Another hot rod

70SATMan asked: "Did the factory reinforce the rear sway mounts on the STs? I think I've seen them boxed in on some cars (probably the RSRs)??"

Michael:

Thanks for asking the question. I had seen some consoles that were modified but did not have a good answer for you as to correct factory preparation.

Here is what a fellow 2,3L enthusiast in Germany has to say on the subject:

"Hello Tom, original the swaybar consoles on the ST 2.3 are the same like 2.2 S - untouched! Not boxed and not welded anything around, also on the front swaybar, all this modifications started with the 2.5 l, 1972.
Also the rear bananas are original, modifications came also 72 and they are the same like on the 2.7 RS from 1973. If you want to race your car in club races etc. I would do the mods if not I would leave it original."

No doubt many of the 2,3L cars were updated, perhaps out of necesssity over the course of a few race seasons.

And, all you 2,5L guys can now get the welder out.

Michael, thanks again for asking the question.

Jon: Let me know what days you plan on being in Norwalk in September!
Gib: Thanks for the kind words - very much appreciated. You, Hugh, Raj, OliveR, Milou and many other guys on the board have helped me get up the learning curve on all things related to ST. The hot rod thread is my contribution to the common effort. I was trained in history and like to research stuff.
Mike: I will get the name of the source of the flat head rivets for you.

I think the rear sway bar mount reinforcement was done as wheels/tires got wider and bars got bigger. The 73 RSRs went to 19 mm bars, but they may have been available for the 2.5L cars. With the larger bars, more grip from wider wheels, and more powerful engines (275 hp in 72), I am sure those mounts were getting twisted without reinforcement. We'll probably never really know for sure when the practice of reinforcement started, but we do know that independent racers were an inventive lot, and as with most of the ST build specifications, many got modified for competition events.

Raj:

You are right about the John Skoien's RSR being the most original around. But it does have a shock tower brace....it is black, and hard to see. I took pics of this RSR at both the R Gruppe meet in Santa Rosa (2006) and that Parade meet in Sacramento (2000), when it was parked next to Tom Linton's 74 Light Yellow IROC car. I just hung around for several hours with my tongue hanging out.

Gib

Getting ready...

These images detail the body being prepared for another trip to the paint booth for final color.

All the panels are wet sanded to ensure that the surfaces provide the basis for a highly reflective final color coat.

The factory ALU door skins are attached to the original steel door frames with factory style, large diameter, flat head rivets.

Unfortunately, the Race Department lacked the modern adhesives that we benefit from today and their use of rivets contributed to damage resulting from electrolysis caused by moisture combining with bare ALU on steel.

As a precaution against corrosion from the effects of electrolysis, a modern adhesive has been applied to the joints where the old ALU skins fold over the steel door frames. Each rivet is individually sealed using the same SEM adhesive.

You can see in the first image that the holes are now drilled for the Cibie Pallas lamps. We will mount the Pallas lamps next to headlamps. Another board member's MY 1972 2,5L factory built ST circuit racer has the tell tale mounting holes in this same location. This location strikes me as most appropriate for a car with a balsa lid.

The replicas of the Race Department mounting plates for the rear harness straps that were welded to the under side of the rear parcel shelf are now in paint.

These reinforced mounts feature as standard equipment for the ST, shown as "Attachments for sports security belts" for the Competition Equipment 911S specs in Sports Purposes. See attached list of standard specifications for Competition Equipment 911S.

Prepped for final color, the car goes back to the spray booth.

The northeast finally had a few days of dry weather and the welcome respite from rain allowed application of final paint.

The door frames were cleaned up for color. The guys made sure some bare ALU showed on the inside surface of the door skins.

Next image shows final color coat on the outside of the old ALU skins.

The flat headed rivets are finished in body color, just as the rivets were finished by the Race Department. We saw an example of this previously on the old blutorange ST ALU door we used as a "source document" for spacing the rivets.

This panel fastening technique is typical of lightweight ALU body work of the era and was used acrosss Europe from AC Cars, Ltd. to Abarth. To my eye it is most reminiscent of superleggera exotica from the likes of Zagato.

Of course, AC, Abarth and Zagato all built what were essentially hot rods.

An initial look indicates a satisfactory result.

Right now the shop is finishing the assembly of another early S.

Once done, the hot rod follows.

Meanwhile, we will get a look at painting the loose parts, buffing, etc.

And, there are still several old original ST and Race Department bits not seen before that bear close examination.

The early 1970s witnessed rapid development in tire technology. As tread widths increased and aspect ratios moved towards lower profiles, the introduction of improved rubber compounds allowed GT cars to realize significantly higher cornering speeds.

In order to gain advantage of the revolution in tire technology the Race Department considered means to improve rigidity of the 911 chassis beginning in 1970. The engineers focused first on the area of the front strut towers. The engineers did not have far to look , but only needed to cast their eyes to the parts bins left overflowing from the 917 race programme. The 917 trailing arms and rear suspension cross members were particularly interesting as these components were built in the English fashion with adjustable rod ends which eliminated the need for rubber bushed installations.

One such component that drew their eye proved particularly interesting: the 917 upper trailing arm locating the upright for the rear half shaft . For the 2,3L 911S prepared to Group 4 specifications, this bar with its distinctively thin rod ends was judged suitable to the task of providing additional rigidity for the front end.

In 1970 and 1971 the Race Department built several 911S chassis to Group 4 specs with the pirated 917 cross member affixed between the strut towers. Race and rally prepared chassis known to have been spec’d with this part include such illustrious 2,3L cars as those sponsored by Oldenkott Pipes and Chiquita, the 2,3L car prepared by the Kremer brothers in Koln and all of the factory built Safari cars. This style brace is characteristic of most MY 1970 and MY 1971 2,3L cars prepped by the Race Department.

The cross member assembly was comprised of the following components: a length of thick walled aluminum tubular stock tapped on either end to accommodate threaded rod ends; two thick guage cupped washers to be welded around their circumference atop the respective strut towers; two hex head through bolts and matching nuts to affix the assembly to the chassis. As space was limited beneath the frame of the front lid, the heads of the through bolts were turned down on a lathe to reduce the installed height at the attachment points. The machining marks on the heads of the through bolts were typically left in high relief and not finished to a smooth surface.

Once welded to the towers, the cupped washers were finished in body color. The cross bar was finished in satin black and was then sometimes over painted in body color with satin black underneath.

Images attached to this post include:

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- Porsche 917 chassis - detail of left rear suspension upright and upper trailing arm
- Werkfoto of freshly constructed 1971 Safari ST
- 917 style cross member assembly sourced for the hot rod
- Later photo of unrestored fuel bay of a 1971 Safari ST

Back in a previous post readers were asked to identify a factory preparation technique illustrated in an image attached to that post but that was otherwise unidentified. Gib came very close, inquiring whether the hot rod was using a strut brace, but Dave Bouzagoulou of TRE Motorsports identified the purpose of the body colored cupped washers seen in the photo. Dave wins full points for his knowledge of ST trivia. Later versions of the ST strut tower braces employed for the 2,5L cars and 2,8 RSR are illustrated in another thread.

This first foray into adding rigidity to the 911 chassis did not prove long lived (two seasons only) as the ongoing development of race tire technology put much greater demands on the 911 chassis in subsequent seasons. However, the 2,3 strut brace story provides a glimpse into how the 911 was perceived at the time. As a race car, the 911 was considered by the engineering team to be suitable only for customers and not sufficiently serious to merit a custom made part when something already sitting in the parts bins could be pressed into service. However, with the departure of Piech, all this would change...

One of the goals for this hot rod is to conform the details of the fuel bay as per MY 1971 for for a factory built ST. The strut brace a la 917 is one such detail and provides us a nice bit of ST lore to consider.

Here are the pics: