2/6 Rod bearing fix?
03-09-2014, 05:17 AM
#76
Addict
Rennlist Member
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Just a thought and not discounting all the other issues to do with oiling but one known issue for those rebuilding an engine is rod bearing size and there hardness.
IIRC GB and probably others have alluded to the fact that the rod bearings are very soft by comparison with other "better" designs. (And the crankshaft is as tough as) . And there is the known issue of getting bearings in the correct sizes - having to buy three or four sets to make one that fits perfectly, just because none of the suppliers will sell +5thou + 10thou etc under or oversize.
It strikes me that in comparison with some of the other "re-design by 928 gurus and owners" commisioning Glyco or whoever (I don't have an axe to grind or know enough about bearing manufacturers) to produce rod bearings with a harder white metal element and in a range of sizes. would require little research and little or no design. I'm thinking something along the lines of "What would GB buy if it was available of the shelf. Further it is not like the 928 community would be asking Glyco or whoever to do something they've never done before - ie it's less development work than asking Laso to put a sleeve in the Water pump bearing. All it is use the existing steel shells that they already have the design of and put a slightly different white metal compound to slightly different thicknesses on that steel shell.
I would have thought that with the combined buying power of 928intl, 928srus, 928sp, 928ms this would be a no brainer.
I for one would buy a set of "better" rod bearings in say std, -5 thou, and -10 thou purely as insurance for when the time comes to change again and do it properly as oppsed to just installing a set of unkown Glyco's
IIRC GB and probably others have alluded to the fact that the rod bearings are very soft by comparison with other "better" designs. (And the crankshaft is as tough as) . And there is the known issue of getting bearings in the correct sizes - having to buy three or four sets to make one that fits perfectly, just because none of the suppliers will sell +5thou + 10thou etc under or oversize.
It strikes me that in comparison with some of the other "re-design by 928 gurus and owners" commisioning Glyco or whoever (I don't have an axe to grind or know enough about bearing manufacturers) to produce rod bearings with a harder white metal element and in a range of sizes. would require little research and little or no design. I'm thinking something along the lines of "What would GB buy if it was available of the shelf. Further it is not like the 928 community would be asking Glyco or whoever to do something they've never done before - ie it's less development work than asking Laso to put a sleeve in the Water pump bearing. All it is use the existing steel shells that they already have the design of and put a slightly different white metal compound to slightly different thicknesses on that steel shell.
I would have thought that with the combined buying power of 928intl, 928srus, 928sp, 928ms this would be a no brainer.
I for one would buy a set of "better" rod bearings in say std, -5 thou, and -10 thou purely as insurance for when the time comes to change again and do it properly as oppsed to just installing a set of unkown Glyco's
03-09-2014, 09:41 AM
#77
Nordschleife Master
ACL said $40k for tooling etc. if they can find some existing bearing that is close. That's before they went bankrupt. They were kind of old school, so small series were cheap to them and that was probably the best bet. I was kind of toying with the idea, just in case the AUD would crash again like it did in winter 2008-2009.
If Michael Mount's and Ake's and Erkka's solutions work with existing bearings, then that's a lot easier route. In particular, if MM's solution works in the 944 it's guaranteed to work in the 928, because everything is much more stressed in those 944 race engines. And the whole mod with $350 per set of four, including bearings in resized bog ends, is a really fair price.
If Michael Mount's and Ake's and Erkka's solutions work with existing bearings, then that's a lot easier route. In particular, if MM's solution works in the 944 it's guaranteed to work in the 928, because everything is much more stressed in those 944 race engines. And the whole mod with $350 per set of four, including bearings in resized bog ends, is a really fair price.
03-09-2014, 12:20 PM
#78
Drifting
This is, in a nutshell, the answer to the question it would seem.
Aside from this i see truths i what both Mark K. and Greg B. are saying.
Think they should bury the hatchet.
From my limited experiences rebuilding water and air cooled motors,
experimentation leads to longevity issues. Simply put something else breaks.
6, 12, 24 months of spirited street driving and you're pulling out the motor again.
ACL said $40k for tooling etc. if they can find some existing bearing that is close. That's before they went bankrupt. They were kind of old school, so small series were cheap to them and that was probably the best bet. I was kind of toying with the idea, just in case the AUD would crash again like it did in winter 2008-2009.
If Michael Mount's and Ake's and Erkka's solutions work with existing bearings, then that's a lot easier route. In particular, if MM's solution works in the 944 it's guaranteed to work in the 928, because everything is much more stressed in those 944 race engines. And the whole mod with $350 per set of four, including bearings in resized bog ends, is a really fair price.
If Michael Mount's and Ake's and Erkka's solutions work with existing bearings, then that's a lot easier route. In particular, if MM's solution works in the 944 it's guaranteed to work in the 928, because everything is much more stressed in those 944 race engines. And the whole mod with $350 per set of four, including bearings in resized bog ends, is a really fair price.
Think they should bury the hatchet.
From my limited experiences rebuilding water and air cooled motors,
experimentation leads to longevity issues. Simply put something else breaks.
6, 12, 24 months of spirited street driving and you're pulling out the motor again.
Last edited by The Fixer; 03-09-2014 at 05:45 PM.
11-04-2014, 11:59 AM
#79
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Join Date: Feb 2011
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928 rod bearing upgrade.
From the 944 forum. The 944 and 928 share the same bearings.
Åke
https://rennlist.com/forums/944-and-...aring-fix.html
Åke
https://rennlist.com/forums/944-and-...aring-fix.html
