wanted: Chev CMP chassis views

[Tony Wheeler]

Originally Posted by Hanno Spoelstra

Next question: is this tapering also apparent on the CGT chassis? The picture below is well known and (to me) it seems to show straight frame rails, at least on the rear section. I recall seeing pictures of a Cab 13 CGT in Norway with straight frame rails too.

haha, it's an optical illusion Hanno! I've fallen for it myself in the past with Chevs. It only happens in photographs, because they're two dimensional, so we lose our distance perception. When photographed from rearward, the Chev siderail taper is cancelled by parallax, so the brain interprets the image as straight channel, based on a lifetime of conditioning by common straight channel. In other words we see what we expect to see. Conversely, when photographed from the side, there's no parallax effect, so the brain perceives the taper quite readily. It's easily perceived in Phil's sideview, but in the 3/4 rear view you'd almost swear it was straight channel. It's even more difficult to perceive in partial view, even if photographed only slightly rearward. I think you'll agree the taper is virtually undetectable in the pic below, and yet my tape measure shows almost 40mm difference end to end. The camera doesn't lie, nor does the tape measure - it's our brain that lies!

IMGP1627 - Copy (2).jpg

Of course, when we view the actual chassis, the brain is receiving distance input, which enables it to factor in parallax when processing visual information, and come up with the right answer! Try it next time you're near a Chev chassis, you'll find the taper quite obvious from any angle. The brain can't be fooled in three dimensions!

Getting back to your question Hanno - the CGT frame is nothing more than a C15A frame. Unlike the FGT frame, which is a modified F15A frame, there's no difference between the CGT and C15A frame. Likewise throughout the whole CMP 4x4 range, because unlike Ford frames, all Chev frames were built with a winch crossmember. It's sometimes suggested the CGT frame is different by virtue of double skinned midsection, but that's standard on the C15A frame.

I find the best way to think about CMP frames in general, be they Ford or Chev, is to consider the siderail as 3 separate sections: front section, rear section, midsection - the latter being straight channel. All front sections are identical, and all rear sections are identical - it's only the midsection that varies, and only in length, according to wheelbase. No doubt this greatly simplified production, and may have been standard industry practice in truck manufacture. Of course, it also means you can cut and shut a 60L or 60S chassis to SWB.