1977 Tucker 1642 Cummins

Hello all!

With the 542 and 442 now complete, we are moving back to the 1977 1642. Powered by a Cummins 12 Valve and Allison Auto!

After we picked this up from Minnesota in 2019, we began the teardown process starting with the journals. It was terribly knock-kneed and the grousers had been hitting on the fifth wheel plate so we knew they needed to be taken apart and inspected. This machine was used to groom snowmobile tracks and had burned up the original Chrysler 318 before being fitted with the reman Cummins.

We found that the metal on metal journals were worn thin and cracked - called tucker and ordered replacement journals with the new UHMW sleeves that are supposed to take wear better than the originals. Cut everything out after making a jig, then burned the new ones back in. Rear axle tube was bent and bowed so we had a new one made as well as a truss for the front axle. Welded up all cracks on the carriers and made sure they were healthy.

We also started making a headache rack and relocating the fuel tank to the bed. Ordered new sprockets, bogies, idlers, and all new bearings and seals. We stopped working on it right around that time and it has been on the back burner ever since.

Attached are all pictures from 2019

Today we dropped out both fifth wheel plates, separated them from the axles and springs, cut out the tie-rod cups, and found lots of cracks in them. Tomorrow we will begin welding everything up and doing the same circular 1/2' thick reinforcement plates to fill the two large holes like we did on the 542. Funny that they both had cracks in the exact same spot!

PP has been providing a wealth of knowledge, insight, and engineering background to make sure that our frame holds up to the torque of the Cummins and the binding forces of the 6 wheel rubber track carriers. This of course is amplified by the fact that the frame was lengthened 12" in order to fit the Cummins when it was repowered from the 318. The added wheelbase cuts down our turning radius quite a bit.

PP suggested that we ditch the swing arm and current hydraulic setup for a double ram set-up. This will take the stress off the fifth wheel plates by making the attachment points on the axle (instead of fifth wheel) and further away from the weak hourglass zone on the frame. It will also helps us gain back some turning radius by removing the factory stops and increasing them 2". We removed the factory swing arm, tie rods, ram, and the transfer case. Looks as though the original chain drive transfer case was swapped out for a gear driven case at some point. There were 1/2" shims in-between the rotted original transfer case mounts on the frame and the transfer case itself to make up for the difference in width between the two cases. We will cut these off tomorrow and burn in some new beefier ones. Figured we needed to keep the exact mounting location of the transfer case, so we cut out some scrap pieces and drilled matching holes and tack welded to the outside of the frame for when we cut the inside ones off.

Attached are some pictures from today. Tomorrow we will hopefully get started on boxing in the frame, adding extra bracing, and getting the transfer case mounts built. More pictures to come as we progress! Big thanks to PP for all the help.

This is a great approach.

Agreed!

Yesterday and today we finished up adding in our upper frame and boxing everything in. A ton of torching, cutting, grinding and welding.

We also finished up one of the fifth wheel plate reinforcements, as well as rebuilt the fifth wheel slider block assembly mounts where they meet the frame. Previous owner had ripped it out one too many times and just stick welded washers back into the holes (see attached pics). New mounts and reinforcements should be plenty strong enough.

We still have to finish the upper frame from the rear of the cab back to the rear of the cat and weld in the rest of the exterior frame plates up front. Seems overkill, but that's how we like it.

Waiting on our new transfer case from tucker so we can get the mounts built and burned in. For now, our templates remain tacked on the outside of the frame.

the Davis boys are truly an impressive father and sons operation, true respect for each other, never seem such a great team effort and boy, do they get things DONE!!!, looking forward to seeing the progress, so much to learn from the Davis boys

their business operation is well thought out and runs extremely well, quite sure it is a great company to work for, much like Talley trucking.

folks like the Davis boys do make the Forums a better place to enjoy and share all things snow cats, there are so many great folks here on the forums, the davis boys fit right in.

hey hey hey, red sqwrl, you need to join us at snow cat serenade 2026 and meet the Davis boys, you will find them most interesting and they will challenge your creativity

Damn. Between you boys and the SLC crew and select others, some serious SKILLZZZZZ on this forum. And, thank you very much for all of the pictures documenting the upgrades. I wish my 442’s return to life had happened in a month!!

Wow, (surprising absolutely no one) you guys have been busy! It’s truly wonderful to see the craftsmanship as the projects take shape. Please pass on to your sons, Best Wishes from The Utah Knuckleheads.

We look forward to reconnecting at snowcat gatherings next year.

Not to distract from the thread but love the old school Pete with the Detroit!

Thank you for the kind words PP, Davenet and Blackfoot. We still have a lot to learn from you all - but that's half the fun! Thankful to be part of the group and watch everyone's projects come to life. Safe to say we are looking forward to this years gatherings and spending time catching up.

Kevin is itching for a hill climb this season to see if this is going to perform or just dig a hole (I am pretty curious myself). Either way, turbo spool and black smoke will provide endless smiles Too bad we couldn't throw those 500 series Pontoons on here.. the weight alone would probably buckle the fronts, and the torque would finish off whatever remained.

End of last week was busy and we didn't get much time to work on the Tucker. Today, we finished up the front plating, cut the rest of the air vents out, and installed mesh in them. Kevin was cutting out templates faster than we could weld them in. We then sat the motor into the frame to make sure everything still fit and that the mounts were still aligned. Also needed to do this so that when our transfer case arrives (hopefully tomorrow) we can bolt the stubby driveline up and position the case exactly where it needs to be. Not much room for error in there.

After that was complete, we finished up the rear framework and added some "J" rail left over from one of our tanker rebuilds. Also cut out some vent holes and installed mesh there as well to keep the look. Cut out the original gussets in the back and made much larger ones.

Started cutting out the deck for our coffin hatch like we did on the 442 for some extra storage and began making the rear "bumper" to match the back of our 542.

Dropped radiator off at Macs Radiator to have the ports relocated and re-sized. Inlet/Outlet on our Cummins is 2" and I believe the radiator was only 1 1/2" (as well as having the port on the wrong side for lower connection).

More to come later in the week but a solid start for Monday!

Kevlar said:

Not to distract from the thread but love the old school Pete with the Detroit!

Click to expand...

Ahh, I was wondering if anyone was going to catch that 8v92 lurking in the background..

We appreciate that you too also love the old iron! Cheers

Care package arrived today from Tucker.. Big thanks to our dump truck driver Trevor for making a sand run down to Cave Junction and backtracking to Tucker to snag it. Nothing like a 15 hour day!

Spent a couple hours fab on rear deck - coffin storage is going to be nice. More to come on this tomorrow and hopefully we will get transfer case mounted.

New transfer case (guaranteed to 420 ft. lbs. of torque) We now have a trail spare!
New rear trunnion assembly (take a look at the difference between the old and new)
New chunk of pipe for trunnion sleeve (in case anyone needs to know, it is 2-1/4 OD x 1-7/8 ID seamless pipe) - ours was egg shaped and had 1/4' of slop. Will have to torch old pipe out and weld in new
New slider blocks
New longer length slider clamps for front and rear of our plates

Thanks to Dan @ Tucker for the help!

That OG trunion was the staple for decades light duty and heavy duty on these 50s-80s. I think the 2000 series or possible the ME forward cab models started beefing up with steel tables at some point.

On a 68 442 I did, we chucked that up in the lathe turned it round down to the next seamless ID tube size then replaced the tube in the frame. Draw back was it reduced the wear surfaces but works for most cats and better than oval.

Your new is for sure theway to go. Tremendous about of pressure and force is transmitted though that area amplified by diesel and torque ponies!

Sweet setup for sure.

Don’t be disappointed when the pontoon cats outclimb under flathead power and I once saw a slant/6 1443 rubber crawl up stuff 5/6/7 series with more track and power couldn’t.

500 series tooner for the win!

very impressed with the work and more so with the desire to learn and do it right...

big thank you for sharing and posting about your latest build, it is inspiring,

hill climber ??? mmmm.....

Finished up the coffin box today, as well as burned in the transfer case mounts. Will have to do a bit of notching tomorrow to get the rotor and caliper to clear the new mounts. Should be plenty strong being made from 1/2" plate.

Swapped over all hardware from old transfer case to new. Had to do this twice as I didn't notice the small spacer that previous owner had used to bring the yoke out and make clearance for the rotor. Without this spacer, the rotor was hitting the back of the transfer case and would not spin.

I am guessing that the rotor and caliper were from the original chain drive transfer case that was changed over who knows when.

Please share the Omaha Orange glove supplier!