Overhauling Abel
Rebuilding the rear end – and much else – of our faithful 1957 220 Ponton
Not many 1957 220 Pontons have their own Facebook page; there is only one that informs his followers about his global travels. As related in The Star’s May-June 2018 issue, “Abel,” the beloved Ponton of Fred and Elisabeth Smits – known as the Classic Striders – passed the 100,000-kilometer mark of world travel in December after leaving New Zealand in June 2014. But earlier this year, soon after leaving Santiago, Chile – and heading north after a year in South America – a note of concern was posted on Abel’s Classic Strider Facebook page.
“In Rio de Janeiro, I started to have this little click-clack noise in my rear axle that became worse and worse,” Abel noted. “Having just mapped out a route that included higher mountains and rough conditions on the way north through Bolivia, Perú, Ecuador and into Colombia, from where I will be shipped to Europe, my owners decided it was time to take me off the road for a few months.”
Taking advantage of Kaufmann Mercedes-Benz in Pajaritos, a suburb of the colonial capital of Santiago, the Classic Striders wanted to check that rear axle … and thoroughly refresh the restoration performed when prepping Abel for their round-the-world adventure.
Abel was appalled that Fred and Elisabeth would pull the tires out from under him.
“I love the tough stuff,” he gushed, “such as driving the beautiful South America continent – sometimes in temps higher than 40°C (104°F), sometimes in gales and storms, sometimes through snow while climbing thousands of meters over the Andes, over gravel roads or through dust, water and mud – the very same driving conditions that Dr. Fritz Nallinger wanted Pontons to handle when he designed us in the early 1950s.”
He’s proud of his heritage – and stamina – but admits to being a bit tuckered out.
“When I, Abel, am parked somewhere waiting for Elisabeth and Fred, I often hear people say, ‘What a beautiful car; it should be in a museum.’ Well, that really gets my radiator water boiling – I, the able Abel … in a museum? No, thank you very much; that is just not me. Unfortunately, age could be catching up with me.”
A proper job
We, Fred and Elisabeth, are taking up the story for an indisposed Abel, who is basically under the weather and on the rack, so to speak.
Kaufmann is the sole Mercedes-Benz dealer in Chile, with 32 branches throughout the country, selling and maintaining cars, vans, light and heavy trucks, minibuses and passenger buses. This highly professional 60-year-old company employs approximately 2,100 people; at the Pajaritos branch alone, where we were, there are more than 550 mechanics, painters, electrical and mechanical engineers, sales and support personnel, carrying out all work – from a sedan’s oil change to the power-train overhaul on a heavy truck.
But the most lovely gift for us as Mercedes- Benz owners is that Kaufmann managers offered to let us use their facilities to fully repair the wear, tear and damage Abel suffered during the 44 months of driving that the always-overloaded 60-year-old car endured through the Americas, often over challenging roads (shhh … don’t tell Abel he’s 60 … or that he has ever been over-challenged)! We couldn’t have found a better place for his 120,000-kilometer service.
While most people find this difficult to believe, we really love working on Abel, looking after his appearance and fixing his ailments; it is as much part of our world tour as driving the miles, standing in awe of the natural wonders and beauty we see, visiting car clubs and participating in car shows and rallies. Doing minor – and sometimes major – repairs on the road offers fantastic chances to meet the locals, and gives us intellectual stimulation, as well as a physical workout.
We worked eight to nine hours each day: We first focused on disassembling the drivetrain and rear axle, making a list of parts and servicing needed. The ease with which we could order parts – so distant from our home and the factory that had built our car – and find knowledgeable people interested in helping us, was one of the main reasons we had originally selected a Mercedes-Benz for our adventure.
While we waited for replacement parts to arrive from overseas, we removed, cleaned, repaired, oiled, greased and protected Abel’s many mechanical and electrical parts. We repainted the underbody, rechromed the fog lights and powder-coated underbody parts; rebuilt the brake, steering, heating, cooling and fuel systems; replaced the many nuts, bolts and washers damaged during the last three and a-half years of (often) rough maintenance and crude repairs … (shhh, don’t tell Abel) and completely rebuilt the drivetrain, including the clutch, driveshaft and rear axle. Effectively, we did a complete mechanical restoration of the car. Abel is now looking and feeling as good as when he left New Zealand in June 2014.
That rear-end noise
Mr. Strider recalls learning some interesting lessons worth sharing with other Ponton restorers as we chased the noise that triggered this now-dubbed “Santiago Restoration Project.” Dismantling the rear axle, we found the cause of the click-clack noise: the differential gears were very worn and loose in their casing with 2-3mm clearance – a condition that could have led to total axle destruction. Even worse was the wear in the sliding U-joint, in which we found at least half a teaspoon of metal filings. Rebuilding with new parts was required.
Because the swing-axle rear end of a Ponton is considered by experts to be bullet-proof – and almost all of them make some noise – this is a job often ignored in a restoration. This may not be a problem in most classic restoration projects, considering the light use they will undergo after restoration. Rebuilding the axle is not overly difficult, but is time-consuming, quite expensive and requires good mechanical skills and special tools. At the very least, we recommend a restorer check the fluids and operation of the differential and sliding joint for the kind of wear problems we encountered.
When reassembling the rear axle, we used a new sliding joint and all-new bearings; we replaced all bolts, nuts, washers and split pins and fitted all-new seals and gaskets. When we finished, the crown and pinon operation was beautiful – with a very small backlash; we didn’t have the tools to measure it accurately, but it was certainly close to the 0.18mm specified by Mercedes-Benz. The planetary wheels ran stiff but smooth, and all bearing movement was close to or within axial specs. We followed the Mercedes-Benz workshop manual to the letter, torqueing every bolt and nut to specification and securing every critical fastener. Leaving nothing to chance, we basically built a new rear axle.
What’s next?
After we were done with the repairs, we still weren’t done: We took a 1,000-kilometer weekend drive with our new classic-car friends, then carefully checked Abel’s vitals. Finding wear on the outside edges of the rear tires, we had the alignment corrected. We changed the differential fluid; we did find metal particles, but only what one might expect from running-in new tight-tolerance gears.
Nevertheless, we made a longer run the next weekend, and repeated the check. Now everything is music to our ears with our noiseless Abel – and he’s looking just as beautiful.
Having spent 13 weeks working with the Kaufmann team, we will miss the many friends we made – from office and management to cleaning and lunchroom staff. We’ll miss the shared lunches, and even the confusion we sometimes had, caused by our limited ability to speak Spanish. “Please torque that M12 nut to 110 Newton-meters, but be very careful not to damage the 12V control cable from the alternator” doesn’t translate easily into Spanish.
From here, we will drive north along South America’s Pacific Coast, returning to Cartagena, Colombia, to pick up “Zambezi,” our camping trailer. Then we will ship Abel and Zambezi by boat to England while we make flying visits to Nova Scotia and Iceland. From England, we’ve tentatively laid out a loop of the British Isles – then a larger look through Europe – and from there to the Middle East and into Asia before eventually making our way home by way of Australia.
And Abel has resumed his Facebook duties; you can follow him at his Classic Striders Facebook page.
Step by Step
1. The Kaufmann Mercedes-Benz workshop in Pajarito, Chile, where we restored and repaired Abel. Kaufmann employs approximately 2,100 workers in 32 shops throughout the country. Aside from cars and vans, the Pajaritos workshop is a major center for truck repair, with 32 truck and bus maintenance bays; most are fully occupied all the time. Here Kaufmann overhauls and repairs heavy truck and bus engines, differentials, gearboxes, and clutches.
2. The first step in overhauling Abel: Fred Smits, “Mr. Strider,” power-washes his car body and engine.
3. While awaiting parts on order from the United States, Germany and New Zealand, we overhauled Abel’s electrical system, replaced a headlight connector that burned out near Rio de Janeiro, and installed permanent wiring for the GPS.
4. Installing a new Facet-Gold electric fuel pump (4 psi), which is a fine replacement for the Ponton’s original mechanical fuel pump; ours is fitted just in front of the fuel tank. We always inspect the car’s underside during lubrication, oil changes, and tire changes or wheel alignment.
5. Setting fuel pressure off at 1.5psi after fitting the new Facet-Gold fuel pump and lines, and overhauling carburetors.
6. Scraping off old underbody paint; we had to wait weeks before parts arrived and took the opportunity to prepare the underbody for a repaint in Abel’s original tan, a rare color used by Mercedes-Benz for only a few months in 1957-1958.
7. Final wash before repainting the underbody. Elisabeth Smits, “Mrs. Strider,” never stops looking after the underbody, engine bay and cabin – the original oak dash receives a monthly coat of wax.
8. New tan underbody paint goes on.
9. Scraping rust off the inside of the trunk, then repainting.
10. It is very important to always follow the clear, concise instructions in the full Mercedes-Benz workshop manual; it is an essential part of our road gear. The manual can be downloaded from the Ponton webpage at www.mbzponton.org/.
11. Start of clutch replacement: removing the clutch linkage.
12. Hmm … that flywheel needs a bit of a grind (0.15mm). It is strongly recommended to replace the clutch pivot and release bearings at the same time as the clutch plate.
13. Just a touch-up of the starter ring. When replacing the clutch plate, always check the flywheel for wear. If it is badly scoured, remove the flywheel for resurfacing. Also, check the starting ring and refit the flywheel with six of those very expensive Mercedes-Benz stress bolts.
14. The “Queen of Clean” gives Abel’s gearbox a thorough wash-out with mineral spirits. We then left the gearbox to dry over a weekend before refilling it with 1.4 liters of that outstanding Amsoil transmission gearbox oil.
15. Gearbox and clutch back in place – note tan underbody.
16. Old parts repainted and ready for assembly – but still waiting for some essential replacement parts.
17. Let’s not forget all those little bits and pieces! While we had the springs, spring carriers and torque arms powder-coated, some small components we simply painted by hand.
18. On March 6, 2018, the rear axle came out. Removing the axle is not difficult: just follow the steps in the manual, but be aware of those springs – they are dangerous. It is important to keep the axle straight and supported at all times: the cast-iron hinge of the swing axle easily deforms or breaks. 
19. Rear brakes coming off. Before getting to the heart of the rear axle we had to remove the shock absorbers, disconnect the drive shaft, brake lines and handbrake cable, and remove the wheels and brakes.
20. Master mechanic Eduardo Mercedes (sic) and Mrs. Strider take Abel’s differential apart – the easy part of the job!
21. Eduardo prefers truck differentials to Abel’s finicky small parts. Rebuilding a differential is a job for a pro – small gears need to turn freely, but stiffly and without play in the carrier.
22. Look, guys, the source of the click-clack noise: far too much play in the differential gears.
23. Another problem: Metal filings from the slip coupling; the slip coupling is a critical part of the swing axle and Abel’s was due for replacement. We are always looking for good replacement parts, and had been able to buy a good NOS (New Old Stock) slip coupling in Montevideo – or so we thought!
24. The devil is in the details: Fitting all 132 as-new little cylindrical roller bearings back into the slip coupling. In an unexpected twist, that NOS slip coupling had turned out to be sticky from age, so Mrs. Strider had to remove, clean (A), correctly lubricate (B), and then reinsert all 132 of the little cylindrical roller bearings (C) back into the coupling by hand.
25. The slip coupling goes back!
26. Be sure to check teeth engagement with Prussian blue.
27. Carefully torqueing the conical bearings in the differential housing using a torque wrench with an operational range of 20-140 NM (Newton Meters; 14-105 lb-ft).
28. After using a magnetic level to ensure a 90-degree angle between the axle tubes and the support during reassembly, the locking key is finally fitted back in place.
29. Our preferred gear oil, Mobil Delvac Synthetic 80W-140 going back in the rebuilt differential.
30. Our set of special tools: A. Shaft for setting up the differential gears. B. Tool to drive swing axle pin in/out. C. Two wheels to locate crown wheel in rear axle housing (bought from the International 190SL club). D. Tools to tighten the pinion nut.
31. Eduardo, that is only a wheel bearing for a little car, not a truck! Truck axle mechanic par excellence Eduardo tightens Abel’s little wheel bearings a bit too much.
32. The rebuilt rear axle being installed. No more noises! Note the Facet pump (arrow) just in front of the fuel tank; it is well protected in the wheel arch.
33. Start-up! Even after 220,000 miles, Abel’s quiet, original engine easily passed the traditional “standing coin” test (arrow); note the surprise and delight on the young Kaufmann mechanics’ faces.
34. The Kaufmann paint shop crew gave Abel a fantastic polish and wax job as a lovely farewell present.
35. Goodbye to all the Kaufmann workshop personnel.
36. It’s finally time to hit the road once again. Ciao amigos, we will miss you; keep up all the good work!