The picture comes from the Master Parts Catalog which is available on CDROM here: 1948-56 Ford Truck Master Parts Catalog CD - HiPo Parts Garage

 

Charlie, you got it! Something just is not right. It gets worse. All four frame wings had the original stock rivets when I originally checked them. I removed the rivets for sand blasting and reinstalled them with grade 8 bolts. Part of the reason I removed them was in case I put the truck all back together never getting the answer to this question. I can swap them out after the truck is put back together easier if I dont have to remove the stock rivets. Just unbolt and swap out. Here is where I get really confused. Both frames are square frame rail to frame rail. When I check the dimensions as you suggest, they are dead on. The problem with the mountinng wings shows up once the frame rails are leveled and squared together. Once frame rails are leveled using four levels (each side rail and front and rear crossmembers), I check the frame for horizonal level (dead on) and measure the distance between frame rails at top and bottom (dead on). No sign of fatigue or cracking in the stock frame wings. No alignment issues with cab to front end sheet metal before I took trucks apart. BOTH trucks have the original cross members. It appears from my observation the original stock frame wings dropped about 1/2" but no one really feels this is correct. On my 56 Ford F-100, the big crossmember that I understand is critical to the cab support is supported at both the bottom and top of the frame so It can not spread in the vicinity of the front cab mounts. This is why Im really confused. It only makes sense that they are level all the way across, but I see no problems with the frame or wings to suggest they were level in the stock position.????

 

James, I dont see a picture attached but I did get the link to the CD and will order that up. If the picture you are referring to is the diagram of the rear mount, I got that one figured out. Its the front mounts I have issue with. In the 56 rebuild thread I seem some build photos of a 56 and the cab wings are pretty clear but not clear enough to tell if that outside end drops 1/2" or is perfectly level to each other and the frame.

 

I'll check my chassis tomorrow AM, it's sitting in the driveway with the cab (and everything else) off of it right now. You have picqued my interest. Hypothetically speaking, the wings do not necessarily HAVE to be level, there are rubber mounting pads that lift the cab about 1/2 inch when the cab is in place. Just as long as the floor of the cab does not contact the frame rail then you should be fine. Glad to hear that the rest of the dimensions check out...

 

Outlaw56, J2Davis had asked havi where he got the picture in post #6, which is why I posted the link for the Master Parts Catalog.

 

oh man thats awesome....I just been waiting for someone with a frame only to compare to what I have. Perfect! Something else to keep in mind is the "Mid Fifty" folks say if there is sheet metal alignment problems (fenders and hood to cab lines) try putting a jack under the cab wings. If you lift the frame at this location and the alignment problems go away, you have issues with the cab wings or frame. When I lift the frame by using a floor jack under the cab wings, I get no flex. The reason this matters has a lot to do with the clearance I have when swappinng out the standard manual transmission for an AOD. The AOD looks like it needs a little fabrication on the floor board to clear. If the cab wings are shimmed level to the frame, the AOD fits perfect between the stock floor and the stock cross member with no modifications. If the cab wings let the cab mount lower, it reduces the clearance between the floor and AOD housing. Knowing the correct position of the stock wings for the front mounts could ultimately have a lot to do with transmission clearance between the floor, cross member, and pinion angle. Obviously the other issue is the alignment of the hood and fenders to the cab once you put it all back together. It may be a lot of these swaps could have avoided removing the stock cross member if the original stock mounting wings were level opposed to 1/2 drop.

 

Ok, thanks James, will definitely order that CD. Thanks again.

 

In a perfect world the cab wings should be level from side to side, but it's not.
One of my mounts is 1/4 low and the other is 3/8 low. The mounts are solid and in good shape but 56 years of bouncing up and down have bent them down a bit.
I have cut two rubber pads from some buna rubber which will "shim" my cab back up to level when it goes back on.

 

I believe the original stock mounts were level. I just have not gotten comfortable with not finding any indication of them settling. I would expect the top surface to not be perfectly flat or the gusseted sides to be bowed. Looking at the brackets, I see absolutely no signs of fatigue. 1/2" drop in the brackets should show up somewhere? On the good side, this means the cab floor will be high enough to clear the AOD as well as clearing the stock cross member and still get a good angle on the pinion.

 

OK, so I unwrap the chassis and get ready to lay the level across the cab mount wings and I find that the transmission is in the way. No problem, I block it on both sides and lay the level across the wings as shown in the photo. I measure each side from the bottom edge of the level to the top of each wing, deduct off the height of the block, and what I got was a 3/16 inch drop on each side. Given some of the other "manufacturing tolerence" issues that I have found with these trucks I think that this is a "non-issue". If you replace the cab mount brackets on the underside of the cab, second photo, then you should have a very solid installation.

 

Ok Thanks so much for taking the time to check that measurement. Its looking like mine are all off up to 1/2". Thats what I really needed to know for sure. I believe the original were level or fairly close to level so thats what I should work towards. Very good news for me since it gives me the clearance I was looking for to get the AOD in between the stock floor board and the stock cross member.

 

Is there an easy way to post pictures?

 

As far as I know, you have to save the pictures online to a site like photobucket. The pics of my truck are here . . TN_53_F100's Library | Photobucket. Once you have done that, there is a little Icon that looks like a mountain range. Click on it to insert a picture. It will ask for the URL of your picture. It's probably best to have photobucket opened in a seperate browser window. When you have the pic opened in photobucket, it will give you a few windows off to the right that have the URL of the photo. It's a little time consuming to set everything up, but it's not difficult.

 

It looks like you have removed the factory crossmember that would have been underneath the bellhousing area. I cut mine out to make room for my AOD trans. Are you concerned about the frame twisting under the torsional load from the cab wings? I am about to put my cab back on the frame, and I can put considerable twist on my frame by pushing down on the cab wings with just my hands. I am concerned that the weight of the cab, interior and me going down the road will cause frame to flex and maybe break something or mess up the alignment of my sheet metal.

 

Here is a force diagram that I did some time ago that analyzes/describes the forces applied on the F100 frame due to the cab mount wings...I am an engineer so I hope that the terms can be understood by those who are not. The take-away should be that there should always be a crossmember of some type employed for the cab mount wings.