Differential pinion bracket bolts?
Thread Starter
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From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
Differential pinion bracket bolts?
Quite a while back when I had the rear end out I misplaced the two bolts that fasten the pinion bracket to the bottom of the housing. I managed to find two mismatched factory looking 7/16" bolts (of some unknown origin) and use them, but over the winter I'd like to look around the shop and find the right bolt(s). Can anyone tell me what the factory bolts look like? 
One of the bolts I have has an integral washer on the head, while the other has a drilled hole at the end for a castle nut and cotter key. They're both about 5" long.
If someone can tell me which (if either) is the correct bolt, and for extra points, what the other bolt might have been for, I'd greatly appreciate it.
Thanks!
One of the bolts I have has an integral washer on the head, while the other has a drilled hole at the end for a castle nut and cotter key. They're both about 5" long. If someone can tell me which (if either) is the correct bolt, and for extra points, what the other bolt might have been for, I'd greatly appreciate it.
Thanks!
Thread Starter
Tech Contributor
Joined: Jun 2004
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From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
Thread Starter
Tech Contributor
Joined: Jun 2004
Posts: 20,936
Likes: 962
From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
Team Owner
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From: Sitting in his Nowhere land Hanover Pa
2024 C2 of the Year Finalist - Unmodified
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Alan do you know when St. Louis changed the congratulation of those two bolts? on mid years only one bolt got the cotter key and the bolts were opposite of each other
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Safety Car
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From: BC
My 69 is the exact same as Alan's and the bolts only go in one way with the head on the driver's side.
Team Owner
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From: Sitting in his Nowhere land Hanover Pa
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I am thinking sometime in the C3 era they changed that bracket. So maybe that's when they changed the bolt configuration
Melting Slicks
Joined: May 2006
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From: Centerville Louisiana
Just did this only go in from drivers side on my 75. Also I might add I used the originals not the ones I got in a suspension kit those were a little short. Not as meaty either.
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From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
Ya got me curious. I dug through some boxes for my lost bracket bolt, and actually found two, but one is about 3/16-1/4" shorter than the other two I have. Got me wondering if any chance the '68 bolts are shorter due to the lack of the reinforcement plates on the bracket.
Safety Car
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From: BC
Melting Slicks
Joined: Jan 2012
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From: myrtle beach sc
Army
I have two 68 AIM's. The newer version very clearly shows the differential bracket without the reinforcement, on the sides. The 68 bracket number is 3868799. There are two different bolt numbers! The forward bolt is number 3846867. It gets a castle nut and a cotter pin. The diagram shows that a flat washer was welded around the outside hole, I think that I remember that feature. The bolt closer to the body of the differential, in other words the rear most bolt is number 193490 and it gets a nut and a lock washer.
The 68 automatic section does show the bracket with the reinforcement. It is number 3921657 and they only show one bolt, but you obviously need two. They are number 3921658, and they get a castle nut and cotter pin. So automatic 68's got the reinforced bracket. Lou.
The 68 automatic section does show the bracket with the reinforcement. It is number 3921657 and they only show one bolt, but you obviously need two. They are number 3921658, and they get a castle nut and cotter pin. So automatic 68's got the reinforced bracket. Lou.
Last edited by loup68; Jan 17, 2017 at 07:48 PM.
Melting Slicks
Joined: Jan 2012
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From: myrtle beach sc
Army
I Just checked my older, ORIGINAL AIM copy, and the part numbers are the same. For you newer Corvette owners, if it wasn't for Mid America Enterprises to have the foresight to salvage these assembly plant manuals, we would all be clueless now! Mid America Enterprises was the first Corvette parts company, that I remember. They are now called Mid America Motorworks.
My two AIMS, a 68 and a 69 all have " Chevrolet drafting graphic " at the top left and then assembly instructions at the top right of the pages. Everyone complains that there is no index for the AIMS. These AIMS have an index in the front and use the H number at the top of the pages, or sometimes it is at the bottom.
Why all of the newer AIM copies do not have the front index and the H numbers is a mystery to me. Lou.
My two AIMS, a 68 and a 69 all have " Chevrolet drafting graphic " at the top left and then assembly instructions at the top right of the pages. Everyone complains that there is no index for the AIMS. These AIMS have an index in the front and use the H number at the top of the pages, or sometimes it is at the bottom.
Why all of the newer AIM copies do not have the front index and the H numbers is a mystery to me. Lou.
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From: Westminster Maryland
Hi Lou,
I agree that the AIM is the most important and useful source of information we have.
It's invaluable to someone taking a car apart and putting it back together.
Here's some information about the AIMs written as only the restorer's friend John Hinkley can!
What a treasure he is!
Regards,
Alan
He wrote it for the Camaro group but applies to what we use too.
http://www.camaros.org/AIM.shtml
I agree that the AIM is the most important and useful source of information we have.
It's invaluable to someone taking a car apart and putting it back together.
Here's some information about the AIMs written as only the restorer's friend John Hinkley can!
What a treasure he is!
Regards,
Alan
He wrote it for the Camaro group but applies to what we use too.
http://www.camaros.org/AIM.shtml
Melting Slicks
Joined: Jan 2012
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From: myrtle beach sc
Army
Thank you for posting that link, Alan. I was surprised to find out that only one or two complete AIM copies were in the whole assembly plant, making a complete one really rare! Lou.