As an adjunct, we also decided to get a set of new from a supplier and put them through the same test. as reference.
We decided to go for a peer review before publishing, and quite frankly that didn't go too well. Too much objection to some of the statements that were part of conclusions. So...we agreed to shelve it for a while...then Ralph got sick...then Ralph passed...and I quite frankly took that event way too hard. (Ironically, Ralphie was always against ChiCom 'stuff' in general, yet with our personal friendship he always went to his local dinner parties and get togethers armed with the latest and greatest actual manufacturing news out of China)
I was looking for something else today using FINDER on my MacBook Air, and this also popped up, long forgotten. One of the appendix to the report draft at the time. Figured may as well post it, folks can always ignore it.
APPENDIX # 1 New replacement Pins and Bushes
As an adjunct to the forensics testing done on the used NOS and used NORS pins and bushes, it was decided to buy a set of new pins and perform full QC testing on the as received in order to have a modern comparison. A bushing was purchased from the same supplier to verify how much ‘meat’ was available for final fit-up. (The bush received WAS a spiral oil groove type with the ends open).
The vendor is ‘nameless’ however the new replacement pin is the type having obvious grinding centers and the ‘step’ in the pin diameter with the larger flywheel end.
The testing was done at one of Chi-com highest level tier #1 test centers which produces and is certified to manufacture and self-test for Mercedes Benz, Ford Motor Company, TRW, and Brembo in a standard format verifiable to the third decimal place, metric.
The results are shown as Figure #1
- FIGURE 1
Conclusion-
• The pin inspected is as near perfect and flawless as possible to basic dimensions. The pin is manufactured to the lower limit (bush end) specified on drawings for the T-3315, factory number 715 pin on original Ford drawings, however that is not a bad thing as bushes are reamed to a ‘fit’ and not to a size.
• Run-out and coplanar (out-of-round) tolerances were not checked. However, due to the way the grinding centers were made and the 4th decimal place (Imperial measure) absolute control ‘to size’ in planes 90 degrees apart, these pins are at least as accurate, probably more, ‘precision’ than original pins made by Ford.
• The hardness although shown 36-40 is the lab way of bracketing hardness reporting when slice and dice photo micro-sectioning is NOT being performed. Nominal is Rc 38 which needs to be compared to the original NOS and NORS forensics when completed.
• The surface finish is 32 on both the flywheel end and the bushing end. 32 is definitely correct for the press fit into the flywheel and some may question the 32 for the bush end as being too rough and look to further ‘shoe shine’ of the surface.
o The reporter holds that 32 is probably the finish that Ford originally intended in spite of lore that micro-lapping to get ‘wrist pin’ smoothness was the way to go. The reporter if of the belief that Ford deliberately allowed the bronze to self micro-lap to conditions for maximum as run material conditions.
o The vendor has been asked to inform their supplier that shipping pins built to this precision open and loose in bags of 3, or shipped in boxes without sleeves from the maker causes small bumps and nicks, some almost microscopic however a simple care in handling, storage and shipping would allow these pins to be used with no further attention to detail once received.
• Since these are the 2 diameter pin a calculation was performed which shows the flywheel end to be EXACTLY 0.0041” bigger than the bush end and this value, when using this maker’s pins needs consideration when determining the press fit into the flywheel.
George R. Mills, P.Eng.