Halfbreed - GMC Z71 + IH Extd Cab

[ERASER5]

Originally Posted by sparkydog

I've saved the GM plastic ducting system as well as the IH plastic defrost diffusers. I hope to McGuyver some kind of hybrid merge between the two.

The wiper linkage, HVAC ducting and the subtle blends between IH and GM sheet metal up in the cowl intake area are probably going to be the hardest part of the whole cab merge. It's going to get tricky.

Tricky? From what I have seen, you are a magician.

[sparkydog]

Did the B pillar/floor blends.

Got one of the two mid-cab mounts re-welded. Boy do I NOT enjoy overhead welding. (Not helped much by the unclean metal down there...) I just keep chanting "die-grinder, sealer, bondo" over and over again!

But it (and the other 15 feet of floor welding) will hold until the day off in the future when I pull the cab and do a proper clean and re-weld.

I also started cleaning and prepping some of the light housings. I was trying to figure out why the IH designers thought it was a good idea to paint the interior of the brake/sig lights black. Eventually I decided they weren't thinking so I'm going ahead and painting them gloss white on the inside because I want the energy from the light to get OUT of the light housing.

[sparkydog]

Finished redoing the middle cab mount welding. That is the last significant "on my back getting sparks and grind slag in my face" that I will have for awhile.

I fished out the wiper gear from both models of truck and started looking at them more seriously. I know I must use (and want to use) the GM wiper motor. I had hoped to be able to adapt the GM wiper posts into the IH cowl wiper station thingys - but after closer inspection that is not going to happen. So the basic task ahead is to adapt the GM motor into the IH wiper posts.

But wait, there's more! The IH wipers are "out of phase" by that I mean they work toward and away from one another, whereas the GM worked "in phase" moving the same direction at the same time. And... the IH are not exactly 180* out of phase but something more like 140* or so (just based on guessing while looking at the "disk/cam" thing on the IH wiper motor.

But wait, there's more!. GM connection linkages have neater sockets that look like they wear better, were meant to deal with intermittent pulses and might be somewhat replaceable. IH sockets more primitive - so I need to try and adapt the GM sockets into the ends of new custom linkages then into a motor cam that mimics the timing and phasing of the IH setup.

And - I have to route this into a cowl area with too much excess sheet metal still in it. I think I will be faced with some real tight cutting/clearing. Maybe I will get to blow up a few dremel disks!!!

Edit: Not to mention that on the IH, the linkage is all on the interior side of the firewall but below the cowl air inlet - but on the GM the linkage is all on the exterior of the firewall up inside the cowl air intake. I'd say that wipers are the only official downside to the decision I made to go with the GM firewall and floorpan.

[Kabwe]

This is just wild and cool. Good work man.

[sparkydog]

Originally Posted by Kabwe

This is just wild and cool. Good work man.

Thanks very much! Just looked over your build project too - you are doing some great work!

[Kabwe]

Thank you Sir, I appreciate that.

[sparkydog]

I almost finished the rear floor patch. I still have a little blend patch to do and then some dirty welding with lots of smoke and little fires to put out. Then I can cross another item off the punch list!

Donor metal courtesy of '97 GMC roof.

[sparkydog]

Does anyone know how these white things were "glued" in at the factory? In my zeal to learn all I can about the GM technology I opened up one of the inspection ports and this thing was somehow sealed - maybe with heat?

I suppose I could just silicone it back on?

[sparkydog]

I towed Halfbreed to work today so I could take it for a joy-ride on the street where I work.

Good news - it pulls hard and seems happy with it's new body.

Bad news - no 3rd gear at all. It (the computer) will shift it at the correct point but something is wrong with the tranny so it goes out of gear and never resets until I slow way down. So add the first thing to the "fix the 225k mile GM" list.

Towed it back home and continued to work on the floor fill-in. Yes my welding is looking especially smoky as my angle grinder finally went from tits to tits up. I have been limping by with a badly damaged lockout button but now it is completely gone so I have to get a new grinder. So the past few days I have been tack welding without virtually any prep and it shows.

The reason for the funny asymmetrical humpy is the GM tunnel is not centered in the cab but the IH leaf spring sculptured cab ribbing is centered. So my little humpy thing had to have an interesting piece added to one side.

[kyull67]

getting close. bummer about that trans.

[67ChevyRedneck]

So it has no 3rd and 4th gear, or it's skipping from 2nd to OD (4th) gear?

If it's the no 3rd and 4th gear, that typical when they go, as you put it, tits up My first 700R did the same thing in my 67. Cruising down the highway, all of a sudden the rpms shoot up RRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRR, when I slowed down, it would shift to 2nd, then when it was time for 3rd, RRRRRRRRRRRRRRRRRRRRRRRRR.

Sorry man, that blows, but with 225K, assuming it's the original trans, that's way longer than most 700R (or did they have the early 4L60's?) last. They're a good trans when taken care of and not abused, but hell, they're trucks, all they do is get abused! Truck is looking great though!!!!

[sparkydog]

It's probably missing 3&4. I didn't try a manual shift. But most likely the 3/4 clutch pack, no? I guess I will try putting it in limp mode just to see what happens.

Yeah this is the flip side of a $550 truck.

[nuke1]

truck is coming along nicely, you have done some fine work my friend, be proud of what you have done in this truck, it just keeps gettin closer everyday!!!!!!!

[sparkydog]

My wife and one of my kids arrived last night from Oregon and they brought a care package for Halfbreed. Now I have:

023 Mig wire
My multi-meter
Fan shrouds
Missing brackets and washer fluid tank
GM wire harnesses for front and rear lights
Cheapo entry level hammer/dolly set
New angle grinder
A stack of cut disks and flapper wheels
A profile gage cause my bro in law had two so why not take one huh?

[sparkydog]

I didn't think that 3D software would have much of a role in my project, but over the weekend I stalled out on a lot of the body mods (broken angle grinder) so I turned my attention back to the wiper linkages and quickly realized I could spend a lot of time screwing up real metal. So I decided to measure up everything and then create a 3D model.

Boy did that pay off! I could have spent the next 3 years playing with the linkages and never would have realized what were the key elements to getting it to work right. Now I feel I have a clear understanding of what I have to do to get this to work.

I have to mimic/adapt the IH style motor cam with the twin arms spaced 150* apart and at the same size as the IH cam was. But I will be using the GM linkage knuckles and will have to have two post heights on the cam so the linkages can sweep past one another. On the wiper post ends, I have to have the same arm length as the IH - or maybe just a little longer if I want to change the amount of sweep over the windshield (the stock IH wipers tend to go a little too far out over the curved ends of the windshield). So I think I will build some adjustment ability into the wiper post arm length and also some ability to adjust the linkages lengths. An eighth of an inch makes a huge difference on these things.

[63chevyll]

wow, good build. you are doing a fine job

[sparkydog]

I installed the fan shroud, the front wire harness, the rear harness, the horns, the ground straps - and all the wiring mods that went with it. I started to install the washer fluid tank and bracket but will have to spend a little time making some mods to the bracket.

I also tried out my 023 MIG wire on the rear cab floor. The wire is certainly better for the thin sheet metal. I wish I would have done all of my welding with 023... But the floor still sucks to weld because of all the grease fires and toxic fume inhalation.

[sparkydog]

Man oh man what a wasted day... sigh. It seemed like virtually nothing went well or that I made any progress. Let's see - on the negative side:

Truck won't start again but now the batt voltage is fine @ 12.4V. I bought a cheap code scanner and get only 1 code: P0102.
EDIT: Ate some dinner and went back out to the shop to show it who Daddy was! Fixed the PO102 code I had a loose MAF connector.

Even if it did run I would still have the tranny problem.

Then I discovered that there's a lug nut on one wheel with the head stripped completely off so I can't get the wheel off.

MIG welder took a minor crap when the wire feed switch stuck on.

On the positive side:
The weather is nice.
It is my 23rd wedding anniversary today.
I fixed (or delayed the breakage of) the MIG switch.
I got the long-missing washer fluid tank and mounting bracket installed - which also meant I finally got the vapor canister and plumbing as stock as it can be.
I cleaned up both the IH TAll rear bumper and the GMC rear bumper and mocked up each along with the GMC receiver hitch - trying to see what I can do for a rear bumper.
I ground down all my bleeping welds from yesterday and decided that I am still a crappy welder even with 023 wire.
I found yet another wasp nest under the IH rear bumper. Also a black widow.
EDIT: Also the IH + GMC horn combo sound is nice.

If anybody finds my mojo let me know cause I lost it!

[pickup67man]

What a fun day. For the lug nut try hammering on a smaller impact socket, 13/16" may work. You may be able to make new sides on the lug nut. Then use an impact gun to break it free, don't use a lug wrench. This can prevent ruining the wheel.
Have fun with the rest of your issues.

[ERASER5]

They make an E-Zee out type socket for stripped lug nuts or any nut for that matter. Tap it on with a hammer and twist it off. Easy. Call the local tire stores, someone will have the tool. Tow the IH over and have them remove the nut. If you let the tire look at your truck, he may do the job for free. Just don't let him drool on the metal.

[ChiefRocka]

Way cool man ... just read thru the entire build ... Awesome !

[sparkydog]

Even though Sunday felt like a bust - I mentioned how I went back out in the shop and "thought" I got it running. Notice in these pictures how the truck has moved and is facing into the shop! (Hah!) I had fun mocking up the receiver hitch and a simulated big modern rear bumper and the TAll skinny old rear bumper. I think I like the basic look of the bigger step bumper and I suspect I can eventually find one that will blend better with the squarish shape of the IH bed. After studying awhile I decided not to rush into any commitments on the tow hitch or bumper and maybe wait until I have the suspension lowered before working the bumper design.

Then I parked the truck, made SURE that it was starting and running reliably and turned it off for the night...............

Monday eve I rigged up a little set of brackets that will allow me to run the stock GM instrument display (on a temporary basis) while being able to fit the modified IH dashboard over the top. So I thought I would celebrate this little fab job and start the truck up.......

Oh, but wait! Now the truck won't work again! Dang I hate intermittent problems like this. One day it runs great and the next it won't start.

I just quit fretting about the truck running and I started marking up my cut plan for the rear doors. Pics to follow soon.

[sparkydog]

Here is my 1st round of thoughts on cutting down the rear doors:

First and foremost - cut up the passenger side first in case I discover a better way I can make the driver side look better which is what I will see most of the time!

Door Frame will be made by combining the forward pillar and of most of the window top of the TAll with the rear pillar and window side of the PUp (similar to what I did with the cab sections). There are several reasons why. Most important is the shape of the pillar and rear edge of the outer door skin have several differences so it is easier to get blue to match blue and white to white when blending with cabs. Second, the location of the door latch is about 1/4" difference between white and blue so why mess with modifying when I can graft?

Outer skin is going to be mostly white but also a little blue. Most body guys will tell me to take all of the white skin off and then tack, fold and spot (plug) weld the white skin back onto the new shorter frame but I am going to have a small vertical seam near the rear edge.

On the interior it is mostly about getting the white inner panel to section shorter because I want to use a shortened TAll rear door panel inside a shortened door panel cavity. So the squarish cavity has to be there instead of the swoopy cavity off the PUp. So I am going to cut out the inner white panel as if it was a skin, then section it shorter and graft back onto the new white/blue door frame combo.

[sparkydog]

Friday afternoon I decided that the rear floor and I were at a stalemate and it was time to call it - so I cleaned up the surfaces and then put some primer and cover coat on it.

Then I marked up and rough cut my first rear door.

And later on that eve I putzed around by welding in some end brackets for the dash. This positioned the dash properly and now I can go into stealth mode with the gages.

[sparkydog]

Today I cut the other 3 doors and started mocking up.