The Stovebolt Site Forums The Shop Area General Truck Talk Clutch head screws question

So I was told there's going to be lots of clutch head screws on my 41 Chevrolet 1/2 ton I haven't found any does any one know what year they started using them? All mine are slotted flat head in cab
Thanks

I have a 1941 pickup made in Oct. 1940 in Janesville. It has slotted interior screws. Only 7 or so clutch head screws in the entire truck. I needed some replacement slotted interior screws for it so I took them out of a 1940 pickup. It has philips screws holding on the door hinges

I have a 1941 parts truck made in Dec. 1940 in Janesville. It has clutch head interior screws. The door hinges are also held on with philips screws. Later trucks have clutch head screws holding on the door hinges.

Have done several 41-46 and the door weatherstrip metal strips had clutch head screws. Windshield frame screws were also. Can't remember door panel screws but I think they were also. The reason I definitely remember the weatherstrip screws is if they were seized up the clutch head dimple holds a drill (or bit to you non-machinists) centered.

Not sure what month mine is but it was built in Oakland 1212 units in. only clutch screws I've found are one s holding the data plate on so far
Oh hindges are Phillips

The sequence resets each month. I'm guessing you know that the last 2 digits of the first half of the serial number indicate the month made. Are they illegible?

On my 1941 made in October, the only places that had clutch head screws were the data plate, the front sections of hood lace, and a tubing clamp on the chassis.

its 6AK09 so then its September ??
Thanks

Have you found anyone that carries the flat head slotted screws I'm missing some?

My February 41, May 42 and Sep 42 parts truck all have clutch head for nearly everything in the cab less the floor and toe board. Even the door hinge screws are clutch head.

If the truck was messed with in the past, the clutch head screws are often discarded and more common slotted or philips were used.


If you are looking for slotted screws, they are 8-32.

Every single screw on my '41 was clutch head.

Now they are not.

I always chase each screw/bolt hole with a tap before putting a screw/bolt back in to clean the rust and crud out of the threads. The extra step actually saves a lot of time.

Likely September 1940. This would fit with my observation that only trucks built in the first few months of the 1941 model year have the slotted interior screws.

Those slotted screws are not like something you could get at a hardware store (their tips are reduced in diameter and unthreaded) and I have seen the exact same type on a handful of different quite original 1940 and 1941 trucks, so I do not think that they were replaced wholesale later in life.

My '46 is the same as coil over described. The inner door panel were removed by the PO, so I can't say for certain what the correct fastener should be.

I had a 55 once, and every screw was clutch head. My 57 GMC does not have one anywhere. All Phillips, even the door hinges.

Sput why do you say 1940 ?
and I agree these are not at Ace hardware. flat head slotted with a smooth tip I have never seen before
The truck sat from 1966 in barn still had original tube radio under dash original headliner dash etc.
NO one messed with the screws!!
Anyone know a supplier?

sput ok I thought about it and figured it out, your saying it was built in Sept 1940 as a new 1941 model year truck GOT IT

It seems that the GMC trucks of this vintage commonly used Philips head screws for the interior. I thought that clutch head screws were consistent on the Chevys. I have seen some variability in clutch head fasteners on other parts of the trucks, and date of manufacture did not appear to show a trend. Perhaps assembly plants had some autonomy. The ones I have samples from were assembled in Atlanta and Baltimore.

What is unique about these slotted screws? A picture would say a thousand words.

https://lh4.googleusercontent.com/-WMgi0Qnd-Gk/VCtKOXIvtHI/AAAAAAAABq8/Pz-GjAQSkWM/s800/IMG_4730.JPG
https://lh4.googleusercontent.com/-CZNnd6_eVyQ/VCtKPZOvrNI/AAAAAAAABrE/0pGoEY_DpYc/s800/IMG_4739.JPG

The slotted screw on the end is from my earlier 1941.
The middle screw is from a 1940 model year truck.
The clutch head screw is from my later 1941.

All are the same length and have the same reduced diameter unthreaded tip.

You could get close with a Pan Head machine screw.

Thanks Sput for the pictures those are what I have
all interior screws exactly those
My truck was built in Oakland if that helps

Sput,

Thanks for the images, it is often difficult to get such small items in focus but you did well.

Do you think Chevrolet was just starting to use clutch head screws in 1941? Perhaps if we could get some feedback for folks with 1930's model trucks it may help?

The tapered tip certainly aids in installation as those screws are very easy to cross thread in the body sheet metal. I had to repair numerous threads on my cab as the threads were too distorted to properly hold screws. I then drilled and re-tapped for new screws.

Learn something new every day.

Paul

Round head vs pan head screws.

Clutch head screws were patented in 1933 (1931 filing date).
Phillips head screws were patented in 1936 (1934 filing date).

Cadillac was the first GM division to use Phillips head screws in 1936/37.

When GM started using clutch-head screws and when they stopped using them is an interesting question.