Restoring your flathead
Although my Dad has been gone for over 40 years, he continues to get smarter as the years go by. He was a mechanic in the Army in World War I and for many years after. He helped and guided me through my first engine overhaul.
He continues to help me to this day as I remember some of his advice and helpful hints. It is well known that the ’37 to ’48 Cad and LaSalle flatheads are my main “cup o’ tea,” and, although many of these general procedures will apply to most engines, we will go through the process of restoring a ’37 to ’48 flathead with a manual transmission.
Let’s start with some of the supplies you will need. To start with, you will need a supply of various-sized freezer bags and a marking pen. These should be on hand even before pulling the engine. As the bolts, nuts and small parts are taken off, they should be placed in a bag and marked to indicate where they came from (i.e. motor mount bolts, U-joint bolts, transmission mounting bolts, etc.)
If a bolt becomes damaged or broken while taking it off, bag it with the rest from that assembly. A tablet should be on hand to list parts needed.
Jumping ahead a bit, when the take-apart is done, inventory all the bolts and nuts that will be needed for reassembly. List them by size, length and thread count. When the list is completed, go to a good fastener or bolt-and-nut supply house and get enough new ones to finish the job. Never get less than grade 5, and for high-stress points, use grade 8.
I personally believe that it is wise to replace all the nuts and bolts on these old cars, because after 50-odd years of heat and cold under stress, it would be a shame to ruin a good rebuild with a nut or bolt that fails. This can happen if these have crystallized, warped, have partially stripped threads, or weakened by rust or corrosion.
For the purists who do not want modern grade markings on your old LaSalle or Cadillac, these markings can be ground and/or polished off. If the bright bolts and nuts are not wanted, they can be colored with extra-strength gun bluing, available at any gun shop. Then place the right amount of new bolts in each bag with the old ones, and everything will be ready when reassembly time comes.
The idea of dumping all the old bolts into coffee cans is a good idea only for people with a photographic memory and total recall. This plan of freezer bags and marking should follow through with the rest of the restoration.
The next thing needed will be two engine stands. One will be the saddle type that the complete engine and transmission unit can be placed on to start your disassembly. Also needed will be a rotating engine stand to mount the engine on when the transmission, clutch and flywheel have been removed.
All of this on hand, it is time to start the dismantling. Let’s assume that the engine and transmission have been pulled and placed on the saddle-type stand. The first thing will be to remove the transmission from the bellhousing and put it aside for now; that is a separate project to be tackled later.
To do this, first remove the retainer that looks like a funnel and fits into the rear of the bellhousing. Clean and polish up this unit, checking for any flaws. (Here is a little side note to keep in mind throughout the entire restoration: As each piece is removed, clean it, polish and/or paint it making it ready to reinstall. You will thank yourself over and over again as you start the reassembly process.)
On the back of the bellhousing, there will be a large slot head ball stud that is holding the clutch yoke into the housing. After removing this ball stud, the whole unit can then be pulled out through the side opening. At this time, a new throwout bearing should be placed on your parts list along with the pilot bearing. They may seem to be okay, but it is much easier to replace them now than having to replace them after starting to drive the car later.
It is now time to remove the clutch unit and this can be a little tricky, due to the heavy springs. First of all, put a punch mark on the clutch cover (pressure plate assembly) near one of the bolts and an identical mark on the flywheel, so when reassembled, these parts go back into the same location. This is very important.
Now loosen two of the bolts slightly and then rotate the flywheel one-third of a turn and loosen two more, rotate another one-third and loosen the other two. Continue rotating and loosening until the clutch assembly can be taken out of the bottom of the housing. Now loosen the bolts holding the flywheel onto the crankshaft and drop the flywheel.
The clutch disk and pressure plate should be taken to a clutch specialist for professional refacing and truing, if needed. The flywheel should be taken to a good machine shop to be refaced, and if the teeth are worn on one side, the machinist can remove and reverse the ring gear.
The bellhousing can now be removed, cleaned and painted with cad green engine enamel. With the bellhousing off, it is time to move the engine from the saddle stand and mount it on the rotating engine stand and prepare to start on the engine itself.
I don’t know about you, but this seems to be a good time for a break and a rest, so we will continue next month with the dismantling of the engine. While you are waiting, it would be a good idea to clean the whole exterior with solvent and a pressure washer. This will make it a lot easier to work on and you won’t get as dirty. This always makes the wife happy.
Well, Dad, how am I doing so far? See ya all next month.