69 Center axle bumper - two styles?

[KevinW]

KevinW,

Interesting info on your 06? Camaro!  Is your trim tag stamped 05A and should I correct this in the list?

Dave

Dave, yes trim tag is stamped 05A. it's up to you how you want to place it in the list.  It's kinda the same as the stuck convertible Norwood 06A trim tag error, which based on VINs were produced for the whole month of June.

Lloyd, thanks for the bolt on snubber pic.  Now I check to see I have the correct bolts!

[Dave69x33]

KevinW, since your trim tag is 05A, I’ll note it that way.

AMK Products list screw 3958062. Here is a pic. It’s self tapping 5/16-18 which matches the thread called out in the GM catalog when replacing the bumper with bolt-in style #3962763.

[Dave69x33]

List updated with correction to KevinW's "06?" SS VN Camaro to "05A."

10B ('68), std. 327, NW, push in, from KevinW
10D ('68), std. 327, NW, push in, from Dave69x33, original owner, unrestored.
12B ('68), RS Z28, VN, push in, HOT302
01B, X11, NW, push in, Iowa Jon
01B, SS/RS 350, VN, push in, from x66 714
02B, X33, RS 28, push in, from Edgemontvllage, original unrestored
02D, X33, NW, push in, from RikerZ28
02D, X66 L78 SS396 (survivor), NW, bolt in, from Edgemontvillage, Doug Perry's car
04C, model?, plant? push in, from L78 steve
04C, L48 Pace Car, VN, push in, from 169INDY
04C, Z10, NW, push in, from Dusk Blue Z
05A, SS, VN, bolt in, from KevinW
05A, X33, NW, push in, Dave69x33
05A, X77, NW, push in, from Iowa Jon
05A, X77, NW, bolt in, from x77-69z28
05A, X77, NW, push in, from Dusk Blue Z
05E, X77, NW, bolt in from copo
06A, X44, NW bolt in, from copo
08E, X66, NW, bush in, from x66 714
09C, X77, NW, push in, from Badshifter
09C. X33, NW, push in, from john jay 69Z
09D, X44, NW, push in, from R68 GTO (COPO BE axle)

[Dave69x33]

Based on the suggestion from bcmiller that perhaps the bolt on center axle bumper was launched as the plant was prepare for the changeover to the 1970 Camaro, but then Edgemontvillage shared an early 02D Norwood build original Camaro with the round bolt-on style center bumper.

This prompted me to review my GM Master Parts catalog for the 1969 vs 1970 center bolt-on style axle bumper and try to find pictures of GM NOS or original GM bumpers. I found the following.

Here is the 1967 - 1970 GM Camaro Parts Catalog Group 5.395 which calls out center axle bumper #3923564 push-in for 1968 - 69, and #481834 bolt-in for 1970.

Heartbeat City Camaro and OER are a couple of supplier that cell reproduction push in #3923564 bumpers (see pictures for reference) but I can not find a reproduction of the 3962763 bolt-in bumper.

[Dave69x33]

Doing further internet search, I did find these references to a used 3963763 bolt-in style bumper from a 1974 Nova from the folks on StevesNovaSite.com. The contributor "Pullus" stated he could make out the part number on his original bumper and was looking for a replacement. The pictures resemble the bolt-in style shown earlier in this discussion. 

[Dave69x33]

When I searched for the 1970 Camaro #481834 bolt-in center bumper, I found this picture. The #481834 looks very close to the #3962763 called out for the 1969 bolt-in style bumper.

Notice the GM box states #481834 but #525419 was written on the box so I searched it next.

[Dave69x33]

The round bolt-in style bumper resembles the style Edgemontvillage shared in his photo of the original Norwood 02D build SS L78 Camaro.

Top Flight Automotive sells a reproduction #525419 round style bolt-in pumper for the 1976 -1981 Camaro. 

Note: In the picture I posted of the NOS #525419 round style bolt-in bumper, included a footnote stating the center pinion nose bumper GM #481834 was for for 1970-74 Corvette, and #525419 for 1975-81” Corvette. For those looking for the round style bolt-in for a Camaro, this may help you broaden your search!  I am not sure if the center-to-center distance between the mounting holes, and overall height of the bumper is the same for a Camaro application.

At this point, based on the small data sample of '1969 Camaros, the push-in center bumper was the most common, but evidence shows a few received the bolt-in style, round and rectangular.  We need more data from restored survivor '69s and/or pictures of the center axle bumpers before restoration.

Thanks again for everyone's input!   

[Edgemontvillage]

Dave, none of the photos of bolt-ins posted accurately resemble the pinion snubber / bumper on Doug's 1969 L78 SS, the closest I've seen is a 1968 Dodge Charger 8 3/4 Rear End (adjustable) snubber. The base is very different but the rubber bumper is almost identical.

[bcmiller]

I kind of have my doubts on the bolt in style. Those could have been replaced if the original was damaged.

[Dave69x33]

Lloyd,  I agree and noticed the differences in the chamfered ends on the mounting plate and more rounded nose on the rubber bumper in Doug’s car. Hopefully over time more folks with ‘69 survivors will post photos of their bolt-in center axle bumpers.

I assume the differences in axle bumper design is what we sometimes in a component installed at the factory vs. the service replacement GM part; they don’t alway look identical. A change to the plate or rubber that does not affect the form, fit, or function of the component in the final assembly may have not required an engineering part number change which includes all the clerical work in the GM system, and validation of a new GM supplier/component. It’s also odd GM would make a change to this piece that adds complexity and more assembly work content. You would expect the design to change from bolt-in to push-in. I worked for a GM division for 15 years, Chrysler for 10, and now 14 years back at Allison Transmission, a former GM division. In both the GM and Chrysler plants, lower assembly content and complexity was always the goal. Keep in mind that this change also required additional tote dunnage for the bolts and installation tools along the assembly line. This might be the reason we see the push-in design more commonly used during the ‘69 model run as it was a less complex install. However, the ‘69 Camaro mounting structure was designed for either a push-on or bolt-on style bumper. Over time, the (2) outer frame mounted axle bumpers also got more complex changing from push-in to bolt-in bumpers. So there must have been issues with the push-in bumper design that eventually drove the change to bolt-in bumpers. I did not show it but the 1974 Nova application that used a very similar bolt-in center bumper as the ‘69 Camaro, showed the floor pan and the structure did not include a slot for a push-in.

What is interesting is Doug’s ‘69 SS is the first early car observed so far with the round style bolt-in bumper while most ‘69s in the study use the push-in style.  Could this have been be a slow ramp up production supply of the bolt-in bumper?  Did Norwood/Van Nuys make this a “running change” to pilot test the install of the bolt-in bumper?  This is the reason I am pushing for more input and pictures from survivor ‘69 Camaros.

Kinda crazy so much attention is given to such a small detail…but that a what we do!  Details…details…details…lol!

[KevinW]

Here is what I used to "replace" the rubber of the snubber. stamped part number is 3958061

[Dave69x33]

List updated with a couple more entries of friends' '69 Camaros that live in my area:

10B ('68), std. 327, NW, push in, from KevinW
10D ('68), std. 327, NW, push in, from Dave69x33, original owner, unrestored.
12B ('68), RS Z28, VN, push in, HOT302
01B, X11 SS350, NW, push in, Iowa Jon
01B, SS/RS 350, VN, push in, from x66 714
02B, X33, RS Z28, push in, from Edgemontvllage, original unrestored
02D, X33 Z28, NW, push in, from RikerZ28
02D, X66 L78 SS396 (survivor), NW, bolt in, from Edgemontvillage, Doug Perry's car
03E, X33 non-RS Z28, NW, Legends Certified 2023, push in,from Dave69X33 (friend's car)
04C, model?, plant? push in, from L78 steve
04C, Z11 L48 Pace Car, VN, push in, from 169INDY
04C, Z10, NW, push in, from Dusk Blue Z
05A, SS, VN, bolt in, from KevinW
05A, X33 RS Z28, NW, push in, Dave69x33
05A, X77 Z28, NW, push in, from Iowa Jon
05A, X77 Z28, NW, bolt in, from x77-69z28
05A, X77 Z28, NW, push in, from Dusk Blue Z
05C, Z11 Pace Car, NW, push in, from Dave69x33 (friend's car)
05E, X77 Z28, NW, bolt in from copo
06A, X44, NW bolt in, from copo
08E, X66 SS396, NW, bush in, from x66 714
09C, X77 Z28, NW, push in, from Badshifter
09C. X33 Z28, NW, push in, from john jay 69Z
09D, X44 427 COPO, NW, push in, from R68 GTO (COPO BE axle)
09D, X77 Z28, NW, push in. from Dave69x33 (friend's car)

[R68GTO]

Maybe they had a special tool to install the push in style - based on my experience, the giant PITA of getting the push-in style installed would be enough reason to change to bolt-in style.  Bolt in add complexity, but if it reduces time, it might have driven a change.

[Dave69x33]

R68GTO, good point. I guess we’ll never know why the change was made.

It’s times like this when I miss input from JohnZ and his experienced working I the Norwood plant!

[68camaroz28]

We looked at Skip's 09D (late) NOR survivor today and it's a bolt in.