1967 Big Block Outer Flange and Inner Half Shaft Cap Bolts

[Richard M.]

Frank Tetro(Harbor Auto Restoration in FL) and I were talking this morning about Half Shaft Outer Flange and Inner Cap Bolts which attach the U-Joint to the Differential Flange.

I told him I'd take some pictures of the Bolts removed from this '67 I have here. I sent them to him. He got me curious as we had some confusion about bolt usage, so I dug in....
P5190018.jpg

The Outers(Flange to the TA axle) are Grade 8, circle surrounded by 6 lines. (300M Grade)

P5190020.jpgP5190021.jpg


The Inners on this car appear to me to be original. They are RBW, 3 lines, Grade 5(280M). The AIM UPC L36 Sheet A12 calls out Part# 180126.
P5190019.jpgP5190022.jpgP5190023.jpg


The JG on Page 208....."Attachment to the differential yokes is via forged steel caps secured with cadmium or zinc plated hex-head Grade 8 bolts with lock washers, typically with an A headmark."

Firstly, most Grade 8 bolts I've encountered are not zinc plated but typically black phosphate.

Secondly, I did a little research and found the 180126 part# referenced in the Master Parts Book X-164001 September 1963
The lower right of the above page describes bolt grades. Default with no special "otherwise" means the bolts are 280M(Grade 5-3 Lines)

The Next Page of the above link (Here) shows the 180126 as a 3/8"-16 x 1 1/2" bolt..............Default is 280M (Grade 5).

So there appears to be a hiccup in the 1967 JG ???

Just some more information I always learn about these cars and their parts.

Rich

[Douglas L.]

Re: 1967 Big Block Outer Flange and Inner Half Shaft Cap Bolts

Just went out and looked on my Jan 15 build 68, exact same outer flange bolts but inner bolts have the "A" head marking.

[Richard M.]

Re: 1967 Big Block Outer Flange and Inner Half Shaft Cap Bolts

Just went out and looked on my Jan 15 build 68, exact same outer flange bolts but inner bolts have the "A" head marking.

Douglas, Are they(Inners) Grade 8(6 lines) or Grade 5(3 lines)?

I'd suspect there were many different manufacturers of the bolts, therefore various head markings.

Thanks for checking.
Rich

[Joe L.]

Re: 1967 Big Block Outer Flange and Inner Half Shaft Cap Bolts

Frank Tetro(Harbor Auto Restoration in FL) and I were talking this morning about Half Shaft Outer Flange and Inner Cap Bolts which attach the U-Joint to the Differential Flange.

I told him I'd take some pictures of the Bolts removed from this '67 I have here. I sent them to him. He got me curious as we had some confusion about bolt usage, so I dug in....
[ATTACH=CONFIG]60768[/ATTACH]

The Outers(Flange to the TA axle) are Grade 8, circle surrounded by 6 lines. (300M Grade)

[ATTACH=CONFIG]60769[/ATTACH][ATTACH=CONFIG]60770[/ATTACH]


The Inners on this car appear to me to be original. They are RBW, 3 lines, Grade 5(280M). The AIM UPC L36 Sheet A12 calls out Part# 180126.
[ATTACH=CONFIG]60771[/ATTACH][ATTACH=CONFIG]60772[/ATTACH][ATTACH=CONFIG]60773[/ATTACH]


The JG on Page 208....."Attachment to the differential yokes is via forged steel caps secured with cadmium or zinc plated hex-head Grade 8 bolts with lock washers, typically with an A headmark."

Firstly, most Grade 8 bolts I've encountered are not zinc plated but typically black phosphate.

Secondly, I did a little research and found the 180126 part# referenced in the Master Parts Book X-164001 September 1963
The lower right of the above page describes bolt grades. Default with no special "otherwise" means the bolts are 280M(Grade 5-3 Lines)

The Next Page of the above link (Here) shows the 180126 as a 3/8"-16 x 1 1/2" bolt..............Default is 280M (Grade 5).

So there appears to be a hiccup in the 1967 JG ???

Just some more information I always learn about these cars and their parts.

Rich

Rich-------


The GM #180126 bolt was a GM material grade 280M bolt (SAE grade 5; 3 lines); that's for sure. The information I have indicates that it was zinc plated. In fact, one of the bolts in your photo is zinc plated. I can't account for why the others are not but I'm virtually certain they're original. All I can assume is that bolts of both finishes were used on the assembly line. However, I would expect that the bolts with the phosphate finish were of a different part number.

If any Corvettes were built with GM material grade 300M bolts (SAE grade 8; 6 lines), then it was a substitute bolt used on the assembly line and certainly not a GM #180126.

[Richard M.]

Re: 1967 Big Block Outer Flange and Inner Half Shaft Cap Bolts

Joe, I was hoping you were there. Thanks very much for verifying my research.

Yes.... All of these 180126's are zinc plated. I cleaned one with a wire wheel to identify the head marking better. Someone in the past painted all of them, likely when attached. Sorry if the earlier photo confused you. I should have mentioned that.

Here are a few more closeups of the sides clearly showing the zinc finish.
P5190024.jpgP5190025.jpgP5190026.jpg

Thanks,
Rich

[Rich P.]

Re: 1967 Big Block Outer Flange and Inner Half Shaft Cap Bolts

Inner cap bolts no question grade 5 cad plated.

[Douglas L.]

Re: 1967 Big Block Outer Flange and Inner Half Shaft Cap Bolts

Douglass, Are they(Inners) Grade 8(6 lines) or Grade 5(3 lines)?

Grade 5, 3 lines(like yours, but rather than "RBW" around the perimeter, a single "A" in the center.

[Jimmy G.]

Re: 1967 Big Block Outer Flange and Inner Half Shaft Cap Bolts

Any period bolt should be acceptable and I think you will find that they can be phosphate also.

[Richard M.]

Re: 1967 Big Block Outer Flange and Inner Half Shaft Cap Bolts

Grade 5, 3 lines(like yours, but rather than "RBW" around the perimeter, a single "A" in the center.

Thanks Douglas. That helps confirm.

Any period bolt should be acceptable and I think you will find that they can be phosphate also.

Yes Jimmy I'd agree, but definitely Grade 5 not Grade 8.

The issue that I see now is that when these are judged, the Guide says Grade 8, so the Judges will likely be looking for "6 lines". It has been now proven that Grade 8 was not originally used. It may not be a big point deduction, but now the dilemma of what owners/restorers should install arises.

The engineers chose the Grade 5 for a reason, why I have no idea. It is interesting that the Outers were Grade 8 and the Inners were Grade 5.

LI Corvette specs a Grade 8 in their catalog, I would imagine this is based on their interest to follow the JG.

LI 51-42C
LI_InnerBolts_51-42C.jpg

I'll drop a note to the 1967 Team Leader and he can review this research and consult with his Judging Staff to decide if a change to the JG should happen.

Rich

[Douglas L.]

Re: 1967 Big Block Outer Flange and Inner Half Shaft Cap Bolts

What are the torque specs for these bolts, perhaps that may give some insight as to the choice of bolt material. Also, the inners are only in tension while the outer are in tension as well as shear.

[Wayne M.]

Re: 1967 Big Block Outer Flange and Inner Half Shaft Cap Bolts

here's what is on my late 396 (on the right). Can't vouch that they are the originals. A little fuzzy, but you can make out the 3 lines and the R-B-W.




a

[Jimmy G.]

Re: 1967 Big Block Outer Flange and Inner Half Shaft Cap Bolts

50 foot pounds AIM should verify this number outers are 90 foot pounds

[Douglas L.]

Re: 1967 Big Block Outer Flange and Inner Half Shaft Cap Bolts

50 foot pounds AIM should verify this number outers are 90 foot pounds

Makes sense, I'm gonna go out on a limb and say that GM decided they needed additional clamping force on the outers to keep the flange from spinning in relation to the spindle due to the fact that the flange doesn't register on to the spindle and a grade 5 bolt isn't designed to be torqued to 90 ft/lbs.

[Richard M.]

Re: 1967 Big Block Outer Flange and Inner Half Shaft Cap Bolts

here's what is on my late 396 (on the right). Can't vouch that they are the originals. A little fuzzy, but you can make out the 3 lines and the R-B-W.




a

Exactly what I have here Wayne. Thanks for the confirmation and photo.

Also, interesting showing the 2 differential flanges. Are those casting numbers the same? It seems possible that the castings were identical, however machined differently for the SB versus BB applications, creating 2 unique Part #'s.

------

I sent a note to Nick (Team Leader) and he sent back a reply that he and the group will review the issue. He did ask for additional confirmation so as time goes by if any of you find Grade 5 bolts on your BB Inner Caps please specify here.

Thanks,
Rich

[Richard M.]

Re: 1967 Big Block Outer Flange and Inner Half Shaft Cap Bolts

Nick replied back to my inquiry and based on the information accumulated here he stated that a comment will be added to the JG referencing the Grade 5 bolts with varying period correct head marks.

Thank You Nick, and thanks to all of you with your research and references.

Rich