Bearing Notch Orientation
Discussion
Two questions for Dave, Peter etc...
I'm getting confused with leading and trailing so will describe it like this... When looking at the front of an normal type inline 4 cylinder engine the correct way up, should the big end bearing tags be on the left of the engine or the right.
Question two... Does it matter?
I'm getting confused with leading and trailing so will describe it like this... When looking at the front of an normal type inline 4 cylinder engine the correct way up, should the big end bearing tags be on the left of the engine or the right.
Question two... Does it matter?
The primary purpose of the tags is to control the axial position of the shell when installing it. Once it's installed, the interference fit keeps it from spinning. This is commonly referred to as bearing crush.
Sometimes, and usually in high RPM situations and when you cannot increase the crush any further, the tags can be somewhat relied upon to provide a small amount of cover against shell rotation, providing the slots in the rod are designed with best practice, i.e. diagonally opposed in cap and rod, so the tag comes up against a 'hard stop'. Sorry difficult to explain without a diagram.
Anyway to actually answer your question I'd say it doesn't matter providing your connecting rods are symmetrical : )
Sometimes, and usually in high RPM situations and when you cannot increase the crush any further, the tags can be somewhat relied upon to provide a small amount of cover against shell rotation, providing the slots in the rod are designed with best practice, i.e. diagonally opposed in cap and rod, so the tag comes up against a 'hard stop'. Sorry difficult to explain without a diagram.
Anyway to actually answer your question I'd say it doesn't matter providing your connecting rods are symmetrical : )
I did say normal type four cylinder trying to be generic as possible but I guess this is PistonHeads. lol
Aware of how the notches work and lack of them in recent engine design.
Reason I ask is I have a engine spec sheet from a Hyundai WRC engine and it states bearing notches leading. Yet A former engine designer at Judd says trailing yet couldn’t provide an answer. I have always fitted them on the right side of the engine which i guess is the leading side.
Aware of how the notches work and lack of them in recent engine design.
Reason I ask is I have a engine spec sheet from a Hyundai WRC engine and it states bearing notches leading. Yet A former engine designer at Judd says trailing yet couldn’t provide an answer. I have always fitted them on the right side of the engine which i guess is the leading side.
Edited by 99hjhm on Tuesday 18th September 22:55
Just for the sake of conversation and interest:
I've been helping a friend do some some analysis on a certain type of engine, he's basically buying them up cheap, stripping them and inspecting, trying to work out failure modes, how best to rebuild, modify etc. Anyhow, we got one in that was knocking and my diagnosis was lack of oil at sometime. It wasn't permanent, just under load (when you blipped the throttle) and then when you backed off. As expected it got worse as the oil got thinner when hotter so we pulled it and started to strip it.
Don't get too excited, but the two bits I found vaguely interesting were:
1. Up until now every engine (out of only two!) bearing failure was on number two, this one was No.1 and we don't know why.
2. That the bearings (which have no locating tabs and had most of the soft layer missing, but not all) had actually walked sideways in the rod, but not begun to spin. This meant that whilst some 95% of the width had been worn away, there was a higher lip left on the edge where that part of the bearing was hanging into the recessed rolled fillet area. I'm putting this down to some vibration or resonance set up by it being hammered up and down causing it to vibrated sideways.
I did a quick check with the micrometer whilst it was still in the block and the journal is untouched. One thing I did notice was excessive endfloat, but sadly a stuck crank pulley and the need for a beer and curry ended proceedings so we haven't investigated that yet.
Before what I have seen recently I would have written off a crankshaft (or expected a re-grind) when an engine was knocking or bearing material found in the filter, but no longer. It does seem that on some engines if you catch it in time the crank is untouched and all it needs is a new set of bearings fitting.
I've been helping a friend do some some analysis on a certain type of engine, he's basically buying them up cheap, stripping them and inspecting, trying to work out failure modes, how best to rebuild, modify etc. Anyhow, we got one in that was knocking and my diagnosis was lack of oil at sometime. It wasn't permanent, just under load (when you blipped the throttle) and then when you backed off. As expected it got worse as the oil got thinner when hotter so we pulled it and started to strip it.
Don't get too excited, but the two bits I found vaguely interesting were:
1. Up until now every engine (out of only two!) bearing failure was on number two, this one was No.1 and we don't know why.
2. That the bearings (which have no locating tabs and had most of the soft layer missing, but not all) had actually walked sideways in the rod, but not begun to spin. This meant that whilst some 95% of the width had been worn away, there was a higher lip left on the edge where that part of the bearing was hanging into the recessed rolled fillet area. I'm putting this down to some vibration or resonance set up by it being hammered up and down causing it to vibrated sideways.
I did a quick check with the micrometer whilst it was still in the block and the journal is untouched. One thing I did notice was excessive endfloat, but sadly a stuck crank pulley and the need for a beer and curry ended proceedings so we haven't investigated that yet.
Before what I have seen recently I would have written off a crankshaft (or expected a re-grind) when an engine was knocking or bearing material found in the filter, but no longer. It does seem that on some engines if you catch it in time the crank is untouched and all it needs is a new set of bearings fitting.
Yes had the same with an engine last year, lack of main bearing clearance (Which was known about on the build, another story) and very high oil temperatures, slight drop in oil pressure, split the filter and FULL of bearing material!
Stripped engine, crank was perfectly reusable, infact, after the extra .001" was ground from it to correct the bearing clearance there were no signs of any damage, even the big ends had not suffered, but were changed, oil pump also fine. Many of the main shells were down to the steel backings. This was with King race bearings. Done a fair few hours and the customer didn't want to stop using it.
Also stripped an MGB race engine last year, one of the intermediate mains that don't feed a rod bering had spun a shell, shell had blanked off the oil hole and survived for god knows how long like it. Again, crank wasn't too bad.
Stripped engine, crank was perfectly reusable, infact, after the extra .001" was ground from it to correct the bearing clearance there were no signs of any damage, even the big ends had not suffered, but were changed, oil pump also fine. Many of the main shells were down to the steel backings. This was with King race bearings. Done a fair few hours and the customer didn't want to stop using it.
Also stripped an MGB race engine last year, one of the intermediate mains that don't feed a rod bering had spun a shell, shell had blanked off the oil hole and survived for god knows how long like it. Again, crank wasn't too bad.
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