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Crank end float


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When stripping my six cyl engine, I measured the crank end float at 11 thou. From what I had read about the weakness of the thrust bearings, I thought I was lucky and ordered the +5 thou thrusts which I thought would bring the E/F to the recommended 6 thou.

 

I came to fit the new bearings yesterday and realised that both bearings are +5 and as they are fitted either side of the rear bearing, it would reduce the E/F 1 thou?

 

I decided to fit one +5 and one original washer to acheive the 6 thou E/F. Is this the accepted way of doing it and why do they sell washers as a pair of +5?

 

The 4 cyl has a much better design IMO.

 

Cheers

 

Graeme

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The acceptable range according to Bentley is .006 to .008" is it not ?

If you measure the end float to be .011 with the old TW's in place, you were only halfway thru the process of determining what size the replacments should be.

You need to measure the thickness of the ones that were in there that gave you that much endfloat.

Suppose the front one was still at the original thickness of .092, but the rear was down to .090.

That would account for .002 of your .011 which is equivalent to .009 endfloat with 2 standard size TW's

With a standard in front and a .005 oversize in the rear the endfloat would be .004.

Just using those numbers as an example to show you really need to know the thicknesses of the existing TW's to determine the thickness needed for the replacements.

Edited by poolboy
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In reality you need to measure end float with 2 new std thrusts in place and calculate from there. Measuring the existing end float with old thrusts just tells you that you have too much not whether the wear is on the bearing surface or the crank or both.

 

Once you have the end float measured with new thrusts you can then work out what you need - frequently you may need to mix and match to get the desired end float. Too little is not a good thing as they can get picked up and mangled as the engine warms at high revs.

they come in a variety of sizes, fortunately they aren't too pricey as you may need to buy more than one pair.

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I my opinion the front one never wears anyway, but I do take you point that the crank may have been ground before and the thrust surfaces widened. So if you push the crank back and set the dial gauge to zero whatever you read pulling the crank forward will be the float at the rear, but you will need to know what's there first to make the necessary calculation and decide the thickness. I have different thicknesses in mine front and back, but the front will be the determining point to keep the crank in the right position. You could also check that the crank gear and the camshaft also line up as a check perhaps, again if its original?

John

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