GM Alternator Upgrade Problem

For those of you that have upgraded your alt. to the gm144, have yall had the top bolt break? I have broke two recently and it backs out and cut my supercharger belt. It shredded a belt on my way to work this morning only to find out that the bolt broke and backed out. I just put a brand new bolt in about a month ago because the original broke. Both of them broke in the exact same spot, right where the threads start. It actually breaks slightly in the alternator bolt hole which leads me to believe that its not shearing off from the weight of the bigger alt. I thought I might have over torqued the first one so the second one, I just barely snugged it up. I'm kind of at a loss. My next thing to try is to figure out what threads the bolt is and put a grade 8 bolt in there. If that doesn't work then I'm going to drill out the threads in the back and put a bigger bolt with a nut on the back. Does anyone know off hand what size bolt it is?

 

ive had no issues at all.


Do you have the lower mount setup right?

 

Yea I'm pretty sure I do. I'm going to check to make sure all of the bolts are tight on the brackets when I get home from work. I had it installed for a while before the first bolt broke but it only took a few weeks to break the second one.

 

Are you using at least a grade 8 bolt?

 

I'm using whatever the factory bolt is. The first bolt was the original that came with the truck and I got the second one from the dealership so it was a toyota replacement.

 

"If that doesn't work then I'm going to drill out the threads in the back and put a bigger bolt with a nut on the back."

That is the best way to solve this problem.

 

Just for future reference for anyone that has this problem and finds this thread, I looked for a high strength bolt that would bolt back in like factory but couldn't find anything. The original bolt is a M10 x 1.25 x 97mm. I went ahead and drilled out the sleeve, alt., and threads to a 7/16 hole and put in a grade 8, 7/16 x 4-1/2" bolt with locking nut. I had to pull out the cast iron bracket and the alt. in order to drill them but that was easy. The bracket is held in by 3 bolts. I also did away with the little sheet metal cover on the back of the alt. bracket.