Triumph Thrust Washer Story Page 3

The crankshaft end float is measured by pushing the crankshaft toward the rear of the car (engine not running) by gently but firmly using a 1" x 4" x 3' piece of wood to force the crankshaft toward the rear of the car. Once you believe the crankshaft has seated in that direction, you can take a measurement between the radiator and the fan blade hub while using a snap gage or inside micrometer (see links on main page for more information). This is a crude way to take this measurement, but after practice you can become very good at this, and it is much easier than removing the oil pan to use feeler gages. This method is usually good enough to determine whether you have a problem in the first place.

After taking the above measurement, press the clutch pedal to the floor. This will force the crankshaft to seat in the opposite direction toward the front of the car. Take another measurement. The difference between the two will determine whether you have a problem or not. If the measurement is greater than .007" you might want to think about replacing your thrust washers, especially if you're using an original thin plated OEM steel version. I recommend taking the above measurements several times for good measure. Once you become experienced at this, it takes very little time, and should be performed on a regular basis.

If you have no idea how many miles since your last thrust washer replacement, then you should probably add it to your urgent list of things to do!

When I inspected the two OEM style steel thrust washers sitting in the bottom of the pan, I found that one was very badly worn and part of it had actually broken off. The other, which I now know was the front thrust washer, was only slightly scuffed. Next, I removed the bearing end cap to inspect the damage. I found that with the absense of the thrust washer, the spinning crankshaft had worn itself into the face of the end cap. Fortunately the wear had not progressed enough to cause any damage to the engine block side. This was good news, because I could have the end cap repaired without having to remove the engine. The surface of the crankshaft had some irregular wear from the thrust washer, but the abrasion had polished the surface, and it was not rough. I decided that since the crankshaft surface had a desirable surface finish, I might try to solve the problem by repairing the damaged bearing end cap. Not realizing at the time that the OEM style thrust washer was steel with a "very thin" copper alloy plating on the face, I decided to order a new pair from my supplier, and then make an attempt to salvage the engine instead of planning an expensive engine teardown.

While waiting for my new thrust washers to arrive, I cleaned all the sludge from the bottom of the oil pan, then took the end cap to a local professional welder to have him weld some material onto the worn part of the end cap where the washer is held in place. I made sure the welder only welded material onto the area of the end cap that was needed because I did not want the heat from his torch to cause any warpage to the end cap. After the welding process, I had the welded area ground back to normal by a machinist to make it as close to the original surface as possible. This was important to make sure the two bearing journal surfaces mated back together exactly as they were originally.

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When the OEM thrust washers arrived, I popped them back into place and took another set of end float readings. The result was .006". I reassembled everything, and feeling confident, I drove the car for approximately 150 miles before taking my next end float dimensional check. Unfortunately, the reading was .045". I removed the oil sump, pulled the end cap, and found that the rear thrust washer had worn very quickly. This is when I realized the thrust washer was made of steel, and the thin copper plating had worn very quickly. Once the thin coating had worn through to bare steel, the two very undesirable steel surfaces (thrust washer and crankshaft) created a lot of friction, which caused rapid damage.

Early digital camera = poor image quality

The Thrust Washer Blues

The Story of the Triumph TR6 Solid Alloy Crankshaft Thrust Washer Developement