1960-1963 was a remarkable period of time when GM introduced a number of innovative vehicles, the result of an adventurous spirit in the air (or something in the water) at GM. The rear engine Corvair, the Buick aluminum V8 and cast-iron V6, the Tempest with its independent rear suspension and flex-drive, the turbocharged Olds Jetfire and Corvair Spyder. GM seemed determined to break out of its rather conservative mold on a number of fronts.
And the trucks were not spared either; in 1960, GM did something very unusual, even to this date: it equipped almost all of it s truck, from light duty pickups all the way to HD semi-tractors with torsion bar independent suspension. And like so many of the innovations from that period, this one didn’t last either; by 1963 solid axles were back, and the light duty trucks got a conventional coil-spring front suspension.
Presumably, that big-truck IFS was less than successful on several levels, because finding one still on the road has become nigh-near impossible. I actually did see one driving not long ago, but I couldn’t shoot it. So this handsome solid-axle ’66 Chevy C60 will have to stand in, and be a testament to the fact that not all innovations pan out.
The Chevrolet and GMC trucks were all-new in 1960, and were the first really substantial change since the Advance design trucks from 1948. The pickups and light duty trucks were significantly lower, due to an all-new frame that allowed the cab to sit lower, and new suspensions front and rear.
The rear suspensions on the ½ and ¾ ton light trucks had a new coil spring rear suspension. But the really big news was up front: a totally new SLA (short-long arm) independent front suspension with torsion bars. And all the way up to the heavy duty models (C80).
The frames for the light duty trucks shows how it drops down behind the front wheels, allowing for the lowest cab at the time. And the frame has a center X member, adding rigidity.
Only the 4WD and forward control models were spared the new IFS revolution. GM made a bold gamble with this, and like quite a few other of its bold moves during this period, it just didn’t pan out. No wonder GM became so conservative technically in the mid 60s and later.
Here’s some images I found at 6066gmc.guy.com of a C60 series truck’s suspension. I can’t find any conclusive information anymore as to why GM dropped the design after 1962, but I remember some anecdotal comments years ago about it being more maintenance intensive. And possibly not quite as rugged in difficult service conditions. And undoubtedly being more expensive. I suspect the last one was the over-arching reason it was dropped, as presumably there was no competitive sales advantage, and a higher associated cost.
What’s clear from these pictures is that the system for the larger trucks was not only much more rugged than the light-truck version, but the torsion bars act on the upper A-arm, whereas on the light trucks it works on the lower A-arm, like the Chrysler system. Undoubtedly this was done to keep the torsion bar out of the way of the undercarriage.
As a kid, I was surprised to not see the typical solid dropped front axle on some of these Chevy trucks, until I figured out what was going on. And they became rarer with time. So until I chase down that running C50 stake bed with IFS that I saw, we’ll have to move on for now and savor the solid axle of this C60.
And yes, it is a ’65, thanks to its tell-tale badge being in this position, and not down lower like the ’66.
And what is feeding those twin exhaust stacks? Sadly, I neither heard it running, or was willing to pop the hood as there were workers nearby from the company. But if it’s the original engine, we can make some guesses.
The standard engine for the Series 60 (15,000 to 21,000 lbs GVW) was the 292 six, rated at 170 gross and 153 net hp. Yes, truck engines back then were always shown with both gross and net hp, as the second number was the one that really counted. BTW, 153 net hp is pretty stout for an old-school in-line six with a one-barrel carb, more than a lot of V8s would muster in the 80s.
The optional engines (for the C60) 327 V8 with 185/158 hp, and the 348 with 220/180 hp. Note that the 292 had more net hp than the 283, and almost as much as the 327. That helps explain why it was commonly used in medium sized trucks; lots of torque and plenty of hp. And its torque came in at 1600 rpm, unlike the 283’s at 2400 rpm.
When I worked on a construction crew in Iowa in the early 70s, we had a C50 truck with the 283. Not surprisingly, for a truck engine the little 283 was a relative screamer, as it needed (and was happy to provide) lots of revs, unlike the Y-Block Fords in the other truck. Quite the contrast; but caning it to 5000 rpm for each shift did make me wonder how long it would last.
The 409 was reserved for the even bigger trucks (C80), but who knows, there could be any permutation of Chevrolet V8 under there now, even a 427, which made for a wicked-sounding truck engine at full chat. For that matter, nothing sounded better than the 348 and 409, with their distinctive exhaust bite.
Even if IFS didn’t pan out, we can still mull over the joys of Chevy V8 sounds through twin exhausts; even more memorable, and enduring. And here’s a question: has any other truck maker tried IFS in the heavier weight classes, other than Tatra?