You didn’t come here looking to find out what the best way to wash your Alfa did you? If you did, you will have to come back another time for the article on the best way to wash your car. Oh, yes there is a right way and wrong way to wash a car. I digress.
This article is about all those little flat things that are left over in a container after a rebuilt that you scratch your head asking yourself, “Where do those go?” Ready for an education on “washers”?
“A washer is a thin plate (typically disk-shaped) with a hole (typically in the middle) that is normally used to distribute the load of a threaded fastener such as a screw, bolt or nut.” Typically the outside diameter of the washer is twice the inside diameter.
“Washers are occasionally used as a means of minimizing frictional scatter besides the common reason of reducing the bearing stress on the joint face. The friction condition between the washer and nut face can be reasonably well defined and controlled, more so than the joint surfaces usually can. By controlling the friction, the preload can be more reliably achieved. To do this consistently, a close fit is needed on the inside diameter of the washer. One way in which this can be achieved is by the use of a SEMS unit (in which a washer is held captive on the bolt shank). The same can be achieved by using a KEPS unit (a washer being held captive on a nut).” You would find SEMS/KEPS units on Japanese vehicles.
On the Alfa Romeo there are several types of washers that are used: flat washers, spacers, lock washers, Belleville washers, leather and wave washers. What is not used are star washers.
Lets start our education with the wave washer. It is used in low torque applications. The best place I can think of where they are used is in the cam caps. They use a wave washer for a very clear reason. First it doesn’t need a lock washer, or star washer. The wave washer spreads its spring load over the surface of the nut well enough to keep the nut in place. You only need 12-15 ft. lbs of torque to hold the cap down in place. The cap has locating pins that sit into a recess, so the cap won’t twist in place. So only a minimal torque value is applied to these nuts.
Where there is a potential for the nut to come loose, a lock washer (spit washer) is used. If in doubt about the integrity of a lock washer, toss it. They don’t cost that much that you can’t put a new one in its place. So, you are asking…”Ok. Do I toss the old ones into the recycle bucket?” No, I have a huge can of used washers that I toss them into. When I have a project that requires a washer and I don’t have one, I dump the can into a large sorting tray and start digging. The lock washer is designed to allow torque in a clockwise direction, and resistance in a counter-clockwise direction.
flat washer and split washer
I can tell your mind is running around in circles now that I have gotten you this far. Let me ask you a simple question, which is correct to use…a 1/2 inch lock washer or a 6 mm lock washer? You are thinking, there really isn’t that much difference between them. Yes, there is if you go by this, ” By controlling the friction, the preload can be more reliably achieved. To do this consistently, a close fit is needed on the inside diameter of the washer.” There is a few thousandths difference between the two washers on the inside, and you can “get by” using a 1/2 inch lock washer.(yes, even I have done this very thing). Remember, what we are trying to achieve is consistent torque on all the nuts and bolts.
Ready for the really hard question? Is there a right way or wrong way to install a lock washer? Wave washer? Lock star washer? Belleville washer? No for all of them except for the last one. The same action takes place regardless of whether it is one side or the other. When it comes to the Belleville washer, there is a right way and a wrong way.
“What in the heck is a Belleville washer?” I first saw these on the Alfetta exhaust pipes. These are conical (cone) shaped washers. The top of the cone goes against the head of the bolt or nut. As torque is applied the load is spread over the base of the washer, applying a locking force against the top of the cone to hold.
“Belleville washers are typically used as springs, or to apply a pre-load or flexible quality to a bolted joint or bearing. Some properties of Belleville washers include: high fatigue life, better space utilization, low creep tendency, high load capacity with a small spring deflection and possibility for high hysteresis (damping) by stacking several Belleville washers on top of each other in the same direction.”
Flat washers go under the acorn nut and against the head. If you notice they have a flat bottom side and on the top side is a rounded corner. The flat side down! It is essential that these washers be flat for even torque and not have a Brinelling mark from over torquing or corrosion. This is an indentation in the washer that would ruin a good constant torque. The flat washer typically goes where the hole is larger diameter than the fixing nut.
In the interior is a large flat washer that has a small hole and a large diameter. These are called Penny washers after the British penny. These have small bolts or studs that when used are to spread the load over a large surface. These you will find to hold the heater box to the body.
A serrated or star washer isn’t used as it bits the material on the ends of the washer. There are 4 styles of these washers.
On the 750-101 cars you will find leather washers used in a couple of places that I can think of. One is on the shafts of the Weber carbs. These are behind the flat washer on the ends of the shafts. These keep water and contaminants out of the shaft bearings as they usually cover up the grease that is in the bearings.
The other location is in the trunk. This is where we separate cars in a concourse event. These leather seals are a thin brown leather about the size of a dime. They go between the push on lock tab and the body of the trunk lid. They are used to keep out water from the trunk where the emblems go through the holes.