Trimming the back cab flange

[Fordman114]

I have been searching thru all the posts looking for some information on how much to trim off of the flange on the back of the cab. I haven't found anything and very few pictures. I am planning on using the SS bed floor, at least for now, may eventually put my own wood bed on top of it.

But I am ready to mock up the bed sides and tailgate but need to know where the bed front panel sits on the frame and how much extra fiberglass to trim off of the back of the cab. The instruction manual is not any help with this. Can anyone help with pictures or dimensions? Forum searches are not getting me anywhere.

[edwardb]

I looked through my build pictures and also skimmed through my build thread. I didn't recall making any major cuts to that area. The kit was delivered with it sitting on that flange against the frame. So if I did anything it would have been to straighten for the best fit. But i wouldn't cut anything without fitting the cab. Taking too much off would change other things like the firewall fit, doors, etc. The cab fits in that flange along the back, but isn't affected by either the SS floor or whatever wood or bed covering you use. Probably not much help but FWIW. Small other hint, one of the issues I had when mine was completed was that joint between the cab and the flange squeaked and made quite a rack while driving. I put some rivets in there after the fact. Would have been easier to do something during the build. Mentioned in this post in my build thread: https://thefactoryfiveforum.com/showthread.php?37287-EdwardB%92s-35-Hot-Rod-Truck-Build-Well-Traveled&p=524709&viewfull=1#post524709

Edit: My response has several errors. Let's fix that. You're asking about the horizontal flange that extends along the back of the cab. I remember now. Didn't initially. I trimmed it back to about 1/2". My truck was the original small cab version and did come with the aluminum channel shown in the manual. I remember the channel went under the SS bed floor. I left a few screws at the front off the SS piece until it was in place. The flange on the back of the cab didn't interfered with the wood (aka vinyl over aluminum) I had in the truck bed. The SS wall of the bed behind the cab was beyond the flange. My advice about bonding/riveting that back edge of the cab, as mentioned, still stands.

[Guardm16]

OK, I can help. I debated this part for quite some time, no, the manual is no help at all. In fact if you have the extended cab truck, the manual is wrong.
After calls and emails to FFR. The rear cab-to-bed aluminum piece is not included with the extended cab version. So I bought a 1.5x1.5x1/16th inch 6 foot long piece of aluminum angle. I attached it flush upward with the back of cab lower aluminum caulked and riveted the angle to the frame. The upward arm of the angle is up against the inside of the cab, for a tight seal.
214526
Now for trimming the cab flange. It all depends on how tight you want the bed, up to the cab. The flange is about 1.5 inches and for me, that was too far away. You cant get it too close as that may cause clearance issues at the tailgate. I settled on 1 inch. You still need the full 1.5 inches on the sides of the flange to give the bed sides something to attach to. With the aluminum angle, the thickness of the cab and the radius the cab wall to cab flange, the end of my 1 inch cut and the end of the angle are a dead fit. This allows me to attach the back piece of the bed directly to the chassis without the cab flange in the way. The stainless bed fits just on top of the rear facing flange on the back wall of the bed.
214529
You can see the nut zert for the bed side. Note: their are metal tabs on the chassis at these locations, but in order to attach the bed into these, the bed would have to be too far forward for my liking. So, the cab flange will be attached to the bottom metal tab and the bed sides will be attached to the cab flange.
My cab is off the chassis right now getting ready for paint, otherwise I would send a picture of the completed fit.

Hope this helps.
V/R
Steve

[Fordman114]

OK, I can help. I debated this part for quite some time, no, the manual is no help at all. In fact if you have the extended cab truck, the manual is wrong.
After calls and emails to FFR. The rear cab-to-bed aluminum piece is not included with the extended cab version. So I bought a 1.5x1.5x1/16th inch 6 foot long piece of aluminum angle. I attached it flush upward with the back of cab lower aluminum caulked and riveted the angle to the frame. The upward arm of the angle is up against the inside of the cab, for a tight seal.
214526
Now for trimming the cab flange. It all depends on how tight you want the bed, up to the cab. The flange is about 1.5 inches and for me, that was too far away. You cant get it too close as that may cause clearance issues at the tailgate. I settled on 1 inch. You still need the full 1.5 inches on the sides of the flange to give the bed sides something to attach to. With the aluminum angle, the thickness of the cab and the radius the cab wall to cab flange, the end of my 1 inch cut and the end of the angle are a dead fit. This allows me to attach the back piece of the bed directly to the chassis without the cab flange in the way. The stainless bed fits just on top of the rear facing flange on the back wall of the bed.
214529
You can see the nut zert for the bed side. Note: their are metal tabs on the chassis at these locations, but in order to attach the bed into these, the bed would have to be too far forward for my liking. So, the cab flange will be attached to the bottom metal tab and the bed sides will be attached to the cab flange.
My cab is off the chassis right now getting ready for paint, otherwise I would send a picture of the completed fit.

Hope this helps.
V/R
Steve

I had emailed FF about that rear cab to bed aluminum piece and they told me that that piece is not used on the extended cab version. My flange on the back of the cab is 2 1/2 " and that is how far the bed floor overhangs the rear of the frame if I slide it up to the flange on the cab

[Fordman114]

214534214535

[Fordman114]

I looked through my build pictures and also skimmed through my build thread. I didn't recall making any major cuts to that area. The kit was delivered with it sitting on that flange against the frame. So if I did anything it would have been to straighten for the best fit. But i wouldn't cut anything without fitting the cab. Taking too much off would change other things like the firewall fit, doors, etc. The cab fits in that flange along the back, but isn't affected by either the SS floor or whatever wood or bed covering you use. Probably not much help but FWIW. Small other hint, one of the issues I had when mine was completed was that joint between the cab and the flange squeaked and made quite a rack while driving. I put some rivets in there after the fact. Would have been easier to do something during the build. Mentioned in this post in my build thread: https://thefactoryfiveforum.com/showthread.php?37287-EdwardB%92s-35-Hot-Rod-Truck-Build-Well-Traveled&p=524709&viewfull=1#post524709

Thanks Paul, by the way I have been wanting to ask you where you got the vent grills on your hood side panels?

Randy

[edwardb]

Thanks Paul, by the way I have been wanting to ask you where you got the vent grills on your hood side panels?

Randy

Those grills are from Street Dreams by Ross. 24" street rod vents. I bought them unfinished but he also offers them finished. http://www.streetdreamsbyross.com/vents.php

Note I added a note on my previous response to your question about the rear flange. I completely misunderstood the question (and didn't remember exactly...) so my response wasn't great. :( I added some more verbiage that hopefully is more accurate. Mine was the original short cab version so I can't say how it applies to yours with the newer cab.

[Guardm16]

I had emailed FF about that rear cab to bed aluminum piece and they told me that that piece is not used on the extended cab version. My flange on the back of the cab is 2 1/2 " and that is how far the bed floor overhangs the rear of the frame if I slide it up to the flange on the cab

That was my experience also, but I wanted the gap between the bed and cab to be smaller, so I cut 1.5 inches off the top portion of the cab flange. Going any closer would have the bolts/nuts for the tailgate hinge very close to the chassis.