stainless exhaust studs

[garyS-NJ]

looking to replace the rusty exhaust bolts that were in my bike when purchased and so I purchased a same length (40mm) set of m8x1.25X40mm stainless studs which have an allen key drive to install. well I measured the thread depth in the head and seems these 40mm studs (and the 40mm bolts) seem a little short. forget about threading the new studs all the way in (might need 55 - 60mm long) but to allow room for a nut and lockwasher, seems I can only thread in about 10mm of the 40mm stud. I feel like it deserves 15-20mm insertion to be really secure. there must be an engineering rule for this. any you folks have good alternatives to rusty bolts and advice on stainless studs? also, I planned to install with red locktite to protect against galvanic corrosion (steel against aluminum head). But I'm worried the stud would never again come out with just the allen key drive. One ebay seller advertises these style stainless studs with copper antiseize...

 

[Nessism]

Yes on antiseize over loctite.

 

[hannibal]

I thought I read to use locktite on the stud and antiseize on the nut. Why would you ever need to remove the studs?

 

[Guest]

Stainless steel is used in electrical connections where aluminum is the base metal. Stainless is considered a noble metal, so galvanic reaction isn't a concern. I've never had a problem with this combination.

 

[exdirtbiker]

It's been a while, but I was once told that "if your screw ( or stud) goes in at least as deep as the diameter, anything deeper is wasted material and $, and does not make it stronger. "
But that may have been with similar materials, which you don't have.
SO I guess i'm not helping, am I ?

 

[Nessism]

Stainless steel is used in electrical connections where aluminum is the base metal. Stainless is considered a noble metal, so galvanic reaction isn't a concern. I've never had a problem with this combination.

Stainless in aluminum is BAD. Anti-seize is necessary.

 

[Agemax]

loctite on the studs into the head, it still provides a barrier between the s/s and the ali and will prevent the studs from screwing out when removing the nuts.
anti seize on the nuts.

 

[garyS-NJ]

thanks all!

I found an engineering guide on Practical machinist which said a stud should be inserted to a depth 2.5 times the diameter. I think that spreads the load and no more strength is obtained until going to a larger diameter stud. with about 20mm inserted, looks like I need the 50mm studs which are available on ebay from jonsautoshack. He's a nice guy and swapping my 40mm at no charge.. As for locktite vs the copper antiseize, for sure we want something to protect against galvanic corrosion which might weld the stud into the head. and **** happens so I want to be able to remove the studs. I understand that turning the nuts off might thread the studs out if I don't use Loctite in the head but worried with Loctite, I wont be able to get the studs out. Also jon's autoshack sells the studs with the CU antiseize so that's the route I'm going. Thanks all again!