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Making the 356 Safer

September 22, 2010 | Safety & Driving

The Tradeoffs Between Saving Your Butt and Originality

By Barry Lee Brisco

The 356 was designed long before government safety regulations placed significant restrictions on automobile engineering, and by current standards it is rather lacking in features aimed at occupant safety. Despite this, modern 356 owners cheerfully look forward to hopping in their sporting machine and hitting the highway, jousting for space with two-ton, eight-foot high SUVs that are literally armored with protective devices, vehicles that could roll over a 356 and barely notice the impact.

There are a number of ways that the 356 can be modified to improve the safety of the occupants, bmut clearly it cannot even approach the safety of a modern car no matter what is done to it. Some modifications are hardly noticeable and not particularly expensive, while others can alter the character of the car so much that it begins to look like something designed not by Porsche but by a disparate group of back yard hot rodders. The intent of this article is not to tell the owner precisely how to make such modifications, but merely to outline the possibilities and briefly discuss the pros and cons.

Seat Belts  |  Seats  |  Brakes  |  Wheels & Tires  |  Fuel System  |  Lights

Seat Belts

3-point seat belts mounted in an A coupe Seat belts were never standard on the 356, though they were an option from early on. Yet they were rarely ordered by new owners. My father's new 1959 A coupe never had seat belts during the ten years he owned the car, and many happy miles were enjoyed by the entire family (my sister and I in the back seats) in that "beltless" state.

Rosy reminiscences aside, adding seatbelts to a 356 is a relatively simple thing to do and provides obvious benefits that hardly need to be elaborated on (Mounting seat belts was covered extensively in the July/August 2005 356 Registry Magazine, view that article here.). A 3-point belt is clearly superior to a basic lap belt in preventing the occupant from pitching forward into the steering wheel and dashboard in the event of a sudden stop (it is not possible to use your arms to brace yourself in a hard impact). Diest Safety makes a comfortable non-retractable 3-point system for owners who want to minimize any hint of modernity, or there are retractable inertia reel belts (like those from PEP or Andover Restraints, see Dave Wildrick's comments below) for those who prefer that convenience. If you are still using a basic lap belt, close your eyes and picture a dashboard induced skull fracture suffered by your valued passenger, or your chest being crushed by the steering wheel since the steering column is non-collapsible...and then install a 3-point system. A 4-point shoulder belt system is even better, but mounting becomes difficult, and this is rarely done in street cars (Seat belt sources listed below).

There is a potential issue of spinal compression occurring in an impact caused if the shoulder belt mounting point is too far below the level of the occupants shoulder. The problem is that in a stock 356 there is no good location to attach the shoulder belt mount point so that it is at the same level as, or higher than your shoulder. The B pillar is too weak to use, it was not designed for that purpose. It could be reinforced with extra metal welded in, but this is rarely done and would probably alter the appearance of that area. I have seen some 356s with the shoulder belt mounted almost on the floor behind the front seats. It is done to try to hide the bulky retractor mechanism. However, this is a poor location because of the severe downward angle the shoulder belt. In an impact, the belt will pull the occupants left shoulder down towards the floor, twisting and compressing their spine with potentially serious consequences!

Another approach is shown in the photo at right: each side of the 2-piece shoulder harness is secured to an eye bolt attached to the engine firewall behind the rear seat back. NOTE! The firewall sheet metal is not very strong. Remove the rear upholstered panel and weld in some reinforcing pieces (make sure their corners are rounded, not sharp), then drill your mounting holes. This is a decent solution, even though it lacks any redeeming aesthetic qualities.

Adding a roll bar to the car and using that for the shoulder belt mount point brings new risks: because 356 seat backs are very low, if you are rear-ended your head is going to snap back, impact the roll bar, and a skull fracture is the likely result. Roll bars are for race cars where the drivers are wearing helmets, and in racing the rules specify they be padded. Roll bars in street cars are rarely padded, and street car drivers rarely wear helmets. For more on that, read this article.

David Jones states: "My 59 A has lap and shoulder belts with the retractor mounted in the same place as in a "C" below the rear window. The angle of the belt back to the retractor is shallow and can vary depending on height of driver but not much as it depends more on seat back position as to where the height of the over the shoulder portion resides. The recommended angle from all the information I have read on seat belt installation is about 10 degrees downward slope."

David also suggests that when "fitting seat belts to pre "C" cars, add a piece of 1/8" thick by 1" wide angle under the car where the eye bolts go. Weld two nuts 10" apart on the angle and then thread the eye bolts through from inside. This gives more than enough reinforcing to the eye bolt mounts to be sure they will not pull through in event of a sudden stop such as against the legendary immovable object."

Dave Wildrick contributed this useful information: "I installed PEP retractable 3-point belts in my 65C coupe a few years ago.  They look nice and work well but seemed a little pricey: currently about $340.  For my 64C coupe, I installed a set of 3-point retractable belts from Andover Restraints.  Their current price for the same setup I bought would be $150.

You buy the Retractable Lap And Shoulder Harness Seat Belt Without Door Post Extension-With 20" Non-Sleeved Buckle End--$75, in various colors (w/85inch retracting shoulder belt). These belts do not come with a "hook end" for the floor mounting spots (eyebolts on C cars), but these are available if you ask for them (they are sold under "end fittings", part #8713 @ $15/each: 2 3/4" long with 1/2" eyebolt snap-in slot, Bright Chrome). So you are at $220 for a set with the hook ends (4 required @ $15) or $150 with the standard non-hook, bolt-down floor fittings. Contrast this with $340 at PEP.

If you have a T6, you will also need to get an M8 bolt (8mm x 1.25 x 35mm) IIRC from Home Depot or Lowes to attach each retractor to the factory mounting point. If your car is a T6 but does not have eyebolts in the floor attachment points and you are using the non-hook end fittings, you will only need a couple of non-metric bolts plus lock washers (get from Andover or Lowe's, Home Depot, etc.). If you need the eyebolts, PEP has them for about $6/each.

I see little difference in operation or quality between these two 3-point belt systems." (end of comments from Dave Wildrick)

Starting with the 1963 model year, a year after the T6 model was introduced, all Porsches (with possible exceptions in some cars manufactured in late 1962) had built-in reinforced seat belt mounts (captive nuts welded into the floor pan behind the front seats and a rear mount for a shoulder belt) even though belts were still an option and not standard. However, the factory shoulder belt mounting point is flimsy and does not go through the inner fender well, so be sure your mounting hole goes into the body sheet metal. In earlier 356 models, drill holes for the mounting points and use large fender washers for reinforcement. Much better is to weld in some reinforcing plates (make sure their corners are rounded, not sharp), then drill the holes. Mounting seat belts was covered extensively in the July/August 2005 356 Registry Magazine, view that article here.

"Factory" Seat Belts in the 356

Comments from Jim Breazeale: "Very few, if any, 356s bound for the US came with "factory" seatbelts. Seatbelts that were installed by US dealers are not "factory" seat belts. If vintage seatbelts have a Porsche crest on them, they are not "factory". Those belts were installed in the US and made by ASE/Hickok. (ASE is short for American Safety Equipment). True "factory" installed seatbelts were done on a random basis up until the 1963 year models. Again, it is my opinion (based on 43 years of "hands on" experience with these cars) that true "factory installed" seatbelts are very rare or non existent in cars bound for the US from the factory."

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Stock 356 seats are comfortable (the infamous Speedster seats being a notable exception) and were considered reasonably supportive for their day. But even for street use, what they conspiculously lack is any sort of head restraint to prevent whiplash in the event of a rear end impact. The optional 356 "head rest" bolster was not designed for safety but for comfort, as the mounting method is too flimsy to withstand the forces generated in a major impact.

The internal seat structure can be modified to modestly improve the factory head rest mount by welding nuts onto the mounting holes in the internal seatback frame and using a bolt instead of the stock sheet metal screw to attach the headrest. The same result can be achieved with removing the seat back upholstery by the use of "Rivnuts" (read this article). This is probably a worthwhile improvement, and of course is completely hidden from view, though if you use Rivnuts the bolt heads are visible. The only alternative is to replace the 356 seat with an aftermarket racing seat, thereby radically changing the visual character of the car, or taking the somewhat milder approach of installing a 1968—1973 era 912 or 911 seat where the optional head restraints were designed to prevent whiplash and not simply cushion your head. Unfortunately, later model Porsche standard seats do not fit into 356 seat rails (they are too wide) so some work is required to make them fit.

Note that 1974 and later Porsche seats had an integrated headrest, but they also require modifications to fit into a 356 and they look a long way from "period".

Another option is to use reproductions of 911R and 911ST racing seats, manufactured by Vintage Seats (if you can find real ones to restore you will be shocked at the price!). These seats were designed for racing with plenty of head and shoulder support, and were sometimes ordered by early 911 and 912 owners for use in their street cars. Some seat mount modifications may be necessary for use in a 356, so be sure and consult with the manufacturer. Also keep in mind that those racing seats are narrow, and not everyone will fit in them (source listed below).

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Classic & Speed Parts disc brake on a 356A front end. The drum brakes supplied by Porsche on all 356 models built before the C was introduced in late 1963 with disc brakes were over-engineered for street use, and when in good condition are more than capable of stopping the car in an emergency. That said, some 356ers prefer to equip their A and B cars with Porsche discs or an aftermarket solution (sources listed below), as they prefer the increased resistance to fade and more reassuring feel of the discs. However, it is debatable whether a 356 with discs has a significantly shorter stopping distance than a 356 with drum brakes in proper working order (also keep in mind that discs are heavier than drum brakes, adding to unsprung weight). And with many suppliers offering all kinds of parts to keep drum brakes working, there is less reason to convert to discs out of necessity as opposed to preference.

Every 356 ever made came from the factory with a single circuit brake system. In the event of a burst line or master cylinder failure, the driver had to rely on the "emergency" brake to activate the drum brakes on both rear wheels using a system independent of the full 4-wheel system (this system is markedly different from modern "parking" brakes that merely apply a clamp to the driveshaft, which is much less effective). Note that in the 356C model with disc brakes, the emergency brake activates smaller non-disc brakes on both rear wheels, which are not as powerful as the earlier 356 drum emergency brake system.

Single circuit sounds perilous by modern standards, yet many veteran 356ers cannot recount a single incidence of a properly maintained 356 single circuit system ever failing catastrophically, and take the position that modifying the stock system is unnecessary provided that correct and timely maintenance is carried out. Others insist that they have heard of 356 single circuit failures and strongly believe that a modern update is the best approach.

For the 1968 model year Porsche switched to dual circuit, and many 356 owners have converted their cars to that system using kits available from several vendors (sources listed below). It places the front and rear brakes on separate systems. Certainly dual circuit is theoretically safer (and considered essential for race modified 356s), but given the minuscule failure rate of properly maintained single circuit systems, reasonable people can differ as to the importance of this conversion in a street car.

Important: If converting to dual circuit, have it done by a qualified 356 mechanic. Whether single or dual circuit, regular brake system maintenance by a qualified mechanic is essential! Al Zim advises replacing the master cylinder every 10 years if the brake system is flushed annually, more often otherwise. Also, using steel braided brake lines is not recommended in cars used exclusively on the street. They are used in race cars, and the lines are changed annually.

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Changing your tires every 9 years (no matter how good they look) and checking tire pressures before driving makes it highly unlikely that a modern tire will come off the rim or have a tread separation (learn how to read your tire date code here). Most 356ers run their tires anywhere from 26 to 30 front, 28 to 34 rear, and maintain approximately a 4psi differential front to rear. For more about tire pressures go here.

For the 1968 model year Porsche changed their steel wheels to 5 1/2" and incorporated a "safety bead" around the rim that was intended to prevent a blown tire from coming off the wheel (the optional Fuchs alloy wheels did not get this change until 1972 according to Jim Breazeale). So changing a pre-1968 car to a 1968 or later wheel may make it just a bit safer. However, few 356 owners bother to make the change for that specific reason, and of course later wheels won't work on drum brake cars. If you feel this is a critical feature, consider a modern aftermarket wheel designed for drum brakes and with the safety bead such as the "Brazilian" chrome wheel or modern alloys (sources listed below). For more on this topic, see Tires With Tubes – Original Yes, Needed? No

Whether changing from 4 1/2" to 5 1/2" wheels and wider tires makes a 356 any safer is open to discussion, though it certainly changes the handling while providing the owner with a wider selection of tires to choose from (see a list here). Many take the wider wheel approach claiming improved cornering abilities, while others prefer the perhaps nimbler feel and original look of the narrower tires. Bruce Baker's preference is 5 1/2" on the rear and 4 1/2" on the front, the intent being to reduce trailing throttle oversteer (though this setup makes rotating the tires from front to back a bit more work, since they have to be unmounted and then remounted). Radial tires should be rotated (front to back, not side to side) every 6,000 to 8,000 miles to ensure even tread wear and maximum tire life. It's simple not to include the spare in your rotation schedule, but don't forget to check its pressure periodically. There is nothing worse than pulling the spare out in an emergency and discovering it's so low it can't be used. Sitting in the trunk, the spare can appear full at a very low pressure.

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Fuel System

The location of the 356 gas tank, directly above the lower legs of the driver and passenger, strikes many as perilously close, and certainly would never be allowed under modern auto safety regulations. Fuel Safe makes 356-compatible "bladder" style tanks commonly used in racing but also suitable for street cars. The stock tank can be replaced, or a bladder can be fitted into it to try and maintain a more vintage look (source listed below). Steven Smith had this done to his A coupe's tank (shown at right, more photos here) at a cost of $850 because, as he said, "The oxygenated fuel they use here in Oregon attacks the stock fuel cap gasket and led to fumes and sloshing in my trunk. The Cell's screw cap is a hundred times better at sealing the stock tank."

It is important to periodically check the integrity of the gas tank components. On A/B tanks, the gas cap is made in two parts, the inner part is held in by friction and sometimes comes loose, potentially letting fuel slosh out of the tank, so check the fit. Cork gas cap gaskets can deteriorate more rapidly when using gas with ethanol, so replace the gasket regularly. Also check the vent system to make sure its clear and the hose isn't rotten.

Many experienced 356ers recommend against using add-on plastic fuel filters, advising that it's best to use metal filters that are more resistant to heat and breakage. A good location for an additional filter is in the fuel line that runs under the car next to the transmission, not in the engine compartment (sources listed below).

In the A and B models, the location of the fuel petcock and fuel line under the dash makes it exposed to potential damage in an accident. In any case, make sure it's not seeping fuel. Replacements that look exactly like originals are readily available (sources listed below). While the petcock may look dangerous, Bruce Baker notes that after 40 years of seeing a few hundred 356s get mangled in accidents, he cannot remember a single incident of a fuel-related fire or a leaking gas tank.

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Lights: Front, Rear, and Sides?

By modern standards, 356 brake lights are weak: difficult to see during the day, and placed rather low. The problem of low luminousity cannot be solved just by switching to significantly higher wattage bulbs than the standard 15w units, as they generate too much heat and draw too much current: the stock flasher switch will fail (though you can use 18w bulbs without a problem, and 10w bulbs instead of 5w for the rear runing lights). One approach is to replace the turn signal flasher with a modern electronic unit that can handle up to 24w bulbs, a significant increase. As a bonus, the new unit makes a nicely audible clicking sound to remind you to turn your signal off if your self-cancelling mechanism no longer works (source listed below).

For the ultimate in brightness, consider replacing the standard incandescent bulbs with some type of LED array light. Read more about LED lights here.

Even the brightest replacement brake lights are still only 18" off the ground, and these days people are used to seeing lights come on closer to eye level. You can add a separate "third" brake light mounted up high, either behind the rear window (suction cups hold it on) or under the deck lid grill where it is barely noticeable when not in use. Units are available in both wired and unwired versions (source listed below). While this addition certainly increases the likelihood that those to the rear will see your brake lights come on, it is no guarantee: a friend was recently rear-ended in his third brake light-equipped 356C while stopped waiting for a signal to change. The driver who hit him was talking on her cell phone!

356 rear running lights (the inboard lights) are also pretty dim by modern standards. The stock 5w bulbs can be replaced with 10w bulbs, and 6v versions of them are available. Though the perceptible difference is much less than double the luminosity as one might expect, for the cost of a few dollars it is certainly worth doing.

356 headlights are not known for the luminousity (though in their day they clearly outclassed any British sports car!) but improvement is relatively easy to come by. The combination of H4 bulbs along with Joe Leoni's "HLr" headlight relay kit (particularly advantageous in models with the headlight dimmer function on the steering column) can more than double the light output compared to the stock system. More details here. This is well worth doing to any 356 that gets much night use, or for those who like the idea of running headlights during the day for extra safety (sources listed below).

356 lights are barely visible from the side of the car. The change to the 911/912 body style included wraparound front and rear turn signal lights, and in 1968 the US government even mandated side reflectors on all cars.

On your 356...don't even think about it.

Summing Up

Certainly this is only a partial list of the safety modifications that could potentially be made to any 356. Roll bars could be added (though that brings new risks), doors could be strengthened internally, steering wheels replaced with modern padded versions, the list is endless. But at some point the car starts to lose its essential character and becomes not a classic vintage vehicle but a hodgepodge of aftermarket "improvements" that have no relation to Porsche's original design concepts: and the car is still a long ways from being as safe as any modern automobile.

The only safety-related changes I've made to my 59 coupe are to add 3-point Diest belts, CuLayer LED brake lights, the Leoni HLr kit and H4 headlights, and accepted a previous owner's modification of the brake system to dual circuit (I probably wouldn't have done it). Other than that, I'm perfectly comfortable with the car just as it is, including the stock 6 volt electrical system.

Ultimately, the best way to stay out of trouble in your 356 is to properly maintain the car, be familiar with the quirks of rear-engined 50's era handling, and concentrate on your driving! So stay safe, and keep the faith.

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This list of vendors, in alphabetical order, is not necessarily comprehensive, and additional companies may also offer similar products. Note that where possible, links are provided directly to a specific product page if available.

356 Electrics: headlight relay

Andover Seat Belts

Classic & Speed Parts: disc brake conversion kit

EASY: seat belts, C disc brake parts

Elevenparts (Europe): LED brake light, drum brake parts, fuel petcocks, gas tank caps, H4 bulbs, TechnoMag alloy wheel

Fuel Safe: fuel cell bladders

Klasse 356: master cylinder conversion kit

NLA: LED brake light, fuel petcocks, gas tank caps, H4 bulbs, "Brazilian" chrome wheel with safety bead, drum brake parts, "MgTek" alloy wheel

PEP: seat belts

Stoddards: fuel filters, fuel petcocks, C disc brake parts, drum brake parts, other brake parts,

Top Serve: third brake lights

Vintage Seats: reproductions of 911R and 911ST racing seats

West Coast Haus: alloy wheels

Zim's Autotechnik: disc brake conversion kit, master cylinder conversion kit, H4 headlight bulbs, electronic signal flasher, fuel petcocks, metal fuel filter, seat belts and eye bolts