1979 Chevrolet C70 Conversion to OEM Air Conditioning

[Airdirect]

Here are pictures of progress. Got the cowl, roof, door openings, and rocker panels sanded, rear of cab to go then prime and paint.

[Airdirect]

Removed a hail dent from the roof. Installed new left and right doors. Took some adjusting to get them to line up correctly. The original doors fit terrible, I was in hopes the aftermarket doors might align better. In the 1979 era, fit and finish were not anything like today's standards. After some twisting bending and lots of adjusting I got them to fit slightly better than the original OEM doors. Time will tell how they hold up.

[Airdirect]

Made a little progress, transferred mirror mounting holes from old doors to the new. I used masking tape to make a template and then moved the template to the new door. I use multiple layers so it does not stretch when removed and reinstalled. Once the holes were all drilled (used a step drill bit to get a nice smooth hole with no stress risers) I then primed the holes.

[Airdirect]

More progress:

[Robert1970C20rstbukt]

Making some good progress! Were you able to get a fan clutch for the 4-53? I'm running R12 in my welding truck and pickup, got a decent deal on two cases a couple years ago. I installed one electric fan on my '84 to help with all the heat the 454 makes, it can get down to freezing with no trouble idling.

[Airdirect]

I have not purchased a fan clutch and fan. I am still looking for one.

[Robert1970C20rstbukt]

Found this on ebay, correct for a medium duty with a 350. That bolt circle would fit on the 2797 fan clutch. Seems like the catalog might have been wrong, as a 2801 clutch is for a 366 and 427 that takes a larger fan. I'm betting this fan and the 2797 will fit your truck if the mounting dimensions are right.

https://www.ebay.com/itm/CHEVROLET-C...YAAOSwH-daKvZX

https://www.rockauto.com/en/moreinfo...793626&jsn=573

[Airdirect]

Thanks Robert, I really appreciate your help!

[Airdirect]

Robert,

My current fan has a 22" diameter. It also has seven blades.

David

[Robert1970C20rstbukt]

You're welcome, we did our best to locate things when I worked at the parts store and that stuck with me. I look up my own parts before I go to the store to avoid unnecessary headaches haha. Seems like that fan would work, the 2" difference in diameter shouldn't hinder the cooling any I would think. The depth that the fan goes into the shroud is important for sure. The height of the 2797 clutch is about 3 5/8" roughly. The bolt spacing for mounting the clutch to the pulley/pump is 2.5".

[Airdirect]

I need to measure the depth to make sure I have room for it. I will take some more measurements and post the results.

Thanks Robert!

[Airdirect]

Shortened the frame back to its original wheelbase (203 in).

[Airdirect]

Been going through the brake system replacing wheel cylinders and hoses. I have also taken the opportunity to strip and prepare to repaint the Dayton hubs. I have new tubeless 11 - 22.5 rims and radial tires ready to be installed. I wanted to keep the original 9.00 - 20 rims, however radial tires for them were almost impossible to find and very expensive. I know in the long run the tubeless is a much better option.

[Airdirect]

Continuing to make progress on the brakes. Front brakes, master cylinder, and hoses are finished. The passenger side rear is ready to have the drum reinstalled and it will be finished.

[jumpsoffrock]

Can you post a picture and hopefully a part number of the brake spring tool you used?

When disassembling my C50 brakes I used big ass sheetmetal pliers but it was not fun.
Thank you.

[Airdirect]

Originally Posted by jumpsoffrock

Can you post a picture and hopefully a part number of the brake spring tool you used?

When disassembling my C50 brakes I used big ass sheetmetal pliers but it was not fun.
Thank you.

Here is a picture. It makes spring removal and installation a breeze. No effort required.

[Airdirect]

Finished brakes, installed new rear transmission seal and parking brake shoes. Installed new front shocks, my sons Noah and Micah stripped and repainted the front and rear hubs and clamps. Installed new tubeless rims and tires (11.00R 22.5 radials) Next step is to acquire a bed and we will be ready to haul.

[Airdirect]

Drove the truck to town and got it inspected and licensed. The truck rides terrible with the new tires. The air pressure is 85 psi. The old bias ply tires rode much smoother. The left rear duels wobble just a bit, will have to loosen and re tighten them to see if I can correct. I sure hope the bed weight will smooth things out! Any ideas?

[Robert1970C20rstbukt]

Best thing to do is jack up the front/rear and spin the tires by hand and check for run-out. We had that happen on our old '79 Ford L8000 water truck at the fire department. The front wheels were actually worse, when I looked out the driver's door while rolling I could see the tire/wheel wobbling in and out. Local tire shop apparently never worked with Dayton wheels before. I'm actually going to look at a 1989 C70 cab and chassis next weekend if they don't sell it by then. Has a 366 and a 5+2, has the same wheels but it has 10.00-20 tires.

[Airdirect]

Thanks Robert, I will jack it up and check the run out. Hopefully that will fix the problem. I hope it is not a bad tire. I still need to get the A/C fan clutch installed. I am sure it will reduce load on the engine and noise. The current fan is fixed and very noisy. With a Detroit Diesel cooling is not much of a problem. I cannot imagine why GM did not make the clutch standard on this model. Thanks for all your input!

[Airdirect]

I am having trouble with my new Accuride de-mountable rims. The part of the rim that clamps to the wheel runs true. However the outer rim wobbles. It appears that when the welded the clamp ring to the wheel they did not have it square. Anyone else had problems with Accuride rims?

[DT3Ton]

Thanks for documenting this so well.

Were the AC donor parts from a pickup or MDT? I would like to add air to my crew cab.

[gmtech68]

Find an experienced tire guy. It is part art, part skill to tighten clamp nuts so the wheel runs true.

[jumpsoffrock]

What is the bed Weight? I am so envious..lol
Man that's gonna be one sick truck.

[Airdirect]

I weighed the truck, without the bed it was 9,600 lbs. I do not know what the bed weighs.