What size bolts are on our exhausts? I went to install my car back yesterday and I realized there is no chance im taking the bolts off, they are completely rounded, and there is no thread to them. From the way it looks they are all like that. Any help would be appreciated. Thanks.

 

14mm........

 

Just get a dremel and cut them off. You can buy the bolts at Home Depot. Just make sure they are stainless steel (and metric) and you'll be fine.

 

+1. I use te dermel for anything that I can't take off.

 

Drilling back through the holes (b-pipe to muffler for example) SUCKS.

 

whats the easiest way to get the rusted *** stock screws connecting the stock Y to the stock cat off?

 

Try and spray some "PB Blaster" on the bolts and let them soak for a few minutes. It's also a good idea to let the car warm up and wait 'til the exhaust system gets warm (not hot, where you can't touch) and then try to loosen. Bolts tend to loosen better when heat is applied (especially when they are rusted and stuck on there).

 

if you are putting on a new catback, just worry about the bolts at they Y and cat. once those are off, somehow cut (dremel or hacksaw) the piping near the rear beam so that you can just pull it out in two pieces. that's what i did and it was easier than messing around with another set of hardware.

 

Are they all 14mm? and if so, if I wanted to replace them all from the catback how many would I need? I dont have access to a jack or ramps often...otherwise i would check myself.

And what would be the best technique for removing them? I have heard about cutting them off...but I dont see how that will help because a small piece of the bolt will still be holding the pipes together. I have also heard about cutting a small slit in the top of the bolt and putting in a screw driver and then turning it, but as i said, there is not much of the bolts left, they are blobs.

I dont wanna ruin the holes on the cat, as I will be keeping the stock one.

 

There are no threads inside the holes of the flanges. The bolts go thru the holes of the flanges and are tightened on the other side with a nut. If you cut the bolt as close as possible near the flange, all you have to do is pry apart and the pipes should come free. Nissan doesn't use "loose" bolts on their exhaust systems. They always weld a set of bolts on one of the connecting pipes (along with a flange) and tighten with a nut thru the connected flanges.

 

i had the same problem with the bolts on my cat. they were all stripped to hell. i took it to my mechanic and he used an air wrench and torqed em off with a extractor socket he hammered on the bolt. if you have a good mech. the'll do it 4 free

 

I just tried to take off my exhaust from the cat...there are no nuts at all holding the cat to the pipe. Looks like just a weld...if that. Ive been trying to for hours to dremel off the bolts at the muffler and it just wont cut it. Anyone have any ideas?

 

Check with local exhaust shops to see how much it'll be to torch off and replace the bolts - should be $5-$10/bolt

 

I had: 1bolt from Y/Cat 2bolts from Cat/test and 2bolts from test/b replaced by a muffler shop not too long ago, I also drilled out the b-pipe to muffler flange and replaced those. I can now drop or replace my catback in about 40 minutes including O2 sensors and hangers.

I would HIGHLY recommend going this route to anyone that is facing this problem but wants to do the work themselves. Like JaTaN said, it will be a couple bucks a bolt and they will be well worth it.

Also, on my cat there was a significant amount of rust IN the holes so they drilled new holes, this makes a WORLD of difference.

 

4 1/2" angle grinder w/cut-off wheel and a set of good cobalt drill bits worked for me.

 

OMFG!! that was a pain in the *** but it worked.