7 replies to this topic

[Gdowle]

Hello,

How do i know wether i need oversize thrust washers? where do i measure? is this something the machining shop will tell me when they reface the crank shaft?

Thanks

[Guess-Works.com]

If the crankshaft is being ground then the any respectable machinist will tell you the thrust requirements ( assuming you're on about the crank thrusts )

[Ethel]

Are they Mini specialists? It would be best to measure the end float with the existing thrusts, then grind the crank accordingly for the next size up - if it needs grinding at all.

[Cooperman]

This is what you do:
When the crank has been ground, fit it into the block with new standard thrust bearings. Now get a DTI (dial test indicator) and mount it so that the probe is longitudinally onto one of the crank wabs. With a screwdriver against the centre main cap and the crank web, push the crank as far as it will go in one direction. Zero the DTI at this point whilst holding the crank in the max position in that direction. Now put the screwdriver in the other side of the cap and force the crank as far as it will go in the other direction. The reading on the DTI is the actual crank end float. If it is 0.004" or less use standard thrusts. If it is 0.005" to 0.007" use one pair of +0.003" thrust bearings on the clutch side of the cap only. If it is 0.008" to 0.011" use 2 pairs of +0.003". If it is 0.012" or more you will need to get some +0.030" thrusts and have the machine shop surface grind them to give the correct float (this is most unlikely).

[mike.]

A quick comment i'd add about thrust washers is to keep the old ones if you can.

When I rebuilt my engine, I fitted new thrust washers and with them fitted I had very little or no end float on the crank. I don't know if this would be classed as bad practice, but since my old ones didn't seem excessively worn, I refitted them and when measured they were within the endfloat limits in the haynes.

Whether or not I was given oversized thrusts by mistake, I don't know, but just keep the old ones incase you have a similar situation.

[Cooperman]

I've had new ones come up a bit too tight and all I did was linish a thou or so off the steel backing until I got 0.0015" end float which was fine.

[snowsports1]

The company that did my engine are very good so I feel a bit more confident it is just a clutch adjustment issue. Having said that I have read a few posts saying slight reduction in revs is ok/normal? I don't have anything to compare as this is my first mini.

[tiger99]

The reduction in revs when operating the clutch strongly suggests that the clutch overtravel stop nut needs to be correctly adjusted. If there is not a thrust washer problem, there soon will be, if it is not adjusted.