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!