Timing Belt Compatibility/Part Research Question

[jwalters]

(Tl;dr at the bottom)

Hi, I recently acquired a JDM GC8D WRX STi with an EJ20K engine and was looking to do the full list of periodic maintenance, preferably with OEM parts. A big part of the task is researching compatible American parts instead of importing, so I found on PartSouq that the original timing belt is 13160AA060, however parts.subaru.com says that part is not available. I then check on Spareto which lists many aftermarket timing belts, the first one on the page being Bosch 1987949199. This Bosch timing belt lists compatibility with Subaru parts 13028AA072, 13028AA240, 13028AA250, and 13160AA060. Checking fitting vehicles for 13028AA072, 13028AA240, 13028AA250 on parts.subaru.com, it shows that 13028AA072 is more for late 90's models, 13028AA240 is more for 2000's models, and 13028AA250 is more for 2010's models. However, looking at Gates timing belts on Spareto shows a different set of compatibilities, with Gates 5384XS listing compatibility with Subaru parts 13028AA072 and 13160AA060, but Gates 5612XS listing compatibility with Subaru parts 13028AA240 and 13028AA250 without 13160AA060.

How can some timing belts be more compatible than others? Is it just a matter of the aftermarket company not certifying specific replacements? Also, is there a better/easier way to find compatible parts without just buying everything original?

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[Unabomber]

I'm sure the answer is out there, look in the Conversions forum and the Pre-2002 Factory Turbo Powertrain forum. Also the problem is in part numbers as they change them like their underwear. I'd first try to find the compatible car and use that as a guide. Making up lies here, once you learn that your car can use the timing belt from a 2004 STI, then source a 2004 STI timing belt vice worrying about part numbers.

Did a **** search on google and this was the first result which says any old EJ timing belt will work. https://forums.nasioc.com/forums/sho....php?t=1115109

[jwalters]

Thanks for the reply. I did find that thread early on in my searches, but that thread and a lot of other information out there is very old, so I wanted to initially research newer compatible parts by crosschecking parts websites, then see if others have successfully used those parts. I thought the process would be straightforward, but I wasn't aware that a part made by one company could be installed in engine A and B but the same part made by a different company could be installed in engine A but not in engine B, that was the confusing part.

[Elbert Bass]

IIRC one consideration is the shape of the teeth on the sprockets and belt. Unfortunately my TRBs with that information are at the shop, and the chances of any of my USDM traning materials applying to a JDM product is very unlikely.