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Posted by: rfinegan Aug 21 2020, 08:18 AM

I stated the backdating of my rear BUB and thought I would share the Solution for the bumper shock holes. The are spacers and flyers from Lowes H/W electrical hole fillers and reducers held in place with seam sealer...and while the seam sealer is out I did the cover hold down deletes and sprayed some color
Enjoy

More pic s the project continues

Posted by: rfinegan Aug 21 2020, 08:19 AM

another pic

Posted by: jim_hoyland Aug 21 2020, 12:12 PM

Nice ! Can you show the individual pieces before installation; I’m going to be doing h th his soon

Posted by: rfinegan Aug 22 2020, 07:54 AM

Here is the knock out seals I used..

1 1/4 knock out seal
2' 1 1/4 reducing washer

Theres is a Large knock out seal that may fit the hole directly but the bottom hole may not be covered and will need be filled. Seam sealer will work too but I did not go that way as I would have to go back to the store again (up to you)





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Posted by: rfinegan Aug 22 2020, 07:55 AM

here is a pic of a large Knock out seal



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Posted by: jim_hoyland Aug 22 2020, 10:17 AM

Does the heat shield or muffler have to be removed to install the lower bolts; IIRC, they are below the trunk floor...

Did you drill out the rubber bumper holders at each end ? or Cut ?

Posted by: rfinegan Aug 22 2020, 10:47 AM

Here is an alignment tip: Use the seem and the roll ed edge off the bumper top seen here:

Posted by: rfinegan Aug 22 2020, 10:48 AM

and the other side:



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Posted by: rfinegan Aug 22 2020, 10:55 AM

Need to move about an 1/8 inch to the right

Posted by: rfinegan Aug 22 2020, 11:01 AM

I did pull the lenses and tail lights our to ensure the cover and bumper did not hit them or get paint on them when i removed the cover hold downs.

The muffler and shield are not in the way. But an extension was needed pull the shocks.

I used a spot weld cutter (Harbor Freight ) Fist time user. And they work very well with little cutting on the fender.

I used a cut off wheel and die grinder to sooth out and covered with seam sealer..then paint

MY cover had "nail "Rivets on the corners and under the lenses that I tapped our from under the car with a punch. I could have just pulled the cover off these but want to same the cover and the rivets had to come out anyhow
Seen here:


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Posted by: rfinegan Aug 22 2020, 11:16 AM

hold down removal:




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Posted by: rfinegan Aug 22 2020, 02:54 PM

need the tops now...




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Posted by: Cairo94507 Aug 22 2020, 04:49 PM

Probably the single biggest difference you can make to the appearance of the late cars to increase their beauty. Once you get a bumper top you will love it even more.

Posted by: RiqueMar Aug 24 2020, 11:27 AM

So. Much. Better.

Posted by: maf914 Aug 24 2020, 02:08 PM

rfinegan,

Nice work and thanks for the writeup. Could you comment on locating the four bumper mounting bolt holes? Any tips would be appreciated. Do you intend to use nuts, bolts and washers for mounting? Or some sort of riv-nuts and bolts? Thanks.

Posted by: jim_hoyland Aug 24 2020, 04:52 PM

I'd like to know too, since I'll doing this

Posted by: rfinegan Aug 25 2020, 04:32 AM

Factory is bolts and lock washers. I decided to use studs by cutting the heads of the bolts and chamfering the ends and nylon lock nuts. This lets you install the bumper with one person and not have to align the bumper and try to get the bolts stated in the holes at the same time. 8mmX1.25x50 May be just a tad long but worked fine

Also have the Dog bones handy when you do this . They have the correct spacing/ the same as the bumper and can help ensure the holes are going in the right location

FWIW: I was Following the post here on Sticky on where to drill the holes, BE CAREFUL.. Mine were off and needed to be opened up/drilled again...in the right location. My bumper is not new and may have a few tweeks. Use you bumper to find your holes and double check before drilling


1) Tape the area where the hole will be drilled with blue painters tape
2) Cut the heads off the 8mm 1.25x50 bolts and screw the new studs into the top holes of the bumper.
3) I left the bottom valance on to help center the bumper. This will ensure the correct vertical spacing as the fit has just a little play/spacing
4) Center the bumper in the desired area and give it a tap with your open hand to mark the tape in the location for the top holes
5) Go back and measure the hole to the sticky in the forum (this is the relaity check)
6) Drill the holes with a 1/2 step drill. They are cheep and do a great EZ job on this
7) Insure bumper is desired location top to bottom and left to right. Open holes as needed to fine tune
8) Add lower studs and dog bones(optional but helps minimize scratches)
9) Install bumper studs/dog bones in top holes in new fine tuned location
10) Tap bumper for new location for lower holes on blue tap
11) Drill bottom holes with 1/2 step drill
12) Install and fine tune as needed

-Robert


On a scale of 1-10 for difficulty
1=new gas cap/seal
10=Transition overhaul
This job is a 2-3. There is some drilling, cutting and grinding but can be done in a few hours (less paint)

I can measure my holes once I get the Gel cote tops. But for now they are installed

Posted by: jim_hoyland Aug 25 2020, 06:12 AM

That's great info Robert; I see from your pic the bumper top is off; does the top need to be attached for fitment ? Or do you rely on the valene fo fitting

Posted by: rfinegan Aug 25 2020, 07:05 AM

Not sure, this is my first too... I post back soon when i get my Gel coat tops

I am sure some one can make a full size template from the back of a Factory car with little effort using the seam and ledge as a reference.

That would be a big help to everyone backdating

Posted by: maf914 Aug 25 2020, 08:56 AM

Robert,

Thanks for all of the great info. I am gathering parts at this time.

Here is a detailed thread from the Classic Thread Forum: http://www.914world.com/bbs2/index.php?showtopic=225743&st=0

Posted by: rfinegan Aug 25 2020, 09:55 AM

Mike, I wold follow the classic and mine..if the holes are in the same place START DRILLING

Posted by: rfinegan Jun 25 2021, 02:33 PM

Just installed a 914 rubber bumper top for my back date project. Fit was very good and with out hassle. All that is left is the license plate lights.. Then a good coat of paint one day down the line...

Posted by: rfinegan Jun 25 2021, 02:34 PM

another

Posted by: rfinegan Jun 25 2021, 02:35 PM

one more

Posted by: rjames Jun 25 2021, 02:53 PM

Looks great! What about the front?

Posted by: rfinegan Jun 25 2021, 03:11 PM

NOPE, I'm doing that 73 corvette thing...

Rubber front steel rear!

I like the BUB front with fogs..ITs a mid 70's thing
Hated the rear. Its like they did not even try to get the style right

Posted by: Shivers Jun 25 2021, 03:30 PM

Pretty good man, KO plugs and Chinese money. It even looks good.

Posted by: jim_hoyland Jun 25 2021, 06:10 PM

I ended up doing the 73 corvette thing too. First gave it thought when Mueller brought it up several years ago.


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Posted by: PaulFV8 Jun 25 2021, 08:31 PM

Which early years came with black bumpers?

Posted by: Shivers Jun 26 2021, 08:22 AM

Painted Bumpers? Up to 74 non-appearance group. Black rubber 75-76