Extended wheel studs and rear hubs fitment

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There's been a number of requests for clarification on this topic from vendors, but curiously the information itself is never posted in any of the wheel stud installation threads on any major forums, and I believe this is mostly because people do not opt to spend the premium for genuine Nismo studs.

Certain vehicles, Skyline/Skyrine, Fairlady/300zx, Cima/Q45, etc. commonly used the "large" sized wheel studs in the front hubs, and "small" sized wheel studs in the rear hubs. Nissan uses a common thread pitch across their models, so we are only concerned about the knurling or splined section diameter on the studs themselves. Nissan has many part numbers referencing many wheel studs with minor differences, so minor that in most cases, substitution is very simple. There is one exception to this cross-compatibility, and that is the Nismo catalog.

Unlike the general Nissan parts listings, Nismo catalogs list exactly 2 styles of wheel studs, each with two available lengths, one with 14.3mm 36-tooth knurl, the other with 13mm 32-tooth knurl. RT wheel studs are dimensionally based on 60mm long Nismo studs, they use the same diameter knurl, the same number of splines, the same thread pitch, with some minor differences at the shoulder, and the surface treatment -- oddly, Nismo studs are poorly protected from corrosion?

The issue arises when using the 13mm knurl studs in those rear hubs, some wheel hubs, namely on the vehicles listed above, actually use a knurling size significantly smaller, they are approximately 12.7mm with finer splines than the more common 13mm studs used on the front hubs of most Nissans/Infinitis. For example, the front wheel studs on 180sx/240sx/Silvia are 13mm.

The point is, a 13mm spline is too large to fit into the 12.7mm holes of those rear hubs. The solution most of the aftermarket stud manufacturers chose, is to undersize the splined section to 12.75-12.85mm, this allows them to fit the smaller rear hub holes, while loosely fitting the more standard sized holes in the front hubs of a 240sx. While undersizing is not the best solution for strength, they also don't use the same tooth count, so they are creating a new deformation pattern, which to some extent does create more mechanical interference to prevent spinning.

Nismo and RT studs are not undersized, and they use the correct tooth pattern, if they are removed, another Nissan/Nismo or RT stud can be inserted without having damaging the splines created in the hub; having sustained no damage, they will remain stronger, longer. This is not true for other brands, there doesn't seem to be any consistency with their knurling.

The net result of this is simple, if the 13mm knurl RT or Nismo studs are being problematic, refusing to be hammered into the rear hubs of those vehicles, the solution is to pre-drill the holes with a 12.8mm (0.504") drill bit. The ideal diameter for a wheel stud's knurl is about 0.008" larger than the hole; the 13mm knurl wheel studs will generally vary between 0.508-0.513"

Feel free to check the Nismo parts catalog for "Long hub bolts", part number: 40222-RS025

Important note: All wheel studs should be hammered, or pressed into place, never draw them in with an impact wrench

RT 13mm wheel studs hammered into a 240sx front hub, direct fit:


Installed in a '87-89 300zx Turbo front hub, again direct fit:


Installed into a 90's 300zx Twin-Turbo rear hub, required drilling:

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Nismo studs catalog: http://www.nismo.co.jp/en/products/comp ... /bolts.pdf‎

Fastenal 12.8mm jobber drill $13: http://www.fastenal.com/web/products/details/0346084