Battery hold down clamp bolt

[GaryL]

Sorry for this small anal question, but what is the orginal bolt for the battery hold down clamp? The size is 5/16NC but does it have a captured washer and no threads on the end just like a door hinge bolt?

[JohnZ]

Mine, which I believe to be original, is a 5/16"-18 recessed hex head with a captured conical washer and a reduced-diameter round flat point (we called them "dog-point" bolts in the plant).

[KevinW]

Nice timing on this!   John, what size is the captured washer? Thanks!

[GaryL]

That souinds like what I bought, but the washer has teeth. It lokks exactly like a door hinge bolt.

[Marty]

I have an original bolt off a 68 full size car that I will look at when I get home. I think the head markings are RBW but I'll double check. I'll try to take an image of it tomorrow.

[JohnZ]

Washer is 7/8" in diameter, and it does have serrations ("teeth") on the bottom.

[Marty]

The one I have also has a 7/8" diameter washer but it doesn't have serrations on the bottom. The length is 1" including the washer.
RBW head marking, grade 5 (three lines). Remember, this is off a 68. Anyone else have an original bolt?

[GaryL]

Washer is 7/8" in diameter, and it does have serrations ("teeth") on the bottom.

That's what I thought. It is exactly a door hinge bolt, but the closest they could come. There is no AMK Products listing for the GM part number in the AIM.

[GaryL]

Wow. I go out to my spare bolt bag and find 2 like you guys describe. If only I had known.

[Dave69x33]

JohnZ,

What is the marking inside the head?  Is it an "N" like the one shown?

This is AMK's individual bolt kit #G4352, $1.50.  It is also avalible in a set of (6) for $5, item #B-11915.

Its a 5/16-18 x 7/8, 1/2 across the flats, 3/4 conical encapsulated washer, phosphate gray-black color.  It has a "lead point" tread start nose tip w/o treads for about first 1/8".

[JohnZ]

<<JohnZ,

What is the marking inside the head?  Is it an "N" like the one shown?>>

Here's a photo of the bolt on mine. Although the overall configuration of the bolt is similar to the door hinge bolt, I wouldn't expect them necessarily to have the same headmark - Fisher Body released and purchased the door hinge bolts under their own part number, and Chevrolet released and purchased the battery hold-down bolt under their own part number.

[Pex68]

John,

See your clamp is painted, is that correct?  I always thought those were phosphate like in Dave's photo.

[JohnZ]

John,

See your clamp is painted, is that correct?  I always thought those were phosphate like in Dave's photo.

I suppose they could have been either way, although I've only seen them painted; mine is original to the car.

[Dave69x33]

I purchased mine hold down clamp from Paragon Corvette Reproductions, Kit Item #1515K, $5.00 which includes bolt Item #1498, "E" head mark.  I must assume there could have been a couple of different bolt head markings uses.