After my motor build I was missing one of the altinator bracket bolt, I figured id put to in and grab another next time I was at the hardware store. Well long story short is both of the bolts snapped off while I was driving and fried my altinator. I decided to fix it right and tapped out the bolts, got a new altinator and put it back together. Well tonight I heard a giant sqweel coming from the engine and sure enough my altinator bracket is being held on by one bolt and the other two are snapped. The bolts I used are from a local auto store and I assumed that would be good enough but im obviously wrong. What grade bolts would you guys recomend?
alternator bracket bolts keep snapping
- Thread starter gabe3586
- Start date
if theyre soft steel bolts, i'd recommend going to a grade 5 or grade 8 bolt. I mean ideally youd just use the factory bolt, but since those are long gone you have to use whats available to you. You arent running like a 1.21 jiggawatt alternator are you? putting any extra stress on the bolts than factory (or 3g alternator)?
BullittStangV8
Founding Member
just get grade 8. The cost is like an extra .20 over a grade 5. Also, is your belt tension too tight? (maybe putting more stress then ideal on the alt?)
the pony boy
Founding Member
Maryland Stang
Active Member
It takes an incredible amount of force to break even a cheap bolt. Did you know that the run of the mill 12 penny nail can withstand 2,000 pounds of shear force?
There's something else going on here and grade 8 bolts won't fix it. They may hold but there is still an underlying problem.
There's something else going on here and grade 8 bolts won't fix it. They may hold but there is still an underlying problem.
Ive looked over everything, The belt is the right fit and everything else checks out. My last Mustang altinator bracket was being held on by 2 bolts for years and I never had this problem, I may look into getting a smog pump pully. Another question that I had that may sound ghetto. One of the bolts is damn near impossible to get out, ive tried every kind of easy out/tap out bit, I cand even drill through the bolt. Could it cause damage to my head if I welded a stud were that bolt broke? Im running gt40ps.
XLR8TR
New Member
Oh man...the same thing happened to me! I have the same setup (GT40p heads, no smog pump, and a 3g alternator) and have been running it for a few years now. Then last month I was just cruising along and smelled burnt rubber, stopped, and found the alternator and bracket hanging down at an angle and the belt was chewed up big time. Thought the bolts had backed out (and I used Lock-tite) and went to tighten them and they were gone...the two lower bolts had snapped and the upper one was barely hanging on. Took me several hours to tap the busted ones out, and the upper one I had to drill and rethread because it had been wallowed out so bad. Replaced them with Grade 8 bolts, and looking at the route of the belt I can see where there would be alot of tension on the alternator and bracket because of the smog pump not being there anymore. So to be safe I'm putting on a smog delete pulley.
BullittStangV8
Founding Member
Yep. I've sheared off bolt heads with a hand held torque wrench...I know I'm strong guys... not that strong.
