Cracked Bellhousing: repair?
07-02-2015, 04:04 PM
#21
Team Owner
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Since neither the flywheel or the bell housing flexes very much at all, that would sound like adequate clearance. I have no idea what the factory specification would have been for that clearance, but it would not have been very much, as more clearance than necessary makes for a larger bell housing which is heavier, more costly, and would result in a need for more transmission tunnel space.
07-02-2015, 08:05 PM
#22
Race Director
Hard to believe that it would deflect that much under jacking loads and then elastically recover. Maybe someone took a mallet or pry bar to it later and bent it back.
07-06-2015, 06:05 AM
#23
Melting Slicks
Thread Starter
07-06-2015, 06:22 AM
#24
Melting Slicks
Thread Starter
Just to keep you guys updated: the bell housing is on and all is fine now.
after the repair I checked first the Bellhousing alignment. I measured 0.005" which is exactly at the max of the spec. So I decided to tackle that, and bought some 0.007" offset dowels (expensive, but worth it). It took me 12 adjustment cycles and the good part of an afternoon to get it right (now I am at 0.002). That included double checking everything, like taking the bell off and putting it back on to see the variances. In case you wonder, the numbers in my notes are in in 1/100 mm. The position of the dowels are coded with the hour indication off a clock. As you can see the last measurement was almost 0 all around. But that does not hold once you take the bell off and put it back on. But still under 0.002.
Once that done, I checked if the bolt plane of the bell housing was orthogonal to the crankshaft. Luckily it was, otherwise I would have needed to resurface the housing at an angle. I measured both around the mating perimeter and at the extreme ends. All were less than .002 .
after the repair I checked first the Bellhousing alignment. I measured 0.005" which is exactly at the max of the spec. So I decided to tackle that, and bought some 0.007" offset dowels (expensive, but worth it). It took me 12 adjustment cycles and the good part of an afternoon to get it right (now I am at 0.002). That included double checking everything, like taking the bell off and putting it back on to see the variances. In case you wonder, the numbers in my notes are in in 1/100 mm. The position of the dowels are coded with the hour indication off a clock. As you can see the last measurement was almost 0 all around. But that does not hold once you take the bell off and put it back on. But still under 0.002.
Once that done, I checked if the bolt plane of the bell housing was orthogonal to the crankshaft. Luckily it was, otherwise I would have needed to resurface the housing at an angle. I measured both around the mating perimeter and at the extreme ends. All were less than .002 .
07-06-2015, 07:21 AM
#25
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Well done. I doubt that one in a hundred would do that level of checks, but then, you did have a smoking gun.
07-06-2015, 02:15 PM
#27
Melting Slicks
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Last edited by alexandervdr; 07-06-2015 at 02:21 PM.