So, I'm in the process of replacing all of the hardware in the front suspension on my '90 (see build thread).

I ordered all of the parts through Rosenthal; however, it became apparent post-shipment that the 28-091 nut is not shared between the upper and lower control arms (duh!). I can't for the life of me find the nut in Rosenthals database. A call yielded no further clues.

I'm looking for this guy:



Thanks in advance,
Zach

 

Alternative request:

Can anyone confirm whether the upper control arm bolt thread is m14? My thread gauges unfortunately stop at m12.

Worst case, I go McMaster-Carr/Fastenal for the nut, though, I'm not sure they'll have class 10.9 locking nuts, particularly if it's 1.5 (fine) thread pitch.

-Zach

 

...so McMaster-Carr only has Class 8 (apprx to SAE grade 5).

Part of me thinks "eh, it shouldn't see high loads."

The other of me thinks "No, idiot"

-Zach

 

A Spec Miata forum resolved the issue.

M14 w/ 1.5 thread spacing. Case closed.

 

Fun fact, this is the only bolt and nut that I've found on the miata that use standard ISO specs rather than JIS. If this was a JIS bolt and nut the wrench would be 19mm instead of 21mm.

 

That is a fun fact.

Fortunately for me, BelMetric is 15 minutes away from my employers. M14 fine threaded conical locking 10.9 flange nut ... in stock ... for $1.45.

-Zach

 

I wish I was closer. At least my local hardware store carries most sizes of JIS hardware.