem until several years after I bought it, they shipped me a new, good one and said to keep the old one.
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Re: 1965 Cabriolet Rejuvenation - Pedals

#9 Post by Mark Dionne »

Pedals were a good project for cold winter weather. The nut on the clutch cable was badly frozen and I ended up cutting the cable with a Dremel tool to get the pedal cluster out of the car.

Pedals and rust and a bit of more recent floor patch to the left.
pedals 4.JPG
The bracket holding the accelerator and wooden pedal cover to the floor had long turned to rust. Dad had bolted the accelerator to the pedal bracket.
pedals 3.JPG
When you need to make a panic stop you don't want paper-thin rusty metal holding the brake pedal to the car. Fabricating the repair piece (from 16 gauge steel) was not that difficult. The hardest part was getting the old part shaped correctly to fit to the new piece for welding--it had some thick welds that needed to be ground away.
pedals 2.JPG
Mostly done. I used POR-15 paint on the rusty areas, epoxy primer on the new metal and then Rustoleum gloss black. Probably not authentic, but most of this is hidden from view.
pedlals 1.JPG
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Re: 1965 Cabriolet Rejuvenation

#10 Post by Vic Skirmants »

VERY nice!

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Re: 1965 Cabriolet Rejuvenation

#11 Post by Mark Dionne »

My dad made some special Porsche and VW tools. I posted photos of them here:

http://porsche356registry.org/356talk/1/29535.html
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Re: 1965 Cabriolet Rejuvenation - Front Torsion Bar Supports

#12 Post by Mark Dionne »

Here's how the lower left front torsion bar end looked when I got the car. You will not find repair parts for this in any catalog.

Image

Note the old sway bar support repair. Originally there was a bracket bolted just below that rust hole.

Here's how it looks today:
torsiontubes.JPG
Some people will insist that this has to be fixed by an "expert", and restored to tolerance within a millimeter or so. But that's not how things are done in my establishment. See "philosophy" back in the first post above. I figure the tolerances have been off for many years already and the car did not keep trying to go around in circles on its own.

I've been pondering what to do about this for several years. Now that I have more experience welding, the latest plan is to fabricate a new piece matching the lower 6-7 inches of the vertical support, bending around the sides, and weld it right over the old one. It will be heavy gauge metal, 14 or 16 gauge, plug welded down the sides and lap welded at the top. There will be a hole for the lower torsion tube with extra diameter to clear the old weld bead and lie flat over the old piece. Since this will not support the torsion tube directly, I might add a ring that will cover the gap over the weld bead, fit tight around the torsion tube, and be welded or brazed to the bigger patch piece. It's important to keep heat away from the torsion tube bearing areas.
sketch.JPG
The cons: Purists will see the top seam of my patch. I don't plan to try to duplicate the original compound rounded corners at the bottom.

I'm rigging up a press brake to make the bends.

Edit: See more about this in my March 18 post.
Last edited by Mark Dionne on Mon Mar 19, 2012 9:47 am, edited 1 time in total.
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Re: 1965 Cabriolet Rejuvenation

#13 Post by Vic Skirmants »

Looks good to me.

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Re: 1965 Cabriolet Rejuvenation

#14 Post by Larry Coreth »

Mark,
If you are going to the trouble to fix this rust properly, via the newly fabricated lower column holding the torsion bars, why not just pull the lower torsion bar bearings, the needle bearing and the plastic bearing ? End of problem for possible heat damage ! This will allow you to cut out the rust completely and replace the metal directly as opposed just covering it up. It has been my experience that removing the rust completely is the best method to prevent future internal rust.
Over the years especially in the early days,(late 60’ & 70’s) I saw many rust repairs that were incomplete or just patches because the decision was made not to disassemble the car enough to eliminate possible heat induced damage to other components. The classic example is the floor patch where they tried to avoid frying the electrical cable in the tunnel, not always successful. This is personal experience here on the first 356 I ever worked on.
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Re: 1965 Cabriolet Rejuvenation

#15 Post by Mark Dionne »

Larry,
Thanks for your response. I have already removed all the bearings. I'm concerned that the welding heat will warp the tubes which are precisely reamed to fit the bearings. I suspect that the original reaming by Porsche was done after the welding was done.

The original sheet metal around the torsion tubes is .065 inch [Correction: it's actually closer to .041 inch] while the torsion tubes walls are .129 thick. I don't feel comfortable trying to weld this joint. The weld ought to penetrate half way through the tube wall. I contacted a few professional welders about it, and the bottom line was they stopped calling back.

Now I'm about to reveal some secret 356 knowledge only known by a few. Here is the view from the bottom of the torsion tower on my car:
torsion.JPG
There is a hidden U-shaped piece inside the hollow part that is welded to the torsion tubes. Where the tube passes through a hole in the main longitudinal bulkhead it is not welded.

Replacing all the rusty steel in this area would be extremely difficult and require making precise jigs to hold things in place. The "proper" way to do it would probably be to tear apart the whole front end and transplant a new torsion bar assembly from a donor car.

The scheme I described above is not difficult to reverse in the future if someone wants to "do it right". (The horizontal strut, missing in the photo above, must be installed after my patch, and it would need to be cut.)

I do see a weakness in my plan: my scheme supports the torsion tube laterally but it does not hold the tube against rotation, which is important since the force of road bumps ends up as rotational force on the tube. Notice the cracking in my earlier photo. (There's also a brace in the middle of the car that attaches the two tubes and helps prevent rotation.) The ring part could be brazed to the torsion tube or perhaps held to it with set screws. I don't think the heat of brazing would warp the tube, but it would be a bit risky and make things harder to reverse in the future. It looks like there is enough room to make the ring up to about 10mm thick, enough for set screws.
Last edited by Mark Dionne on Fri Mar 16, 2012 10:35 pm, edited 1 time in total.
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