Conrod side play

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enekoizagirre

enekoizagirre

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Jun 8, 2010
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Hi everybody,
rebuilt my crankshaft with new AN conrods (old ones were cracked) and found that side play is about 0,03" when manual says 0,013"-0,016". Do you think this is acceptable?
Thanks
 
There has to be a reason it is so far out of spec.

I'd check the radius on the journals, they've probably been re-ground excessively. If they weren't properly radiused, the crank is waiting to explode already.
 
Fortunately the rods tend to self center so likely an not issue in street engine but do check the cheek radius or lack of it.
What I'd like to know is what cracked your Norton rods and where and how the cracks detected. Only the liter size race engines taken beyond designed torque and rpm limits of factory parts report rods breaking before something else wrong first.
 
an improper radius will not show up as excessive side clearance but if to large cause an interference to the rod bearings and also close off the oil so it cannot cool and properly lube the bearing. IF your crank grinder took to much off the sides of the thrust surface OR the replacement rod is narrower and you have to much side clearance it can cause low oil pressure.

grandpaul said:
There has to be a reason it is so far out of spec.

I'd check the radius on the journals, they've probably been re-ground excessively. If they weren't properly radiused, the crank is waiting to explode already.
Click to expand...
 
Hi,
I remarked to the grinder the radius issue, but right now I have no way of mesuring them. Cracks in the old rods were detected going from the bolt head hole towards the big end center (maybe too much tightening?) Iĺl take pictures tomorrow and post them.
Thanks
 
if you still have an old con rod use it to see if the side clearance is different. if so than it was the machine shop that made the rod journal to wide if not than the replacement rod is narrower than stock.

enekoizagirre said:
Hi,
I remarked to the grinder the radius issue, but right now I have no way of mesuring them. Cracks in the old rods were detected going from the bolt head hole towards the big end center (maybe too much tightening?) Iĺl take pictures tomorrow and post them.
Thanks
Click to expand...
 
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