Once again the Formula One season ends here in Mexico City, on the 5-kilometre circuit set in the vast sports park. As usual the high altitude of the city (7,300ft) causes mixture problems not found anywhere else in the F1 programme. Last year the Honda was able to lose less power through lack of oxygen than most of the other cars and once in the lead no-one could touch it. This year, although without a doubt the most powerful car, it was also the heaviest, which did not give it the advantage it had last year.
The cars had been transported down from Watkins Glen in time for work to be completed before first practice. The entry lacked any Ferrari participation due to the racing shop at Modena being rebuilt to enable fuller coverage for 1967. Lotus had three cars for Clark, Arundell and Rodriguez. Clark’s number was on the H16 with which he won the United States GP. The engine was the same and had not been returned to England. Arundell was in the BRM V8 and Rodriguez in the Climax V8. All three cars were fitted with the latest Firestone tubeless tyres.
BRM had three cars and three engines had been sent home and returned rebuilt after the damage at Watkins Glen. Hill was again driving the true “H16” while Stewart had his number on the other two cars, both fined with “double 8” engines. The two Brabhams for Brabham and Hulme were unaltered, one still fitted with Bosch coil ignition and the other on Lucas transistorised ignition.
Both Eagles were as well turned out as ever. The 3-litre Weslake engine had been back to Rye, but still had done no track testing, which meant once again that practice was to be used to sort out the many problems not necessarily applicable to this circuit. The Cooper team had flown out a spare car for Solana to drive: this had the tracting for the air intakes together down the centre while Surtees, and Rindt’s cars were as raced at Watkins Glen, both using coil ignition. Honda had discovered that transmission oil overheating had caused the gear troubles in the previous race, so on both cars an oil cooler had been fitted at the back on a frame that held it out in the air stream. Ginther was still driving the wide-track mar, while Bucknum was with the narrower car.
The McLaren was unchanged; the engine had been to Detroit where Fords had looked it over. A new set of stainless steel exhausts had been made up but were not fitted to start with. These had shorter primary pipes which were aimed at giving a bit more power at the top end. The same four private entries that competed in the US GP were here, Ireland driving the Bernard White 2-litre BRM, Spence in Parnell’s Lotus-BRM, Siffert in Walker’s Cooper-Maserati and Bonnier in his own Cooper-Maserati.
First practice was on Friday from 1 to 5pm. The track was opened for a short period in the morning to let those who wanted to go round for a few laps to start getting their mixture right. Bonnier and Gurney went out the moment practice started and before the first hour was up everyone had some laps to their credit.
McLaren was having starting trouble again and after several efforts at pushing, the car was taken away to be towed. This towing behind the pits and going straight out on to the track was done several times by McLaren. Solana was in difficulty from the start with gears and it was some time before he overcame this problem. The two Brabhams were in convoy and going very slowly as though they were running-in new engines.
Both BRM drivers were still sorting mixture in the opening stages of practice, and after Stewart came in with oil all over the back of the engine of the training car he went out in his own car. Both BRMs were back on Dunlop for most of practice, these being the new tyres Dunlop have been rushing through since Monza.
Rodriguez in the 2-litre Lotus Climax started setting the pace with a 1min 55.71sec lap which was 0.13sec faster than the lap record held by Gurney. He didn’t hold fastest lap for long, for Brabham was now beginning to go and in a very short while was under 1min 55sec. Surtees was pushing his Cooper hard but was suffering all sorts of problems. First his high-pressure fuel pump was not functioning then when this was changed the fuel metering unit started to play up and had to be changed and at the same time the water temperature was running very high. Rindt was not suffering from these problems and in his usual wild-looking manner was getting his time well down.
A problem always found at this circuit is the number of stray dogs that manage to get on to the track. This year was no exception and when one darted at Ireland he was able to miss hitting it with the radiator but he did bend the steering arm and badly buckled the nose. Both Hondas were sounding good but their times were well down. This was due to the poor handling and after persevering for some time the front ends were taken down and new springs fitted. At the same time certain adjustments were made to stop the vicious oversteer both cars were suffering from.
The Weslake engine was still misfiring due to fuel feed problems, while an added difficulty had arisen when each time the car-came in it was smothered with aerated oil from the crankcase breather. Gurney was also out with a new nose in the car which allowed more air through the radiator but which spoilt the distinctive line of the Eagle. Stewart did several laps with the nose of the BRM off when he found his water temperature needle giving him an “oil pressure reading.” Neither BRM driver seemed very happy with the handling and this was reflected in their poor times.
“A problem always found at this circuit is the number of stray dogs that manage to get on to the track. This year was no exception”
Clark was beginning to make the H16 Lotus really go and as he lifted off after putting up a lap time of 1min 54.06sec the bolts in a crankshaft balance weight broke and bits came out of the top of the engine in a cloud of steam, hot oil and metal particles which scorched the back of Clark’s neck and necessitated an overnight engine change. This engine had run the 200-mile United States GP and about 100 miles in practice which is the same distance Stewart’s engine in the USA had gone when a balance weight destroyed it.
Also stopped out on the circuit with a wrecked engine was Spence with the Lotus-BRM. Just as practice was closing Gurney went out in the 2.7 Climax car and lapped about two seconds faster than Bondurant. Brabham also went out in the closing minutes and as if to prove he is not world champion for nothing he dipped 0.11sec from Clark’s time to give him a time of a 1min. 53.95 sec. a speed of 157.964kph.
When practice ended Bucknum was puzzled by the peculiar handling of his car. Through left-hand corners it was now almost stable while through right-hand curves it skated all over the place. Looking through the tyre temperature chits it was noticed that the centre of the left rear tyre was much hotter than the centre of the right rear. A closer look and the use of a straight edge found this left tyre to have a well-rounded profile while the right tyre was flat as it should be. This fault is caused after moulding when those particular tyres have to be quickly inflated to an exact pressure and left to cool.
Second practice on Saturday was again from 1 to 5pm and very noticeable were the increased nose sizes and airscoops. Most cars were suffering from overheating and fuel vaporisation due to the liquid’s lower boiling point. To stop vaporisation while in the pits wet rags and slowly poured water were for the most part doing the trick. Surtees, Hill, Stewart, Bonnier and Solana were off the moment the track was opened.
Both McLaren and Gurney were having a hard time starting and both cars had a long tow. Hondas were out with the new spring and suspension settings but there was no improvement so they were changed back to where they started. Early on in practice Suttees found a head gasket gone, also he was losing fuel pressure due to vaporisation so an engine change was decided on but before starting work Suttees went on doing two-lap runs, and finally got pole position with a time of 1min 53.18sec.
Brabham was putting in a number of laps trying some track tyres flown in overnight when something broke which threw all the timing out. This necessitated an engine change and the mechanics started work immediatley. The Weslake V12 was still pumping out oil even though an air/oil separator was fitted. It was now reckoned to be oil building up in the head and then over-flowing. As Ginther finally began to find the most suitable layout for the suspension and so get quicker times, so Bucknum was in trouble. First it was a cut water hose, then the clutch jammed down, next the car jumped out of gear past the pits, then it stuck firmly in third gear.
The BRMs were still not happy either with the engines. which were suffering all the altitude problems, or the handling, which doesn’t seem to be improving. Clark’s H16 was on a tight schedule to get ready, for Chapman wanted to keep the laps down to enable Clark to have a reasonable chance of finishing before a balance-weight flew off at around the 300-mile mark. This H16 problem will be fully sorted as two more 8-pin cranks are finished and they are sell-balancing. The oil over the backs of both BRMs was due to a leaky plug on the oil relief valve.
The Weslake engine was in trouble still and it was decided that Bondurant should drive at a speed which would keep the crank pressure down and so stop oil being sprayed around the track. Before the end of practice a hub bolt on Spence’s car fell off and as he braked the wheel and caliper fell off and he hit the guard rail many times before coming to a halt with the car badly damaged. The private entries were all suffering from fuel vaporisation and overheating which they were beginning to overcome.
Pratice ended and there was a lot of work to be done before the mechanics pushed the cars out on to the grid. A Goodyear track tyre had been flown in overnight and was found to be one second a lap faster than the new Dunlops so both BRMs were fitted with them.
Race morning was warm and sunny. Surtees’ new engine was not functioning very well as the mixture was well out and there was no way of getting it right except by luck. Brabham was having similar problems and at any rate his engine was 15bhp down on the practice engine. Gurney had made the decision to switch cars and both cars were re-numbered on race day. McLaren had been forced to move the rear-mounted fuel-pump to a cooler position, putting it in the airstream just behind the driver’s right shoulder. Only other activity in the pits prior to the start was the welding up of the cracked lower wishbone mounting on the H16 Lotus.
Sharp at 2:30pm the flag dropped and the race was on. Ginther made a good start and was in the lead as the 18 cars went into the first corner. At the end of lap 1 Ginther still led from Rindt. Brabham, Hulme, Surtees and Clark, the two on the front row had not been able to hold their places. Next in a long string came Stewart, Rodriguez, Bucknum, Siffert, Solana, Hill, Gurney, Bonnier, Ireland, McLaren and with Arundel last.
“As they went off on their second lap, Surtees and Hill’s engines sounded ‘off-song’, while Clark was having gear trouble”
As they went off on their second lap, Surtees and Hill’s engines sounded “off-song,” while Clark was having gear trouble. At the end of the second lap Brabham had gone past both Ginther and Rindt and was pulling away. Rodrigucv dropped two places, to he behind Bucknum and Siffert when he spun at the hairpin. Bondurant, in the Eagle-Weslake dropped from 15th to last as vaporisation caused Misfiring froth the end of the first lap.
As the 3rd lap started Surtees had moved up two places and the woolly note in his engine had gone; afterwards he said it cleared as soon as it got really hot. It only took two laps for him to pass his team-mate Rindt, and then he was right on Brabham’s tail. Brabham kept him there for one lap only, then he was in the lead with Brahham having to work hard to keep in the slip stream.
For some laps the leaders settled down. Stewart, who had lain seventh for the first three laps, began to get more confidence in the BRM’s handling and although he had a permanent plume of oil smoke from the left rear of the car, he was beginning to pull through the-field. First he got by an unhappy Clark who was having gear trouble, then next lap he was past Ginther. It took a few laps to come up with Hulme but on the 10th lap he came round in front.
The first car to the pits was Solana who had very high water temperature; after a short while he went on for one lap then retired on lap 9, when he also noted that the oil pressure was well down. Also on the 9th lap, Clark came into the pits and retired with a broken gear selector. Gurney was well down in the 2.7 Climax-engined Eagle at the start but as the race began to settle down he started to pull up. Between laps 4 and 9, he went by Solana then Siffert and Bucknum to put himself in the slipstream of Hill’s “H13 or 14.” As the BRM got worse so Hill was unable to hold Gurney any more and when an old 4-cylinder went by this seemed the last straw and he retired on the 18th lap when a metallic clanking started.
Three cars were now out and the fourth was to follow soon, as it was lying last and misfiring badly due to vaporisation. This was Bondurant in the Eagle-Weslake and he finally gave up on the 24th lap. The leaders had all closed up again there being only about 200 yards between the first four places. Stewart in fourth place was right on Rindt’s tail and with a big effort on lap 25 he was in third place and closing the gap on the leading pair at just under a second a lap. However, before he could get really to grips with the Brabham his oil gave out due to the slow but continuous leak and he retired at the hairpin on lap 26. Rodriguez had been delighting the Mexican crowd as he closed on Hulme and made several attempts to pass him. On lap 23 he got by to the cheers of the crowd and two laps later Hulme who was trying to get back the place, spun and as he had no clutch he had a lot of difficulty trying to restart, which lost him almost a full lap.
Ireland pushed his BRM V8 back to the pits when something went in the gearbox. However, this was of no avail and the car was retired. Two identical failures took place on the 32nd and 33rd laps. Rindt, lying in third place, slowed as he came off the slightly banked 180 turn before the pits with his left front wheel leaning in at a crazy angle and he pulled in on the grass beyond the pits with a ball joint having broken. One lap later, Siffert came slowly into the pits with an identical fault to his left front suspension.
The halfway stage was now passed and the field was reduced to 10 cars. Surtees and Brabham were still fairly close and Brabham was really working very hard to reduce the gap making use of the wide grass verges on many occasions. Third, half a lap behind, was Rodriguez; behind him, now going fairly well, came Ginther and Gurney. Lying sixth and slowly was Hulme, seventh and misfiring badly came Bucknum, then Bonnier, Arundell and McLaren.
“Smoke began pouring up from between Bucknum’s legs and glancing down he saw flames. Braking and scrambling out before the car stopped, he found the seat on fire”
For a few laps this order remained unchanged then on lap 38 McLaren moved out of last place by passing Arundell but two laps later he retired with a dropped valve. Bucknum’s was the next car in trouble. As he went down the straight he thought he smelt burning, but could not be sure. Then as he got away on the other side of the circuit, smoke began pouring up from between his legs and glancing down he saw flames. Braking and scrambling out before the car stopped, he found the seat on fire. When the burning bits were pulled out it was found that an electrical connection had touched the frame and caused a short. Leaving the burnt seat where it was, Bucknum bent the connection away and sat on it until he reached the pits, where the bare connections were taped, a new battery fitted and the Honda rejoined the race in last position.
Hulme was still making progress and he passed Gurney into fifth place behind Ginther and began slowly closing the gap on the Honda. On lap 49, to the dismay of the crowd, Rodriguez came into the pits and after only a brief examination he retired with gearbox trouble. This left only Arundell running for Team Lotus and when he pulled in on lap 55, it looked as though the whole team was out, but Arundell’s fault was the water temperature gauge giving inaccurate readings and in last but one place he trundled on until the end.
Brabham gave up any hope of catching Surtees and when he lapped his team-mate and then Ginther, who were both going very hard, he stayed just ahead of the Honda, until three laps from the end Hulme passed Ginther and then both Brabhams drew away and crossed the finish line 0.25 seconds apart but with Hulme one lap down. Surtees in first place drove a perfect race, never putting a foot wrong and deserved to win. Brabham and Hulme brought a complete Brabham team into second and third places, fourth came Ginther and to him went the fastest lap at 1min 53.75sec, a speed of 158.241kph. Fifth, and still only one lap down, was Gurney, then two laps down came Bonnier, four laps down Arundell and eighth and last was Bucknum.
And so the 1966 season was over; the start of the 1967 season should be at Kyalami in South Africa on January 2nd.