X-ray spec: Under the skin of the Brabham BT34

Despite its distinctive nose, Ron Tauranac's last Brabham, the BT34, was hardly the pick of the bunch. But it should not be sniffed at, writes Keith Howard

Brabham BT34 cutaway header

Graham Hill in the Brabham BT34 at the 1971 Race of Champions at Brands Hatch

Fox Photos/Getty Images

Perhaps I just don’t eat enough seafood, but I’ve never quite been able to picture how the Brabham BT34 earned the soubriquet ‘lobster claw’ — although its unusual disposition of twin radiators and central front wing was sure to earn it some kind of nickname. It was the last car Ron Tauranac designed for Motor Racing Developments, the company he and Jack Brabham had set up in 1961, before his departure following the firm’s sale to Bernie Ecclestone. His next stop was Ralt, where the extraordinary Tauranac success story would continue.

Raw statistics suggest that the lobster claw was not exactly the high point upon which Tauranac would have chosen to end a chapter in  his career that had netted two F1 drivers’ and constructors’ championships in 1966 and ’67 and raised him, in many people’s eyes, to the same plane as Colin Chapman. In fact, the BT34 performed nothing like as well as its predecessor, the BT33, which in 1970 secured the team fourth-equal place in the constructors’ championship and rekindled the heady days of the mid-1960s with a win for ‘Black Jack’ himself in South Africa. In 1971, running both the 33 and 34, the team could only manage ninth in the pecking order, although Graham Hill — by then being unkindly referred to as ‘over the Hill’ — took the lobster claw to an emotional victory in front of a home crowd at the International Trophy. Next season, following Tauranac’s departure, Brabham was ninth again running the 33, 34 and 37.

Graham Hill with Ron Tauranac in Brabham BT34

Hill and Tauranac. Left, oil cooler sat in its own ducting, otherwise rear of car was typical early ’70s fare, including Ford-Cosworth DFV

Brabham BT34 front

Hairy nostrils: BT34’s wing had two positions. It ran in this high one, but its designer now considers this a mistake

GP Library/Getty Images

But there is some satisfaction for Tauranac in the fact that various design features of the BT34 were borrowed and deployed more successfully elsewhere. He could, in any case, be forgiven for perhaps taking his eye off the ball — not only because of his soon-obvious immiscibility with Ecclestone, but because his workload at MRD was, and had always been, prodigious. From the outset it was in at the deep end, sink or swim. MRD’s first car — originally called the MRD but later renamed the BT1 — was a Formula Junior, as was the BT2. Tauranac notched up his first Formula One car with the BT3, which in the last two races of 1962 was good enough to bag Brabham successive fourth places.

“I was responsible for designing and building cars for F1, F2, F3, Indy and more. From 1961 to 1970 we built more than 500 cars. To keep track of all that and go to meetings, you couldn’t sit down and analyse things in meticulous detail. Other teams employed designers and they had to come up with new cars each year to justify their job. I tended to use the same parts over and over again, and just change the bits where we thought there would be a gain.”

One of the gains he was looking for in the BT34 was some ground effect from its novel front wing, which had the option of a low, track-hugging mounting position and the benefit of the radiator pods at either side acting, in effect, as endplates. However, for reasons explained overleaf, the ground effect front wing was, in the event, never exploited, leaving it to others to inherit the idea and reap its benefits. But it is another intriguing aspect of a car whose principal significance was not its own race performance so much as its legacy.

Brabham BT34 cutaway

 

1. Tauranac: “I’d used inboard rear brakes on the first MRD car, the BT1 FJ in 1961, so we had some experience of it. It was mainly to reduce unsprung weight, but it had a disadvantage: if you have outboard brakes the heat from them warms the rims and the tyres and helps get them up to pressure quicker. This is probably more important at the front than at the back because you can always give the back wheels a bit of a spin like they do in hillclimbing — at the front you had to rely on the brakes. Getting temperature into the tyres was a big, big deal.”

2. “I’m pretty sure this was the first time I’d used an air-box to feed the engine inlets. The intakes were either side of the rollbar because I reckoned you’d pick up more flow there than above the driver’s head, because of deflection of the air by his helmet and the windscreen. You get two effects from the airbox: the first is some supercharging ram. Also, if you ever watch an engine on the dyno there’s some fuel mist standing off the inlet trumpets by about 75mm. If you put a surface parallel to the trumpets a short distance away, it returns that mist and you can control a bit where in the rev range you get your power by adjusting how close it is. Without the airbox that mist just blows away into atmosphere, so you also save petrol. We didn’t have a dyno facility to play with that spacing, but since then there’s been a lot of development on this, particularly in F1 .”

From the archive

3. “I’d always measured torsional stiffness — not religiously, like it is now, but I’d done it in Australia with my home-built cars and I also had a little rig for it at Surbiton. In fact Vanwall sent me its mid-engine chassis to twist there — I still have a copy of the report I wrote on it; it was very weak. I found that if you bounced on the beam used to twist the car you could see where the chassis moved and so identify where to put the diagonals. I’d use pieces of cotton, run them diagonally across various areas and see whether they snapped or hung loose. It was my method of doing finite element analysis before it was invented! With a tubular chassis, if you got 600lb ft per degree you weren’t doing too bad, and with monocoques you were lucky if you doubled it. With honeycomb you could get up to 2000-2500. Compared to modern cars these figures are laughable, but they were enough. All you need is sufficient stiffness so that if you adjust the front rollbar it affects weight transfer on the rear wheels as well as the fronts. As long as we had that, we could adjust the cars no problem.”

4. The BT33 had used inboard front spring/damper units; the BTU reverted to an outboard configuration — something which looks like a retrograde step: “Quite possibly it was. I’d had Ralph Bellamy working for me on a pushrod rocker system, which hadn’t been used up to that time. Because of all the hats I was wearing I hadn’t had a lot of time to get into the detail of its design and at he’d drawn was just a little too complicated for my way of doing things — I liked to keep it nice and simple — so we didn’t adopt it. Ralph left and went to McLaren, and I think the next McLaren had a rocker system on it! This decision happened late, so we had to revert to a conventional outboard arrangement.”

5. Whereas the BT33 had a conventional front wing for the period, the BT34’s was a departure: “With a single radiator you ditched the hot air onto the driver. I thought that if we put the rods out each side we’d get over that problem, and get a better airflow through them so they could be smaller. I had two positions for the central wing, high and low; I was hoping the low one would give us more than a normal wing. But when Graham Hill tested it, he chose the high position. It’s significant that McLaren’s Can-Am car picked up on putting the wing low across the front. Teddy Mayer told me he adopted it after seeing it on the Brabham. It really worked for them; we made the wrong choice.”

6.”Ralph Bellamy had drawn triangular fuel cells for the car, which were adopted by Gordon Murray after I’d gone. When Ralph left I squared them all up because I wanted to have the least surface area for volume of petrol, to keep the weight down, and I wanted as much as we could comfortably put in the seat tank so that the side tanks didn’t have to be so big or reach so far forward. The car’s low top deck reflects this.”

7. “Moving the oil cooler from under the rear wing to this little sidepod made the rear wing work better by reducing turbulence. Hot air from the front radiator outlets mixed with cold air before it reached here so we didn’t have any problem with the cooling. It was a lead-in to putting the radiators back here in ducts. Enclosing and ducting the oil cooler also made it much more efficient; otherwise the air approaching a radiator sees a blockage and skips around it. So, like the front radiators, the oil cooler could be much smaller.”

8. Although always concerned to achieve the smoothest possible airflow to the rear wing, Tauranac did not share others’ enthusiasm for the use of an engine cover: “I found that all engine covers did was increase the temperatures under them by 10 degrees. A curvy engine cover made no difference to your speed because the air didn’t follow it; air will only turn six or seven degrees maximum, otherwise it just breaks away.”

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