Trials Of A Thrust Washer

Below is a lengthy account of my experience purchasing a previously owned Triumph TR6. Shortly after buying the car I learned that it had a mechanical problem that I was totally unaware of at the time I purchased it. This type of experience can happen when buying any used car, but maybe after reading about my experience it may help others to be more cautious.

I have included my purchasing experience as well as the events that led to discovering the problem. I have also included what I have done to remedy the situation without having to remove the engine, tear it apart, and spend a lot of time and money to repair it.

I have since found a very good machinist who I am working with to produce the special solid bronze alloy thrust washer you are about to read about, and currently supply them to your specifications. Please don't hesitate to contact me for any questions.

---

During the month of August 1998, after some serious searching, I purchased one of the cars of my dreams. This car was a beautiful 1976 Triumph TR6. I found this car advertised on The Vintage Triumph Registry web page within their classified ad section. After several e-mail messages and telephone calls to the owner, I decided to drive the 300+ miles to take a better look at the car.

Visual inspection:

Upon arrival, I first spent my time to thoroughly inspect the car inside and out, and was very happy with what I saw. The car appeared to be very original, and well cared for. Overall, it fit the owners description, and my trip didn't seem to be a waste of time.

The owner had told me the car had 38,000 original miles on it, and I believed him after seeing how well preserved the car was. Of course, there are some drawbacks to buying an older car with low miles, because it has most likely been stored frequently during its life, and some parts age over time, such as coolant hoses, fan belts, tires, plug wires, and hydraulic seals that haven't been used on a regular basis, causing them to dry out. But I felt those potential disadvantages were insignificant in this case.

The test drive:

Once I had visually inspected the car, it was time to take it for a test drive. The owner had told me the starter had been giving him trouble from time to time, and sure enough when we tried starting the car, it wouldn't respond to the turn of the key. He opened up the trunk and pulled out a small ballpeen hammer, then opened the bonnet and told me to tap on the starter with the hammer while he turned the ignition key. Many buyers might walk away at this point, but since I had my share of experience with Lucas electrics, this didn't seem out of the ordinary to me. Sure enough, the starter responded to my whacking of the hammer, and the engine started right up. I knew the starter was a simple fix, so I proceeded with the test drive.

I looked at the tail pipe and couldn't see any blue smoke, and the engine idled smoothly and quietly, with its unmistakable signature TR6 sound that so many owners and wannabee owners have fell in love with over the years. I got into the drivers seat, and could tell right away that I was a good fit for this car. Upon take-off the car responded exactly as it should, and after running it through the gears I could tell that it seemed reasonably tight and had a very good throttle response. The overdrive worked nicely in 3rd and 4th gears, and the rear end didn't seem to have any clunking from the potentially troublesome u-joints. When coming to a stop the car did not make any ugly sounds, and it came to a stop nice and straight. Other than a few rock chips, older tires, and the need for some minor refurbishing, I knew this car and I could become very good friends. After the usual haggling over the asking price I loaded my prized possession onto the trailer and headed for home.

A new home:

The drive home was very pleasant, and I was proud to pulling a trailer loaded with my new Triumph. I took every opportunity to sneak a glance at my new toy in the rear view mirror. When I returned home, my family had been waiting for me, and they all came out to take a look at the car I had been talking about so much, and they were all surprised to see a completely finished car on the trailer. Most of the British car I've brought home in the past would barely roll off the trailer, so they were very happy to see one that could be driven. After all the hoopla, I tried starting the car to back it off the trailer. Sure enough, it wouldn't start, so I opened the boot and retrieved the ballpeen mammer the past owner was so kind to let me keep. I instruced my wife how to whack on the starter while I turned the key, but unfortunately, the hammer trick wouldn't work this time. My wife gave a certain look, and since it was getting late in the day, we pushed the car into the garage and called it a day.

Repair jobs:

After a good nights sleep, I stepped out to the garage and removed the starter, and took it to a local repair shop to have it rebuilt. Several days later, I brought the starter home from the repair shop and reinstalled it. I turned the key, it started right up. My daughter heard the sound and came running outside, so we took it for a spin around the neighborhood. I felt comfortable enough to take it for a longer drive, so returned home to retrieve my drivers liscense. While I ran into the house, I let the car idle while parked in the driveway. When I returned to the car, I hopped back into the drivers seat, pressed on the clutch pedal to position the gear shift into the reverse to back out of the driveway. This is where my thrust washer trouble began. When I pressed on the clutch, I heard a loud scraping noise that sounded awfull. I quickly removed my foot from the clutch pedal and the noise went away. But when I pressed on the clutch pedal again the grinding sound returned. After listening closely I decided the sound was coming from the bell housing area, and felt it must have something to do with the clutch. So I spent the next few days removing the transmission to determine what was going on inside.

After carefully inspecting everything inside the bell housing area, I couldn't see anything obvious, but since I was already there, I decided to replace the clutch, throwout bearing, and make some other suggested improvements to that area. After reinstalling everything, I started the car again, and pressed on the clutch pedal. The grinding noise was still present. I was now obvious the noise must be coming from somewhere else.

After doing some additional research, I read about a potential problem with the crankshaft thrust washer, which I learned is often overlooked. This little thrust washer plays an important role to play with keeping the crankshaft centered with the other internal moving parts. Whenever the clutch pedal is pressed to the floor to shift gears, it is subjected to a very heavy force while pressing against the spinning crankshaft. It wears just like any other moving part, and needs to be replaced at regular intervals - and most likely needs to be replaced if you're a TR6 owner and you're not aware of this.

I performed a simple crankshaft end float check, and determined I had a definite problem. I drained the oil and removed the oil pan, and found the front and rear thrust washers had dropped out of place and were sitting at the bottom of the pan. The rear thrust washer had worn so badly, that it was too thin to stay in its nesting place. Due to the excess movement, the front thrust washer was able to work its way out of its place. Without the rear thrust washer in place, whenever the clutch had been pressed, the crankshaft had continued to wear into the side of the bearning journal, and eventually the flywheel teeth were to come in contact with the starter gear, thus making the awful grinding noise.

Checking crankshaft end float: 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 as a pry bar to force the crankshaft toward the rear of the car. Once you feel the shaft has seated itself in that direction, you can take a measurement between the radiator and the fan blade hub while using a snap gage or ID micrometer. Admittedly, this is a crude way to take this measurement, but after practice, it is pretty accurate, and it is easier than removing the oil pan. It 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 as great as .010" to .013", this would indicate your engine thrust washer needs replacing, especially if you're using an original OEM steel (very thin alloy plated) version. If the measurement is much greater than .013", then you shouldn't drive your car. If the measurement is in the vicinity of .100", then you've got a problem to take care of.

I usually take the above measurement multiple times for good measure. Once you become experienced with this routine, it takes very little of your time, and should be performed on a regular basis.

If you have no idea whether the thrust washer in your TR has been replaced, then you should probably add it to your urgent list of things to do!

A proper but crude way to measure the crankshaft end float: (yes crude, but good for a rough measurement)

Force the crankshaft toward the rear of the car as explained above. Place a snap gauge between the face of the fan and the radiator and slide it back and forth until you feel that you have a good square reading, then tighten the end screw on the snap gage to keep it in place. Next, measure the snap gage tip to tip dimension with a pair of O.D. mics or dial caliper then write the measurement down on a piece of paper. Next have someone press on the clutch pedal to force the crankshaft toward the front of the car, then take another measurement in exactly the same place as before. Subtract the second reading from the first reading to determine your end float reading. For repeatability sake, you can perform the measurement two or three times just to make sure you got it right.

The inspection of destruction:

When I removed the oil sump to inspect the problem area, I found both front and rear OEM style steel thrust washers sitting in the bottom of the pan. One was very badly worn and part of it had actually broken off! I removed the bearing end cap and inspected 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 for me because I could remove the end cap for repair without removing the engine. The surface of the crankshaft showed some irregular wear, but fortunately it was very nicely polished, not rough. Not realizing at the time that the OEM style thrust washer was mostly made of steel and had a "very thin" copper/nickel type coating on the face, I decided to order a new pair from a supplier, then make an attempt to salvage the engine instead of planning an expensive engine teardown.

Click here: Thrust Washer And End Cap Destruction

The end cap repair:

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 build up the area at the edge of the ground face 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 (see picture on other page linked above) because I did not want the heat from his torch to cause any warpage. After the welding process, I had the welded area repaired by a machinist so we could make it as close to the original surface as possible. I wanted the two bearing journal surfaces to mate together exactly as they were originally.

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 assembled everything back together, 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 loaded washer had worn very quickly. This is when I finally realized the thrust washer was made of steel, and the only usable bearing surface was a very thin copper/nickel coating on the surface. "It's no wonder there's a problem with this thrust washer", I thought to myself. Once the thin coating wore through to the bare steel, the two steel surfaces (thrust washer and crankshaft) will grind away at one another and cause rapid damage!!

What's next?......Back to the drawing board.....But wait! Read on, there's good news ahead!!

A new thrust washer material:

By this time, I was really bummed out. The thought of pulling the engine on my newly acquired car and spending a lot of time and money to repair it didn't settle well with me. I didn't want to have to admit that I had struck out, so I turned to a Tribologist friend named Dr. Shengli Liu, PHD. Dr. Liu is a very knowledgeable guy who used to work on trucks in China as a young man, prior to coming to the United States to continue his studies and acquire a PHD at the University or Wisconsin in the fields of Metallurgy (study of metals) & Tribology (the study of fricton and wear).

I told Dr Liu all about my problem, and he wasn't surprised to find out what had happened. He knew that once the thin, soft, copper/nickel surface on the steel OEM style thrust washer had worn through, that both steel surfaces wearing together could cause extensive engine damage in a short period of time. Two steel surfaces grinding away at one another is most certainly a recipe for disaster.

Dr Liu suggested a more suitable solid bearing material that is known to have very good friction and wear characteristics under these conditions. (caution: this is not an Oilite type of material) I was able locate a source that would sell the material to me in smaller quantities, and I would then have it machined to my specifications. I calculated the thickness I would need to provide me with a minimal end float dimension, and had one special thrust washer made to test in the rear thrust washer position. I used the original OEM thrust washer for the front position since it had no damage or wear.

A new kind of thrustwasher installed:

Keeping in mind that not every Triumph 6-cylinder engine with this problem can be salvaged, I was very fortunate that I caught the problem early. Other than the OEM thrust washer damage, only the crankshaft surface and main bearing end cap face had been worn. Fortunately the crankshaft bearing end cap was repairable, and the crankshaft had not yet come in contact with the engine block side of the journal, so there was no damage to the block itself. If so, the engine would have to be pulled to assess the damage to determine whether the engine could be salvaged.

Even though the end cap casting had worn an irregular pattern into the steel crankshaft surface, it was smooth and polished. This was an advantage because even though the surface was irregular, it was smooth, and would create less friction against the surface of the new solid bronze alloy thrust washer. Even though some irregular wear had occurred on the crankshaft thrust washer mating surface, I felt that it was minimal enough that I could place the slightly oversized solid bronze alloy washer on that side of the bearing journal and keep an original OEM washer on the unloaded side of the main bearing, therefore keeping the crankshaft at its original centered position.

The new bronze alloy thrust washer was installed in the car on October 7, 1998. From that day, I kept a running check on the crankshaft end float at regular frequent intervals. Initially every ten miles, then twenty, then as confidence increased, I could go for longer durations. I hoped that once the new washer conformed to the less than perfect but smooth crankshaft surface, I would be able to enjoy my TR6 for a long period of time without having to pull the engine.

When performing this kind of work, it's important to use your workshop manual, and if you're not a mechanic, ask for knowlegeable experienced from other people to help guide you. I would strongly recommend anyone sorting out problems of this kind to work closely with a machinist and a mechanic.

Keeping a log:

When I installed my solid alloy test thrust washer, the odometer reading on my car at the time of installation was 38,869. I strived for minimal crankshaft end float at the start because I knew that with my less than perfect conditions the new thrust washer would have to wear-in to the irregular but polished surface of the crankshaft. I was then hoping that once the two surfaces conformed to one another, there would be minimal, if any, significant wear, resulting in a long thrustwasher life.

Upon inspection, I learned that my findings were exactly what I had thought they would be. The solid bronze alloy thrust washer conformed to the irregular surface of the crankshaft, thus slightly increasing the end float dimension. Once the two surfaces conformed to one another, the end float dimension stabilized. When the car was checked at several thousand additional miles on the odometer, it was continuing to do just fine. The end float check would continue to be checked on a regular basis.

Happy to be back on the road again

My 1976 TR6 posing for a photo during a road trip break
(Solid Alloy Thrust Washer Installed)

Below - An owner's attempt at salvaging his damaged engine block

During March of 2001, a TR6 owner contacted me with a thrust washer problem that was very similar to what had occurred with my engine, but unfortunately, he didn't catch the problem soon enough. The OEM steel thrust washer had worn itself to the point where it had dropped out of place and allowed the crankshaft to grind its way into the side of the bearing end cap. The owner was unaware of the problem and continued driving the car. The spinning crankshaft continued grinding its way into the side of the end cap, then continued its way into the engine block side of the journal. The damage at this point was beyond the scope of my thrust washer repair method, and his engine would need to be pulled out of the car to effectively survey the damage.

As a result, he pulled his engine out of the car and was able to work with a local machinist who helped him modify the block to enable the installation of two opposing solid bronze alloy thrust washers. He chose to use brass countersink screws to hold one half in place, and the other half was held in place as normal. His alternative to this modification would be to scrap the engine block.

Bearing journal modified to accept two opposing solid alloy thrust washers