RX7Club.com - Mazda RX7 Forum

I'm in the middle of my DP install right now. I had one stud screw out on me while I was taking the pre-cat off. I bought a new one from Mazduh!!! for about $13. Then I ended up messing that one up, because it wouldn't stay in -- kept coming back out whenever I would try to back the nut off of it, then I screwed it up while I was trying to get the nut off of it :) there's $13 down the drain. so then I went to Pep Boys and picked one up (actually 3, so I would have a few spares :)) for $1.90. Here's the specs:

M10 (10-mm) x 1.5 (thread pitch) x 42mm (length)

This was exactly the same size as my $13 Mazduh!!! one. Although, the $13 replacement stud from Mazduh!!! was a mm or 2 shorter than the original one that came out -- but it's close enough :)

Are you replacing the nuts, too??? The service manual says to. Mazduh!!! wants $5 per nut !!! I went ahead and bit the bullet on that one, since I was also ordering the stud. If you look at the nuts, you'll notice that it's oval-shaped on the top-side. This is to lock it on & keep it from vibrating loose. When you pull them off the studs, if they're still oval shaped, then you can probably re-use them. Or you can do like me & bite the bullet for new ones :)

I'm in the middle of a DP, Y-pipe, thermostat/rad hoses, coolant flush, vac hoses (just the ones I can get to without taking the extension manifold off :)), & oil change. The car's been down for about 3-weeks now :(. The baby was sick, & now I'm sick, so it's really slowed me down :(. Good thing the 7's not my daily driver :)

Good Luck.