I have had to replace a blowing exhaust gasket discovered when I removed the heat shield. I found that it was missing a stud and nut. Checked and confirmed no broken stud and now want to replace all 9 nuts. Dealer price is £5/nut and MX5 parts half that - only problem is I am still waiting for MX5 parts to get them in stock. Found a few other sites where they manufacture the nuts but I have no way of measuring the size of the bolt and thread. Does anyone know?
Thanks
M10 x 1.5mm I believe, but you might want to wait for someone else to confirm. £5 apiece for nuts is, well, nuts!
Edit: M10 x 1.25mm. See below.
When you find out the size there is a Leicester company called All Screwed Up who have never let me down for fasteners - http://www.allscrewed-up.co.uk/
0116 2839900
They are really helpful when I call in, min charge when you walk in is £1 !!!
If small quantities over the phone is an issue I will try and help.
Peter
I think I have found a supplier just need to ensure they are the right size approx £12 for 50 which is a much better price! Will wait and see if anyone can confirm M10 1.5. and yes these are for exhaust manifold nuts.
It seems I was wrong: The correct answer seems to be M10 x 1.25mm. But they’re not plain nuts, they’re nuts for “stove bolts” and they’re flanged and fit a 14mm socket (this might be important as a plain nut would take a 17mm socket, and there might not be room to use one).
Having searched and found half a dozen suggestions of what size they might be, I found a post by Keith Tanner from Flyin’ Miata which is about as close to the horse’s mouth as it’s possible to get:
“Thread specs: 10x1.25
Head size: 14 mm
They’re a stove bolt, meaning they’re a bit oval to lock in to place.”
The “stove bolt” spec is worth asking for. Like the nuts used on the cat converter, they’re slightly “pinched” to grip the stud even if they’re not pressed completely tight against the flange.
If you don’t used torque prevailing nuts (ie squashed ones with deformed threads) they will come undone. Threadlock doesn’t cut it when it comes to stuff at exhaust pipe temperatures. Nylocks go manky really quickly too.
So no sneaky using normal nuts for cheap or you’ll end up fixing your manifold back on every couple of weeks.
If anyone around Leicester needs any nuts and bolts I usually have a garage full of Stainless ones, If I dont have them then there is always a factory I will visit in the near future that has a large supply !!
I think another type are often called “AERO” nuts… They have a cut in the top half of the nut which makes the last part of the thread not in the same alignment as the rest of the nut… Thus causing it to lock in place…I think !!!