Fixing a common cab 12 design problem

[Keith Webb]

Because of the timber frame used to hold the roof onto the cab 12 (and I suspect cab 11) we see a number of different solutions to the problem.

What happens is as the wood shrinks and softens with age the cab separates at the windscreen pillars. I've seen this even in wartime images, so it was definitely a design problem.

Fixes range from long braces to this relatively elegant (but ultimately failed) solution.



What examples of running repairs have you seen?

[Keith Webb]

This one was designed not to come apart!

[Keith Webb]

Fit a cab 13 roof of course! Problem solved.

[aj.lec]

couple of other modifications

[Keith Webb]

Originally Posted by aj.lec

couple of other modifications

The mudguard braces are a popular solution aren't they?

[hrpearce]

Keith another one you know about, I've seen these brackets around farms but carn't remember what they are for.

[Keith Webb]

Originally Posted by hrpearce

Keith another one you know about, I've seen these brackets around farms but carn't remember what they are for.

Yes, that looks familiar, Robert.

The annoying thing is they made a hole in the roof which I'll have to repair!

[Alex van de Wetering]

Nice thread subject Keith! It's the same with the cab 11 indeed....rotting wood doesn't help.
A few weeks ago I removed the winter cover from my unrestored C8 cab 11. I stood on the bumper to remove the timber frame I built over the truck to hold the "tent" when the complete windscreen dropped inside the cab with a loud bang......Which made me wonder how the cab 11/12 windscreen frame is supposed to be attached to the rest of the cab in the first place?And is there a difference between the cab 11 and 12, because the 12 has the "opening" windscreen. Are the brackets (used to the sure the frame to the cab with bolts) welded to the round windscreen tube-frame? or do the brackets have a round section and does the round frame just slide over it? I welded mine temporary, but it seemed I was not the first individual that had a go at "fixing' the frame.

Alex

[Ganmain Tony]

On my beast Keefy, it almost started happening straight away. I attribute it to the fact the cab is bolted rigid to the Chassis. A massive improvement was acheived in changing this in the Cab 13 design.

Any movement over bumps and the poor old thing sounds like a square rigged ship of the line in Nelsons Column...

It may also have been exacerbated by the excursion I had into a table drain when I came around a blind corner on a dirt road at 70 km/h and discovered I was at a T intersection.

The ensuing bump when the front wheels touched ground again caused suprisingly minimal damage, but they did cause those two timbers to come loose at that left hand windscreen corner.

Ive seen some impressive mods including the entire frame replaced with metal and welded to resemble the hull of a T34.

But in the end, they all seem to come apart

[Hanno Spoelstra]

Or fit a new windscreen and cab top. . .

AWM ID Number: 116992 / Summary: SINGAPORE, STRAITS SETTLEMENTS. 1945-09-05. TROOPS OF THE MADRAS REGIMENT, 5TH INDIAN DIVISION SUPERVISING JAPANESE PRISONERS OF WAR AS THEY REMOVE AN UNSERVICEABLE TRUCK FROM HILL STREET.