I'm about to order some 316 Stainless M10 hex head bolts (30mm, fully threaded, 16mm hex drive) to replace the stock stud+nut setup. A lot of folks have done this, but I couldn't find what they used.

Will the plain hex head style fit? Should I use a small washer get a flanged head instead?

Is another type of head easier to work with?

Dave

 

When I installed my DP (actually I didn't do it my mechanic did) one of the studs were broken off and had to be backed out...My mech recommended ordering the originals from Mazda so I did...

 

mine has 17mm heads on the top 2 bolts and 14mm heads on the bottom bolts. i think if the bottom ones were any bigger it would be a real pain to get them tightened down properly, or loosened if they have been on there for a while because it is hard to sqeeze a wrench or socket in between the bolt and the pipe. hope that makes sense.

 

Does hex-head = Allen-head?

Reason I ask is that I found some Allen-head bolts for the bottom holes. The stock studs would not fit with the dp I bought. There are some crappy pictures here.

 

No, allen keys are for socket heads. Hex head is driven by a regular 6-point socket drive.

Dave

 

i am switching over to socket heads after going with hex heads for a couple years. the socket heads might fit better if the holes in the flange on the downpipe are a tight fit which mine is.

 

why order them? pep boys has them in the ricer section, they're called exhaust manifold bolts

they also have them in "HELP!" parts

 

The allen wrench sticks out of the socket on a hex socket, which gives you less clearance and makes it hard to put on and take off. If you can afford the disposable OEM studs and crush nuts, get those instead.

 

My hope was to buy a better quality material - like 316 Stainless or a high temp alloy steel. Or is the salty OEM stuff still best?

Dave

 

I've heard something about the OEM stuff being better, probably on http://www.scuderiaciriani.com/rx7/d...e_install.html

read that over, there was a lot about bolts vs studs/nuts.

 

My mechanic uses the allen type ss bolts. He has a short allen key cut to fit the lower hard to get to bolt, turns it with a small box or open end.