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Tr3a rear crank oil seal....

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Personally I would go with Neils option, at least you know what youve got then, ;)


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Hi ~


Just to let everyone know that it's not possible to line bore the caps again. As we all know, blocks and caps are matched and cannot be interchanged. I've therefore got a spare bare block from TR Bitz.

I would like to thank all members for their valued help in this matter ~ this is what's so special of being a member of the Register.



Edited by Fireman049
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Hi Neil ~


Thank you for that. How can the caps be sorted? The engineering works near here say if the main caps are line bored then they become oversize and the bearings won't fit??


Regards ~



Edited by Fireman049
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Hi Tom,


Trying not to jump all over Neils reply here but thats why I've asked if you have measured the internal dias of the caps when fitted. We assume (very bad) that the rear cap is the only one not concentric to the centre line of the crank but it is possible that the centre and front caps have problems also even though they are allowing the crank to turn.


The best premise which gives you a chance of reclaiming the block is that the caps are concentric at 90 deg to the line of the crank


:ie their dia at the split line of the cap runs out and coincides with the blocks diameter either side (this may be a strong possibility because with centre cap and front cap fitted the crank spins !).

We need to ascertain that the rear cap also is concentric in the same plane (measure it please Tom) and the diameters of the cap when fitted coincides with the blocks dia either side AND THAT THE PROBLEM IS THE DIA OF THE CAP RUNNING IN LINE WITH CRANK WHEN TORQUED UP.


ie the cap moves too far towards the centreline of the crank when tightened. If this is the case the rear cap ONLY should be jigbored which would probably mean the removal of possibly only 1 thou or 2 from the arc of the cap which would then run out and match at the width of the cap which we hope is correct.


Because it's difficult to explain let me show you on this diagram where I use a large letter u to represent the rear cap.


ie U

Remove here /\ from the inside edge of the cap.

This is where an engineering firm wins out over an automotive reconditioning firm, they have the skills to use their machines in a discerning manner to achieve what is needed. If we can ascertain that the cap is "tight" in this area then it can be reclaimed, the cap would be bolted up tight and the block placed on end and the operator would "clock" the jigborer up concentric to the rear mains dia. Then he would "touch on" to the high point of the material in the high point of the valley of the cap and delicately machine the high amount off (likely only 1 or 2 thou) the cuts when completed would gently merge with the already completed dia of the block and cap.

Tom if the cap is as outlined it can be saved, I am a Jigborer and could do it. If the reconditioning firm are doubtful, then do it yourself by hand.


Rework the cap by scraping or filing the plus amount from out the throat of the cap, about 15 mins work. Don't be nervous there is nothing to lose the block is scrap without this action anyway. Take measurements and compare every 5-10 strokes blending the finish of the file strokes into the horizontal split line of the block. My "benchmaster" in toolroom engineering was a master at it and it is possible.


However without the measurements to confirm whats to be done you cannot pick the correct plan, PM me if you wish to discuss further.



Mick Richards

Edited by Motorsport Mickey
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