Posts Tagged ‘Jo Siffert’

monza bros

Siffert, Pedro chillin’, Redman and Kinnunen- JW squad 1970 (Schlegelmilch)

The JW Gulf boys relax before the off, the winning duo were Pedro Rodriguez and Leo Kinnunen…

There was only one Porsche 917 amongst the first nine cars home at the duration of the Monza endurance classic on 25 April but the German flat-12 was first, Pedro Rodriguez and Leo Kinnunen were happy winners.

Three Ferrari 512S followed them home, the Ignazio Giunti/Nino Vaccarella/Chris Amon Spyder 1.5 minutes adrift of the John Wyer Porsche.

It wasn’t a happy season for Ferrari in sportscars. Supremely competitive in F1 with the first of its flat-12 engined cars, the 312B, the 5 litre V12 512S really didn’t receive the development it needed to knock off the Porsches.

The German cars mainly raced at 4.5 litres in capacity that year but it was still more than enough. A win at Sebring in the second round of the Manufacturers Championship was Ferrari’s best result, and the flat-8 3 litre, nimble, light Porsche 908/3 mopped up on the tight, twisty circuits unsuited to the 917. The dudes from Stuttgart had the game well covered.

seppi

Seppi in conversation, and for the horologists he is sporting a nice Heuer Autavia chronograph  (Schlegelmilch)

The speed of Ferrari’s evolved 512S, the 512M was clear at the Osterreichring 1000 Km in October, so 1971 looked to be a great battle of two amazing 5 litre cars but effectively the Scuderia waved a white surrender flag before the seasons commencement.

They chose to race a new 3 litre flat-12 engined prototype, the 312P in 1971 with an eye to the rule change to cars of that capacity in 1972, rather than the factory race the 512M.

The Ferrari privateers did their best against the Panzers but it was ineffective, the speed of the beautifully prepared and superbly Mark Donohue driven Penske 512M duly noted. The 1971 endurance season could have been the greatest ever had Scuderia Ferrari raced those cars!

monza car

Pedro drives, Leo and the boys ride

Back to Monza 1970. The other ‘works’ Porsches were well back- the JW 917K of Jo Siffert and Brian Redman finished 12th, the Porsche Salzburg 917K’s of Vic Elford/Kurt Ahrens DNF with puncture damage after 92 laps and the 1970 Le Mans winning combo of Hans Hermann and Richard Attwood were out with engine failure on lap 63.

Still there was strength in numbers, Pedro and Leo were there at the end, in front…

Credits…

Rainer Schlegelmich

Tailpiece: Tifosi @ Monza, not as many as if a 512S won…

monza

(Schlegelmilch)

 

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lotus boys

Nina Rindt keeping a close eye on Jochen, Jo Siffert and Graham Hill all doing their best to focus on their Loti and need for speed rather than the black booted babe…

A famous Rainer Schlegelmilch shot at Monza in 1969, i don’t think its ever been established exactly who ‘boots’ is? Quite a tidy unit.

Jackie Stewart took the race, the best placed Lotus 49 was Rindt in 2nd. Siffert was classified 8th but withdrew with engine failure, Hill retired his 49 the lap before Jo with driveshaft failure and was classified 9th.

Photo…Rainer Schlegelmilch

Le Mans start 1969

#14 Stommelen/Ahrens Porsche 917LH, #20 Siffert/Redman Porsche 908/2, #22 Lins/Kauhsen Porsche 908LH, #23 Schutz/Mitter Porsche 908LH, #2 Bonnier/Gregory LolaT70 Mk3b Chev, #7Hobbs/Hailwood Ford GT40…and the rest (unattributed)

Spectacular start of the tragic Le Mans 24 Hour Race June 1969, the last with the traditonal driver sprint to the cars…

The Porsche 917 was a tricky, somewhat under-developed beast in its original specification even for experienced professionals, British privateer John Woolfe lost control of his on the first lap of the ’69 race perishing in the subsequent accident.

Despite that, a 917 took pole and lead Le Mans for 20 Hours, maybe its been somewhat maligned in its formative year?

Groups 5 and 6…

917 homologation CSI

By 1967 the Commission Sportive Internationale (CSI) were concerned about the growing speeds of the unlimited ‘pushrod production’ 7 litre Ford GT Mk4 and Chaparral 2F and 4 litre ‘racing engine’ Ferrari P4 and banned them by increasing the homologation numbers and the lowering engine capacity limits for homologation, or admission of cars into both classes.

For 1969 there were no minimum limits to qualify in Group 6 ‘3 litre Prototypes’ and a minimum of 25 cars built for homologation into Group 5 ‘5 litre Sports Cars’. Effectively this allowed the existing Mark 1 Ford GT40 and LolaT70 Mk3b cars eligible to keep grid sizes up but with the hope or intent that 3 litre prototypes would be built in large numbers, Formula 1 having the same capacity limit at the time.

Porsche would not have had the 908 ready to race in 1968 had they not anticipated the rule changes for 1968 which were only announced by the CSI in October 1967.

50 cars were required to be built to qualify in Group 5 in 1968, but that was reduced, as stated above for 1969, which left the door ajar for Porsche…

The FIA, as the governing body then was, had another crack at rewriting the rules to encourage 3 Litre prototypes with effect 1 January 1972 given the speed of the 5 litre Porsche 917 and Ferrari 512S in 1970 and 1971 but that is another story…lets not get ahead of ourselves.

Porsche had come close to Le Mans victory with their ‘class cars’ and wanted to win outright, to do so they audaciously built 25 4.5 litre air-cooled Flat 12 engined cars, the 917 in 1969.

Having thrown down the gauntlet, Ferrari, with his coffers full of Fiat money, having sold his road car division to them in 1969, built 25 5 litre V12 512S to go head to head with Porsche in perhaps the two best years of sports car racing ever; 1970 and 1971.

On 12 March 1969 a 917 was displayed at the Geneva Motor show with a price tag of DM140,000 a fraction of the cars development costs. The cars above were displayed for inspection at the factory to the CSI on 20 April, Ferdinand Piech cheekily offering the CSI inspectors the opportunity to drive any of the cars to prove they were complete and running, the offer was declined.

917 at Geneva Show

917 homologation

25 917’s lined up at Zuffenhausen awaiting the CSI chassis count for homologation into Group 5…22 April 1969. (Porsche AG)

Design and Construction…

917 brochure

Sales brochure for the 917, a snip at DM140,000 in 1969

Eng Ferry Piech said that Porsche would not have built the 3 litre 908 had they known the CSI intent in relation to the 5 litre Group. At the time they built the 908, a Group 6 car, the minimum production number for homologation into Group 5 was 50 cars not 25, so he can be somewhat forgiven for not being able to read the minds of the rule-makers, then as now unpredictable.

The regime of rules was not about encouraging 5 litre cars with ‘racing’ as against ‘production’ based engines.

Porsche surprised everyone, until then they had built class contenders rather than outright cars, and even then it was not thought possible to build a 5 litre air-cooled engine, to that time a Porsche specialty. Water cooled Porsches’ were not to appear for nearly a decade.

Work started on the design of the 917 in July 1968, Porsche convinced they could build a car down to the class minimum weight limit of 800Kg based on the 908 which was 300lbs lighter than their Alfa, Matra and Ferrari 3 litre rivals.

917 engine cutaway

Cutaway shot by Vic Berris of the aircooled, flat-12, SOHC 2 valve, fuel injected engine. Capacities/power  1969 4494cc/580bhp@8400rpm, 1970 4907cc/600bhp@8400rpm, 1971 4998cc/630bhp@8300rpm. Torque 376/415/425 lb ft. More than enough to see off the 512S/M Ferraris’…cooling fan absorbed around 17bhp@ maximum revs, far less than that absorbed by a water radiator @ equivalent speeds.(Vic Berris)

To speed up the development of the 917 engine the same reciprocating parts, bore, stroke, valve and port sizes of the 908 engine were usedgiving a cubic capacity of 4494cc with a bore and stroke of 85X66mm. Porsche belived initially at least it wouldn’t be necessary to build a car to the full allowable 5 litre limit to dominate.

All the fuel injection and valve timing settings were taken over albeit the valve angle differed to allow cooling air passages between the valves. Four valves per cylinder was never an option for this reason.

Apart from the above the flat 12 is an entirely different engine to the 3 litre flat 8.

A long crankshaft did not allow anything other than a central power take off to avoid catastrophic torsional vibrations. The long crank hence became effectively two shorter cranks joined together at their flywheels, which were just a gear in mesh with another on the output shaft running parallel to and under the crankshaft which ran on 8 main bearings.

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917 engine on the dyno in 1969 (GP Library)

The power output shaft drives the triple gear type oil pump with 4 additional small oil pumps driven by the exhaust camshafts.

Another shaft running symmetrically with the crank drives the 2 distributors of the electronic ignition, the Bosch fuel injection pump being driven off the left hand exhaust camshaft.

The engine had few steel or iron parts; the crankcase, cam covers and timing gear case were magnesium. The heads and cylinders were aluminium and titanium was used for conrods, auxiliary drive shafts, the main output shaft and later in the engines development valves and valve springs.

The cooling blower and most of the air ducts were plastic.

The 4.5 litre engine weighed 528lb in original form and developed 542bhp on its first dyno run, this rose to 580bhp@8400 by the time the car arrived at Le Mans in 1969.

A new gearbox was built to take 376lb ft of torque, the case was magnesium, used Porsche synchromesh, a wet sump and incorporated a ZF ‘slippery diff’ with 75% locking factor.

917 engine cross section

Cross section of the incredibly complex 917 engine, 200 hours to assemble. Magnesium crankcase split along its centreline. Power takeoff by pinion between the 2 middle main bearings, 8 main bearings. DOHC per bank, 2 VPC sodium filled. 2 plugs per cylinder. Not winning was not an option! (Porsche AG)

917 assembly

All hands on deck…homologation and timeline pressures created surely one of the most amazing production lines ever!? (Porsche AG)

The chassis was largely that of the 908…suitably reinforced, the spaceframe was welded aluminium tube. Note that later in the program three chassis’ were built of magnesium.

The wheelbase was 90 inches and track in 1969 58.8 inches front and 60.4 inches rear with 15 inch wide rear wheels.

As with all Porsche racing cars the frame had to withstand 600 miles of hard driving on the Weissach ‘Destruction Course’ but even so a tyre valve was incorporated into the 103lb frame to allow it to be ‘inflated’, a loss of pressure indicative of chassis cracks…sub-optimal in a car of this performance!

Again, magnesium, aluminium and titanium parts were widely used for the running gear; titanium for spherical joints, hubs, springs, gear lever and steering column. Magnesium for uprights and wheels and aluminium for the steering rack, this obsessive approach to weight ensured the car tipped the scales at less than 800kg.

917 spaceframe

Porsches’ obsession with weight extended to the chassis which was welded aluminium tube. Total weight 103lbs. The one on the right is unfinished. Strong and light…both 917 and 512S Ferrari were spaceframe chassis’, hardly state of the art in 1969/70 but effective all the same. Porsche did not build an aluminium monocoque racing car till the 956 in 1983. (Porsche AG)

The suspension geometry was the same as the 908but incorporated anti dive geometry by angling the upper and lower wishbone pivots to each other.

Wishbones were used at the front with coil spring/damper units and an adjustable sway bar. At the rear a single top link and lower inverted wishbone was used. Radius rods provided fore and aft location, and again coil spring/damper units were used and an adjustable sway bar. Bilstein provided the shock absorbers.

Initially 9×15 front, and 12×15 inch magnesium alloy wheels were used, with a single centre aluminium lock nut, the same as the 908.

The suspension was largely set up at the Nurburgring, long suspension travel, plenty of camber change and tyres of a rounded tread section necessary for performance there. This did not translate at other circuits where the car was ‘under-tyred’ and the geometry unsuitable as well. More of this later in the article.

Brakes in 1969 were ATE aluminium calipers operating on cast iron ventilated rotors/discs.

917 rear suspension drawing

Factory rear suspension drawing. Upper top link, inverted lower wishbone & progressive rate coil spring & damper unit. Titanium driveshafts with ‘rubber donut’. Magnesium uprights, titanium hubs. ATE aluminium brake calipers clamped ventilated iron discs. Wheels in mag alloy with aluminium lock nut. (Porsche AG)

The bodies were developed in the wind tunnel…

917 cutway 1969 LH

Both short and long tails and were interchangeable, with the latter 236mph on the Mulsanne Straight was reached in 1969. The ’69 bodies were fibreglass which was bonded to the chassis and incorporated two seats and doors.

Stability of the cars were critical, front spoilers were fitted and a ingenious setup of mobile rear flaps connected with the rear suspension in such a way that if the suspension was compressed the flaps would create an aerodynamic force to raise the tail whilst if the suspension was extended, the flaps would angle up to push the tail down.

In 1969 these appendages caused major dramas as only two weeks before Le Mans the FIA banned movable aerodynamic devices on all racing cars, a consequence of many wing failures in F1.

As the 917 was almost undrivable without the flaps, with which it was designed and homologated, the cars were allowed to race at Le Mans but the devices had to removed thereafter. 25 sets had been made to comply with homologation requirements but only 2 or 3 used!

917 Wing flaps

Porsche factory drawing showing how suspension deflections actuated the rear wing flaps, from full to no downforce. Movable aero devices banned by the FIA from the end of Le Mans ’69. Changes to bodywork design obviated the need for the flaps in both short and longtailed forms in 1970/71. (Porsche AG)

porsche 917 tail

’69 spec long and short tail comparisons. (Porsche AG)

Racing the 917…

The traditional Le Mans test weekend took place on the weekend of April 4, the 917 making its public circuit debut. Rolf Stommelen drove the car and achieved a speed quicker then the 908LH,(LH is ‘Langheck’ or Long Tail) on paper the car had potential but the handling and levels of stability were frightening.

917 Le Mans test weekend

The first public on circuit appearnace of the 917 was at the Le Mans test weekend in early April 1969. (unattributed)

Le Mans test weekend 917 in Paddock

Fettling the 917 at Le Mans test weekend. No amount of ‘at the track fettling’ would deal with the high speed instability the drivers were experiencing at the time. Body is fibre glass, bonded to aluminium chassis. (unattributed)

Spa 1969 917

First race apperance for the 917, Spa 1969. Gerhard Mitter and Udo Schutz shared the car but an engine failure early in the race meant only Mitter got a race drive. (unattributed)

After little testing testing two cars were entered for the Spa 1000Km in May. Jo Siffert and Brian Redman tested their 917 but chose to race a 908 and won the event from Pedro Rodriguez/Chri Amon in a Ferrari 312P and Vic Elford/Kurt Ahrens in another 908.

Gerhard Mitter started his 917, having qualified 8th but retired with engine failure on lap 1 having possibly over-revving the engine at the start. The 917’s were experiencing high speed instability, the reason Siffert electing to race a 908LH.

917 Spa 1969

Mitter wrestles his 917 around Spas’ La Source hairpin, early aero with adjustable wings at rear and no winglets at front…compare front of the 917 at the Osterreichring below. ’69 cars exhausts exited from both the rear and aft of the doors. (unattributed)

Mitter and Udo Schutz won the next event, Targa in a 908, their were no 917’s entered on a circuit totally unsuited to them.

Frank Gardner 917 Nurburgring 1969

Frank Gardner and David Piper brought the 917 home for its first race finish at the Nurburgring 1000Km .(unattributed)

For Porsches’ home event, the Nurburgring 1000Km on 1 June they hired two hardened sports car professionals in Frank Gardner and David Piper to ‘bring the thing home, that they did in 8th place having wrestled the unruly beast around 44 laps of the ‘Green Hell’ Nurburgring.

Gardner was a noted test and development driver, Porsche were keen to get his views on changes to make the car competitive. The race was won by Siffert/Redman in a 908 ahead of two other 908’s.

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Gardner/Piper 917 ahead of the Hobbs/Hailwood Mirage M2/300 BRM DNF and Ortner/van Lennep Abarth 2000SP NC (Schelgelmilch)

 

Le mans start 1969 Siffert in lead

’69 LeMans start. Jo Siffert #20 908/2, Elford #12 917LH, Schutz 908LH, #7 Hobbs Ford GT40, #2 Bonnier Lola T70Mk3b Chev, #64 Hermann 908LH, #22 Lins 908LH…and the rest. (Porsche AG)

Le Mans 1969…

Other than more power, 580bhp and with the anti-dive geometry of the suspension reduced from 50% to 5% the 917 arrived at Le Mans as designed, fortunately, as described above the cars were able to race with their adjustable rear wings. Commonsense prevailed from a safety perspective.

At Le Mans Porsche famously, narrowly lost the race, the Herrmann/Larrouse 908LH being just beaten by the Ford GT40 of the ‘two Jackys’, Ickx and Oliver, winning in chassis ‘1075’ the same JW Automotive GT40 which was victorious the year before.

Elford retires 1969

The pole winning Stommelen/Ahrens 917LH retires on lap 148 with an oil leak, the car was hard driven, the teams hare. (unattributed)

Rolf Stommelen put his 917 on pole, outlining the cars potential but the car failed on lap 148 with an oil leak. Vic Elford qualified his car second, co-driven by Richard Attwood, the car lead the race for 20 hours and did 327 laps, enough for 9th place the car was not running at the finish having withdrawn with a cracked bellhousing.

John Woolfes’ car was destroyed in his fatal lap 1 accident, the car having qualified 9th in factory driver Herbert Linges’ hands. Car owner Woolfe started the race rather than the far better credentialled Linge…

elford 917 le mans 1969

Vic Elford in the car he qualified 2nd. He shared the car with Richard Attwood, they lead the race for 20 hours, DNF after 327 laps with a cracked gearbox bellhousing.(unattributed)

Le Mans finish 1969

Ickx wins from Hermann…the GT40 margin from the 908LH, 2 seconds after 24 hours despite losing 20 minutes in a long pitstop for the 908 to replace a front wheel bearing. (unattributed)

The First Win, Osterreichring 1000Km 1969..

Porsche did not take the 917 to Watkins Glen but were victorious again, Siffert and Redman winning in a 908 from another 2 908’s.

Osterreichring start 1969

Starting grid Osterreichring 1000Km 1969. #29 Siffert/Ahrens winning 917, #33 Bonnier/Muller Lola T70 Mk3b Chev (2nd) #9Ickx/Oliver MirageM3 Ford (DNF). The 3rd placed Attwood/Redman 917 in white is behind Siffert. #42 Matra is Servoz-Gavin/Rodriguez (DNF)…and the rest. (unattributed)

The Osterreichring was the last round of the Manufacturers Championship in 1969 and a fast track, 130 mph average, well suited to the 917’s qualities, and so it was that a factory 917 driven by Siffert/Ahrens beat Jo Bonnier/Herbie Muller in a Lola T70Mk3b Chev from Richard Attwood and Brian Redman in David Pipers 917K with Masten Gregory and Richard Brostrom 4th in the first ofthe 908’s.

It wasn’t the strongest round in terms of depth of entry of the 1969 championship but a win all the same.

Porsche 917 Spa Siffert 1969

1969 Osterreichring 1000Km winning Porsche 917K of Jo Siffert and Kurt Ahrens, the first of many victories for these fabulous cars. 4.5 litre Flat 12 at this stage. Early rear aero treatment clear in this Shell promo shot, in its first 2 races (Spa & Nurburgring) the car raced with a small fixed rear spoiler. Compare with the shot in ‘Etcetera’ below of the 1970 tail. (unattributed)

Siffert and Ickx Austria 1969 1000km

Jo Siffert leads Jacky Ickx, 4.5 litre Porsche 917 ahead of the 3 litre Mirage M3 Ford Cosworth. Osterreichring 1969. JW Engineering, the entrant of the Mirage would be contracted by Porsche to race and develop the 917’s in 1970 and 1971, becoming the dominant team…Le Mans excepted! (Unattributed)

Race Development, Testing and the 917PA…

Jo Siffert Porsche 917PA Bridgehampton 1969

Jo Siffert Porsche 917PA, Bridgehampton CanAm 1969. The race was won by Denny Hulme, McLaren M8B Chev , Jo finished 3rd. (Unattributed)

Whilst a short tail 917K won the Austrian 1000Km race against weak opposition, other than at Le Mans the cars were still uncompetitive, a mix of track, skid pad and wind-tunnel tests improving the car.

The team stayed on in Austria to test improvements to the car after its victory.

The 917 was modified in its aerodynamics by having the waistline of its doors raised and raising the tail to give the car more of a wedge shape, the changes increased drag but critically improved downforce and stability, the rear flaps now long gone. The aero changes were partially attributable to JW Automotive, who were to race the car on behalf of the factory the following year, the aero changes alone improving lap times by 4 seconds per lap at the Osterreichring.

Testing showed that wider wheels and tyres were quicker, as were stiffer springs however the suspension geometry itself was unchanged.

The engine was largely unchanged albeit the exhausts now exited at the rear whereas the front cylinders gasses had exited via the doors. The Fichtel and Sachs clutch was replaced by a triple plate Borg and Beck item and the gearbox and clutch housing was reinforced to avoid the failures experienced at Le Mans.

To further test some of the changes made an open car was built, designated the 917PA (PA ‘Porsche Audi’ the US importer of Porsche) for Jo Siffert to drive in the 1969 CanAm series, late that year.

The 917PA competed in 6 races with best results a second and a third, the car was ‘blown away’ by the 7 and 8 litre Chevs, Bruce McLaren and Denny Hulme dominant in their McLaren M8B Chevs. Valuable experience was gained for the 1970 Manufacturers Championship as well as a tilt at the Can Am series and information which would prove useful for Porsches’ successful assault on the CanAm championship in 1972 and 1973 with the awesome, turbo-charged 917/10 and 917/30.

Porsche had a fantastic season winning all but Le Mans..the Manufacturers’ Championship, the GT Trophy and the Endurance Triple Crown despite not winning the most important race of the three…

For 1970/1971 Porsche changed their approach to racing the cars, the factory continued to develop them but the race organisation was contracted to JW Automotive and Porsche-Salzburg, but those seasons of success are another story…the seeds of dominance were sown in 1969.

Porsche 917PA and 917K late 1969

Porsche media day late in 1969, the Porsche 917PA CanAm car and 917K in shot…Brian Redman, Jo Siffert and Pedro Rodriguez in attendance. You can see the refinements to the rear bodywork of the 917K, reputedly ‘cribbed’ off the Lola T70Mk3b in shot, and also on the #23 1970 Le Mans winning car below…(unattributed)

Etcetera…

Porsche kaleidescope le mans 1969

Porsche kaleidescope of 908 and 917 wings Le Mans 1969. See the text for the operation of these rear wing flaps, 25 sets made for homologation but only 3 or so actually used!. Flaps banned post Le Mans. (unattributed)

Porsche 917 at Le Mans

The original 1969 917 body in all its glory. #15 Linge/Redman/Lins car which tested but did not race at LeMans. Its a 917LH spec note front trim wings but lack of adjustable wing flaps @ rear. (unattributed)

917 cockpit

Porshce racing cockpits have always been about function…Momo steering wheel, lever for 5 speed synchro (sometimes 4) ‘box. Ally tube frames on floor visible. 6 point harness, minimalist instrumentation. (Geoff Goddard)

Jo Siffert Porsche 917PA Laguna Seca 1969

Jo Siffert being chased at Laguna Seca CanAm by Denny Hulmes’ McLaren M8B Chev, the dominant car of 1969. Porsche 917PA. Bruce McLaren won the race from Hulme, Jo 5th.(unattributed)

Hermann 917 1970

Quintessential 917K (short tail) 1970 spec car. Here the Porsche Salzburg Le Mans winning Hermann/Attwood car. Shot included to show the changes made to the cars body work very late in 1969; different door line, no exhaust exits aft of the doors, wedge shape and Lola inspired rear deck. (unattributed)

Larrousse Porsche 917L Le Mans 1970

For the sake of completeness the 917LH evolved into this bodywork in 1970…here the Martini Racing Team ‘Hippy Car’ of Larrousse/Kauhsen, 2nd at Le Mans 1970, compare and contrast the swoopy, curvaceous long tail body with the 1970 917K above. (unattributed)

Le Mans poster 1969

Credits…

Vic Berris cutaway drawing, Porsche AG, ‘Cars in Profile Collection 1’ Paul Frere, Geoff Goddard, Rainer Schlegelmilch

Tailpiece: No time to admire the scenery for Gardner! 917/004 during Nurburgring 1000 Km practice in June…

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(Schlegelmilch)

Finito…