Otter LRC CM4647296 comes home

[Hanno Spoelstra]

Originally Posted by Jordan Baker

Any idea if this makers plate could be dated?

Jordan, possibly by the someone at Nederlandse Radiateuren Fabriek (Netherlands Radiator Factory, NRF)? https://www.nrf.eu/contact/

[maple_leaf_eh]

Originally Posted by Jordan Baker

Todays allotted time in the shop (kids are napping) I managed to get the original battery tray removed. It was held in by 4 carriage bolts. I tried removing the nuts but the bolts ended up spinning around in the wood. In the end I used a Zip disk to cut the heads off the bolts. Yes this did mean that I had to cut into the wood and produce copious amounts of smoke in the shop. However the wood was too far gone to use again. Lots of dry rot had taken place.

The wood shall provide a very nice pattern to make a new one. I should also be able to use all of the original metal parts. It’s a simple construction of three pieces of white oak with a tongue and groove slot. Two metal angled pieces along the long top sides. One the end there is two flat bars with the vertical retaining rod and counter sunk holes for screws. It’s refreshing to see true 1” thick pieces of wood.

The last picture shows just how much crud came loose from the tray’s removal. The area had been vacuumed prior to removal.

You may have progressed beyond the battery box by now. A thought, white oak flooring is readily available, comes prefinished, and just about every manufacturer makes it with tongue and groove edges. Like the world has been waiting for your installation.

[Grant Bowker]

Originally Posted by Bob Carriere

.... I was wrong, it looks more like regular cab 13 rad.... your dis-assembly process is fun to follow on the forum....... it is just so massive!!

I would be cautious assuming that the Otter and cab 13 CMPs used the same radiator.
My cab 13 has the overflow pipe running from a small dome located in a depression directly in line with the upper hose to the thermostat housing rather than into the filler neck. This isn't a firm indicator since it is completely possible that radiator may have been replaced by a non-original one at some time (although it does have both the overflow tube and the steam tube fittings and has one of the larger type drain cocks at the bottom tank). A quick look at the Otter parts list and the list for all CMPs issued 1942 listed different part numbers for the radiators. I also checked the C60X list since it also uses the 270 engine and again the radiators were different. I'm not sure how different but something was different to justify different part numbers...

[Jordan Baker]

Thanks to Frank Von Rosenstiel, the radiator and the mount were the same as the CCKW. A quick google search found that they do look the same. The only difference is the Otter rad had a different fill port on the top.

[Jordan Baker]

Just a small update today. Finally got around to changing out the gauge cluster surround to an original NOS one. Also a picture of the gauge cluster with the glass removed showing the gauges and the gloss white and black paint inside the unit.

[David Dunlop]

Evening, Jordan.

What was the purpose of the horizontal bands of black and white paint?

David

[Jordan Baker]

David,
I’m not sure but I suspect it was to help evenly distribute the light from the two small dash lamps and help light up the bottom ones. The gauge clusters I took apart all had the remains of the white and black paint.

[Jordan Baker]

Small steps. Ignition filter refurbishment all done. I replaced the main wire with new wire and braiding. The original was broken in a few places. The filter components inside were bypassed as the part number on the case is for a 6v vehicle. I did not want to burn anything up running 12v through it. But it’s also easy to revert back to the original if needed down the road.

[Jordan Baker]

It’s all in the details…..

I needed to make up one of these stamped parts. It held a voltage reducer for two of the gauges on the dash. I made up a stamping die from bits of steel I had. With a bunch of trial and error I was able to make a stamping I was happy with it. It was a lot of work for just needing one part, especially since it won’t be seen. But…I do enjoy challenging myself to make parts.

[Jordan Baker]

The finished stamping after cutting off the excess and sanding the edges smooth. Two of these were needed on the backside of the gauges. More detail to come another day once I sort out the actual voltage reducing insides.

[Jordan Baker]

The voltage reducer project is done. I’m very happy with how these turned out. I was able to reuse the original brass terminals for the one reducer. The other one I sourced out some similar brass screws. As for the actual reducer I used Zener Diodes. These drop the voltage from 12v down to 6.8v. I then ink stamped the ends to differentiate the 12v from the 6v. Lastly, they were installed on the back side of the dash on the appropriate gauges.

[Jordan Baker]

The rest of the pictures.

[David Dunlop]

Wow!

Nice Ink Stamping, Jordan.

That is a skill I want to investigate one of these days. A lot of wireless equipment used ink stamping for identifying the major circuit components on the adjoining chassis surfaces, usually in black, or dark blue ink. Sometimes varnished over, sometimes not. Over time, or during rebuilds, these markings are often damaged or lost completely.

Thanks for the great confirmation it can be done. I will likely be contacting you down the road for lessons!


David

[Bob Carriere]

Has the resident electric wiz .....can you explain how a Zener diode works to reduce the voltage??? all the voltage drop devices I have used were rather a "resistor" that reduced the voltage and usually air exposed to dispel heat.....

Jordan...... what is the identifier for the Zener....as in part # or its capacity to reduce by exactly 50%??

Never too late to learn.....

Bob C

[Lynn Eades]

Bob, from the web.

ADVANTAGES OF ZENER DIODES FOR CIRCUIT FUNCTIONALITY
A zener diode is a type of rectifying semiconductor diode that is used to regulate voltage in a circuit, working in a reverse-bias mode to avoid failure. Semiconductor diodes allow a current to flow in only one direction, but zener diodes allow the current to also flow in the opposite direction when exposed to enough voltage. Zener diodes provide excellent solutions to several common circuit needs.

Below, Solid State Inc. reviews the applications, operations and advantages of zener diodes.

WHAT IS THE DIFFERENCE BETWEEN A DIODE AND A ZENER DIODE?
As noted, a diode is a semiconductor that conducts in a single direction only, whereas a zener diode conducts in both forward and reverse biased directions. If a normal diode operated in reverse, it would be destroyed, though no damage occurs with a zener diode. Instead, zener diodes take full advantage of the amount of reverse voltage applied.

ZENER DIODE: BASIC OPERATIONS AND APPLICATIONS
Zener diodes operate the same as a PN junction diode when in the forward-bias direction, but it’s typically used for the reverse mode in its applications. That said, zener diodes also regulate voltage one way (regular) or both ways (bidirectional). It has a wide variety of voltages and, as reverse voltage increases to its breakdown voltage, a current will start to flow through the diode. Because the voltage remains fairly constant across a wide range of power supplies, these are used for voltage regulation, surge suppressors, clipper circuits, and as reference elements across a variety of applications.

If you are handling diodes to build or use within a circuit, it’s essential to determine which way to point the diode. The two terminals of a diode are referred to as the anode to case (AK) and cathode to case (KK). An anode is an electrode that a positive charge will flow through into the device from an external circuit; a cathode is an electrode that directs the current to flow out of the device.

ADVANTAGES OF ZENER DIODES
There are a number of benefits of using zener diodes in circuit applications, including the following:

Less expensive than other diodes
Ability to shift voltage
Easily compatible and obtainable across systems
High-performance standard
Protection from over-voltage
Ability to regulate and stabilize circuit voltage
Greater control overflowing current
Usable in smaller circuits
In review, zener diodes are designed to operate in reverse biased mode at which they begin to conduct substantial current. It may function as a voltage regulator by drawing less current if the voltage is too low, or alternately drawing more if the voltage is too high.ADVANTAGES OF ZENER DIODES FOR CIRCUIT FUNCTIONALITY
A zener diode is a type of rectifying semiconductor diode that is used to regulate voltage in a circuit, working in a reverse-bias mode to avoid failure. Semiconductor diodes allow a current to flow in only one direction, but zener diodes allow the current to also flow in the opposite direction when exposed to enough voltage. Zener diodes provide excellent solutions to several common circuit needs.

Below, Solid State Inc. reviews the applications, operations and advantages of zener diodes.

WHAT IS THE DIFFERENCE BETWEEN A DIODE AND A ZENER DIODE?
As noted, a diode is a semiconductor that conducts in a single direction only, whereas a zener diode conducts in both forward and reverse biased directions. If a normal diode operated in reverse, it would be destroyed, though no damage occurs with a zener diode. Instead, zener diodes take full advantage of the amount of reverse voltage applied.

ZENER DIODE: BASIC OPERATIONS AND APPLICATIONS
Zener diodes operate the same as a PN junction diode when in the forward-bias direction, but it’s typically used for the reverse mode in its applications. That said, zener diodes also regulate voltage one way (regular) or both ways (bidirectional). It has a wide variety of voltages and, as reverse voltage increases to its breakdown voltage, a current will start to flow through the diode. Because the voltage remains fairly constant across a wide range of power supplies, these are used for voltage regulation, surge suppressors, clipper circuits, and as reference elements across a variety of applications.

If you are handling diodes to build or use within a circuit, it’s essential to determine which way to point the diode. The two terminals of a diode are referred to as the anode to case (AK) and cathode to case (KK). An anode is an electrode that a positive charge will flow through into the device from an external circuit; a cathode is an electrode that directs the current to flow out of the device.

ADVANTAGES OF ZENER DIODES
There are a number of benefits of using zener diodes in circuit applications, including the following:

Less expensive than other diodes
Ability to shift voltage
Easily compatible and obtainable across systems
High-performance standard
Protection from over-voltage
Ability to regulate and stabilize circuit voltage
Greater control overflowing current
Usable in smaller circuits
In review, zener diodes are designed to operate in reverse biased mode at which they begin to conduct substantial current. It may function as a voltage regulator by drawing less current if the voltage is too low, or alternately drawing more if the voltage is too high.

[Jordan Baker]

I’ve referred to the below website previously.

http://devestechnet.com/Home/Native12VUpgrade

The part on the Zener diode is near the bottom of the above link. I’ve included the relevant section as an image.

It’s full of very well thought out modifications to inline 6 engines. However a lot of what they write about can be applied to any make of our vintage vehicles.

[Jordan Baker]

As a follow up, I emailed the guy who created the above website asking if a heat sink was required. His reply is as follows.

As for my setup, I thought about adding heat shrink, however the diode is mounted to the fibre board then kept inside that housing.

[Bob Carriere]

.....and get rid of the old resistor color chart.....

Zener diode CZ5342B CT-ND 6.8 volts.......will try that........

Thanks

Bob C

[Alex van de Wetering]

Nice work as usual, Jordan. I like how you did the small pressing....small modelling jobs on a big vehicle.

[Jordan Baker]

Bob, I bought 10 online with shipping for about $20 Cnd. One was bad or I fried it on my variable DC power supply. The rest were fine. Compared to the other options, I find these are a great deal with very little to go wrong. The Runtz ones have more components and require a dedicated ground. Basically more things to go bad.

Alex, the time spent on making the stamping die was substantially longer than pressing the one successful piece. By that point it was simply more of the challenge to see if I could stamp out a part like this.

[Jordan Baker]

Pulled the engine the other night. She is one heavy power plant with the bell housing and transmission all attached. I’ve still got to build a simple wooden cart to hold this engine so it can easily be moved around the shop. Once that is done, the plan will be to pull the transmission and get it taken apart and rebuilt.

The oil filter was also removed from the frame rail. I took advantage of the warmer weather and got it all cleaned up and painted. When I was cleaning the grime off, I realized the filter had been over sprayed with KG#3. But only the side that was visible and not covered by the frame. When I removed the mounting brackets they were the proper gloss black and the filter was the early grey colour. For now the filter will stay grey. But once it’s back on the frame I plan on giving it the same overspray of KG#3

Lastly I’ve started removing the floor panels. Lots of sand, rust and other debris is coming out of the Otter. It’s amazing just how much crud has accumulated in this vehicle.

[Bob Carriere]

...... was it enlarged for CMP use????? got a photo showing the extension done....pleezz

...and are the rear engine mount CMP style to the Bell Housing or C60x with special GMC mountings??.... is the carb a Zenith???

I have a dead 228 if you ever need some tidbits....flywheel to pump but seized

[David Dunlop]

Hi Jordan.

any sign the Oil Filter had an ID or Instruction Decal applied to it?


David

[Jordan Baker]

Bob,

The engine used a unique oil pan compared to the other GMC270’s I’ve seen. The one on this engine matches the drawings in the Chevy Master Assemblies book.

The rear engine mounts use the same vibration isolator mounts that the CCKW used. The actual mounts themselves a very heavy duty and a different design than what’s on my C15A.

The transmission is also a much larger unit. It’s very similar to the CCKW with some differences. It’s similar in size to the Muncie SM240.

[Jordan Baker]

David.

I looked hoping I would see the remains of a decal. But nothing. It looks to have simply been painted the light grey then over sprayed with KG#3. It still had some oil in it along with a filter.


Lastly a picture of just how much crud had accumulated inside the Otter. This was all under the drivers seat and inside the seat base bolted to the floor.

[Bob Carriere]

Thanks for the pics.....

Ooooh what fun you will have changing that huge filter mounted sideways!!!!!!!

You have spare engine I presume????

PS...... half the weight is the crude build up !!!!!

[Jordan Baker]

I don’t know why the designers thought mounting the oil filter sideways was a good idea. I much prefer the later style mounted on the engine vertically.

Yes I do have a spare engine. It’s a RCEME rebuilt/crated engine with the Cnd double pulleys. Same setup as used in the Otter. Came from a fellow in New Brunswick.

The vehicle is getting lighter for sure. The shop vac is getting heavier though.

Did a little bit of work tonight pulling some more parts. The front floor panels are now all removed. I’ve also removed the brake/clutch pedal assembly, the handbrake lever assembly and the transfer case lever. All will be their own restoration projects.

[Jordan Baker]

Four shims were found under the brake/clutch assembly. The entire assembly is interesting as it comes off with the removal of 8 bolts. Four hold the master cylinder mounting bracket to the frame and 4 hold the pedal linkage to the frame.

[Jordan Baker]

Well it was a beautiful 25 degrees outside today. So taking advantage of this lock weather I decided to get a bunch of my otter parts all painted up.

[Bob Phillips]

Jordan, I have some NOS 270 engine parts if you have not already completed a rebuild. Give me a shout for more details.