Guide: Porsche 935/77
Background
As a result of mid-season rule changes, poor reliability and a stronger-than-expected challenge from BMW, the 1976 World Championship for Makes had been a more closely fought campaign than Porsche would have expected.
Porsche had begun the ‘76 season in dominant fashion with easy wins at Mugello and Vallelunga. However, a mid-season slump meant BMW quickly recovered ground; Porsche only managed to clinch the title thanks to victories at the last two races of the year (Watkins Glen and Dijon).
As had been the case in 1976, for 1977, the World Sportscar Championship was split into two separate competitions. One was for out-and-out Group 6 Prototypes and the other for Group 4 and 5 GT cars.
The FIA had originally planned to abandon Group 6 Prototypes completely for 1976, but caved to manufacturer demand and created two contests so as not to upset those firms that had developed cars for the Group 5 category (which had been conceived as the new premier World Championship class).
During 1976, Porsche had campaigned a handful of 935s exclusively as works entries. Customers were supplied with the less highly modified Group 4 class 934.
For 1977, Porsche would run their own twin turbocharged 935s of which three were built. Customers would now be offered replicas of the single turbo 935 from 1976. In total, 13 single turbo Customer cars were produced for the 1977 season.
Additionally, the Martini-backed factory squad constructed a two-litre car with a new spaceframe chassis dubbed the 935/2. This one-off machine was raced on three occasions outside of the World Championship and is covered separately.
Engine / Gearbox
Undoubtedly the most significant update ushered in for the works cars in 1977 was a twin turbocharged engine.
The new Type 930/77 unit offered drastically reduced turbo lag which made the cars much easier to drive. Boost pressure for the brace of smaller KKK turbos was normally set at 1.4 bar.
A 0.4mm bore increase (to 92.8mm) meant displacement was fractionally higher than 2856cc but still within the swept four-litre limit when the 1.4 multiplier for turbo engines was taken into account.
Otherwise, the 930/77 unit was another all-alloy, dry-sumped, single overhead camshaft unit with two valves per cylinder. It was fitted with a horizontal cooling fan, titanium connecting rods, forged steel rocker arms, twin plug ignition and mechanical plunger-type fuel-injection.
Just about the only parts shared with the standard 930 were the crankcase and crankshaft.
As in 1976, the compression ratio was 6.5:1.
Peak output went from 590bhp to 630bhp at an unchanged 8000rpm. The torque rating was the same as before: 433lb-ft at 5400rpm.
Transmission was via the same short-shift four-speed oil-cooled gearbox found in the 934. A spool for permanently locking the rear driveshafts meant there was no need for a limited-slip differential.
Titanium driveshafts were fitted with constant velocity joints and rubber couplings.
Chassis
For 1977, the existing steel monocoque was modified to incorporate re-positioned front and rear bulkheads.
To make the steering lighter and reduce driver fatigue, the 935’s front suspension was re-engineered for 1977 with new strut and pivot points. This made the steering noticeably lighter; Porsche had initially looked into installing a power steering system but such a feature was deemed impractical.
Other updates included cockpit-adjustable front suspension settings, servo-assisted brakes and magnesium hub carriers.
Suspension was via MacPherson struts at the front, double wishbones at the rear and gas-filled Bilstein dampers all round. The suspension assemblies were custom fabricated, fully adjustable and riddled with lightweight components.
Anti-roll bars were fitted at either end. The one at the rear was adjustable from within the cockpit.
Anti-dive was also employed.
The dual circuit brake system was imported from the 917 and featured ventilated discs with four-piston calipers at each corner.
Centre-lock BBS wheels were shod with Dunlop tyres. The front rims had a 16-inch diameter and were 10.5-inches wide. The backs had a 19-inch diameter and were 15-inches wide.
Body
The 1977 season 935 used by the factory team was immediately identifiable on account of several cosmetic enhancements designed to improve aerodynamics.
The front apron was more intricately contoured with recessed sections around each corner.
The exterior mirrors were now cowled within fences mounted atop each front fender.
Down each flank, the wheelarch extensions were boxed in with a running board skirts along the sills. The rear wheelarch intakes were re-profiled as well.
New regulations enabled Porsche to raise the rear roofline and integrate a completely faired-in rear windscreen. As part of this back-end redesign, engine cooling intakes were added behind the rear quarter windows and a new rear spoiler was installed.
The new variant was the same width and height as before, but now measured 150mm longer.
Interior
Inside, the cockpit was suitably pared down.
An aluminium rollcage was installed along with a single bucket seat trimmed in fire-retardant upholstery. The 930’s familiar five-gauge instrument binnacle was retained although the dash was now left in bare metal.
A toggle switch for the turbo boost was located under the centre of the dash.
Weight / Performance
As had been the case in 1976, the 1977-spec. 935 weighed in at well below the 970kg class minimum so was brought up the required figure with strategically positioned lead ballast.
Top speed went from 209mph to 217mph.
The 0-62mph time dropped from 3.2 to 3 seconds flat.
1977 Season
Although the 1976 title had been a close fought affair, BMW decided to contest the two-litre Group 5 class for 1977 which left a paucity of opposition for Porsche that season.
As it transpired, the customer teams that had purchased single turbo 935s represented the stiffest threat when it came to outright victory at individual races.
The 1977 World Championship for Makes comprised nine events, most of which were held over six hours or 1000km. The exception was the 24 Hour season-opener at Daytona.
As had been the case in 1976, Le Mans was a standalone event because the organisers elected to allow both Prototype and GT cars to run alongside one another. This put them at odds with the FIA who excluded them from the main championships.
1977 Daytona 24 Hours
The 1977 season kicked off with the Daytona 24 Hours whch took place over the weekend of February 5th and 6th.
The Martini-backed Porsche squad entered a single car for Jacky Ickx and Jochen Mass. However, because none of the latest twin turbo variants were ready, a well-used machine from 1976 was taken to the US (chassis 002).
Chief opposition would come from a pair of new Customers 935s (from Kremer and Jolly Club) plus a handful of Prototypes that the organisers had allowed to run in a Sports category.
Mass took pole for Martini Racing with a lap time seventh tenths of a second faster than the Kremer 935. A pair of works Inalteras were third and fourth followed by the Jolly Club 935 in fifth. Interscope Racing’s old 911 2.2 Carrera RSR Turbo lined up in sixth.
After a spirited early battle, the works 935 established a healthy lead, but as night began to fall, Mass came in with a tyre failure which had ruptured the turbo system, cracked an oil cooler and damaged the body. An hour was lost in the pits and a door had to be borrowed from Interscope whose car had retired after 35 laps with a blown piston.
The delay left Kremer’s 935 in the lead.
Ickx and Mass drove rapidly throughout the night and, despite losing 300rpm because of the disturbed airflow caused by the bodywork repairs, they moved back into second position at 4:30am.
When dawn broke, they had cut the deficit from 22 to nine laps. However, soon afterwards a tyre blowout occurred when Mass was flat out on the banking. The car skittered up to the wall, slapped hard against it and then slithered down to the infield. With major suspension and chassis damage, the Martini crew were out of the race.
Victory ultimately fell to the Ecurie Escargot 911 RSR of Hurley Haywood, John Graves and Dave Helmick. After a series of delays, the Jolly Club and Kremer 935s placed second and third.
1977 Paul Ricard Tests
In the weeks that followed Porsche headed to Paul Ricard in the South of France where the finished twin turbo 935 underwent several days of extensive tests.
1977 Mugello 6 Hours
Round two was the Mugello 6 Hours on March 3rd.
Porsche entered two cars: 004 was a brand new twin turbo example for Jochen Mass / Jurgen Barth while 003 was a previously unraced single turbo machine for Rolf Stommelen / Manfred Schurti.
Having experienced a seized turbo in the first practice session, Mass went on to take pole. The older sister car of Schurti went second quickest followed by the customer 935s of Kremer, Jolly Club and Vittorio Coggiola’s privateer example. Next up was the fastest 934 (that of Jolly Club in sixth).
In the race, Mass and Stommelen led the field away followed by Bob Wollek in the Kremer example.
Towards the end of the first hour, Wollek went past Stommelen and set off in pursuit of Mass.
Shortly afterwards, Mass (who was feeling ill) came into the pits for Barth to take over. Mass explained that he had been having trouble with the brake pedal not returning - he had been using his foot to pull it back!
Wollek then handed over the Kremer car to John Fitzpatrick and Schurti swapped for Stommelen.
At the 90 minute mark, mist and rain started to move in. Both the works cars came into the pits for wets but Fitzpatrick stayed out in the Kremer 935 to assume the lead.
Around the two hour mark, Barth went passed Fitpatrick to re-take the lead in the twin turbo Martini entry, but in his spirited pursuit, he had overworked the brakes. 15 minutes after he had passed Fitzpatrick, Barth came in for a pad change and attention to the alternator. He emerged from the pits just as Fitzpatrick flashed by.
Barth, who had not primed his new pads, arrived at the corner brake-less; he ploughed into the back of the Kremer Porsche and took both cars out of the race.
The single turbo Martini entry of Stommelen / Schurti subsequently purred around to take a comfortable victory from the second-placed Jolly Club 935 and the Coggiola machine in third.
Chassis 004 was returned to the factory but never raced again.
Chassis 003 was also retired from any further competition duty.
1977 Silverstone 6 Hours
For the Silverstone 6 Hours on May 15th, Porsche entered a brand new twin turbo 935 (chassis 005) which was allocated to Jacky Ickx and Jochen Mass.
Silverstone was round three of the championship and saw the Martini Racing crew trying out new finned and drilled brakes for improved cooling.
Qualifying saw the works car on pole from the customer 935s of Kremer (second), Georg Loos (third and fourth), Jolly Club (fifth) and Kannacher (sixth).
When the flag dropped, Mass pulled away and on lap two he set the fastest lap of the race. It was not necessary for the car to be driven that quickly again. By lap eleven he had lapped all bar the other 935s in the race.
Ickx then took over just after the hour mark and rejoined with a lap lead over the rest of the field.
The Belgian was back in for his second stint at mid-distance. However, the new brakes were increasing pad wear and after 18 minutes he returned to the pits for a set of rear pads (the fronts had already been done). This left the Kremer 935 of John Fitzpatrick just 25 seconds behind.
When Ickx handed back to Mass for the final stint with just under an hour to go, the Martini team had to change an alternator belt as well as fit another set of new pads. Having spent nearly three-and-a-half minutes stationary, Mass emerged 53 seconds behind the Kremer 935.
The Kremer car came in for its final stop two laps later and emerged ten seconds in arrears.
Mass pushed hard to stretched his lead to 30 seconds at which point he kept the gap constant until the end. Wollek / Fitzpatrick claimed second for Kremer and Rolf Stommelen / Toine Hezemans rounded out the podium in their Georg Loos entry.
1977 Nurburgring 1000km
Two weeks later, the Nurburgring hosted a 1000km race for round four of the World Championship (May 29th).
The event was open to cars from Group 1 through to Group 5. 86 cars were entered and 57 made the cut within the 130% qualifying rule.
During unofficial practice, Mass went off the circuit at the same point where Niki Lauda had crashed his Ferrari 312T Formula 1 car the year before. The Porsche’s front and rear ends both incurred damage but Mass still ended up going fastest in qualifying the next day.
One of the Georg Loos 935s started second followed by Kremer’s freshly uprated K2 variant in third. The Max Moritz 935 qualified in fourth with the second Georg Loos entry fifth and the Josef Brambring machine sixth.
By the end of lap one, Stommelen had taken the lead from Ickx in his Georg Loos 935. Stommelen had established a 30 second gap when he retired on lap four with gearbox trouble. As a result, he joined Tim Schenken and Toine Hezemans in the Georg Loos sister car.
Ickx briefly retook the lead until Manfred Schurti went passed for the Max Moritz crew.
With six of the 44 laps gone, Ickx handed over to Mass. However, after just one lap, Mass was back in the pits as the car would not rev cleanly. The Bosch technicians tried to sort the problem, but it soon dropped out of the reckoning. Mass did ultimately rejoin the race, but he retired for good on lap eleven with more fuel-injection trouble.
Schenken, Stommelen and Hezemans took the win for Georg Loos while Bob Wollek and John Fitzpatrick claimed second in their Kremer K2. Third place went to the BMW Junior Team 320i of Marc Surer and Manfred Winkelhock which also claimed victory in the two-litre category.
1977 Le Mans 24 Hours
Even though it was not part of the World Championship, the Le Mans 24 Hours was still the sports car race that every manufacturer wanted to win.
The 1977 event took place over the weekend of June 11th / 12th and Porsche sent a three car team to France in the hope taking their fourth outright win at la Sarthe. The Martini-backed works squad comprised a brace of 936 Prototypes and a solitary 935.
The 936s were entered for Jacky Ickx / Henri Pescarolo and Jurgen Barth / Hurley Haywood. The 935 was allocated to Rolf Stommelen / Manfred Schurti.
Having won in 1976, the 936s were highly fancied for a repeat victory. However, the Renault-powered Alpines and Mirages represented a serious threat, as demonstrated by their speed in qualifying.
Pole position went to the works Renualt Alpine A442 of Jean-Pierre Jabouille / Derek Bell. The sister car of Patrick Depailler and Jacques Laffite was second. Then came the Ickx / Pescarolo 936 followed by the other works A442 of Patrick Tambay / Jean-Pierre Jaussaud and the privateer Hugues de Chaunac example of Rene Arnoux / Didier Pironi / Guy Frequelin.
Stommelen / Schurti lined up fifth in their 935 and the other 936 of Barth / Haywood was sixth.
After just eight laps, Stommelen came into the pits where he was delayed for some time with a loose rocker shaft.
The 935 subsequently emerged, but ran at a very slow pace; because it had lost a substantial quantity of oil and the rules stipulated no top ups were permitted until 16 laps had been completed, Stommelen was forced to circulate at well below the car’s potential. By the time he was finally allowed to address the situation, the 935 was three laps down on the leaders.
After three hours, Stommelen and Schurti had recovered to hold tenth position. Unfortunately though, with 45 laps gone, chassis 005 was retired with engine trouble.
Nevertheless, Porsche did go on to take the win; after his car had retired, Ickx went on to join the 936 of Barth and Haywood which won by eleven laps from the Mirage M8 of Vern Schuppan and Jean-Pierre Jarier. Porsche also claimed the GT class thanks to the JMS Racing Team customer 935 of Claude Ballot-Lena and Peter Gregg which finished in third position overall.
1977 Norisring 200 mile Trophy
On July 3rd, Porsche contested another major non-championship race when they sent chassis 005 to the Norisring for the big money 200 mile event.
In addition to the regular 935, Porsche sprang a surprise by attending with a second car: the diminutive 1425cc 935/2 which was nicknamed the Baby. Created for the Division 2 class of the Deutsche Rennsport Meisterschaft, the 935/2 was built around a special spaceframe chassis to test the kind of sub 1.5-litre turbo engine that would soon became the norm in Formula 1.
The Norisring meeting was split into three events: the separate Division 1 and Division 2 DRM races were held in the morning and the annual standalone 200 mile event took place in the afternoon.
Rolf Stommelen won the morning’s Division 1 race driving a Georg Loos customer 935 and Eddie Cheever won the Division 2 contest in his BMW Junior Team 320. Jacky Ickx moved up from twelfth to sixth in the 935/2 before he retired from heat exhaustion at mid distance.
For the afternoon’s 200 mile Trophy race, chassis 005 was wheeled out for Bob Wollek to drive after the engine in his Kremer 935 had blown earlier in the day. Ickx was out again in the 935/2.
The top five grid slots were all occupied by 935s. Pole went to Rolf Stommelen (Georg Loos) and Wollek was second in the works car. In third through fifth were Toine Hezemans (Georg Loos), Manfred Schurti (Max Moritz) and Peter Gregg (Kremer).
Hezemans blasted off the line to take an early lead followed by Schurti and Wollek. However, a slow puncture forced Hezemans out of the equation and he retired with 13 of the 50 laps remaining.
Stommelen then took over at the head of the field before he was forced to pit after a stone damaged his oil cooler.
This left Schurti to take the win while Wollek finished second in the works car having struggled with poor brakes throughout. Peter Gregg rounded out the podium while Ickx finished seventh overall in the 935/2 (third in the under two-litre class).
1977 Watkins Glen 6 Hours
After a six week break, the World Championship resumed with round five: the Watkins Glen 6 Hours on July 9th.
Chassis 005 had been flown out to the US immediately after its appearance at the Norisring. It was entered for Jochen Mass and Jacky Ickx who would be up against the trick BMW 320i Turbo which had been developed in conjunction with McLaren and successfully campaigned in a number of IMSA races.
The Martini 935 pipped the BMW McLaren of David Hobbs and Ronnie Peterson to pole by just under half a second. In third was the Vasek Polak 935, fourth was a John Greenwood Corvette and fifth spot went to the Bob Hagestad Porsche 934/5.
Mass took an early lead from George Follmer in Vasek Polak 935 and Peterson in the BMW. Unfortunately, the BMW challenge did not last long; Peterson suffered a brake failure on lap 20 and although he made it back to the pits for Hobbs to take over, the Englishman retired on his first lap owing to the accident damage that had been incurred.
A little later, Mass came in as a valve cover gasket had chafed through and oil was leaking onto one of the exhaust pipes. Twelve minutes were lost and the Martini entry emerged in third place behind the 934/5s of Haywood / Hagestad and Heimrath / Miller.
For the next two hours, Haywood / Hagestad managed to stay clear of the works 935. However, Ickx and Mass pressed on and just before the five hour mark, Mass retook the lead. Half an hour earlier, Ickx had been about to do the same thing, but a broken alternator forced him to pit, at which point Mass took over for the final stint.
Martini Racing eventually won by three laps from Follmer / Lunger in the Vasek Polak 935. Haywood / Hagestad in the 934/5 dropped to third after their front spoiler tore off in the final stages.
1977 Mosport 6 Hours
A six week gap ensued before round six of the World Championship took place in Canada.
The Mosport 6 Hours was held on August 20th. Porsche sent chassis 005 across the Atlantic for Jacky Ickx and Manfred Schurti to take on BMW’s turbocharged 320i.
Ickx put the works 935 on pole with a time over two seconds clear of the Vasek Polak customer 935.
He dropped behind Follmer’s Vasek Polak 935 off the line, but re-took the lead on lap two and pulled away.
Ickx had to make an unscheduled stop at the half hour mark with a blistered rear tyre, but rejoined still in the lead.
However, 20 minutes later a piston broke and the head gasket blew. The race was over with 34 laps gone (one eighth distance). Manfred Schurti did not even get a chance to drive.
In a rare off day for the 935s, the other two cars in the race (those of Vasek Polak and Jim Busby) were also out barely a quarter of the way into the race.
Ludwig Heimrath and Paul Miller took a comfortable victory in Heimrath’s Porsche 934/5. They finished three laps clear of the Eddie Cheever / Gilles Villenueve works normally aspirated BMW 320i which also won the two-litre class.
Third overall went to the Group 44 Jaguar XJS driven by Bob Tullius and Brian Fuerstenau.
1977 Brands Hatch 6 Hours
Round seven of the World Championship was the Brands Hatch 6 Hours on September 5th.
Notably, one of the works BMW McLaren 320i Turbos was on hand for Ronnie Peterson and Hans-Joachim Stuck.
They put up a tremendous effort in qualifying, at one stage, it looked like Peterson was headed for pole, but Ickx turned the boost up and went a tenth-of-a-second quicker.
The race started in very wet conditions. Ickx and Stuck battled fiercely on the opening couple of laps. However, on lap three Stuck crashed out from the lead at Hawthorn Bend and the BMW’s race was over.
During the next couple of hours, Ickx and Mass threaded through the slower cars to establish a big lead. With the rain getting harder and harder though, the race was stopped two hours in.
It resumed 75 minutes later. Mass was at wheel for the restart and motored off into lead followed by the 935s of Schurti (Max Moritz) and Wollek (Kremer).
Schurti soon went passed Mass and established a big lead, but when the sun came out, the track quickly dried and everyone came in for slicks; the Martini crew were much quicker and Mass rejoined with a healthy advantage over Schurti.
Thereafter, Ickx / Mass set about building a one lap lead and then cruised to victory. Schurti / Doren were second in the Max Moritz 935 and Joest / Wollek were third in the Kremer example. Other customer 935s were fourth (Kremer) and fifth (Valvoline Deutschland).
1977 Hockenheim 6 Hours
Even though Porsche had long-since secured the 1977 World Manufacturers’ title, attending the penultimate round of the year on home soil was a must. On October 8th and 9th, Hockenheim played host to a brace of three hour races. The overall result would be decided on aggregate times.
This time, Jacky Ickx was partnered by Manfred Schurti as Jochen Mass was racing for McLaren in the Canadian F1 Grand Prix.
Unusually, the works 935 was beaten to pole; the trick Kremer 935 K2 driven Bob Wollek / John Fitzpatrick started at the head of the field after Wollek bolted on a pair of super soft Goodyears and set the best time just as the flag came out.
During the first hour of Race 1 on Saturday, Ickx held third, shadowing the Georg Loos 935 of Rolf Stommelen and Wollek in the Kremer K2.
Schurti took over from Ickx and rejoined in second. He then blasted into the lead on his second lap out and proceeded to build a 30 second lead. Schurti looked set for win before dramatically retiring with 25 minutes to go; the cylinder head gasket had blown as a legacy of turning up the boost too high.
In Race 2 on Sunday, Kremer began with a four lap advantage and weren’t about to risk losing the overall victory to win the second heat.
The works Martini car led from the off and by the two hour mark the were two laps clear.
However, with 35 minutes to go, Schurti lost everything but fourth gear and slowed dramatically. The Kremer car began to close rapidly, until it too encountered trouble (a broken throttle linkage to one bank of cylinders).
Nevertheless, the two sick Porsches held out. The works Martini car ultimately finished a lap ahead of the Kremer machine driven by Wollek / Fitzpatrick. Unfortunately though, Ickx / Schurti were not classified in the overall standings after their failure to finish the day before.
The JMS Racing customer 935 of Ballot-Lena / Lafosse was second and the works two-litre class BMW 320i of Marc Surer / Eddie Cheever rounded out the podium in third.
With more than three times as many points as their nearest rival, Porsche skipped the final race of the year (the Vallelunga 6 Hours on October 23rd).
1977 World Championship Standings
Porsche ended the year with 140 points. Their closest challenger was BMW whose two-litre class 320s amassed 55.5 points on their way to the Division 1 honours.
Text copyright: Supercar Nostalgia
Photo copyright: Porsche - https://www.porsche.com
