Since March 2024, we have been working on Nonna’s interior and exterior. I’ve had two long break and worked on other vehicles from time to time, so it may not sound that productive. It’s true that on unfamiliar projects such as painting, I didn’t compress time to speed up the progress because I was still learning, time was never saved for less result.
We’re probably halfway there now, and the rest is the “non-artistic” work, which is everything under the body. Based on initial assessments after the underbody was dry ice blasting in April, the entire powertrain and suspension had to be rebuilt, and preparations for this had already begun a long time ago. We’ve removed the front and rear axles this week, before we start the restoration it’s worth talking about how to be more efficient on the upcoming tasks.
Funny to say, I initially had an unrealistic idea to complete all the work on Nonna before September 10th. For some reason, starting in July, I missed my high school teachers very much, and I decided to visit them at school first time in last decade. But they are all on vacation, so Teachers’ Day after the new semester starts in September sounds like a good idea. I haven’t seen them in 12 years, and I don’t know where to start talking about many things. What am I doing? What did I do? Apart from my family and these cars, I don’t have much to be proud of. It would be great if I could drive Nonna to the high school. I don’t even know if the school allows visitors’ cars in, though. But it doesn’t matter anymore, completing everything in 30 days is completely unrealistic.
Given our experience with the chassis repair of Octavius, the same work on Nonna should naturally be properly arranged. Although 30 days is unrealistic, I do not intend to delay this work until the end of the year, which would make 2024 too inefficient. Therefore, the principle of work is to compress time as much as possible without sacrificing results, which is not a paradox. Because there are many projects involved, there are plenty of opportunities to waste time. We did waste a lot on Octavius ​​(the same work took 10 months), and there are also many opportunities to improve efficiency. Before talking about how to speed up, I suggest finding the factors that delay progress.
- Supplier speed
There are almost no true suppliers at Octavius, all works were done in-house. We purchase the necessary materials from suppliers and do it ourselves. For example, for galvanizing fasteners, the advantage of doing it yourself is that the risk of lose is low and it is available at any moment, but the disadvantage is that it takes a lot of time. In the past few months, we have tested and approved suppliers. They can save time, but they can also waste time if the planning is wrong. For example, in the galvanizing and chrome plating of parts, whether it is damaged or lost, sufficient quantity must be ensured before the installation begins. The supplier needs a week of work time, and the shipping takes an additional week, which makes a run become at least two weeks. Two weeks can do a lot, or nothing can be accomplished because of the lack of a bolt. The supplier’s beat is largely determined by us. If we make a detailed classification of parts with different treatment processes, the supplier is unlikely make mistakes. In order to reduce the loss of time caused by damage and loss, it is necessary to get double the parts from the donor. The deadline for sending parts to suppliers is before the installation begins, so in order not to wait in vain, some parts should be prepared in advance instead of waiting for two weeks. - Timeliness of parts
It takes a long time to order and ship parts. For local MB dealers, most 140 parts can only be shipped from warehouse in Germany, with a time limit of about 14-30 days. Local suppliers can deliver within 3 days, 2 days if necessary. Parts are the biggest obstacle for all restoration projects, but for us they are the second. Because without parts, the restoration will not start. The first part is that we have our own parts library, which contains many common rare NOS parts and common parts that always meet the restoration of 2-3 cars. The second part is preparation for a specific car. After receiving Nonna in December last year, we immediately started hunting for potential parts, especially those that Mercedes aftersales no longer provides. New parts requirements are generated every minute and every second during the disassembly process. The closer to the end of disassembly, the more timely the parts procurement must be updated. In order to reduce time waste, for low-value parts that can only be sent from Germany, even if we are not sure whether they are needed, we order them in advance. There is no need to wait a month for a 1 Euro O-ring. - Installation Logic
The first two factors are more or less controlled by others, this one is completely up to us. The assembly of the car has its own specific order, and violating the order may lead to complete jamming or rework. In addition to relying on dogmatic repair manuals, we must always be vigilant. For a group such as the rear axle, it should be installed after the underbody repair. For a part such as the half-axle bolt, it should be torqued before the rear axle is painted. Each element has its own unique queue range and must be fully considered. But it is impossible to write the order of each part in the plan in advance, because the time budget for writing the plan is also limited… Even WIS is not 100% referenceable and cannot be completely relied on. In addition to taking pictures during the disassembly process and remembering the order in mind, the complete WIS file, from group 1 to group 98, is ready. Read these manuals in spare time to see if there are any places that are not considered. Also keep in touch with colleagues in the workshop and discuss in advance when encountering problems that are difficult to find answers.
What does the plan look like? The principle of work is to divide the nature of the work into two parts, “low uncertainty” and “high uncertainty”. “Low uncertainty” work refers to those with low risk and can be started and stopped at any time. This is usually some simple or repetitive mechanical work. It can be an action, such as glass blasting. Or it can be a project, such as rebuilding a generator. These jobs have little variation and are unlikely to get stuck. “High uncertainty” work refers to those with high risk and a big impact on the installation sequence. It cannot be skipped or suspended. This is usually some complex work or difficult to predict the troublesome projects, such as engine rebuilding. The engine rebuild is almost the starting point of the work, because the engine must be there to install the front axle. But the problem of the engine is unclear even at the last minute, such as whether the valve needs to be repaired. Many complex situations also impair judgment. Under the parts covered with sludge, can’t find which bolts need to be replaced until they are cleaned. Therefore, a lot of effort is even wasted. Even some jobs that require outdoor work are weather critical. You definitely want to be outside blasting suspensions with dry ice in cooler weather, not in the heat and mosquitoes of the summer.
Therefore, under the premise of complying with the installation order, the low uncertainty work is postponed and the high uncertainty work is prioritized. Because the high uncertainty work may be forced to stop at any time, it is better to do the low uncertainty work to avoid waiting in vain. For example, once the engine is disassembled, the parts that need to be processed are checked and sent to the supplier first, and then the engine parts are cleaned during this period of about 2 weeks. Cleaning parts can start anytime and anywhere, they are “boring” work. Another example is rebuilding some rare parts, such as a rear axle connecting rod that is very expensive. Check them immediately, install new grease and dust boots if they are still usable, and order them immediately if they are scrapped. Now that the work has actually started, here are some brief plans.
1.Repair the body This repair is planned without using the lift, as we plan to expand this room later to avoid damaging the car during construction. After removing the front and rear axles on the lift, a bracket is made to move the body to a relatively static workstation. Therefore, in order to minimize the time occupied by the lift, the repair of the body is given priority.
1) Cleaning Dry ice blasting has been performed before removing the front and rear axles, but the parts blocked by these and the exhaust pipe are still very dirty. First, further remove the parts in the engine compartment and clean the engine compartment and the bottom.
2) Paint There are many paint peelings on the bottom, which are easier to repair on the lift. First remove the rust, then apply epoxy primer, and color paint that matches the E-coat color. We plan to expand this room next week, and there is no compressed air available yet, so the spraying of the engine compartment will be put off until later.
Another part that must be tried is to repair the insulation felt on the firewall without removing the firewall (so without removing the fuel pipe).
2.Disassemble the front axle
It is expected that the front axle with the engine will require much more work and accessories than the rear axle, so the front axle will be disassembled first. In this case, there is more time to prepare the parts for the front axle.
1) Cleaning
Previously, only the lower part was blasted with dry ice, and now all parts need to be thoroughly cleaned. When the engine and front axle are quite complete, they are generally waterproof, so it is the best time to clean the exterior.
2) Disassembly
During the disassembly process, the most important thing is to check each part and decide on the way to deal with them immediately, according to the supplier’s category. For example, chrome plating, galvanizing, purchasing titanium alloy fasteners, etc. Only the gearbox does not need to be disassembled for the time being, and it will be sent to the gearbox expert together with the car after the whole car is completed.
3.Disassemble the rear axle
This time, the differential will not be completely disassembled. Based on current experience and past experience, the differential does not have to be completely rebuilt. So the work on the rear axle is lighter.
1) Cleaning
Similar to the front axle, only the lower part has been blasted with dry ice, so the upper part needs to be cleaned. Perform external cleaning before disassembly. Don’t worry about water entering the differential or half-axle at this time.
2) Disassembly
During the disassembly process, check each part and decide on the way to deal with them on the spot. Classify according to the supplier’s category, such as chrome plating, galvanizing. All bushings and connecting rods of the rear axle have been assumed to be replaced, so the rear axle requires less part preparation time.
4.Prepare the parts
Disassembly is almost the last chance to know the condition of the parts, so the preparation of the parts is also carried out at the moment of disassembly. In the best case, the preparation of the parts is also completed when the disassembly is completed.
1) Order the parts
Order in a tolerant manner. Although a large number of parts are worth and necessary to be reused, it is inevitable to discard some of them. Reusing repaired fasteners is risky, they may break during installation and kill the plan. Therefore, for low-value parts, order redundantly.
2) Repair the parts
Many parts need to be repaired in house or sent to suppliers. For the parts of suppliers, they are prioritized and sent as the first batch after the disassembly is completed. For the parts repaired in house, they mainly need to be cleaned, sandblasted and painted, and they are carried out step by step. This will take up more than half of the repair time.
5.Assemble the engine
The current engine is healthy, visible engine work includes resealing and replacing most external accessories, and replacing the valve seals. Hopefully further diagnosis of the engine will determine the depth of the work to stop here.
1) Renew the front
Includes resealing the timing cover, and renewing everything in the front. Including the water pump, power steering pump, generator, AC compressor, and the small parts around them.
2) Renew the rear
The crankshaft rear seal has been leaking. The starter also needs separate maintenance.
3) Renew the top
Replace the valve seals, renew the valve cover and intake manifold, and renew the injectors.
The engine and unrestored transmission are married and jointly mounted on a new mount in preparation for re-attaching to the front axle.
6.Install the rear axle
On a 2-post lift, the rear axle is missing but installing the front axle will easily cause the body to tilt, so install the rear axle first.
1) Assemble the rear axle
Replace the bushing of the subframe when it is unloaded, and then install the differential, half shafts, suspension and brakes. Some screws will be difficult to tighten after the rear axle is installed on the body, so they need to be torqued in advance. Some screws should be tightened after the suspension is installed and under load.
2) Install the rear axle
After installing the subframe, install the shock absorber and spring.
7.Install the front axle
The width of the M104 engine allows the engine to be installed from the bottom to the body together with the front axle.
1) Spray the engine compartment
At this time, the workshop for disassembly, painting and dry ice blasting has been expanded and compressed air is available. The body should be returned to the lift and the engine compartment should be sprayed before installing the front axle.
2) Assemble the front axle
Assemble the front axle while the paint in the engine compartment is waiting to cure, mainly returning the engine and transmission to the front axle. At this time, there are not many parts that can be installed on the front axle, mainly bushing and motor mount.
3) Install the engine compartment
At this time, the paint has dried. Many parts in the engine compartment, such as the reservoir and the warm water valve, are easier to access when the engine is absent, so it is necessary to install them before the front axle returns.
4) Install the front axle
Most parts of the front suspension need to be installed after the front axle is married to the body, including the steering system and suspension.
Below the clock: time tests truth. The only eternal truth is that time always pass. This reminds everyone in the workshop to manage their time well, but not to be stingy in investing time in the car.