The Truth About Cars » torque tube http://www.thetruthaboutcars.com The Truth About Cars is dedicated to providing candid, unbiased automobile reviews and the latest in auto industry news. Sat, 02 Aug 2014 03:20:50 +0000 en-US hourly 1 http://wordpress.org/?v=3.9.1 The Truth About Cars is dedicated to providing candid, unbiased automobile reviews and the latest in auto industry news. The Truth About Cars no The Truth About Cars editors@ttac.com editors@ttac.com (The Truth About Cars) 2006-2009 The Truth About Cars The Truth About Cars is dedicated to providing candid, unbiased automobile reviews and the latest in auto industry news. The Truth About Cars » torque tube http://www.thetruthaboutcars.com/wp-content/themes/ttac-theme/images/logo.gif http://www.thetruthaboutcars.com Curbside Classic: 1963 Tempest LeMans- Pontiac Tries To Build A BMW Before BMW Built Theirs And Almost Succeeds http://www.thetruthaboutcars.com/2010/12/curbside-classic-1963-tempest-lemans-pontiac-tries-to-build-a-bmw-before-bmw-built-theirs-and-almost-succeeds/ http://www.thetruthaboutcars.com/2010/12/curbside-classic-1963-tempest-lemans-pontiac-tries-to-build-a-bmw-before-bmw-built-theirs-and-almost-succeeds/#comments Tue, 14 Dec 2010 17:25:19 +0000 http://www.thetruthaboutcars.com/?p=376863 In the thirties and forties, GM pioneered and brought to market some of the most innovative, successful and lasting new technologies: diesel-electric locomotives, the modern diesel bus, automatic transmissions, refrigeration and air conditioning systems, high compression engines, independent front suspension, and many more. But GM’s technology prowess was just one facet of its endlessly warring […]

The post Curbside Classic: 1963 Tempest LeMans- Pontiac Tries To Build A BMW Before BMW Built Theirs And Almost Succeeds appeared first on The Truth About Cars.

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In the thirties and forties, GM pioneered and brought to market some of the most innovative, successful and lasting new technologies: diesel-electric locomotives, the modern diesel bus, automatic transmissions, refrigeration and air conditioning systems, high compression engines, independent front suspension, and many more. But GM’s technology prowess was just one facet of its endlessly warring multiple personalities. Planned obsolescence, chrome, fins and financial rationalization were the real moneymakers, especially during the technically conservative fifties. But in the period from 1960 to 1966, GM built three production cars that tried to upend the traditional format: the rear engined 1960 Corvair, the front-wheel drive 1966 Toronado, and the 1961 Tempest. And although the Corvair and Toronado tend to get the bulk of the attention, the Tempest’s format was by far the most enduring one: it was a BMW before BMW built theirs. If only they had stuck with it.

A high performance four cylinder engine with four-venturi carburetion, four-wheel independent suspension; four speed stick shift; perfect 50-50 weight distribution; a light, compact yet fairly roomy body; decent manual steering; and neutral to over-steering handling qualities: sounds just like the specs for the all-new 1962 BMW 1500/1800. Or a Mercedes, or a Rover 2000 perhaps? But none of them had this: a rear transaxle and a totally revolutionary flexible drive shaft.  When GM gave its engineering talent the freedom to innovate, the results were often extraordinary. But in true GM fashion, penny-pinching resulted in the 1961 Tempest arriving flawed, like the Corvair. But unlike the Corvair, The Tempest never got a second chance to sort out its readily fixable blemishes. If so, the result would have been even more remarkable than the 1965 Corvair.

John DeLorean may be more famous for the ’59 Wide-Tracks, the GTO, the Pontiac OHC six, and the ’69 Grand Prix during his tenure at Pontiac, but in my opinion, the 1961 Tempest is his most ambitious and creative engineering effort. He was aware as anyone of the limitations of the Detroit big car formula: too big, thirsty, front-heavy and dull-handling. With the 1960 Corvair in the wings, DeLorean’s lingering plans to build a truly advanced and practical car finally came to (not quite ripe) fruition.

DeLorean was particularly interested in the benefits of independent rear suspension that so many European cars like the VW, Porsche and Mercedes had been using since the thirties. In the mid fifties, his engineering team developed an even more radical evolution of the Mercedes approach for the 1959 full-sized Pontiacs: a rear transaxle to balance weight distribution, and connected to the engine with a flexible shaft drive inside a rigid torque tube. That innovation was his alone, and he received a patent on it. And please don’t call it “rope drive;” good luck trying to send power through anything resembling a rope. It was a single flexible piece of steel, more akin to a torsion bar or a speedometer drive shaft.

The big 1959 Pontiacs arrived with their ad-friendly wide tracks, but were otherwise utterly conventional. But GM wanted to foist the new rear-engine Corvair on Pontiac, in order to spread its high development and production costs. The prototype Pontiac Polaris (above) was classic badge-engineering: a ’59 Pontiac-ish front end grafted on an otherwise unaltered Corvair. But the Pontiac brass Bill Knudsen, Pete Estes and DeLorean weren’t buying it, in part because DeLorean was already familiar with the Corvair’s tricky handling and nasty habit of spinning or even flipping when it got pushed too far.

DeLorean’s initial plan was to use the Corvair body, but turn it into a front-engined car while leaving the whole Corvair rear suspension and its transaxle in place, not even turning it around to face the motor. By using a hollow shaft, the Corvair transmission would actually be “driven” from the rear of the car, resulting in the torque converter hanging off the back of the differential, where it would normally have mated up to the Corvair’s rear engine.

Very creative indeed, and rather bizarre to see the torque converter just sitting there in the open like an appendage (above).  The drive shaft had three inches of deflection (curvature), and that curvature was strictly induced by applying the appropriate stresses on each end; there were no intermediate bearings necessary to locate it within the torque tube.

The rigid torque tube’s benefits went well beyond resulting in an almost-flat floor. It was a key component to adapt the four cylinder engine and help tame its vibrations. A four cylinder theoretically has perfect primary balance. But because it has only two power impulses per crankshaft rotation, second order and torsional vibrations can be quite significant, especially in a larger displacement motor. Traditionally, Europeans kept fours to two liters or less for that reason. Mitsubishi reintroduced the balance shaft with its 2.6 liter four in 1975, and it is highly effective and now very common in smoothing large fours.

This is why Detroit shunned fours like the plague; in order to provide American-style torque and power, American fours had almost always been large. At low engine speeds, like in the Ford Model T and A, this was not too bothersome. A suitable six might have been perfect, but Pontiac had little choice but create a compact and low-cost four by building it the quick and dirty way: eliminating one of the banks of its 389 CID V8. This was very cost effective, because it used a high percentage of the V8′s parts, and could be machined on the same lines as the V8.

Rigidly mounting the four to the front end of the torque tube eliminated the need for the engine mounts to control its front-to-back movements, so it was possible to isolate it and its vibrations from the body to a much greater degree than if had been mounted in the usual fashion. The mounts on the four only had to control its vertical movements, so they could be very soft. That does result in an impressive display of vertical “jumping” when the throttle is opened from idle.

That’s not to say that the 195 cubic inch (3.2 L) four’s noise, vibration and harshness issues were all miraculously solved by DeLorean’s innovative mounting solutions. It’s a very big four, for better or for worse. It does have a fatter torque curve than a comparable six or eight for its displacement, and therefore is very responsive. And thanks to Pontiac’s high performance experience, it could be quite powerful; output started at 110 hp, and went up to 165 hp with the optional four barrel carburetor. That overshadows the 1961 Corvair’s 98 hp optional engine.

As it turned out, Pontiac didn’t have to use the actual 108″ wheelbase Corvair body after all; GM relented and let them share the Corvair-based but slightly larger 112″ wheelbase Y Body that Buick and Oldsmobile were preparing for their 1961 compacts. But Pontiac was given a very tiny budget to adapt it, so the 1961 Tempest (above) used most of the Olds F85 sheetmetal with a ’59 Pontiac-derived front end and a new rear end grafted on. But the four cylinder, flex-drive and Corvair transaxle and its rear suspension were retained, for better or for worse.

The worst was that it was a simple swing axle: rigid half-axles jointed only at each side of the rigidly mounted differential. This was the hot new thing in Europe back in the thirties, but its tendency to jack up in fast corners and create snap oversteer and flipping had become all-too well known.

That’s why Mercedes developed its innovative single low-pivot rear axle (above) with an anti-jacking compensating spring in the early fifties, a temporary step before it adopted a double-jointed irs in 1968. BMW’s “Neue Klasse” 1500/1800/2000 sedans first arrived in 1962 with a double-jointed rear suspension. As did the Jaguar S sedan. Europe was moving on, and GM would quickly learn this painful lesson in penny-pinching. The 1963 Corvette Sting Ray had a new double-jointed rear axle, which the 1965 Corvair also adopted to great effect.

I showed you the odd Tempest automatic transaxle earlier, but here’s the (leaky) four speed in the featured convertible. That round bolted cover on the end is where the Corvair bellhousing would have attached.

And here’s the front of the same unit, showing the shift linkage which the Tempest conveniently shared with Corvair too. It wasn’t a model of precision and quickness, but Porsche had to have something left to improve when it adopted a highly similar torque tube rear transaxle for their 928 and 924/944/968. The 968′s three liter four was only slightly smaller than the Tempest 3.2, and its ferocious torque showed to best advantage the benefits of a large displacement four with balance shafts. If John Z. had remembered about the 1904 Lanchester’s patented balance shafts and adapted them, the Tempest would really have been a milestone car.

Speaking of Porsche’s claims about their pioneering:

a minor error in the text

The ’61 and ’62 Tempests did also offer a version of the aluminum Buick 215 CID V8 optionally, but only 1-2% of them were built with it, and only a tiny handful with a stick. Theoretically, the combination of the light and smooth V8 with a four speed and the Tempest’s independent suspension and perfect weight balance would have potentially made a very appealing package. But the V8 was troublesome from the beginning, and Pontiac had to “buy” it from Buick, so the four was pushed heavily. And the hi-po four did make almost as much horsepower as the V8.

The Tempest was widely (and rightfully) hailed when it arrived. It won Motor Trend’s COTY, and accolades from the press: “a breakthrough for Detroit”…”a wonderfully refreshing automobile”…”a significant coup of major import”…”may be the forerunner of a new generation”…”unquestionably a prototype American car for the sixties”. Testers praised its 50-50 front-rear balance, which resulted in lighter steering, less understeer, better traction and braking, and a good ride. But its ability to create the dreaded snap oversteer in the wet or on quickly driven curves was not left behind with the Corvair’s rear engine. The Tempest’s handling could also be tricky, and its agricultural sounding four could not be fully tamed, even if some of its shaking was mitigated. Consumer Reports was not so enthralled.

1962 Tempest LeMans

The Tempest met its sales expectations, selling 100k in 1961, 140k in ’62, and 130k in ’63. That helped Pontiac clinch third place in the sales stats. But it suffered the same problem as the Corvair: profitability was not up to snuff. The extra costs in converting the Olds body and the drive shaft and rear transaxle bit into the already slim margins on compact cars. The whole ambitious Corvair/Tempest/Olds F85/Buick Special Y-body experiments left GM with a bad aftertaste, especially since Ford was doing so well with its utterly conventional Falcon and Comet. The dull 1962 Chevy II was the effective replacement for the Corvair, and the B-O-P compacts became highly conventional mid-sized cars in 1964.

Our next door neighbor in Iowa City, a Russian professor, drove a white ’62 LeMans convertible like the one above. I vividly remember the throb of the big four as I rode with her to Sears to get her lawnmower fixed. But the open top was even more effective than DeLorean’s other efforts to drown out its agricultural sounds, at least above thirty or so. And I once briefly drove a co-worker’s base ’61 sedan in LA: despite being elderly, its intrinsic balance (which could be all-too easily upset for amusing purposes) and decent steering for an American car was downright un-American. If only its engine ran sweetly like my Peugeot 404′s. But the trade-off was the torque: very American indeed.

Our featured car is a 1963 LeMans, which was the sporty/upscale variant analogous to the Corvair’s Monza with the same bucket seats and higher trim. The ’63s were restyled to make them appear bigger, wider and longer. This convertible has all the right options, at least for those that have a soft spot for the four. I found it in front of this shop where it had just been converted to the factory 165 hp four barrel setup. And it also has the four-speed stick. Not surprisingly, its owner turns out to be a ’63 Tempest junkie; it was the car he always wanted in high school.

Norman has over half a dozen ’63s in and a round his shop and back yard, including this sedan still on the trailer that he just picked up. And he has another convertible (below) with the optional 326 V8 that replaced the aluminum V8 for 1963. This was a prescient move by DeLorean, and foreshadowed the 1964 GTO.

The 326 is a 389 with smaller bores (and actually displaced 336 cubic inches), and although no lightweight, it still results in a quite decent 54/46 weight distribution because of the rear transaxle. With a two barrel carb, the 326 made a fairly modest 260 hp, but the Tempest was light (2800-3000lbs) so with the V8 it scoots right along.  Because of limited funds, the four speed was not upgraded to handle the V8′s torque, so as far as is known, all the 326s came with the three speed stick or the two-speed Powerglide/aka: TempesTorque automatic. Norman says his fours get 18 – 20 mpg, and the 326 around 16 – 18 mpg.

To mitigate its handling rep, the 1963 Tempest’s rear suspension was revised with a modified control arm geometry and other tricks. But it was still a swing axle, and the Tempest’s end was already in sight, to be replaced by live-axle conformity.

But in my imagination, I see a 1965 Tempest coupe based on the stunningly beautiful ’65 Corvair body, with the 230 hp Sprint OHC six under a lengthened front end and sharing that Corvair’s new Corvette-based rear suspension. What a genuine American BMW that would have been, right down to the dash (the BMW’s Tempest look-alike dash appeared on the ’66 1602). In my oft-repeated GM coulda-shoulda dreams.

A scan of an in-depth SIA article on the Tempest is here

Over two hundred other Curbside Classics are here

The post Curbside Classic: 1963 Tempest LeMans- Pontiac Tries To Build A BMW Before BMW Built Theirs And Almost Succeeds appeared first on The Truth About Cars.

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