TR6 Engine - Botton End Float / Rebuild

[jstone]

Hi,

Have just taken out the engine to replace the clutch release bearing. Now  I have the engine on the stand, sump off, I have just read about end float, big end bearings and shims etc.

My question is how do you measure the float if the engine is out and you cant use the clutch and does any body have a simple idiots guide as to what has to be done to replace shims , bearings, washers etc. I have read haynes and the TR restoration manual and it still is not crystal clear to me.

Many Thanks 

[Nick Jones]

End float is simply the amount that the crankshaft can move lengthwise relative to the block.  This movement should be controlled by the thickness of the half-moon thrust washers mounted either side of the rear main bearing.

This is of particular interest on this family of engines because there is no positive retention for these washers and if they wear too thin they fall out.  If not caught very quickly the resulting damage can scrap the crank and block.

I don't have a TR6 manual to hand but the Vitesse one quote a figure of 0.1 - 0.2mm (0.004 - 0.008 in), which is not much!

The rough check is to simply grab hold of the crank pulley (or flywheel if exposed) and alternately push into engine /pull out of engine.  You should feel no more than a hint of movement.  If there is noticeable 'clonk' or visible movement, further investigation is needed. 

If you have a dial gauge you can repeat the above process and get an actual figure to compare to the spec.  If you don't you can use feeler gauges but you really need to remove the sump and rear main cap to do this.

The thrust washers are available in different thicknesses and it is permissible to mix thicknesses front and rear to get the desired endfloat.  Normally the thicker one should be fitted to the rear - this is the one that wears faster due to clutch loads.

The rest of the bearings can be inspected by removing the caps (Note that cap position and orientation is CRITICAL so mark them!).  Bearings in good condition will be an even matt grey across their whole working surface.  Scoring, patches of material pulled off or areas worn down to the backing all indicate the need for new bearings and preferrably proper measurement of the crank to see if a regrind is needed.  Note that the decent Vandervell bearings are now hard to get (esp. big ends) and the Tri-metal King ones (often branded County) are reckoned to be better that the Glacier ones.

Hope this is helpful

Nick

[jstone]

Thank you Nick, that it most useful. Will go and check later today ! 

[jstone]

I have just gone and checked out the float / movement. I moved the crank in and out and could feel the movement, it was quite hard to pull and push. I could also notice a slight movement by the rear bearing. I took some measurments and with the crank pulled as far possible as I could get it the gap was 0.9mm.

With the crank pushed back, the gap was 1.05 mm giving a variance of 0.15mm.

Does this sound in tolerance ??

Cheers

Jeremy

[Nick Jones]

Jeremy,

Not quite sure how you measured it, but 0.15mm is centre of the tolerance band - which is good!  I am assuming the the figure quoted by Haynes for the Vitesse is the same as the quoted figure for a TR6 - probably is - but wise to check.....

Nick