Alternator Mounting Bolt Info Needed
Thread Starter
Melting Slicks
Joined: Nov 2005
Posts: 3,323
Likes: 142
From: Green Valley Arizona
Alternator Mounting Bolt Info Needed
Seems that I have lost an alternator mounting bolt; anyone happen to know the details of the bolt...thread pitch, length, grade???
Have no idea when or where it went or even how long it has been gone.
Appreciate it.
Have no idea when or where it went or even how long it has been gone.
Appreciate it.
Race Director
Joined: Aug 2000
Posts: 11,470
Likes: 764
i'm showing a M10 x 1.5 x 25, property class or PZOR (what we call grade) 9.8 -- GM part number, 14063755. not 100% sure, but it might be a flange bolt with a 21.5mm flange diameter. 
Last edited by Joe C; Apr 8, 2016 at 09:56 PM.
Team Owner
Joined: Sep 2003
Posts: 25,398
Likes: 2,742
It's for sure a "flange head" and a later spec for it indicates it would be maybe 30mm long BUT it's only a 26mm thread and a 4mm shoulder "under-head" where it passes trough the 2 braces. That isn't likely important and JoeC has the thread/pitch correct.
On a dealers shelf you might find a 12337993 but it could be a "hit-miss".
On a dealers shelf you might find a 12337993 but it could be a "hit-miss".
Last edited by WVZR-1; Apr 8, 2016 at 10:11 PM.
Thread Starter
Melting Slicks
Joined: Nov 2005
Posts: 3,323
Likes: 142
From: Green Valley Arizona
Thanks for the bolt info.
Went looking with my new LED flashlight and lo and behold...found the bolt laying on the frame!!!
But now this is where something strange is going on:
Retrieved the bolt and went to put it back in the alternator but it would not tighten down...thought oh great the alternator threads are stripped out! I checked the bolt threads and decided to try running the bolt through a die; grabbed the thread pitch gauge and the bolt was not metric....is it a 3/8 x 16, and the head does not indicate a metric bolt....???....
Checked the alternator threads and yep they are 10 x 1.5...
Removed the same looking bolt out of the AC compressor (hidden behind ASR in picture) and it is also a 3/8 x 16??
Now I have had this car for over 10 years and did swap alternator from a '95 Corvette and this '96 some years ago....but pretty sure I kept the same bolts on each car..???
IDK....off to ACE Hardware to see if they have the correct bolt, if not then call to local Chevy dealer.
This is just strange!!
Went looking with my new LED flashlight and lo and behold...found the bolt laying on the frame!!!
But now this is where something strange is going on:
Retrieved the bolt and went to put it back in the alternator but it would not tighten down...thought oh great the alternator threads are stripped out! I checked the bolt threads and decided to try running the bolt through a die; grabbed the thread pitch gauge and the bolt was not metric....is it a 3/8 x 16, and the head does not indicate a metric bolt....???....
Checked the alternator threads and yep they are 10 x 1.5...
Removed the same looking bolt out of the AC compressor (hidden behind ASR in picture) and it is also a 3/8 x 16??
Now I have had this car for over 10 years and did swap alternator from a '95 Corvette and this '96 some years ago....but pretty sure I kept the same bolts on each car..???
IDK....off to ACE Hardware to see if they have the correct bolt, if not then call to local Chevy dealer.
This is just strange!!
Last edited by LannyL81; Apr 9, 2016 at 10:08 AM.
Race Director
Joined: Aug 2000
Posts: 11,470
Likes: 764
Thanks for the bolt info.
Went looking with my new LED flashlight and lo and behold...found the bolt laying on the frame!!!
But now this is where something strange is going on:
Retrieved the bolt and went to put it back in the alternator but it would not tighten down...thought oh great the alternator threads are stripped out! I checked the bolt threads and decided to try running the bolt through a die; grabbed the thread pitch gauge and the bolt was not metric....is it a 3/8 x 16, and the head does not indicate a metric bolt....???....
Checked the alternator threads and yep they are 10 x 1.5...
Removed the same looking bolt out of the AC compressor (hidden behind ASR in picture) and it is also a 3/8 x 16??
Now I have had this car for over 10 years and did swap alternator from a '95 Corvette and this '96 some years ago....but pretty sure I kept the same bolts on each car..???
IDK....off to ACE Hardware to see if they have the correct bolt, if not then call to local Chevy dealer.
This is just strange!!
Went looking with my new LED flashlight and lo and behold...found the bolt laying on the frame!!!
But now this is where something strange is going on:
Retrieved the bolt and went to put it back in the alternator but it would not tighten down...thought oh great the alternator threads are stripped out! I checked the bolt threads and decided to try running the bolt through a die; grabbed the thread pitch gauge and the bolt was not metric....is it a 3/8 x 16, and the head does not indicate a metric bolt....???....
Checked the alternator threads and yep they are 10 x 1.5...
Removed the same looking bolt out of the AC compressor (hidden behind ASR in picture) and it is also a 3/8 x 16??
Now I have had this car for over 10 years and did swap alternator from a '95 Corvette and this '96 some years ago....but pretty sure I kept the same bolts on each car..???
IDK....off to ACE Hardware to see if they have the correct bolt, if not then call to local Chevy dealer.
This is just strange!!
Team Owner
Joined: Sep 2003
Posts: 25,398
Likes: 2,742
OP - nearly every brand of automaker uses that spec bolt.
Nearly every body fastener has the flange head. You could very likely just "borrow" one from another less critical position on your car.
A GM dealer may likely NOT have it on the shelf by part# but it seems you understand what you're looking for so if you just ask the dealer to check their "shop" hardware I'm very sure you can be helped and also with the correct "under-head" shoulder for the bracket stack. There's some very unusual mixes of hardware that continued with GM even after the change from the L98 to the later LT engines. It's very easy to confuse one's self. If you were doing a JY swap using a 3/8-16 by mistake is very easy and "yes" it would have eventually "shook out'. The 3/8-16 is something closer to a 9.5mm AND THAT ALLOWS THAT TO HAPPEN.
Shop a dealer (any brand) for your bolt to get the flange head. The under-head isn't near as critical but if you could you would like to avoid - "thread to head"
Nearly every body fastener has the flange head. You could very likely just "borrow" one from another less critical position on your car.
A GM dealer may likely NOT have it on the shelf by part# but it seems you understand what you're looking for so if you just ask the dealer to check their "shop" hardware I'm very sure you can be helped and also with the correct "under-head" shoulder for the bracket stack. There's some very unusual mixes of hardware that continued with GM even after the change from the L98 to the later LT engines. It's very easy to confuse one's self. If you were doing a JY swap using a 3/8-16 by mistake is very easy and "yes" it would have eventually "shook out'. The 3/8-16 is something closer to a 9.5mm AND THAT ALLOWS THAT TO HAPPEN.
Shop a dealer (any brand) for your bolt to get the flange head. The under-head isn't near as critical but if you could you would like to avoid - "thread to head"
Last edited by WVZR-1; Apr 9, 2016 at 01:02 PM.
Thread Starter
Melting Slicks
Joined: Nov 2005
Posts: 3,323
Likes: 142
From: Green Valley Arizona
Well went to ACE Hardware and got a M10x1.5x30, 10.9 large flange bolt, unfortunately it was thread to head, but it will work. It was only $2.20....so good to go for now.
I have found the odd mix of SAE and Metric bolts on every GM car I have ever worked on, would have thought by 1996 GM would have fully converted to Metric sizes for everything, guess not.
Now I am wondering if I put a Metric bolt in the '95 Corvette along with the '96 alternator when I did that swap five five years ago. No longer have that car but will ask the current owner if he is missing that bolt.....if so...I have it.
I have found the odd mix of SAE and Metric bolts on every GM car I have ever worked on, would have thought by 1996 GM would have fully converted to Metric sizes for everything, guess not.
Now I am wondering if I put a Metric bolt in the '95 Corvette along with the '96 alternator when I did that swap five five years ago. No longer have that car but will ask the current owner if he is missing that bolt.....if so...I have it.
Last edited by LannyL81; Apr 9, 2016 at 02:57 PM.
