Exhaust bolt replacement ...Stainless or ?
 

I have one of my secondary cat bypass pipes off right now, the bolts while still quite functional are ugly from the heat of 15 years and 70K miles....I have a great supplier locally who has everything from Stainless to Grade 8 and up in bolts. What would you guys use to replace yours ? and if stainless would you use anti seize to help the next time they are removed ??

Thanks in advance

Dwight

Yes, and yes.

Wow M8 x 1.25 carriage bolts are hard to come by

Use stainless everything.Bolt nut washers and lock washers.
Grade 8 is the wrong application.

I am
 

I already sourced them at Mr. Metric , I know Grade 8 is carbon

So you're saying I'm not likely to find them at Home Depot tomorrow after work. I was hoping to have these pipes buttoned up tomorrow night

Carriage bolt ? Don't you mean hex head ? Carriage bolt is for wood .

carriage bolts
 

Part of the exhaust hardware are some bolts that look like carriage bolts. Pan head with no slots and a shallow self locking square just above the threads and below the head.

http://cf-design911-1.datadial.info/...61111101lr.jpg

Nope, carriage bolts are used in the exhaust clamps for the secondary cats/by-pass pipes to U-pipe connection. Metric carriage bolts...
Might be replaced with regular stainless bolts tomorrow afternoon...

Edit
Pdwight got it in first...

Metric carriage bolts are available in stainless steel, even Amazon sells them.

Regular SS hardware for home dope or local hardware will work just fine.

Yes it would
 

Actually anything that would pull the clamps in would be OK......that being said Mr Metric is a wonderful resource for hard to find fasteners (I have no involvement whatsoever with them)

So no love at mr metric. McMaster Carr same. Fastenal has them but want 50 some odd bucks cdn. for a box of ten.
I'll be using regular bright bolts and not worrying about it. They will probably only be on for a year or so before the muffler gets changed out for a magnaflow and the the u-pipes go into the garage attic with the rest of the stock stuff.

Try Here
 

Stainless studs for the headers may also be of interest?

Size
 

Do you know off the top of your head (what a funny way to put that) what size they are ?

It may be easier to 'cheat' and use a 5/16" bolt.Choose your length carefully.Nordlock washers also?
https://www.boltdepot.com/Carriage_bolts_Stainless_steel_18-8_5_16-18.aspx
http://www.ebay.com/itm/Stainless-Steel-Carriage-Bolt-25-5-16-18-x-1-1-2-/201736255999?hash=item2ef86af9ff:g:6nIAAOSw-0xYQZ2H