wanted: Chev CMP chassis views

[Tony Wheeler]

Originally Posted by Hanno Spoelstra

So in the case of the subject vehicle, does the fact that it has "heavy"/"large" steering ends (the type with six bolts on top) means nothing to identify it?

In order to answer that question Hanno we'd need to know Chev practice with the C30, which can only be confirmed by checking wartime photographs and surviving examples. If you find the C30 retained small steering ends universally, just like the C15A, then the large steering ends would identify this vehicle as C60S. On the other hand, if the C30 steering ends were upgraded in later production, just like the C60L/S, they would not be definitive.

My own belief is that the C30 would have retained small steering ends, just like the C15A. Certainly this appears to be the case with the F30 chassis in Australian ambulance use. These were very late production chassis, and they differ greatly from late production F60S chassis supplied to Australia. Based on my own observations:

late production F60S: large steering ends, large steering box, auxiliary springs, reinforced chassis.
late production F30: small steering ends, small steering box, absent auxiliary springs, non-reinforced chassis.

Interestingly though I have seen ONE ambulance chassis which is late production F60S in every respect except absent auxiliary springs. For the moment I've dismissed this chassis as anomalous, perhaps reallocated from F60S production, however it may not be the only one.

On the question of diff ratio - normally this correlates with wheel size: 6/39 diff with 16" wheels; 6/43 diff with 20" wheels. On that basis the C30/F30 diff may seem anomalous, however the C30/F30 ran much bigger tyres than the 15A, so it's not a direct comparison. More importantly perhaps, the 2-speed transfer case would call for the more robust 6/43 diff.

Another identifying factor on the C30/F30 is absent brake booster, just like the C15A/F15A. It's worth noting here that the Ford workshop manual associates the booster directly with steering end size:

BRAKES - All Vehicles Having 6" Steering Ends.
Booster..........Yes

BRAKES - All Vehicles Having 4 7/8" Steering Ends.
Booster.........No

This strengthens my belief that the C30/F30 retained small steering ends universally, which also implies 2" front brakes. In other words the C30/F30 chassis was nothing more than a lengthened C15A/F15A chassis fitted with 2-speed transfer case, 6/43 diffs, and big tyres. My only query concerns auxiliary springs specified in the Ford manual - is it an error, or is the ambulance an exception...?