Reconstructing cab floor and rocker panels

[movario]

Hi
I'm currently doing the cab floor and the rocker panels and have a few questions:

1. Is the rocker panel somehow attached to the cab floor? I know it is by some spot welds at the front and back and the pinch welds on the bottom. But I haven't seen any welds on the top. It's also loose if a wiggle around with a screwdriver.




2. How should I replace the front cab mount, the footwell (that triangle part) and the rocker panel?
My plan is this order:
- Replace front cab mount
- Replace the footwell (without attaching it to the rocker panel, but attaching it to the front cab mount)
- Replace rocker panel (without spotwelding the pinch welds on the bottom)
- Replace the cab floor with the inner rocker panel (and attaching it with the pinch welds to the rocker panel and attaching it to the front cab mount)



The cab is already braced, but I think a will put and additonal strut between the lower A pillars

 

[imiceman44]

Hi
I'm currently doing the cab floor and the rocker panels and have a few questions:

1. Is the rocker panel somehow attached to the cab floor? I know it is by some spot welds at the front and back and the pinch welds on the bottom. But I haven't seen any welds on the top. It's also loose if a wiggle around with a screwdriver.

View attachment 513119
View attachment 513120

2. How should I replace the front cab mount, the footwell (that triangle part) and the rocker panel?
My plan is this order:
- Replace front cab mount
- Replace the footwell (without attaching it to the rocker panel, but attaching it to the front cab mount)
- Replace rocker panel (without spotwelding the pinch welds on the bottom)
- Replace the cab floor with the inner rocker panel (and attaching it with the pinch welds to the rocker panel and attaching it to the front cab mount)

View attachment 513121

The cab is already braced, but I think a will put and additonal strut between the lower A pillars

It's supposed to have spot welds top and bottom

 

[Conner]

1. The cab floor makes a small shelf under the top inside edge of the rocker panel that the rocker panel spot welds down to. I assume yours is loose from the rust. The "inner rocker" is really just the floor pan bending down/vertical. I had to rebuild this on my truck, I have pictures in my build thread you might find helpful.

2. Mine wasn't quite this bad but I had to replace a lot of the same stuff. Again see my build thread, I went into detail there. I basically cut the rocker off, patched the floor support/cab mount piece, patched the front of the floor and put a new kick panel in simultaneously (I had to fanangle them in kinda together otherwise neither would fit if the other was already in place), patched the back of the floor, then put the outer rocker on.

If you're using the replacement floor pans that appear to be the same from all retailers, they do not match the actual floors very well. It probably doesn't matter, EXCEPT for the step down the floor has that the edge of the rocker sits on. For my replacement rear floor, the step down was about half of what it should be (and didn't match the front piece from the same seller?!). Which would have put the rocker too high up, and made the door opening wrong... I did it in halves (front then rear) to ensure I knew exactly where the ledge was supposed to sit vertically by leaving the original ledge there while I did the front half, then matching the back to the front. Again, I detailed this more and included pics in my build thread.

You mentioned bracing the cab, and I think that's smart. Especially with the cab mount being replaced and the side cowl piece off, I would be very careful. Good luck!

 

[imiceman44]

1. The cab floor makes a small shelf under the top inside edge of the rocker panel that the rocker panel spot welds down to. I assume yours is loose from the rust. The "inner rocker" is really just the floor pan bending down/vertical. I had to rebuild this on my truck, I have pictures in my build thread you might find helpful.

2. Mine wasn't quite this bad but I had to replace a lot of the same stuff. Again see my build thread, I went into detail there. I basically cut the rocker off, patched the floor support/cab mount piece, patched the front of the floor and put a new kick panel in simultaneously (I had to fanangle them in kinda together otherwise neither would fit if the other was already in place), patched the back of the floor, then put the outer rocker on.

If you're using the replacement floor pans that appear to be the same from all retailers, they do not match the actual floors very well. It probably doesn't matter, EXCEPT for the step down the floor has that the edge of the rocker sits on. For my replacement rear floor, the step down was about half of what it should be (and didn't match the front piece from the same seller?!). Which would have put the rocker too high up, and made the door opening wrong... I did it in halves (front then rear) to ensure I knew exactly where the ledge was supposed to sit vertically by leaving the original ledge there while I did the front half, then matching the back to the front. Again, I detailed this more and included pics in my build thread.

You mentioned bracing the cab, and I think that's smart. Especially with the cab mount being replaced and the side cowl piece off, I would be very careful. Good luck!

I don't know if the 73-75 door sill is different from 76-91 but my 74 had 3 layers sandwiched there, the outer rocker, the inner rocker which was a flat ish piece to keep the outer piece attached top and bottom making a rigid bridge, the the third layer was the floor.
All 3 connected making the flat section the weather strip goes on.

 

[Conner]

I don't know if the 73-75 door sill is different from 76-91 but my 74 had 3 layers sandwiched there, the outer rocker, the inner rocker which was a flat ish piece to keep the outer piece attached top and bottom making a rigid bridge, the the third layer was the floor.
All 3 connected making the flat section the weather strip goes on.

Oh weird, I didn't know they were that different. Mine (an '85 Blazer) definitely wasn't like that. Thankfully although mine was rusted, it was intact enough to see where all the original panels layered in. The floor pan is the same sheet of steel as the inner rocker. And the outer rocker is what makes the lip for the weatherstrip (the lip is a single layer along the bottom of the door opening).

I assume they must've done it differently on the '73-'75s to give it a little more beef to account for not having a roof.

 

[imiceman44]

Oh weird, I didn't know they were that different. Mine (an '85 Blazer) definitely wasn't like that. Thankfully although mine was rusted, it was intact enough to see where all the original panels layered in. The floor pan is the same sheet of steel as the inner rocker. And the outer rocker is what makes the lip for the weatherstrip (the lip is a single layer along the bottom of the door opening).

I assume they must've done it differently on the '73-'75s to give it a little more beef to account for not having a roof.

They also had a rocker box under the floor to strengthen it even more

 

[movario]

Thank you all, that helps a lot. I think I'll start with replacing the cab mount and from there reattach everything.

I also found out why my rocker panel was so weird and only semi attached.
Someone has been there before and left some shoddy work. Like everywhere where the previous owner tried to "fix" something. He would have better used a can of cavity wax instead of doing this and putting cheap diamond plate wrap everywhere...

 

[movario]

Does anyone know how and where this part is supposed to go? It's named Subframe-Cab Support-Left Hand or right hand.

Subframe Cab Support - RH - 73-91 Chevy GMC CK Blazer Jimmy Suburban

Strengthen the foundation of your 1973-1991 Chevy or GMC CK Blazer, Jimmy, or Suburban with our high-quality RH (Right Hand) Subframe Mount Cab Support. This OE-style component is crucial for maintaining the structural integrity and proper alignment of your vehicle’s cab, ensuring it remains...

www.autometaldirect.com

 

[Conner]

Does anyone know how and where this part is supposed to go? It's named Subframe-Cab Support-Left Hand or right hand.

Subframe Cab Support - RH - 73-91 Chevy GMC CK Blazer Jimmy Suburban

Strengthen the foundation of your 1973-1991 Chevy or GMC CK Blazer, Jimmy, or Suburban with our high-quality RH (Right Hand) Subframe Mount Cab Support. This OE-style component is crucial for maintaining the structural integrity and proper alignment of your vehicle’s cab, ensuring it remains...

www.autometaldirect.com

I'm not sure, but maybe it's one of the floor supports that run front to back near the front cab mount? Here is that area on my truck, on the right hand side. The body mount is the front one, just behind the firewall.





Sometimes those Triplus parts are intended to be patches (vs the entire panel) and/or they don't actually match the original part very well. I'm not sure if that's the case here, but something to consider.

I can take more pictures of my truck if it would help, just let me know the area(s) you need.

 

[movario]

Thanks, that was it. It's a patch panel. It replaces the part where the front cab support and the subfame meet.
But on the original part, there is a indentation of about 1.5mm which makes room for the reinforcement plate of the subframe. The patchpanel is missing that.

i will just replace a part of the subframe. It's the one where I drilled out the spotwelds.

 

[BoondocK5]

Mine were missing the reinforcement patch also. I made do.
I’ll not buy from Auto Metal Direct again.
I had to do a bunch of beating and stretching to get panels to fit

 

[wazzabie]

Mine were missing the reinforcement patch also. I made do.
I’ll not buy from Auto Metal Direct again.
I had to do a bunch of beating and stretching to get panels to fit

What panels from AMD required some work? I thought AMD was the better of the panels.

 

[cheavyk10]

The consensus is they all come from the same plant in Taiwan.

 

[BoondocK5]

What panels from AMD required some work? I thought AMD was the better of the panels.

Floor pan under pedals and rockers

 

[wazzabie]

Floor pan under pedals and rockers

Was the thickness of the AMD rockers the same as factory?

 

[Conner]

Some parts are made by AMD, and some parts they just retail (Triplus, Xparts, etc are the actual manufacturers). I have noticed that parts that are actually made by AMD are better both in fit and in thickness than the non-AMD parts. But a lot of parts aren't made by AMD, yet at least, so the only option is another manufacturer (even if AMD retails it). Thankfully it seems like they are pretty up front about who makes the part. Everything has a brand specified on the individual parts pages on AMD's site.

For example, I got premium fenders, inner fenders, and core support from AMD, advertised as being made by AMD as the "premium" line of parts. I have not installed them yet, but I can say they appear to be truly factory equivalent in that they are correctly shaped and the steel is the correct thickness. I'm sure they will require some fitting/massaging to be perfect like any body parts that aren't original to the individual truck, but it appears to be minimal.

I also bought rear wheel houses from AMD, made by Triplus (I think, but definitely not actual AMD) before I realized they only retailed some things and didn't manufacture them. They aren't horrible but they are probably half the thickness of the factory ones or less. It was bad enough that I opted to fix my originals rather than use the new ones.

 

[BoondocK5]

Was the thickness of the AMD rockers the same as factory?

It was close, even with my little Hobart welder turned all the way down, it still liked to blow holes in the AMD replacement metal. Long before it would blow out the original.
I’m thinking maybe sheet metal welding has a big learning curve. But, I’d still like the new metal to be a little more
resistant to blowing through it.
Be prepared to do a little massaging with. Hammer and grinder. Stuff never fits right up like you’d think it would.
I broke down and bought a piece of .040 steel sheet, and have been trimming what I needed off it to make pieces that didn’t work out quite how I wanted.
That’s what has saved this floor replaced job.

 

[movario]

I was finally able to make some progress and am now starting to do the rear floor panels. Now the beam between the two sides where the bolt holes for the rear floor pans are located is very rusty, so I'm going to do that aswell.
Has anyone ever done this before? I will definitely brace the two sides so that the keep their distance.



If someone needs them, those would be my measurements:

 

[wazzabie]

Wow that is some serious rust. I'm going to check this area for rust and clean it out then treat it.
On your k5 is the yellow line a 90 degrees? Do you have a bend in the floor around the red line? I have a bend in my K5.

 

[BoondocK5]

Wow that is some serious rust. I'm going to check this area for rust and clean it out then treat it.
On your k5 is the yellow line a 90 degrees? Do you have a bend in the floor around the red line? I have a bend in my K5.
View attachment 523082

That’s no worse than any of the rest of us have had to deal with.
Mine was the Flintstone mobile, holes big enough to get you feet through.
Now, I’m about the do a bit more welding in a couple of spots, then grind down any high spots, RTV caulk around the edges and corners, just to be sure.
Then I’m dumping a gallon of Flex seal on it and rolling it until I feel like it’s nice sealed coating.