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

Nice work. Those look great!

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

Another DIY project...

Space is getting tight under the hood of the old GMC. As always, I work down in size starting with the big things and working down to the small ones. The next two big things are the air filter and the batteries.

I decided that I would use two starting batteries. Detroit Diesels do not have any glow plugs or intake heaters and they MUST use single viscosity SAE 40 oil, so I will need some serious battery power to start on cold days. I have installed a block heater so I can get it going from home on cold days; but, that won't help if it has been sitting all day in a parking lot on a cold day.

I spent several hours on the air filter manufacturers' websites looking for an OEM filter that would meet my air flow and space needs. Everything that I found was too big in at least one dimension. So, I decided to make my own air filter housing. Because I was able to fit it in a relatively small space, I could use the stock battery tray and a stock auxiliary battery tray to mount the two batteries.

I found a rectangular K&N filter that would flow enough air and patterned the housing off of it. It is the same filter used in my '99 F-250 Powerstroke so I know it will flow enough air and I love parts interchangeability.

Here's the cardboard template for the base:

Attachment 1660703

Here are the sides in steel:

Attachment 1660704

Here's the top view with the filter:

Attachment 1660705

Here's the auxiliary battery tray modified and installed:

Attachment 1660706

I'll post more photos in the following post.

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

Another DIY Project - Part 2

Got anger issues (I don't, I'm retired ;))? Here's a way to get them out - pounding the crap out of a piece of sheet metal. I decided to make the top of my air filter housing curved so I got out the hammer and sand bag and started pounding on the top. Here's what it looked like about half way through:

Attachment 1660708

Here's what it looked like when I finished:

Attachment 1660709

Here's the completed filter housing on the bench:

Attachment 1660710

Here it is installed in the truck:

Attachment 1660711

I'll install some flexible ducting between the inlet and core support so I will have a cold air intake.

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

Kudos to you! That is a very nice looking air filter box and top! Did you use a regular type tube sand bag?

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

Fine job sir!

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

Thanks for the complement. I used a regular sandbag and teardrop hammer. You can see the bag in the lower right of the photo. I rolled the dents out with an English wheel.

Burnett

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

Very nice! Isn't it amazing how many hours go into doing all these fabricated pieces that a lot of people will never know. I need to get some different shaped hammers and start messing up some sheet metal. An english wheel would be nice too. ;)

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

I agree that making parts takes a lot of time. I'm glad it's my hobby and not my job. I'd starve to death trying to make a living this way...

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

That air box is amazing. Quality work!!!!!!

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

Cruise Control Servo - mounted!

Another under hood item to scratch off of the list (it's still a long list...).

When I finish this truck, I plan for it to become my cruising vehicle. CO is a big state and there are lots of things here that I haven't seen. I decided that cruise control would greatly enhance my driving experience while I am driving in the flat half of the state.

I started by installing the throttle cable & stop cable and then the business end of the cable from the cruise control servo. It is a Dakota Digital CRS-2000. Unfortunately there is no way to shorten the CC cable, so my mounting options were limited.

I made a bracket to organize the cables and welded it to the valve cover. That set the path that my CC cable would have to take. Here's a view of the cables at the governor end:

Attachment 1663221

Here's a side view:

Attachment 1663220

I then attached the servo to the driver's side fender well:

Attachment 1663219

Now that the servo is installed, I can start looking at the coolant recovery and windshield washer reservoirs.

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

It's enough to make a grown man cry!

I was working on mounting the electric vacuum pump today. I had picked a location very close to the driver's side hood hinge so I decided to mount the hinge to see if it would interfere. I mounted the hinge and then looked across to the passenger side and my new air filter housing - my heart sank. With the hinge down, it looked like the end of the hinge might interfere with the housing. A few minutes later, I had installed the passenger side hinge and confirmed that it does interfere. Ouch! I have often been in the "one step forward, two steps back" mode on this project but this is a new low. I have >40 hours into the air filter housing - it was done...

Here's a photo from the passenger's side:

Attachment 1668507

One from the front:

Attachment 1668508

One from the driver's side:

Attachment 1668509

I had mocked up the hood to make sure that the filter cleared underneath; but, I did not think about the hinges. They fold down much farther to the front than I thought. Back to the drawing board...

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

This might be an expensive solution, but are any of the billet hinges shorter? GSI I believe makes them and they can be gotten black anodized to not stand out so much if you wanted. Maybe they would fit and you can retain the nice air box?

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

This thing is awesome.

What kind of power figures does that motor put out?

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

Thanks. New hinges are one of the options that I am considering. I think that I will leave it alone for a couple weeks. After some time has passed, I will be able to evaluate the options more objectively.

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

175 Hp @ 2500 RPM
420 ft-lbs @ 1800 RPM.

I'm going to keep it stock for now.

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

very nice build

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

I don't think I saw this build before. Very cool. And the funny thing is that I'm not normally a huge fan of diesel conversions.

But this one is different. Cool fab skills. AND I have spent hundreds of hours next to a 4-53 just like this one in the engine lab. I love the scream of these beasts. I see the pics and I can almost hear it. And smell it.

Nice work!

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

Thanks for the complement. We share a love of the sounds that Detroit Diesels make.

I haven't made much progress lately. We have a short summer here (the aspen leaves are already turning) so I spend my summers working outside.

I'm currently focusing on completing the underhood - the air filtration, A/C and electrical systems.

Burnett

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

A little restoration is good for the soul...

Summer is over, the chain saw and wood splitter are put up for the winter and the plow is on the Mog. Time to get back to work on the old GMC.

I restored/modified the A/C unit for the truck. I decided to do it now because of my paranoia from the air cleaner housing debacle. I want to make sure that I know where the all parts will be when I finally come up with an air filter design.

Even though I purchased the truck in an area where good A/C is important (St. George, UT), I knew that there were issues. The brass gate valve in the heater hose was the first clue:

Attachment 1700464

In the 5 years that I drove the truck before I started this project, the A/C performance was disappointing. I checked the pressures and they were good - so there was plenty of Freon and the compressor worked fine.

After I disassembled the A/C unit, I found that the warm/cold air damper was binding on both sides so it would not seal in either heat mode or cool mode. In fact, the gap on either side at full travel was more than an inch. No wonder, the A/C didn't work satisfactorily. The only good news is that the heater puts out so much heat that it was able to overcome the cold air coming through the evaporator (at 9000' elevation, heat is much more important than A/C). A little trimming of the damper gaskets solved the problem. Now it snuggles into the gasket on both sides and seals well.

I also decided to convert from the continuous running POA style control to the cycling compressor control. This meant a new evaporator and accumulator had to be installed. I will modify the wiring later when I complete the engine compartment harness.

Here's what it looks like all cleaned up and sitting in the truck:

Attachment 1700465

Now that I have both ends fixed, I can start working on the tubing and hoses for the refrigerant.

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

Looking very nice! I regret not finishing my AC stuff the first time. I'll have to revisit that, uh, sometime? :lol:

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

What is it about electricity?

Every used vehicle that I have purchased has included some electrical modification(s) by the previous owner(s). Every one of the modifications have been dangerous in some way. For one, none of the modifications have included proper circuit protection. Most have included lamp cord - not the best for automotive wiring, few have included any protection from chafing, etc. It has all been bad.

My '72 was no exception. The only difference was that the previous owner(s) were good at hiding their sins. I didn't find the poor wiring until I took the truck apart. Then, I couldn't believe that I had driven it for 5 years without having a fire. I'm happy to be lucky...

I'm adding a few circuits of my own and intend to do the job right. I need both new circuits and relays to control some substantial loads - trailer wiring, vacuum pump and air compressor. I started with a Painless Wiring Cirkit Boss and a Hella Relay Panel.

The Cirkit Boss has 4 circuits powered from a relay that operates from the ignition key and 3 always hot circuits. I have used one on my daily driver for 15 years and it has performed flawlessly.

Since the wires come out the bottom of both the Cirkit Boss and the relay panel, I fabricated a mounting bracket for the to mount to the driver's side inner fender. Here it is on the workbench:

Attachment 1704783

Here it is mocked up in the pickup from the front:

Attachment 1704784

Here it is from the side:

Attachment 1704785

A couple of coats of black paint and it will be ready to go.

Since the hoses for the hydroboost and power steering arrived from Summit Racing, I decided to mock them up as well:

Attachment 1704786

I'm making progress on the underhood equipment, I still have a ways to go...

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

Very nice work! Did you make the hoses or do they offer a kit for them? Those fittings for the hydraboost and pump weren't cheap when I got mine.

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

Unfortunately, they do not offer a kit. I had to order the hose and fittings seperately. They are still not cheap; but, the cost was comparable to the prices that I have paid for other hydraulic hoses. The fittings are reusable so I cut and assembled the hoses myself. At least it saved me a trip to town to have them crimped.

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

Such an awesome build. Love the 2-strokes. I still see a lot of them in generators. I have even serviced some rare ones like 3 qty 24v71's and 2 qty 12v149's. Most of them are 6v92's or 6-71's though. Is there any new progress?

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

Thanks for the compliment. Most of the 2 cycle Detroits that I have seen have been on generators and fire water pumps. Tha largest that I have seen and heard was a 16V-149 on a generator.

I'm still working on the underhood stuff - A/C and batteries. I had to mount the A/C compressor on the driver's side of the engine because the alternator and water pump were on the passenger's side. I didn't want to route the A/C hoses over the top of the engine which created a new set of problems - more modifications to the core support, long lengths of A/C tubing, new brackets, etc. It has been slow going, lots of time and not a lot to show for it...

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

A/C System mock-up - DONE!

I finally finished the mock-up of the A/C hoses and tubing. I had to mount the A/C compressor on the driver's side because the water pump, and consequently the alternator, were on the passenger side. On Detroit Diesels, the water pump is on the side and driven off of the camshaft or balance shaft by a couple of v-belts. The alternator is used to adjust the tension of the v-belts.

Mounting the compressor on the driver's side created a problem - how to route the hoses. I considered going over the top of the valve cover; but, didn't like that option. I decided to go around the front.

Here's a photo of the driver's side showing the compressor and hoses:

Attachment 1716069

Here's a photo from the front showing the condenser and the tubing:

Attachment 1716070

Here's a couple of photos on the passenger side showing the evaporator and the hoses:

Attachment 1716071

Attachment 1716072

I still need to take the hoses to town to have the ends crimped on. Once I get that done, I'll be able to pull the system down and see if there are any leaks.

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

Very nice and clean routing of your ac system!

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

Transmission Overhaul Part 1

With the new year, I thought that it was time to change gears (literally). My brother and my two sons were out for New Year's and I was inspired by the thought of having help to move the parts for this heavy (350+ lbs.) transmission.

The transmission is an Eaton Fuller RT-6610. I have 4 tasks for this overhaul:

1. Replace/refurbish - replace all the bearings and the output shaft seal (the only seal) to ensure the longevity of the transmission.

2. Convert to overdrive - the difference between a RT (direct drive) and a RTO (overdrive) transmission is the input gear, 4/9 gear and the position of the first two gears on the countershafts. I purchased an overdrive kit for the transmission that included new input and 4/9 (now 5/10 - overdrive) gears, a new shift fork and new sliding clutch.

3. Installation of studs for the transmission rear support - although the transmission is perfectly happy cantilevered off of the bell housing, I want to install a rear support for it. The transmission weighs 350lbs. and the engine weighs 1100 lbs. so the rear engine mounts have roughly 900 lbs. on them when the transmission is cantilevered. I don't like putting that much weight on a single point of the chassis. The transmission arrived with plugs in the holes for the studs. The plugs have, so far, resisted all my attempts to remove them. I will probably end up drilling them out.

4. Cleaning and painting - the exterior of the transmission is very rusty. I will remove the rust and paint it.

Here's a shot of the beast on the operating table:

Attachment 1737107

Here's a shot of the two sections apart. It took us hours to get them apart, even though the transmission has jacking bolts to speed the process, because the alignment dowels were rusted to the case.

Attachment 1737108

The left side countershaft did not come out easily either. The rear bearing was on the shaft so tightly that I could not drive it off. I had to carefully cut it out of the transmission. Here's what was left after I got it and the shaft out:

Attachment 1737109

All my help has gone home; but, we were able to complete the disassembly and press the gears off and back on the counter shafts (the difficult jobs). I'm left with the cleaning, painting and re-assembly. That will be the next post(s).

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

Nice work! Those transmissions are getting harder to find around our area.

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

Thanks. It is a very robust, well built transmission. Fuller's support for them is excellent. Too bad they are becoming scarce.

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

Transmission Overhaul Part 2

The transmission is back together. All I need to do now is finish painting it and put it back into the truck. It is now an RTO-6610. Have a look at the photos below and see if you can tell the difference.

Before:

Attachment 1745020

After:

Attachment 1745021

See the photo below for an explanation of the difference.

Attachment 1745022

The gears with the red arrows are swapped for the ones with the green arrows & vice-versa and the gears with the blue arrows are replaced.

This modification converts what was 4/9 (right & up) to 5/10. See the diagram below for the change in the shift pattern:

Attachment 1745023

Every time that I complete an overhaul, I learn something. Here's what I learned from this overhaul:

1. RTFM (I already knew this one; but, it's worth repeating) - Fuller has wonderful manuals on-line and they are free. The manual for this transmission is the most complete that I have ever seen.

2. Take lots of photos and bag & tag the parts (I knew this one too).

3. Expect to replace the synchronizers. There are synchronizers for the air shifted auxiliary section. New synchronizers were not included in the overhaul kit. The ones in my transmission were trashed. I had to wait a week for them to be delivered once I found that they were bad.

4. Assemble the synchronizers in a tub. The synchronizers have 3 very strong springs. To assemble them around the sliding clutch, they must be compressed. If you get the synchronizers slightly cocked, one of the springs will shoot out. In my case, it went 15 feet and rolled under something too heavy to move, leaving me laying on the floor with a magnet to retrieve it.

Attachment 1745024

5. When installing the countershafts into the auxiliary section, slide the shafts in first, align the timing marks and then start the bearings. The instructions say to start the bearings into their registers first; but, I could not see the timing marks on the teeth with the bearings started. By sliding the shafts in first, I could see the marks through the registers.

Once I have re-installed it, I will start working on the rear support.

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

Very nice! I have had to chase down a few of those springs before too. Haha

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

It's been a lifelong struggle for me. After 50 years of working on vehicles (as a hobby), I've finally gotten to the point that I do something after I launch the spring for the first time. At this rate, I won't live long enough to actually anticipate the spring flying out before it occurs; but, I'm delighted that I'm making progress...

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

Just read your build. Good job so far!! I love the sound of the DD. To bad about the air box can you move it forward a little? Love that your building it to be a cruiser.

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

Thanks for the compliment. The air box just fit between the A/C unit and the battery so I can't move it forward. I haven't given up on the idea yet - I'm just giving it some "soak" time.

I'm really looking forward to driving it. I dream of the sound of the Jake brakes echoing off of the walls of Boulder canyon...

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

There are some other players making the billet hinges now. I've been watching these but haven't justified them yet. I haven't researched any reviews on these but the price seems fair and the hinges look nicely made.

https://www.ebay.com/itm/For-67-72-C...4383.l4275.c10

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

Thanks, Ryan. I'll check them out.

Burnett

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

Transmission Part 3/Cross Member Part 1:

I re-installed the transmission. Installing a transmission from above into an open frame is easy. I'll have to remember that if I ever have to pull it from below. I'm sure that it will be difficult.

The last thing to do before calling the transmission complete was to check the operation of the air shift for the auxiliary section. I dialed the shop air pressure down to 50 psi, hooked the supply up to the slave valve and attempted to shift - nothing, not even a hiss. The slave valve was frozen up. And to make matters even worse, the manufacturer, Parker, had used steel screws into the aluminum body to hold the cover on. After years in a corrosive environment, the screws and the body had chemically combined into one. So, the valve was headed for the recycle bin. When I received the new valve, I decided to tube it up instead of using hoses. Here it is installed:

Attachment 1754318

It functions flawlessly - the auxiliary makes a nice clunk when I move the switch on the gear knob and shift through neutral. The transmission is now complete. One more thing to check off of the to-do list.

Time to start on the transmission rear support and cross member. It turns out that this is a multifaceted problem. It involves both the rear transmission support and the front drive shaft.

My first thought was to support the rear of the transmission from above. There is just enough clearance between the bottom of the cab and the top of the frame to sneak in a cross member. The support for the rear of the transmission would be tricky but doable.

Then I had a look at the front drive shaft. The truck is currently sitting about 1" above the bump stops (stock springs with a much heavier engine & transmission). This gives me a good idea of what will fit and what will not. Here's a look from the transfer case toward the front axle:

Attachment 1754319

Here's a look in the opposite direction:

Attachment 1754320

After some measuring, I concluded that the largest drive shaft that I could comfortably fit is 2" in diameter. The problem is that the distance from the center of the transfer case yoke to the center of the front axle yoke is 53". A 2" shaft that long is essentially a piece of spaghetti. A quick visit to Spicer's maximum RPM calculator confirmed this. Their calculated max RPM for a shaft with these dimensions is 2558. That will never do for a truck whose engine has a maximum governed RPM of 2800 and a transmission with a 0.80 to 1 overdrive. Conclusion - I need a center bearing for this shaft.

As an aside, I love Spicer. While some manufacturers act like data on their products are trade secrets, Spicer shares everything and provides helpful tools like the RPM calculator and torsional vibration analysis calculator.

That changed my transmission support design. Now I'm looking at supporting it from below. It's actually going to be a lot easier to connect to the transmission. It looks like Fuller intended that the rear support be from below. Here's my rear support mocked up in cardboard:

Attachment 1754321

I purchased the parts to make the front drive shaft. Spicer has a data sheet that lists all the parts necessary for a 2 piece drive shaft. It's as simple as they could make it. Here are the parts:

Attachment 1754322

Now, it's time to start cutting some steel...

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

That set up is killer!! I love you are using this trans, so cool.

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

I'm very happy with this transmission. It is robust and well built. I have overhauled a number of car and light truck transmissions. This is the first real truck transmission that I have worked on. The difference is dramatic - the other transmissions seemed designed to be assembled at the factory and never touched again. This transmission was obviously designed to be repaired. It was a joy to work on.