Hi Rob,

Thanks for your input - you may remember it was me who came round to look at Toby's engine when it was half-way through the build to try and understand if mine could be fixed in car and to take some measurements from the block.

So, in order to answer your questions:

The fact one bearing is considerably more worn than the other is not a surprise to me, in fact it is what I expected. After all, the "front" bearing carries all the longitudinal thrust loads when the clutch is pressed, but there is no equivalent load in the other direction to wear the "rear" thrust washer. It is easy to see this in action, pull the crank pulley forward with your hand (obviously when the engine's not running, otherwise it will hurt) then watch as the clutch is pressed. It moves rearwards, but does not return forward when the clutch is released. American S2000s have a clutch interlock so you can't start the car without the clutch pressed. Starting the engine with the crank pushed hard against the thrust washer with, by definition, no oil pressure sounds like a truly bad idea, although they are only splash lubricated anyway.

Also, I was measuring the end-float with the magnetic base on the crank pulley itself, and the DTI plunger was facing backwards to touch against a bolt head on the timing cover to measure end float, but as you say you could fix a steel plate to the front of the engine for the magnetic base and then measure directly on the crank pulley bolt which would be an ideal solution. Either way, the important bit is not to mount the DTI on anything except the engine. Mounting on the bodywork and trying to measure the end-float will include a +/- error if the engine mounts move (which of course they do - that's the idea!)


So, thanks to everyone for their input, it's much appreciated. I'll post up periodically with any update on end-float changes with increasing mileage.