i need to replace a nut for the flange studs on the stock NA exhaust manifold (flange between the manifold and cats...or rather the straight pipe i have now that replaced the cats).
i've been looking around and can't seem to find it. it looks to be an M12 size, although the stock nut is a 17mm and M12s are usually a 19mm.
so anyone know? driving around with an exhaust leak is NOT fun...

thanks

 

It's an M12. I manged to find an exact match in size, and IIRC, the label on the bin said "HD". Don't know whether that's some kind of "official" designation though. I don't think it matters though - I'm pretty sure a standard M12 will fit.

Sorry, I don't remember the thread pitch though.

 

In the archives, there is a large thread containing all the nut/bolt sizes.

 

m12 x 1.5 and they are available at Canadian Tire or Parts source in the bulk fastener aisles

 

i'm well aware of that thread, however it does not give the size for the NA exhaust manifold flange. it only gives the size for the manifold engine studs.
maybe you want to add something to that thread if i figure this size out

ok, i will check that out. although 1.5 looked big to me, so i'm going to try to get a 1.25 also.

 

All exhaust nuts/bolts are the same thread on the manifold and engine.

 

They are M12x1.5. I had to buy a bunch because the nuts kept falling off the studs after I installed my Racing Beat exhaust. I eventually double nutted the studs on the manifold and it's been fine ever since.

 

Search newbie. FYI: If you're not certain in the future take the nut, stud, bolt to your local fascener store and have them figure out what will work for you.

 

lol. well i DID search and couldn't get any answer for this particular stud/nut.
and taking the STUD out of the exhaust manifold that is ON the car isn't exactly easy...plus i didn't have a spare nut to bring to the hardware store and compare...

anyways, i tried an M12 x 1.5 and it doesn't really want to thread on. maybe the threads on the stud are buggered, but for some reason i still think it's a M12 x 1.25. unfortunately most places only carry 1.5 and 1.75 thread pitch for the M12. still looking for a 1.25...

 

I'm pretty sure I remember the thread pitch being different on those studs. I picked up all my fasteners from Canadian Tire, but I've been to several and they all stock different items. The one nearest me doesn't stock bulk metric fasteners at all, but one 10 minutes away has the best selection I've seen anywhere. Also check Home Depot, Rona, and don't forget about the smaller hardware stores which sometimes have a great selection.

 

IT WAS A M12 X 1.25 !

so yeah, that's the size

 

Not to bust anyones *** or anything.. But i just PUt on my header today as a matter of fact..I had to pull a stud out because it got crossthreaded by the nut.
I took it to the part store and matched it up.. because I replaced the studs with Bolts anyway..

the stock bolt size for a 89-91 na
is not an m12 1.5

ITS A M10-1.5 i used a 30mm with a 17mm socket head on it..

thats what it is. . .

perfect fit .. and exact same size.

 

It's M10 x 1.5. I just looked at the receipt for the copper "turbo locknuts" I bought.

 

If you buy it from Mazda, you don't have to know the size, just the year and how to count out $6.

On my vert, it was a 12 x1.25.

 

you guys are talking about the exhaust manifold studs. the ones that are used on the actual engine block. yes, those are M10 x 1.5

i'm referring to the exhaust manifold flange, the part where (stock) the precats go on.

M12 x 1.25

 

I'm having the same problem I've tried 12mm x 1.5 and 12mm x 1.25 even went to Mazda to get the nuts and they don't even work. Any idea's its on stock exhaust where the head pipe bolts up.

 

They don't work how, they only thread on a couple turns then stick?

Mine were M12x1.25 as mentioned above, I just had to replace one stud and both nuts...

 

m10x1?