OBS Stock Floor Body-Drop how-to....lay that rocker

[Jimmy P]

*****Under Construction*****

First off a big thanks to 9chevy4 for borrowing his photobucket to me until i get my own

Here is a quick run-down of whats required to do a stock floor bodydrop. I will break this up into a few different parts:
1) Lowering the cab mounts
2) Sectioning the frame under the cab and welding in the 2x4 tube
3) Modifying the cab floor (over transmission, driveshaft and part of the frame)
4) Lowering the core support mounts
4) Bodydropping the bed

Keep in mind as you are looking at these pics that alot of them dont represent what the finished product should look like. For example some of the pics show spot or tack welds ....these were later finished off with a solid bead for strength.

The first thing that I did was to set the frame up on jackstands and level it off and comfortable working level. Here you can see my stock body mounts are in pretty sad condition so I decided to just make new ones. If your body mounts are in good shape you can just reuse them and lower them down instead of making new ones.
I layed a piece of box tube under the frame and took measurements off of that.


To make the new mounts I started with some 4"x4" x1/4" tube and cut it to look like these.


Using the old measurments as a reference I welded the new mounts in place of the old ones ..only they were 2.5" lower.



Once its tacked in place you can cut out the new hole for the rubber body mount. I used torches but a plasma cutter would be ideal for a perfect cut.



Once all 4 body mounts are lowered its time to trim the frame down to make clearance for the cab which will be sitting 2.5" lower. To maintain the strength of the frame I welded in some 2x4 tube. I used 3/16" wall tube...which i feel is plenty strong but not overly heavy. The front of the tube will have to notched since the frame kicks upward right at the front of the cab.


Tuck the piece of 2x4 inside the frame until it hits the front curve of the frame

In the back make a second piece of 2x4 for the kickup at the back of the frame. clamp the 2x4 close to the frame and tack weld the two piece together while they are in the frame


Once the pieces are tacked together you can remove them and weld them together all the way around for a nice solid connection.

RE-install the 2x4 into the frame and clamp it nice and tight against the frame. The more clamps the better.



Now its time to start welding them together. There are a bunch of holes in the outside of the stock frame which allowed me to weld the 2x4 to the stock frame from the outside.

[Jimmy P]

Next up is to weld together the inside of the stock frame to the new 2x4.

I trimmed the 1/2" lip off the bottom of the stock frame that stuck out past the 2x4 just to make a cleaner look when it was welded up.

More welding of the two pieces together


Ok so once the whole bottom of the stock frame and the 2x4 have a nice solid weld(be careful not to get it to hot and warp it) you can start trimming the top of the stock frame off flush with the 2x4. Sawzall would prob be best at this point...I used the torches. I cut half of it ..then welded the top of the 2x4 to the old frame.

TAke notice how I angled the stock frame to blend in with the new frame. This elimates the drop off that would occur. I think the slope looks better and is stronger than just a sharp angle. The only problem is that it will require minor floor mods under the seats.

Now you can go ahead and trim the front sections. I went ahead and made a new top piece to blend the new frame and old ones out of 3/16" plate. I also welded in another piece of 3/16" plate along the side for additional support.



Once that is all welded up it should look like this:

[Jimmy P]

Now you will need to do something with the tranny x-member. Since the 2x4 is welded inside the frame the old one will not work. You can either trim the edges down and weld it in place, make brackets to bold it in place or make a new one like I did. I used some 1.5" 3/16" wall round tube and grade 8 bolts. (If anyone is interested in these x-members please contact me)





To add some strength to the body mounts I went ahead and added some 3/16" gussets to them. Just to make sure they dont go anywhere. The body mounts and gussets were solid welded on both sides top and bottom.


Double check your welds and give it all a nice coat of sealer and your ready for the cab.

Here are a few pics of the clearance with the cab on...its resting on the frame in the back. It needs some small notches under the seats and at the back lip of the cab. Didnt take any pics but its pretty self explanitory once you get to this point. Ill add pics of my floor later.

[Jimmy P]

The center section of the floor will also need to be raised to clear the transmission and driveshaft. Here is what needs to be cut out...I actually cut the whole tunnel out front to back and raised the whole thing up later on.




UPDATE: Here are the pictures of the trans tunnel raised up and welded in. I did the tunnel in three seperate sections only cutting out one part at a time. Once it was welded in I moved back and cut then next part out. This kept the floor stong enough. It may flex/bend if you were to cut the whole part out at once. I raised it up to make sure I had enough room for the driveshaft to clear out back then ran it straight forward. Also in these pics are the channels I had to raise for my exhaust pipes. Depending on how you run your exhaust system and the size of the pipes you may or may not have to do this too. I wanted to make sure the exhaust heat wouldnt be burning the paint off the floor.





And finally your new cab height.

[Jimmy P]

Part 2...dropping the core support: coming soon

[Jimmy P]

part 3 coming soon....
mods: just saving these posts so they stay at the top of questions/comments

[Jimmy P]

one more just in case
semi finished bodydrop(still not laying frame in this pic due to front suspension)

[Hole-Shot]

Sorry to comment, now, but I think a little something squirted out when I read this article. Makes it look so easy!

[CKTA]

Nice work Jimmy.

[HHH]

great article.. Bro.. Now, I just need to get up the nerve and money to body drop mine....

[Socko]

Damn you, damn you to hell Jimmy! Thanks for making bodydrops seem easier to me!!! Damn you :kidding:

To clarify one thing, after you had welded the 2x4 in and began to cut the stock frame, u then welded the top of the old stock frame down onto the 2x4 (besides where it kicks/slopes up)

[Jimmy P]

Originally Posted by Socko

Damn you, damn you to hell Jimmy! Thanks for making bodydrops seem easier to me!!! Damn you :kidding:

To clarify one thing, after you had welded the 2x4 in and began to cut the stock frame, u then welded the top of the old stock frame down onto the 2x4 (besides where it kicks/slopes up)

hehe i do what i can...i figure if everyones truck is in progress i wont feel so bad

Once the 2x4 is welded inside the frame I trimmed what was left of the stock frame that stuck above the 2x4 off. Then I welded the top outside edge of the 2x4 to what used to be the side of the stock frame.

[thecodeman]

Now I want a frame for a nbs 'burban to start on

[Sweet Tea Man]

what about the back of the cab where its sitting on the old frame? why wasnt it cut down too? am i missing something?

[Jimmy P]

Originally Posted by Project 88

what about the back of the cab where its sitting on the old frame? why wasnt it cut down too? am i missing something?

I decided to just notch 1/2" off the back of the cab instead. I dont like the way it looks when it just drops off at a sharp angle so I blended the new and old together.

[Sweet Tea Man]

ya kinda lost me there jimmy.....you got a pic?

why wouldnt you just chop the rest of the old frame off with the rest of it when you welded in the box tubing like above?

[Jimmy P]

Originally Posted by Project 88

ya kinda lost me there jimmy.....you got a pic?

why wouldnt you just chop the rest of the old frame off with the rest of it when you welded in the box tubing like above?

you could do that...and alot of people do.....

But the thing is that it really isnt neccasary to cut that much of the frame off if you dont have to, because the cab has alot more space under the back. This pic shows the cab after the bd and its about 1/2" too high. I decided to just leave it there for more strength and because i think it looks better having it "slope" right onto the 2x4. Other wise you have like a drop off.

[DjLunchbox]

awsome jimmy! trucks looking good!

[cajundragger]

jimmy p-do you think that when I help a friend B/D his 2500 4 door short bed we should use 3x4x1/4 for the tubing or do you think 2x4x1/4 would be stong enough?? Anywaz awesome thread, I deff will be printin it out and stapling it together for a B/D 101 book....haha

[Jimmy P]

Originally Posted by cajundragger

jimmy p-do you think that when I help a friend B/D his 2500 4 door short bed we should use 3x4x1/4 for the tubing or do you think 2x4x1/4 would be stong enough?? Anywaz awesome thread, I deff will be printin it out and stapling it together for a B/D 101 book....haha

If I was doing an ex cab or larger i would prob use 3x4 x 3/16". The only problem I see is right at the front where it needs to slip into the boxed portion of the frame, you would need to trim the inside of the boxed section out to allow the 3x4 to slide far enough into the frame. Not a problem really, but just something to keep in mind.