I purchased a '31 stoneguard and shell recently. I have the service news pg 15 which shows the method of installing the optional guard using special clips etc. I do not know if mine would have been factory installed or after delivery.
Mine was installed using 1/4" SS carriage bolts/nuts at the two bottom corners (not a problem likely to exchange for blind nuts).
My ? is regarding how to affix the top mounting. The shell was fitted with a pair of carefully made (perhaps original?) 1/8" steel plates, a 1&1/2" round one as a backer plate having two small threaded hole and a large center hole, and a second front plate shaped like a tombstone, having 2 3/16" holes on each edge and a 1/4" threaded center hole. The two pieces were "somewhat centered" in the rad opening and screwed together with 2 small steel screws. A 1/4" slotted round head bolt went through the stoneguard into the 1/4"threaded hole and was snugged up.
Does any of this sound about right for the original factory mounted units?

If not, can someone advise how factory units were fitted? Did they have any rubber gasketing at this location to fill the gap between the plates?

Then there is the fitting of the badge. The unit did not come with one, and I have one from a '30 rad, but the mounting "shove-in piece/spring" is in the center of the badge, and needs to be in the lower half of the badge to fit proper hole in stoneguard. I assume a special badge was specified for this with an offset mounting piece/spring?

Finally, this unit came with some small rubber pieces affixed (2 on each side). The service news refers to these bumpers but does not show their size, shape etc. I see where they fit into brackets at the top of my unit (lower brackets are missing). I am not sure the ones with mine are proper, so if any one can describe them great. If not, about how far from shell was stoneguard spaced?

The 1931 parts book which i have list these following parts.

Anchor,Radiator screen upper support.
Rd slotted head bolt ( 1/4" - 20 x 1/2")
Lock washer ( 1/4")
Stud, Radiator screen lowerLower support
Lock washer ( 1/4")
Hex nut(1/4"-20)
Blind nut ( 1/4-28 chrome plate)
Bumper , Radiator screen rubber
Clip, Radiator screen lower support inner
Anti-squeak,Radiator screen Starting crank hole
Name plate ( not used with screen)
Name plate ( used with screen)


So, It looks to me that the lower studs were fed through from the front and then fitted with the plain hex nut and lock washer at the back.(must have had a center raised stop or flat area), Then the screen , followed by the Chromium plated blind nut.

The name plate had a push in fitting , which was in a lower position compared to the non screen version.

I'm going to have to get one of those parts books! Do you (or anyone) have any idea what the part named "Anchor, Radiator screen upper support" looked like? Was it similar to that shown in service news for retrofitted screens and intended for those applications only? I figure the factory installations used something different.

As for the bottom, based on the parts list we assume a threaded stud was affixed to radiator shell using the hexnut and lock washer, and left protruding through front of the shell sufficiently to allow for the thickness of the screen and air space and then a blind nut was used to secure it. Question is what was used to hold stud in place at front surface of shell and to keep screen from moving toward shell as bolt was snugged up? Did stud have a flange of some sort fitting against shell? Was a second hex nut used on outside? Was it meant to be adjustable to allow even spacing of screen from shell? Also, are these "1/4" chrome blind nuts" available?

The 2 lower studs would have been a single unit with a flat spacer already attached, which is simmilar to the standard bolt used when the screen was not fitted. It had a large rectangular shape on the outer side , which was radiused on the face to give smooth / curve look.

You should be able to make the lower studs with a piece of 1/4' stainless steel thread, or brass thread, and then silver braze a plate ( 1/4" thick??) in the centre.

There also is a lower centre clip which looks like it is attached to the lower centre 10-32 bolt in the lower radiator panel.

Have posted a photo of the top attachment.

I have also measured the rubber bumpers at the top of the screen , and they are 1/2" x 1/2" x 1/4 " thick rubber. They
are held in place by a slight crimp of the strap which holds them in place.

The one good rubber which i have sits about 3/16" out from the back of the radiator screen edge, which would give you the spacing of the screen from the radiator shell.

Thanks so much Jack39. Your picture shows the top mounting piece identical to my "tombstone" shaped piece I described at the outset. So now I know just how the top was done. As for the bottom connection(and the rubber spacers), your advice is excellent and I will make up the necessary pieces from stainless, and should be able to get close to the original finished look. Thanks for your help. Cheers.

The Filling Station has them in stock again. I bought one on eBay from them the other day for $20.00 and 5.95 Shipping. The other vender on eBay wants $59.00 plus shipping for the same manual. Get one while you can, they are worth the $$$.

I have seen multiple of these tombstone type of top attachments, the same as we have, I think that the type shown in the 1931 service news may have been a quicker method to install the screen in the service workshops.