Bolt Part Numbers- Size and Finish
Can anyone tell me what size and finish these bolts are from the part numbers. 941075, 941077, 427559
Thanks
Sheldon
Thanks
Sheldon
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Re: Bolt Part Numbers- Size and Finish
I can probably help you, but I will need to know the applications. Part numbers are useless to me unless I can view the AIM page.
If you copied these part numbers off AIM pages, provide the AIM page numbers (UPC/Sheet), Item numbers, and applications (for confirmation). The 71 AIM is probably close enough to the 70 AIM for me to make the connection.Comment
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Re: Bolt Part Numbers- Size and Finish
The part numbers are for bumper bolts for a 71 front and rear. I beleive the 075 and 077 are the same size but maybe different finish. upc 14, sheets A2,A3, B2
Thanks
SheldonComment
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Re: Bolt Part Numbers- Size and Finish
Assuming you left a "9" out of the part numbers, i.e. "941(9)075" and "941(9)077"...
(1) 9419075: 7/16" X 1 1/4", black phosphate (Sheet A2, Item 2),
(2) 9419077: 7/16" X 1 1/4", black phosphate (Sheet A3, Item 9),
(3) 427559: Can't make a positive ID. I believe it's 3/8" X 1 1/2", black phosphate. No Sheet B2 in 70 AIM. This PN also used as Item 13 on 70 AIM Sheet A3.Comment
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Re: Bolt Part Numbers- Size and Finish
From this info then all bolts attaching the bumpers should be black phospahate and none should be cad or zinc is that correct? I thought I had read the ones attaching to the bumper side of the brackets should be cad and that corresponds to the different number 9419077 which is the bolt that attaches to the bumper vs the 9419075 which attaches to the frame. Why would they use two different part numbers for the same bolt.
Thanks
SheldonComment
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Re: Bolt Part Numbers- Size and Finish
I saw that the two part numbers were exactly the same diameter and length in my notes, and I wondered about the differences.
In spite of the similar dimensions, I suspect that they are NOT the same fasteners. One possible difference that comes to mind is threaded length; one fastener could be completely threaded, and another could have an unthreaded shank of some length. Another possible difference is strength, but in this case, that is less likely.
Item 2 on Sheet 14A2, 70 AIM, (PN 9419075) is a capscrew that attaches the front cross member to the frame horns and the center bumper bracket assembly to the cross member. I'm fairly confident that fastener is fully threaded. This part number was also used to attach the front bumper at the two center locations (Sheet 14A3). Part number 427559 is the long 3/8" bolt that attaches the ends of the front bumper
Item 9, Sheet 14A3, (PN 9419077) attaches the top and bottom of the front bumper guard assemblies to the bumper and the cross member brackets...it's less obvious that one is fully threaded, and I haven't looked at them lately.
On a 70 (Sheet 14B1), PN 9419077 is also used to attach the rear bumpers at the four rear positions; the rear bumper ends, or forward locations uses PN 9419075.
There was no evidence that any of these fasteners were ever zinc or cadmium plated on my late 70.Comment
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Re: Bolt Part Numbers- Size and Finish
Sheldon, I believe the 4 external bolts on the rear bumpers were cad. plated. thats the way my 72 is,The inside bolts were blk. phosphate or zinc., I think either way is correct.New England chapter member, 63 Convert. 327/340- Chapter/Regional/national Top Flight, 72 coupe- chapter and regional Top Flight.Comment
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Re: Bolt Part Numbers- Size and Finish
Sheldon, I saw some pic.s of the 300 mile zr1 ,that was recently on the TDB a few weeks ago It has some of the rear bumper area. there were zinc plated bolts on the rear bumper brackets.New England chapter member, 63 Convert. 327/340- Chapter/Regional/national Top Flight, 72 coupe- chapter and regional Top Flight.Comment
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Re: Bolt Part Numbers- Size and Finish
Chuck, my 72 has the TR stamp. on the rear and front bumper brackets and the outter rear bumper and the lower radiator cross brace.New England chapter member, 63 Convert. 327/340- Chapter/Regional/national Top Flight, 72 coupe- chapter and regional Top Flight.Comment
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Re: Bolt Part Numbers- Size and Finish
Mine are mixed "M", "A", "RBW" for 9419075 and 9419077. These are all known original headmarks 68-72, and to my knowledge, were not being reproduced prior to my ownership of the car. The 3/8" bolt on the ends of the front bumper is less common...it has a lower case script "f" with three radial lines.
Zinc plated TR fasteners have been reproduced for some time and have been shamelessly sold as bonified replacements for everything with the right thread size. I'm not saying that yours are reproductions...What I AM saying is, if I were restoring a 72 (or a 70 for that matter) and zinc TR fasteners kept popping up, I would have to vet every one of them as original by confirming that the car was not previously restored or the recipient of owner inspired "improvements" by looking at a lot of other 72s. The "fly in the ointment", in my opinion, is trying to explain how the same part number could have two different finishes depending on where it was used, as Sheldon points out.
There are almost no TR headmarks on my 70; a couple applications maybe. I always thought TR headmarks were more prevalent on midyears. Perhaps 72s really are that different from 70s. That's only one reason why judges should not try to judge headmarks beyond determining if they are period correct...now finish, that's a different matter.
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Re: Bolt Part Numbers- Size and Finish
Chuck, I think your right on the head markings, The ZR1 is a 72 and has the TR markings, 70 and 71 may have had a few different markings. and the plating on my bolts were blk phos. and the plating on the ZR1 look to be zinc. awhile back I was talking to Sal Carbone about the plating on the bolts he seemed to think the zinc was correct. but like most cars I looked at they seemed to be blk. phos.or rusted so bad hard to tell.
Your experience out weights me by a long shot. not trying to disagree, Ive but have been restoring my car and have been looking at a few bow tie cars to see what correct.I think that everyone has a opinion.New England chapter member, 63 Convert. 327/340- Chapter/Regional/national Top Flight, 72 coupe- chapter and regional Top Flight.Comment
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Re: Bolt Part Numbers- Size and Finish
When the discussion gets to this level of detail, I only claim to have experience with one 70 Corvette built G30.
It seems strange that this has not come to my attention during all these years, but there may be a small universe of undiscovered details that apply to 70-72 cars. The only way those of us with experience with one year are going to learn those differences is by temporarily disagreeing until we personally do more study. Using Bow Tie cars as a means of education is a method beyond reproach; in all other cases, we should be slow to jump to conclusions.
It will be interesting to learn the answer to this question.Comment
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Re: Bolt Part Numbers- Size and Finish
OK here is my take:
941075 is the 4 bolts that hold the center bumper brace to the front bolt in cross member. These bolts are fully visable with the hood open.
941077 is the same as 941075 BUT is used in all the non visable locations
So is it possible that bolt 941075 would be called out for cad plating as that would take a few years before it would rust while bolt 941077 would use the cheaper black plating because it would not matter when it started to rust. I know for a fact that both these bolts are completly threaded and grade 5. I have seen original cars with cad plated 941075 bolts and black 941077's. (Hope I wrote this clearly).
bolt 427559 is the outer brace bolt and ALL ORIGINAL BOLTS for this application are grade 8 with the majority of the heads being SBC's.
This is just what I have observerd over the years working on these. As a side note I have much more experiance with 68-69' and not quite as much with 70-72's although most these items carry through the entire 68-72 era.
RichComment
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