Re: Project Screamer - '72 GMC K2500 + DD 4-53T
 

Power Steering Pump Bracket - done! Another item to cross of the list, only 999 to go...

Here's the view from the front. The pulley just clears the belt for the A/C compressor. I may have to move the fan up eventually when I mount the radiator and make a shroud. If I do move the fan, I will just need to buy a couple of new V belts.

Attachment 1403923

Here's the view from the rear. Most of the rear bracket is the original bracket from the 350.

Attachment 1403924

Here's the top view. I will trim the frame a little near the pump to make sure that there is enough clearance when the engine rocks. I have boxed the frame around the power steering box connection, so I won't be giving up any strength.


Attachment 1403925

Re: Project Screamer - '72 GMC K2500 + DD 4-53T
 

Thanks, Ryan. I will check them out.

Re: Project Screamer - '72 GMC K2500 + DD 4-53T
 

I really like how this is going. Looks the way it should. Not too many people that don't know these trucks will know what you have done . Keep up the great work

Re: Project Screamer - '72 GMC K2500 + DD 4-53T
 

Nice work on the brackets!

Re: Project Screamer - '72 GMC K2500 + DD 4-53T
 

Linkage will be the death of me yet...

Since the weather has improved, I have been spending a lot of time on outside projects. But, we are still having those lovely afternoon thunderstorms giving me a chance to work on the truck.

I have been working on the clutch linkage. I have made some progress by repurposing parts from the C-70; but, I am not there yet. Here's the progress to date:

Z-bar, we don't need no stinking Z-bar! This bell crank came off of the clutch linkage for the C-70. With a little bending and re-clocking the arms, it is going to work for the GMC. Here's the side view:

Attachment 1408620

Here's the front view:

Attachment 1408619

The window between the starter and the motor mount is very small. The linkage will go to the rear past the clutch shaft and then back forward to meet the arm at the end of the shaft. I had to repurpose a pivot from the C-70 to make this happen. Here's the pivot mocked up:

Attachment 1408621

I will have to have the clutch shaft machined to shorten it and make a keyway on the opposite side (the arm was originally pointed up and I will need to have it pointed down). After it is machined, I will install the clutch and determine the length of the arms.

While I am waiting for the machining, I decided to make the bracket to mount the transfer case lever. Here's the bracket with the lever installed:

Attachment 1408622

Attachment 1408623

I would have liked to have the lever be a little lower; but, the transmission curves toward the passenger side immediately below where I have the bolt for the lever. If I had made it lower, the lever would have been about 2" further toward the passenger side. As it is, I will have to shorten the lever. I will be looking for one plain (not chrome plated) so that I can modify it.

Re: Project Screamer - '72 GMC K2500 + DD 4-53T
 

Fantastic!

Re: Project Screamer - '72 GMC K2500 + DD 4-53T
 

Vacation is over! Time to get back to work on the old GMC. Vacations are wonderful, even for us retired folks. We had a great time. But, it is time to get back to our normal lives.

I've installed the transfer case shifter and linkage.

Here's the linkage. It is just a 7/16" steel rod with a couple of kinks in it.

Attachment 1418879

Here's the first attempt at fitting the shifter - I knew that it would be too long. At its current length, it is a real knuckle buster.

Attachment 1418880

Here's the shifter after a little cutting and welding. For some reason, GM decided to harden the entire shifter, so cutting it was a pain.

Attachment 1418881

Here's the hump with the holes cut. The case shifts fine and the shifter and linkage clear everything. Another task completed!

Attachment 1418882

Re: Project Screamer - '72 GMC K2500 + DD 4-53T
 

Today's project - install pneumatic bump stops. With the clearance so tight at full articulation and the engine and transmission so heavy, I decided that pneumatic bump stops would be a good idea. At least, I can minimize the chance that the hard parts collide when I hit a big bump.

I purchased some 2" travel bump stops from F-O-A. They included the buckets. I fabricated the 1/4" backing plates:

Attachment 1419267

And installed them on the frame.

Attachment 1419268
Attachment 1419271

I haven't purchased the lifted leaf springs yet, so the bump stops touch. I am talking to the lift suppliers about the weight of the front of the truck. They only offer lifts for the '72 with a gasoline engine. My DD and the RTO-6610 together weigh about 800 lbs more than the stock 350 & 4 speed. I have to get the spring rate right...

Re: Project Screamer - '72 GMC K2500 + DD 4-53T
 

Cool guy parts! Air bumps are awesome. How much lift will you run?

Have you considered a custom pack? Alcan spring is just over the mountain a ways. It might help to get a spring that is tailored to your specific set up, and would likely offer the best ride as well.

Re: Project Screamer - '72 GMC K2500 + DD 4-53T
 

Thanks, Ryan. I am looking for 2" to 2-1/2" of lift. That would give me about 4" of down travel.

Custom springs are my next step. So far, the lift suppliers have not given me confidence that they appreciate the impact (literally) of the extra weight.

Re: Project Screamer - '72 GMC K2500 + DD 4-53T
 

Custom spring shop... Not aftermarket lift springs. Like you said, 72 model, gas only. Because that is what was offered in 72. Custom springs will make it stand and ride nice.

CT

Re: Project Screamer - '72 GMC K2500 + DD 4-53T
 

Have you thought about using a 73 up front spring length ? I have seen the rear shackle move back to accommodate them.

Re: Project Screamer - '72 GMC K2500 + DD 4-53T
 

great work so far. thank you for sharing your build! i have a '48 GMC 1 1/2t that i want to repower with a 453T and an overdrive. it will be my car hauler with a wedge deck....someday. right now it is just collecting dust in my dad's shed, no room at my place to keep it inside. it's been in our family since new, trying to keep it all "jimmy".

Re: Project Screamer - '72 GMC K2500 + DD 4-53T
 

Sounds like a fun build! My advice - start buying the parts now. I found good deals on a lot of the parts that I have purchased because I just kept an eye out and purchased them when they came available.

Re: Project Screamer - '72 GMC K2500 + DD 4-53T
 

Great work! Those pneumatic bump stops are really nice!

Re: Project Screamer - '72 GMC K2500 + DD 4-53T
 

I decided that it was time to complete the clutch linkage.

I had the flywheel resurfaced some time ago. It was really torn up. The previous owner must have let the clutch go too long. It's easy for me to understand why this engine is so heavy. The flywheel must weigh 60 lbs.

Attachment 1422074

I had to install the clutch to make sure that the lengths of the lever arms were correct. This is a pull type clutch with a clutch brake. The travel of the pedal in the cab must match the travel of the clutch. There must be some free play in the linkage when the pedal is up to prevent premature failure of the throwout bearing from constantly being engaged. The throwout bearing must contact the clutch brake before the pedal hits the floor so that the brake will stop the transmission.

Here's the clutch installed - it is heavy too!

Attachment 1422075

I decided to make my own clutch arm because I could not make the old arm work in the space that I have. I made the arm and tacked it to the clutch cross shaft.

Attachment 1422076

I made a new link from the rear pivot to the clutch arm from some 3/8" bar stock and re-used the OEM adjuster. I had to make a new arm for the rear pivot. It is where the ratio between the clutch pedal travel and the clutch arm travel is set. To ensure that everything was correct, I put the cab back on the chassis and had the wife depress the clutch pedal.

Here's some photos of the completed linkage.

Attachment 1422077

Attachment 1422078

Both ends of the clutch travel are correct and the linkage doesn't bind. I am concerned about the OEM rod that goes from the clutch pedal to the bell crank. It does flex some. I may have to fabricate a stronger rod; but, for now I am calling this task done.

Re: Project Screamer - '72 GMC K2500 + DD 4-53T
 

Great work on the clutch linkage! Maybe you can weld a stiffner plate on the top and bottom of the rod to help keep it from flexing/deflecting.

Re: Project Screamer - '72 GMC K2500 + DD 4-53T
 

the linkage work does look tasty. oddly that is the stuff that i like building. i have been daydreaming a tcase shift mechanism for mine for a while.

Re: Project Screamer - '72 GMC K2500 + DD 4-53T
 

Some protection for the NP-205...

I was in the mood for some heavy metal work so I fabricated some protection for the NP-205. It worries me that the front output hangs down so low. At least now, if I hit something it will be with 1/4" plate, not the transfer case.

Here it is on the bench:

Attachment 1424155

Here it is installed from the front:

Attachment 1424156

And the rear:

Attachment 1424157

I received this nice package from Columbia River Mandrel Bends and a muffler from Summit Racing so my next project will be the exhaust.

Attachment 1424158

The muffler is the straight through design. The truck could be pretty loud, especially when I use the Jakes.

Re: Project Screamer - '72 GMC K2500 + DD 4-53T
 

I like designing and fabricating the linkage, too. It's tracking down all the right parts that drives me nuts. For example, I am working on the throttle linkage. I have purchased a nice cable that has a 1/4" -28 end. Unfortunately, the throttle arm on the governor has a 5/16" hole. So, I am looking for a rod end with a 5/16" stud and a 1/4" - 28 female end. Arrrgh!

Re: Project Screamer - '72 GMC K2500 + DD 4-53T
 

I have considered adding a couple of stiffening plates. When I get the cab back on the chassis, I will see how much room I have to add the plates. If I can't stiffen the OEM rod, I will end up fabricating a new rod or altering the geometry of the current setup.

Re: Project Screamer - '72 GMC K2500 + DD 4-53T
 

How goes the project?

Re: Project Screamer - '72 GMC K2500 + DD 4-53T
 

The weather has been good and I have been spending most of my time on outside projects so this project has not got much attention.

I did get a chance to spend an afternoon on it the other day. I cut the tubing for the down pipe and welded it up. Here's what it looks like on the bench:

Attachment 1432233

And installed:

Attachment 1432234

Attachment 1432235

I hope to finish the remainder soon...

Re: Project Screamer - '72 GMC K2500 + DD 4-53T
 

Xfer case skid plate is a beast! Wow!

Downpipe fits like it grew there. Keep the pictures flowing. I'm almost to the point of flirting with a DD for the 1979 C20.

CT

Re: Project Screamer - '72 GMC K2500 + DD 4-53T
 

Thanks for the compliment. It's a labor of love.

Take the plunge and put a DD in your C-20. The only issues with them are that they are heavy and tall (and drip oil, smoke & are loud; but, some consider these to be features...).