BigRed

Hey everyone,

I got my car towed a few weeks ago and the bastards put it up on dollies (they gave me some crap about not being able to put modified/lowered cars on a flatbed)

anyway, one of the dollies pushed up against my catback and pulled out the nut a bit and now it's cross threaded and I'm afraid it'll bust the stud.

I talked to an exaust guy and he said he can pop out that stud and put in a new one no problem, I just have to get it. I called mazda and the stud is part of the cat and can't be ordered individually.

anyone else have this happen? any idea what to use for a replacement? any other options?

thanks

-Greg

spurvo

If it's really cross threaded, you have to drill the "stud" out. Take a dremmel tool or any cutting wheel tool, cut the stud off flush with the face of the cat. Use a center punch (a pointy chunk of steel that puts a dent in hard things) to make a drill start point in as close to the center of the shaved off stud as you can. Drill a small hole (1/8th inch or so) so the location is good, then step up the drill sizes until you get the right size. Go to parts store and get an exhaust bolt. Bolt it up and off you go.

I'd replace the gasket while you're in there, and make sure the bolts really are made for exhaust, including stainless steel bolt, grade 5 or higher, and a flange nut, prefferable with locking grooves. A lock washer set up will work, but will eventually loosen over time (thermal expansion compresses the washer, so the torque is eased).

BigRed

that's the plan! I'm going to have someone else do it, but yeah, that sounds like the best course of action.

I was already planning on the gasket, but as far as an "exaust bolt" goes, what am I looking for? is it a standard part or are there a bunch to chose from?

do I have to order that gasket from mazda or is there an equvalent at an autoparts store?

thanks again!

spurvo

Bolt from an auto parts store. Gasket from either mazda or parts store...

BigRed

I'll check them out tonight. thanks!

wingsfan

Greg, don't fret. I busted 3 out of 4 of the studs on the cat while changing out my clutch. They're easily replaced.

I turned them out with the aid of an impact wrench and a propane torch. I also took two of them out via a set of channellocks, so they can be done by hand. All you have to do is take the crossthreaded nut and put it on the stud (with the cat removed from the car so that it's a free standing piece), heat it up with the propane torch till it's good and hot, and then tighten the hell out ouf the nut (as tight as you can get it). Then let the nut/bolt cool for 5 minutes or so and then try to take the nut off with either an impact wrench, socket wrench, or a set of channellocks.

My studs ended up breaking loose before the nut did, allowing me to back 2 of them out with the impact wrench (I had a friend kneel on the cat to hold it still). The other two I tackled with the channellocks, and I got one to break loose. The last one I had to cut with an angle grinder and drill the rest out.

Also, I don't know what your dealership is smoking, but here's the part number for the studs through mazdatrix.

http://www.mazdatrix.com/getprice.as...m=40-3980-1259

I didn't go that route. I did a downpipe at the same time and I was having alignment issues with the studs (hence the crossthreading), and I figured that the studs would just crossthread again (the metal is really soft)and I would have to repeat the cycle with the channellocks and whatnot, so I replaced all my stuff with grade 10 metric nuts, bolts, and lock washers. No problems to this point and it made aligning everything up a breeze.

Hope that helps

911GT2

I busted one putting on my dp. Meineke heated the hell out of it (glowing BRIGHT red) and turned it out with vise grips. Not too shaby, and it only cost $40.

wingsfan

Holy ****!! $40??? It's a $3.50 stud and a $2 nut! Did the vaseline come with that?

paw140

I busted 3 of the 4 on mine. I drilled the front two out, had a hell of a time, and took it to Midas to get the remaining one out (I tried a propane torch and vise grips and couldn't get it to turn at all). The Midas guy heated it until it was glowing, and was able to turn the stud a little bit, but then it got hard again. He did this a few times and pretty soon couldn't turn it at all. So then he tried to cut it off with his torch, and burn a hole in the flange. The stud metal was harder than the flange, and he started to mess up the flange. So I got it back, all messed up, but was able to drill it the rest of the way out.

Moral of the story? At some point (my car had 90K miles), those things are nearly impossible to remove.