Uncle Loyd's 72' C-10

[cornerstone]

Originally Posted by zicc1835

...had our first grand baby turned 70 and reluctantly started collecting SS..
Jess

I can only hope that I'm healthy and strong enough to do half as much as you do when I hit 70. Congratulations on your grand baby! I envy you there! We don't have any yet...

[cornerstone]

Some seriously long overdue cleaning was in order. It sure felt good to power wash the crud off the truck and look over all the work I've done so far. Now that I have electricity and a few walls up in the pole barn, I wanted to relocate the project to a larger workspace. I used some scrap plate steel and built a tow hitch that bolts to the front frame horns. The skid steer made it a one man job.

[cornerstone]

Is it wrong to have spring fever in February?

I've noticed after this much time I've lost track of what my next course of action was planned to be. I got to thinking about it pretty often so I figured it'd be smart to pull all the cleaned and bagged hardware out and list it on an inventory sheet so I can see what all is missing in hopes of being more ready for assembly. I had the opportunity to mess around with the 72 this afternoon, so I lifted the bed back off to have more room to work. I'm planning on mounting the drop down battery tray and get some battery cables made after that. I also started pre assembling the brake pedal/ steering column/ booster/ master cylinder and proportioning valve. Take a look at these pics and tell me if you think I got the right brake booster. Sorry for the sideways pic. I bought it new at a swap meet a couple years ago. The vendor told me it would work for my application, but it sure looks to be sticking out farther than I expected. Another thing I noticed on the truck is the the stock brake lines only have 2 lines total (one for the front brakes and one for the back brakes), but the proportion valve has 3 ports with one port labeled front right, one labeled front left, and one port labeled rear brakes. The directions were about as useful as a pocketknife left in your sock drawer. Another thing I've been contemplating is loosing the air ride. I probably will end up trying it out since I've already done most of the work involved, but my gut tells my I'm not going to like the general performance (or lack there of). Plus the novelty of picking your ride height will probably fade away pretty fast if I were to guess. I'm second guessing the air tank location and size as well. Any thoughts?

[clay68c10]

The stock front brake lines have a splitter T somewhere on the crossmember. A lot of the prop valves are like your new one with 2 front outputs. You could run new lines or get the single outlet valve. I'm going to run the newer style and mount it down low on the frame, but I need to run all new lines anyway.

[cornerstone]

Happy to report some progress. I got the drop down battery box mounted under the bed behind the cab on the passenger side frame with a custom made bracket. Also installed a 200 amp circuit breaker directly next to the battery box connected to the positive 2 awg. cable and routed it to the front drivers side of the engine compartment. That's where my computer will reside for the L83. I'm pretty much copying TA-C10's design with a couple minor changes. I also dug up my original truck wire harness and gave it a good cleaning and inspection. Happy to report my Uncle Loyd took excellent care of his wiring and only one splice was made over all the years. I plan to take off all the factory tape and separate all the wiring that won't be used in the new set up, then re-tape and loom everything into different sections.

While I was rolling around on my creeper under the truck I was reminded of another issue that needs to be addressed, and that would be to add clearance around the driveshaft. You'll notice in the pics the driveshaft has rub marks on it where it has rubbed the back lowest part of the cab. It is also that close to the top of the driveshaft loop in the CPP lowering center crossmember as well. I may even have to change the pinion angle. In addition, I don't like the way the engine cover is so close to what used to be the wiring channel on the now smooth firewall so I wanna do something about that too. I got to thinking that it may be the custom motor mounts I made are causing both of these problems. It's possible I placed the engine too high in the bay which would cause both of the 2 issues previously mentioned.

[cornerstone]

I also fit the chrome front grille surround and a new ignition switch with bezel. I loaded up the doors with all their components and had some trouble getting both of the upper rollers into the track on the door glass. I'll get my son to be a second set of hands and eyes to help me get it right next time.

[clay68c10]

Looking good!
If you're up for moving the engine around, the Speedway stands look like a good option. I have the Holley version and they really sit the engine down nice and low.

[MySons68C20]

Originally Posted by clay68c10

Looking good!
If you're up for moving the engine around, the Speedway stands look like a good option. I have the Holley version and they really sit the engine down nice and low.

Totally agree with this!^^^^^^

It should solve your problems with the driveshaft rubbing and your pinion angle.

[cornerstone]

One step forward, two steps back. When I started this project the aftermarket had not yet produced motor mounts for my application, so I bought a universal set of "hot rod" mounts and took my best guess where to position the engine. At that time I still had the factory oil pan as well, which kept me from going as low as I wanted to. Now that the Holley 302 oil pan is on it there is much more clearance between the pan and crossmember. Like the 2 most recent comments suggest, I think the pinion angles and driveshaft clearance issues will be resolved if I install properly designed mounts. Yesterday I ordered the parts, and today I took the front end and cab back off. I also dragged it back up to the house and gave it a much needed power washing. The last time I pulled the cab I used a beam that made contact with the inner roof panel. I put some padding between the metal and the beam but it still made some scuff marks, so this time I redesigned the beam to carry the weight on the top of the door jambs. I cut a notch in a 6x6 that allowed the pinch welded flanges room so they wouldn't get bent in the process. This method worked better than the first as the cab was much more solid while up in the air. See pics.

[cornerstone]

I also made a panel to mount the computer, fuse box, and +/- terminals. This idea was directly stolen without permission from TA_C10.

[cornerstone]

Ok. So the new Holley motor mounts are in and it sits about an inch and a half lower in the frame.

[cornerstone]

I'm using the CPP center crossmember for lowered trucks, along with 2" lowering blocks under the axle. In this pic the rear suspension is about 1/2 way through the amount of available travel, and as the truck drops more the driveshaft will contact the hoop in the crossmember. Has anyone else experienced this? To correct this my first thought is to cut the top of the hoop off and weld it back in with as much clearance as the cab will allow, but not sure that's the way I wanna go just yet.

Another factor in this pinion angle debacle is the transmission mount. If I were to lower it in the frame it would help with the clearance issues in the center crossmember hoop, but it will also increase the downward angle of the motor / trans combo. The 6L80E trans has an oil pan that hangs low, so I really don't want to do that.

My rear diff is currently pointed up at 6 degrees and the transmission is down at 4 degrees. Since I need to tilt the rear diff down at least 2 degrees, I considered cutting the needed angle into the 2" rear lowering blocks. Basically, instead of adding the typical shims to get the correct pinion angle, get the same result by removing material from the blocks.

What do ya think SCOTI?

[cornerstone]

I had the entire beautiful day to work on the truck. Now that the motor is in the correct spot I yanked the 2" lowering blocks out and made a mark at 2 degrees using the digital level on my iPhone. With a 40 grit flap disc on the trusty DeWalt grinder, it made short work removing the aluminum no longer needed. Once most of the material was taken off I stuck some 80 grit sandpaper to a nice flat steel surface and sanded them by hand to their final dimensions. After they were reinstalled both important angles were at 4 degrees. Parallelism finally achieved. Pointing the rear diff down another 2 degrees gave the driveshaft another 3/8" clearance in the hoop, but still would make contact if the truck was aired out. At this point I thought I might as well alter the crossmember to get full travel. I got the top of the hoop cut off and cleaned up just as it was getting dark and dinner was on the table. Tomorrow afternoon I'll be ready to weld in 1.25" tall 1/4" bar stock to raise the hoop and eliminate the possibility of metal on metal contact. Feels like I've finally got some resolution to a lingering problem. We shall see... I still have axle bump stops I need to install.

[Kronald_70GMC]

Looks like a good solution to your problem. Though I am definitely no expert when it comes to driveline components. Keep it up!

[CKfan]

Great build, great thread.

Finally finished reading through all of it and the one question I have (even with all the other great work) is:

Post #5, last picture. What was your process for getting that frame so nice and ready for paint?

[cornerstone]

Thanks a lot CKfan. I used a twisted wire disc on a large grinder for the open areas and a wire wheel on a drill gun in the tighter spaces. I also found a dental style pick handy for getting greasy road crud built up in the really tight places.

Brian

[cornerstone]

Another beautiful day in Texas. Man I love it when the time changes back in the spring. I finished up the mods to the driveshaft hoop. Next will be to install the rubber bump stops in the rear frame notches.

[SCOTI]

Sorry for the delay in responding but I was away for a family emergency.

The discussion about the operating angles needed is accurate but there is a major caveat when dealing w/aggressively lowered vehicles that we need to keep in mind.

From what I 'learned' during the quest for knowledge in this subject area is the 'correct' set-up that is industry standardized has the engine/trans pointing downward slightly (toward the ground) & the rear-end pointing up slightly (toward the sky). In this configuration on normal vehicles, the driveshaft/s would be higher in the front (@ the trans output end/s) & lower in the rear.

When your vehicle fits these criteria, the industry standard for the math calculations used when determining the driveline angles works.

But, on aggressively lowered vehicles (where the rear end is at or above the original frame rail placement), w/the engine/trans output pointing down slightly & the rear pinion pointing up, the math is backwards when doing the calcs because the calcs are assuming the rear-end pinion is lower vs the trans output.

Typical math might be:

Engine/trans within the frame rails & pointing down @ 3°
Pinion below the frame rails & pointing up @ 2°
Rear end housing C/L is 8" below trans output height.

With this scenario, you would look @ it a 3°-2° = 1° difference. This is what you want. The angles need to be as close to zero as possible to minimize vibrations w/o actually being zero for good needle bearing life.

Now take those previously listed numbers but do the math on a vehicle where the rear end housing C/L is within the original rail height vs stock ride height which places it way under the rails. That 2° upward angle @ the pinion is no longer subtracted from the engine/trans output angle because it is @ the same C/L or higher. Once that becomes a factor, the angles are added together:

Engine/trans within the frame rails & pointing down @ 3°
Pinion within the frame rails & pointing up @ 2°
Rear end housing C/L is level w/the trans output height.

With this scenario, you would look @ it a 3°+2° = 5° difference. In the extreme drops, the pinion will be close to level or above the trans output heights, so the driveshaft can actually run upward (toward the sky) to the pinion. In these scenarios, one might need to raise the trans output or bring the pinion down to get that target 1° or less angle difference.

All dimensions/angles need to be pulled w/the vehicle @ it's loaded/suspension weighted ride height.
Unfinished vehicles? You can guess @ the set-up to get things in the ballpark but will need to finalize everything w/the vehicle assembled.
*EDIT* Pinion angle 'change' that occurs during extension/compression varies depending on suspension type.

@cornerstone,

I sectioned & raised the hoop on my ECE T/A x-member 2" higher. With my 3" raised rails & frame notch, plus the trans output @ 3° & rear end level @ the pinion, I had .125" clearance on a 3.5" (?) OD shaft w/the suspension fully compressed. It was just a rolling chassis @ that point but I should be able to dial the pinion in easily one the chassis is fully loaded.

[cornerstone]

No need to apologize sir, I hope your family is well.

First off, thank you very much for the thorough explanation. I learned something new and a few things have been clarified /confirmed for me.

Since the post where I asked for your thoughts, I cut out a "shim" from the 2" lowering blocks. Initially I thought it yielded a -4* trans and a +4* pinion, effectively cancelling out all angles... but today with better lighting I saw there is almost a 1* difference in the 2, so hopefully no vibrations.

I tossed the cab back on to see if the interference issues had been resolved and realized I will still need to clearance the pinch weld of the back of the cab. Just a little more minor surgery and that part of the build should be done.

The first picture shows the 3/8" clearance between the cab floor and the top of the recently enlarged driveshaft hoop. I'm happy with how that mod came out.

The second and third and fourth pics are of the suspension fully aired out, just because I thought they looked pretty sweet.

The last pic shows how I welded a bracket to hold the fuse box for the stand alone engine harness above the computer.

[1971Stepside]

Glad to see this project moving forward.

[hewittca]

Awesome work so far, way to keep at it!

[cornerstone]

Lifted the cab back off to trim the cab for driveshaft clearance at lowest setting. I'll clean it up and cap off the support structure next time I can work on it.

[franken]

72' is 72 feet
'72 is 1972 today
Being ignorant is not good. Seriously, really.
Being a moron is bad.

[SCOTI]

Originally Posted by franken

72' is 72 feet
'72 is 1972 today
Being ignorant is not good. Seriously, really.
Being a moron is bad.

Too much time on your hands isn't good.

[cornerstone]

Originally Posted by franken

72' is 72 feet
True, but I like to watch grammar school teachers get their panties in a wad.

'72 is 1972 today
Yes ma'am.


Being ignorant is not good. Seriously, really.
And you're handing out grammar lessons?

Being a moron is bad.
Since it's apparently judgement time... Being an old man yet still a juvenile prick is worse.

...