1951 Mack A40 Ideas for rebuild

[Scottyairborne]

As I contemplate where to go with my newly acquired Mack, I am trying to understand what are realistic options.  I plan to get running reliable as is for summer while I draft a plan forward in my head.

Purpose:  I want to drive a vintage Mack, not a cool cab on a suburban frame, etc.  I might occasionally pull a small trailer (Receiver hitch, not 5th wheel size), but usage would be more in line with parades, in town driving, and occasional trips to shows/recreation.  I would like a safe rpm at 60/65 tops.

 

Appearance:  I would love to move the rear suspension forward and shorten the frame (understanding this will kill any ride improvements I attempt).  I would also like to make a pickup bed that resembles the wrecker/fire truck sides but with the added utility of a pickup bed.  I may stick to cab and chassis first.

 

 

[Scottyairborne]

With all that in mind, I am considering the following areas to be addressed:

Interior:  relatively stock rebuild for now.  Get the seats rebuild (missing foam/covers), hand sand and spray it decent.  A work truck finish is suffice.

Transmission:  I really want to keep the duplex If reasonable.  The twin stick is exactly my vision of a big truck.
 

Rearend:  I haven’t figured out my gearing options, but this may need to be swapped. I would love to run a super single drive tire, on airbags.  Perhaps better to just swap it all and relieve a lot of drivetrain constraints?  I don’t even know what would fit the best, I am not a truck guy.

Front:  Considering replacement of the leaf stack with single leaf and airbags.  Again, I won’t be hauling real loads...  Future power steering box would be very nice if wife/kids ever want to spin it around.

Engine:  The original Magnadyne starts and runs well.  I am strongly considering an eventual 5.9 Cummins 12v swap, which can work with the SAE2 flywheel.  That conversion gives me easy switch to 12volt, power steering options, and even AC options down the road.

Edited June 10, 2020 by Scottyairborne
Forgot sentence

[Scottyairborne]

I don’t know if it is blasphemy to swap an engine and/or rear to make a truck usable in modern times.  Is there people who may want the engine/rear for their non-runner? I know purists have issues sometimes with these talks, if you don’t like it, you can make an offer on the truck in its original state   I won’t be changing things any time soon.

[h67st]

12 minutes ago, Scottyairborne said:

I don’t know if it is blasphemy to swap an engine and/or rear to make a truck usable in modern times.  Is there people who may want the engine/rear for their non-runner? I know purists have issues sometimes with these talks, if you don’t like it, you can make an offer on the truck in its original state   I won’t be changing things any time soon.

There's a lot of old trucks out there with modern engine swaps, like you say if you don't like it then tough. The old engines are neat but we don't all have to have them. It's better to preserve the sheet metal even if you put a different engine in it.

[Brocky]

Scotty

Here is a link to Tom Millard's conversion from a gas 427 CI Continental to a 5.9 Cummins in his 1955 Brockway 155W. Tom is an electrical engineer by trade and a perfectionist restorer. If you search both the Brockway and the Just Old Trucks websites you can find more of his well documented restorations. I also know of a Brockway, with a small wood flatbed, in northeast PA with a Cummins L10 which is running on super single drives. Email me thru here and I can send you a picture and contact info.

http://www.brockwaytrucks.org/messageboard/viewtopic.php?f=1&t=4952

Edited June 10, 2020 by Brocky

[Vladislav]

I wouldn't advice you on engine options since my strong preference is stock configuration which only brings historical value to a vehicle but I would toss an idea on the look. If you're thinking installing pickup bed or so I'd put a big winch or a small crane behind the cab and mount the bed further to the rear. This would allow you to keep long wheelbase and achieve special and a bit agressive appearance. Telling further that may bring you smooth enough ride with stock rear and also front suspension and split the rebuild costs sufficient. Again, your truck means your rules.

[mrsmackpaul]

As Vlad had said, your truck your rules

 

Since your asking I'll offer some thoughts, not instructions, thoughts 

In Australia and I'm guessing the rest of the world is similar, more trucks, cars, bikes etc are wrecked and end up in the scrap bin by well meaning people who are gunna do heaps but it all in bits and life and lack of motivation or the enormity of it all takes over and several years later it goes up on a buy swap and sell site as a started project but ultimately ends up in the scrap

The advice given out pretty often in Australia is, get it running and useable and enjoy it

When this happens it is believed we are far more likely to keep it going and enjoy it and do small mods and improvements 

As for ride, drop some leafs out of the spring packs and reduce tyre pressure to say 50 psi max and you will find it will ride like a Cadillac or better 

Power steering, you will find if you have little weight on and a well lubed front end it will be fine for driving but heavy for tight maneuvering 

Speed is going to be a issue but until you find out what your diff ratio is and what options are available that will remain a unknown 

If your plans are  for driving everyday a 5.9 with a overdrive box might get what you need 

Caster angle was reduced in Australia on the front axle of trucks from new to help when no power steering was about

This has the negitive effect of making the trucks quite hard to keep in a straight line at speed but is fixed fairly easy with wedges in the springs

Good luck and please dont think I'm been negitive or rude, just offering some thoughts 

 

Keep us posted

 

 

Paul 

[mrsmackpaul]

And diff ratio is easy to find out if you aren't sure just ask and plenty of help will be forth coming 

 

Paul

[AZB755V8]

10 hours ago, Scottyairborne said:

As I contemplate where to go with my newly acquired Mack, I am trying to understand what are realistic options.  I plan to get running reliable as is for summer while I draft a plan forward in my head.

Purpose:  I want to drive a vintage Mack, not a cool cab on a suburban frame, etc.  I might occasionally pull a small trailer (Receiver hitch, not 5th wheel size), but usage would be more in line with parades, in town driving, and occasional trips to shows/recreation.  I would like a safe rpm at 60/65 tops.

Appearance:  I would love to move the rear suspension forward and shorten the frame (understanding this will kill any ride improvements I attempt).  I would also like to make a pickup bed that resembles the wrecker/fire truck sides but with the added utility of a pickup bed.  I may stick to cab and chassis first.

Scotty,

It is your truck to make whatever you what. You need ability, money, time, patience, Enthusiast and Interest you do have, to start changing things. I read that you want to change, everything that makes it a

What is an antique , Tough as it comes, hard riding, hard shifting, hard steering, hot, loud, uncomfortable, classic, leaks oil, made to last, what do you want to keep? The trucks were make to get a job done and this one survived for this long all factory original and waiting for you.

It would be fare easier to put the cab and hood and fenders on a modern Ram 2500 with 5.9 Cummins, keeping the 8 foot bed, than what you are talking about. Do you have mechanical ability, not knowing trucks? Asking where to start here, sounds like a kid with a new toy, no disrespect but it is what it it is. Get it running good and road worthy, safety is first seeing you will have the wife and kids along for a ride. Tires, Brakes, Lights, Steering all in good shape is a must before changing anything. Enjoy it for a year or two before changing things, chances are it will not go together as easily as it will come apart. There are many trucks that owners have the best intentions for and never see the road again. My shortest rebuild took 2 years the longest 17 years so there are variables to any project.

If it's a keep it a just my opinion though, most important have Fun 

 

[Quickfarms]

Based on the pictures you posted in the other thread it looks like the axle may already have S cam brakes which is good.

Crawl under there and get some pictures of the tags on the axle and the carrier, center piece.

Changing the gear ratio is not that hard or expensive.

Having the springs re arched and rebuilt to the actual weight of the truck plus a ton or two will make it ride like a car even with the tires at 100 psi

Don’t run old tires at reduced pressure

[Scottyairborne]

I appreciate all the responses...

I do intend to drive this truck all summer... we have long winters here in Northern Wisconsin so I can take on bigger items then.

I appreciate the idea to keep it a Mack, which to me means it needs to be able to do the task at hand.  I have some ideas for what that is, so hopefully I can determine what is realistic.  I have some abilities in the garage, have some amazing mechanics and fabricators in immediate family and friends.  

I was taught to ask questions, listen and learn from those with more and less experience.  It can save costs and mistakes, but also spur innovation and better ways to do something.  I will definitely have fun, including listening to other inputs and suggestions along the way.

[mrsmackpaul]

I was doing some reading and you might be surprised at the fuel economy you will get out of that Mack motor

I would think if you swapped the diff ratio to get closer to what you are chasing as in speed wise you might get between 10 - 14 MPG when your zipping around empty

I have a article on a Holden FJ or FX ( which wont mean a thing to ) Holden was the Australian arm of GM  and the GM brand in Australia 

Anyway, this fella did modifications to the grey motor (the Holden equivalent of a Blue Flame Chev 6 cylinder) and could easily get 20 - 25 MPG on unleaded fuel

I think with modern throttle body fuel injection kits and a electronic dizzy you would be able to get even better

I have a couple of petrol Macks I need to pick up after this Covid 19 debacle finishes and this is the route I think I'll take with them 

Not saying it's gunna be simple but hopefully will keep them fairly original and reliable so I can use them for fun

 

Paul

[Scottyairborne]

That is really good mileage.  I was worried about over working the original engine with a taller gear.  If I can get it safe to close to 60 cruise, I wouldn’t even consider the swap.  

[terry]

45 minutes ago, Scottyairborne said:

That is really good mileage.  I was worried about over working the original engine with a taller gear.  If I can get it safe to close to 60 cruise, I wouldn’t even consider the swap.  

depends how much weight you are hauling to be able to cruise at 60MPH with that engine.   terry

[Scottyairborne]

Exactly why I started this thread.  Nothing would make me happier than keeping the Mack gas engine.  Focusing on rear gears and tire combos to match the existing drivetrain is so much easier to meet my goal.  Since we won’t be loaded, that is not a concern.  Honestly not that worried about mileage, this will be a vintage recreation vehicle, for hobby use and driving pleasure.

[Scottyairborne]

For suspension, I initially plan to disassemble and clean up the leaf packs.  Perhaps pull a few leaves, and see what I get.  Not going to overthink it this summer!  That just might be the long-term solution.

[HeavyGunner]

6 hours ago, Scottyairborne said:

For suspension, I initially plan to disassemble and clean up the leaf packs.  Perhaps pull a few leaves, and see what I get.  Not going to overthink it this summer!  That just might be the long-term solution.

There’s also Teflon slippers (i think that’s what they’re called) that can be installed between your leaves which allow them to slide easier thus giving you a smoother ride. 

[Scottyairborne]

Yes, have used Teflon in leaf packs in the past with good success.

[Scottyairborne]

Drove it home today to my in-law's shop.  About seven miles, took it REALLY slow.  Runs like a pup, the tires are very bad.  Temp tank up on the passenger mirror to bypass the old tank until I can clean it.

Learned a few things about it, it is the EN 377 with a Triplex, which makes me happy.

The Montana title says 1952, not sure if that is relevant or not.  

Wheelbase is 180", which is a nice length.  I am officially searching for a vintage sleeper box (for storage, not sleeping).  Hopefully 24-48" range...

Photos coming...

[Scottyairborne]

[terry]

Quite the ride I bet!!👍   terry

[Scottyairborne]

Inventory on a few missing pieces:

rear lights (I have plan there)

passenger door handle (repairing their make-shift fix will be a project if it’s own)

hood handles for both side (I might have found one in the cab)

Dog emblem on driver side hood

 

I have the battery box cover that is off in the photos.  

 

 

 

[mrsmackpaul]

That looks incredibly neat and tidy, well done and glad you got it home ok

 

 

Paul 

[Scottyairborne]

I think we are fortunate to have one in this shape for a family project.  Not to down play how much it needs, but to be able to drive her home is a great start.  Taking it a bit at time and keeping it driving.

 

First up is complete fluid change, lube, gas tank internal cleaning.

[Scottyairborne]

Found this plate today while going through and measuring things.