Halfbreed - GMC Z71 + IH Extd Cab

[Frizzle Fry]

That looks pretty schweet. Chop does work well on those.

[sparkydog]

Thanks to all of you for your thoughts and ideas. I had PLENTY of time to sort things out while driving back to Portland from Vista this weekend. I also stopped in Jacksonville and met with my coach/cousin-in-law Terry Simmons from T's Rod and Fab. After all was said and done I have decided that I will stick to my original plan and go for the cab-forward look - and deal with the consequences of that decision. When I get back to Vista, my next steps are:

a) position cab fore/aft at final location and make final trim of GMC firewall/cowl so I can drop the cab down to the approx final ride height. DONE!

b) remove GMC fuel tank and cross member (which need to drop 2" to give me the lowest bed ride height). DONE!

c) cut the forward wall off the bed, shave the taller cross ribs and get it up on the chassis for full scale mockup. DONE!!

d) mess with bed and cab ride heights until they match and clamp off at this position. DONE!

e) proceed with tack welding/fab of cab to floorpan and cowl to firewall. DONE!

f) make final cuts to bed and remove section, proceed with tack weld of shortened bed. DONE!

g) mod/refab new cross member and reinstall fuel tank at lower ride height. DONE!

That ought to give me plenty to do for the next 3 weeks of the build.

[Racinaround]

wow if i could only that much done in three weeks!!

[sparkydog]

OK I have a little bit of progress. Got the bed empty and out where I can work on it and up on some blocks.

Welded in a cross brace and marked up the bed where I will rough cut in order to get it mocked up on the GMC chassis.

I also dropped the gas tank and confirmed that not only did I get a running truck for $550 but it had a nearly full tank of gas! Not that I am complaining but now I have to get that fuel over into my Burb because there's no way I can play around with a full tank of gas if I have to modify the ride height of the tank.

Next up is shaving 4 brackets off the bottom of the bed and cutting off the front.

[sparkydog]

Cut the front of the bed off.

Shaved some unwanted brackets off and notched a cross rib.

Added a support strut to keep the wobbly sidewall stable.

[sparkydog]

I was going to wait until Sat morning when I had some help to get the bed up on the chassis. But is was only about 3pm at this point so I did my typical thing and went ahead on my own.

[sparkydog]

So far I am really happy with the progress. I have a few adjustments to make under the bed to clear a couple of things. Then I think the bed will come down about 1/2" in the back and 1" in the front.

I also think I will shorten the bed another 1/2" or so to get the wheel positioned better in the fender well.

Maybe by tomorrow I will have the bed front back in and can start tack welding.

[89muscletruck]

Now thats cool!

[NONHOG]

Man your going to town ! awesome progress

[sparkydog]

Well lads and lassies - mark today on your calendars. Approx 5 months after starting the tear down and after all the sawing and slicing and towing and stowing of chit. I finally started putting stuff together!

Friday and Saturday I morphed the former cab dolly into some overhead beams up in the trusses of my rental so I could hang the bed from the ceiling.

And on Saturday I measured and marked the bed for the final cuts. Today I waited like an impatient little kid for 9am to roll around so I could start cutting. I ended up taking a total of 11" out of the length of the bed.

[sparkydog]

Then it was "jump in the deep end" time and I started lining up the metal and tack welding. Did I mention that I have NEVER done this stuff before?

(But I DO sort of know what I am doing... )

I started in the middle of the floor and worked my way over to each side. Then up and down on each side. I was very, very happy with my first day ever of tack welding. I think I will redo the drivers side exterior wall of the bed but that is not bad for a virgin.

[sparkydog]

Next it was time to dive under the bed and check for interferences. First stop was in the very back where I wanted to see just how close the GMC frame rails came to the back of the rear skirt of the IH bed. I knew is was going to be close (but that I cleared OK) and there it was - just as if I had planned it.

In the photo the dark colored stuff is the GMC frame and the lighter rusty stuff is the bottom of the IH bed. The holes in the frame are where the bumper brackets and receiver hitch bolt in.

Next stop was farther forward where the shortest height IH bed cross rib was. This was the rib I was trying to lay down on the top of the GMC frame rails. As you can see in the pic I have about 1/2 to 3/4 clearance.

All the way forward was the highest point on the GMC frame - the cross brace where the gas tank hangs. This was where the IH bed floor was riding on. So I will have to shave the top off that cross member.

Lastly was an interference with the pass side shock mount bracket. I will have to extend my notch in one of the IH cross ribs in order to clear this.

ALL in ALL NOT.... TOO.... BAD!!!

I will try to knock out these corrections during the evenings after work this week. The the bed will be as far down as I can get it and time to line up the cab and floor with the bed.

[sparkydog]

Oh yeah I have one more interference that I know of. This one I am going to fix with a BFH. The bottom of the IH cab and the top of the GMC stock muffler are going to hit once I start to drop the cab lower to match the bed.

Not interested in spending much time on this one right now. I'll nuke/replace the muffler later on if I ever get this thing running.

[sparkydog]

Took out the GMC cross member that was preventing my IH bed from sitting lower down on the frame. That dern cross member was only in with 6 rivets but it put up a fierce fight. However eventually they gave up. Now the front of the bed is where it will stay and I can move on to the cab/floorpan and finalize their positions and start tack welding. Looks like my computer sketches were just about right on. From the photos I would say the cab is going to drop another .6" or so.

Wish I could get the whole rig outside of the garage and take a nice side shot of everything. But for now I'll have to stick to the close-in 3/4 side shots.

[sparkydog]

This weekend I will probably be tack welding my cab to the floorpan and firewall. So I'm faced with a decision on ride stance that has repercussions later on when I go to do any suspension drop.

In the attached sketch I show an exaggerated view of what I am talking about. In the upper picture I show that I can create a slight rake toward the front depending on how I fine tune the pickup bed and cab before I tack weld.

In the lower part of the sketch I show that the bed and cab are parallel to the frame rails.

I am leaning toward the upper one with the slight rake forward. This gets my front end dropped a little more before I even mess with lowering kits. This means I will get a lower drop on the front without having to work to hard.

Does anybody know of a reason not to do the slight rake between the floorpan and the cab rockers?

[Palf70Step]

I think the the level look would be better.

Create the tilt with the suspension.

[1985-GMC]

This is a cool build! subscribed

[Sven]

Get's better every time I read ... you better get this running after all this work, mate!

[Sub-versive]

I have to say, I can't wait to see this project completed! I really dig your vision!

[sparkydog]

Thurs eve and Friday afternoon I finished the mods to the rear bed mounts and got them in and the bed back on. Now the bed sits as low on the GMC frame as I can reasonably get it without having to do major mods to the floor of the bed. Not the most exciting pictures but they show the new rear mount bolt coming down into the frame and the other two major cross ribs of the bed as they hug the frame. This extra .5" of body drop were important to me.

[sparkydog]

With the bed taken care of I raised the IH cab high up and did a final round of cutting/clearing and primer to the interior of the cowl area before beginning to weld the IH cab onto the GMC floorpan.

I also finally got around to joining up the two rocker boxes. I'm sure some of you were wondering from my photos whether I was just going to leave them 1/4" off in height or not. But all it took was a little scissors jack and some final trimming and they lined up real nice. I also let the jack work on the boxes a little after I tack welded just to get the metal warmed up and relaxed in it's new orientation.

[sparkydog]

I had saved some of the pieces of GMC rockers when I shaved them to get the floorpan to fit inside the IH cab. Now I used these to scavenge off the box sections where the GMC body mount brackets were going to merge with the inner wall of the IH rocker boxes. I also "cleaned" and prepped the IH rocker box areas a bit before sitting the IH cab down into it's final ride height.

The final photo is crappy but it's trying to show that I was using a plumb line to run along the bottom corner of the rockers and the bed to get them to all line up.

[sparkydog]

And again not the most spectacular pictures but these next three represent a HUGE milestone for me. The three trucks have now officially become one truck!!!

..... ......

For the first time early Sat afternoon the GMC chassis and the 67 and 68 IH body parts were all together and a single ground clamp anywhere on them would allow me to weld anywhere else.

WHEEEWWWW that was a lot of work. I sat down to admire and instantly dozed off. So I went in the house and took a proper nap. While I was sleeping some aliens must have came in my room and beat the crap out of me because when I woke up I could barely move I was so sore.

[sparkydog]

I can start fitting and welding in the missing sections of floorpan and lay in a few struts up in the cowl area to solidify the body a bit.

Sunday I dealt with what to do about my fuel tank needing to be lower than stock. I took pictures but they aren't very exciting. By the eve I had decided what to do and brought my mediocre fab skills to their best and had modified the two stock mounting brackets and dropped the tank 2.5" so it would clear the IH cab and bed. Now that it is lower I will have to reroute the filler pipe a bit. But what street rod project would be complete without a filler pipe relo?

And that concludes this week's tinkering folks. I actually got every one of my tasks accomplished for this trip to SoCal. And I still have a couple of evenings after work before I fly home.

[Palf70Step]

Very nice. I am loving watching this one come together.