Multiple things to watch for:
old oem bolts need to be replaced
make sure the timing wheel is flat with no burrs from grinding the slots
make sure whatever bolt you use is not too long. When everything is tight the bolt must not bottom out
This is especially important if you use oversize bolts as the proper length is not available. You must grind the bolts to length.
I have seen many oversize bolts break. One prominent engine builder has been doing this for years, and his have broken also.
I have not seen an ARP bolt break. I have them in all 46 cars for 2 years. But Ralph can break anything.
I also have ARP replacement bolts for caliper bracket mounts and drive shaft bolts
I don't think there is a cure for this. Just several versions of band-aids. Use quality bolts as you see fit, replace at every engine build, check often, use locktite.
IMHO
Dave
Dave Wheeler
Advanced Autosports, the nations most complete Spec Miata shop
Author, Spec Miata Constructors Guide, version 1 and 2.0
Building Championship winning cars since 1995
4 time Central Division Spec Miata Champion car builder 2012-2013-2014-2017
Back to Back June Sprints Spec Miata 1-2 finishes 2016 and 2017
5 time June Sprints winner in Mazda's
6 Time Northern Conference Champion Car Builder
2014 SCCA Majors National point Champion car builder
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2014 Central Division Champion, ITS (Wheeler)
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2007 June Sprints winner, (GT1, Mohrhauser)
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