Start of M37 Rebuild

This is a blog for my 1952 M37 rebuild.  I bought it five years ago with the expectation to rebuild it once my garage bay was empty, as I was building a Herreshoff Haven 12 1/2 in there.  Well, as things often go,the boat took a bit longer to build then I thought.  Mostly because I added teak decks, mahogany cabins and doors and other non-necessary items to make it look like a mini-yacht :)  The boat was finally finished this past spring and the garage bay was open.

The M37 had been sitting in the driveway all winter with the batteries out.  It usually started without problem so I thought that I'd drive it into the garage.  No luck.  It wouldn't start, even with much coaxing of ether and gas in the carb.  Oh well, I thought, I'll use my Suburban and push it into the garage.  Not so easy as one of the rear drum brakes was locked up.  I finally got it in with some coaxing.

I took the whole truck down to the frame in April and May 2010.  Initially I thought I'd have the original in-line 6 cyclinder engine redone and build the truck back up to original specs.  It already had 4.89 differential gearing installed, but even with that, the speed was a slow for today's cars.  The NP200 transmission was great in the low-end gearing, which is great for a 4x4, but not great for what I usually use it for....driving on paved roads.  I want the final truck to look like one of the pictures below.  Lots of work as my truck has a lot of rust cancer.  In other words....a GOOD project :)

Nice CAT Yellow Color

After many discussions with Paul Mierop, in New York, I decided to install a Cummins 3.9/4BT diesel with a NV4500 transmission and a married NP205 transfer case.  Paul has redone four Dodge trucks with Cummins engines: an M37, a Power Wagon, a Power Giant and a Carryall.  He is a great guy and quite helpful and free with his experience and fund of knowledge.  Thanks Paul!

Paul Mierop's Cummins M37

My M37 with the sheet metal removed.

Engine out and front axle removed.

Front and rear axles awaiting tear-down.

Front axle primed.

Saturday, August 14, 2010:

On to the rear axle.  Haven't been able to work on it lately as I've been recuperating from surgery.  I'll be switching out the non-centered M37 rear axle for a centered WC 3/4 ton axle so the drive train is in-line with the new new NP205 transfer case.  Should be less noise and heat.

Used a 4 1/2" angle grinder with 1/16" kerf cut-off wheel to remove the outer rivet heads.  Lots of sparks, which was cool.  Center punched then drilled the 1/2" rivets with consecutively sized drill up to 3/8".  Learned that cutting oil really helps things go faster (and saves the bits) :)  Used a drift and hand sledge hammer to remove rivets and drum plate.  Of course there was more grease to clean up!  After 58 years it's amazing how much grease and crud builds up.

Removed the 3rd member studs with two locked nuts.  Will bring both rear axles to the welder tomorrow to move the wider M37 spring mounts to the centered axle.  They need to be moved outwards about 1.5" and their angle is kept the same.

Rear Brake Drum Backing Plate Riveted On

Drum Backing Plate Rivet Heads Removed

Drum Backing Plate Removed

WC 3/4 Ton Centered Rear Axle

WC centered (back) and M37 off-center (front) rear axles.