1972 #4 Body Mount Reinforcement Replacement

[Roger D.]

Folks:

I've already looked thru the archived posts so please bear with me for yet another question on this subject.

With the total restoration on the '72 coupe coming closer towards completion, I have come to the realization that the #4 body mount reinforcements need to be replaced. I had cleaned them up and thought I had all the rust removed and repainted them but, alas, over time it has become apparent that the new rust I am already seeing is coming from the inside of the reinforcement. So before the newly restored and painted body goes back onto the chassis, I need to replace these.

With the body already off, it would seem that replacing these should be rather straightforward, however, I have a couple of questions to see how some who have already done this approached it.

1) The two inboard rivets appear from AIM (Section 1 B4, page M42) to be inserted from inside the car and downward, however, I cannot see any indication of these rivets from inside the rear compartment. Is there another layer of fiberglass over the tops of those two rivets?

2) The rear vertical section of the reinforcement extends up and between the fiberglass well that the reinforcement surrounds and the fiberglass splashguard behind the rear wheel. There is one single rivet going through this vertical section and is inserted from the inside of the well (where the captured nut resides) and through towards the splashguard. It seems obvious that the rivet was bucked from the outside and before the splashguard was installed? If this rivet is to be replaced, how can it be done without drilling a hole in the splashguard to get access to the rivet?

If anyone has any sage advice to lend success to this endeavor, please reply. Any pictures you might would also be helpful.


Regards,
Roger Dupler

[David H.]

Re: 1972 #4 Body Mount Reinforcement Replacement

Roger,

Visual of inboard rivets requires removal of carpet to gain access to well containing body mount captive nut. Some models have more limited access than others.

As you noted, access to rear reinforcement rivet requires cutting (hole saw). Reinforcement was installed PRIOR to bonding that rear panel - see attached photo. I know some folks that don't install rivet given trailer queen status. I didn't find it a big deal - just save the cut out from hole saw for rebonding later.

In any case, reinforcement sheet metal will require some "massaging" to obtain a good fit.


Dave

[Pete B.]

Re: 1972 #4 Body Mount Reinforcement Replacement

IIRC... I was going to try doing the re-rivit thing... I soon realized that this would be near impossible.

I used round headed stainless allen screws, ground down the heads to match the rivet configuration and just installed them with the nuts on the inside.
I filled the allen head with epoxy and when it came time to lay down the light undercoat that area got a touch more.
I would defy anyone to tell the difference.

[David H.]

Re: 1972 #4 Body Mount Reinforcement Replacement

IIRC... I was going to try doing the re-rivit thing... I soon realized that this would be near impossible.

I used round headed stainless allen screws, ground down the heads to match the rivet configuration and just installed them with the nuts on the inside.
I filled the allen head with epoxy and when it came time to lay down the light undercoat that area got a touch more.
I would defy anyone to tell the difference.

Pete,

Aha!, Now we know!

Roger,

I also used SS bolts, but didn't go to Pete's length for appearance. Thought about doing aluminum rivets per original and decided it would just become another test of the marriage! From the photo - plant workers had MUCH better access.

Dave

[Roger D.]

Re: 1972 #4 Body Mount Reinforcement Replacement

Dave....

Wow! Amazing picture. I never imagined to see that. I really appreciate the information. The task is scheduled for the weekend. I really didn't want to disturb that rear panel if I could help it. We will see how it goes.

Regards,
Roger

[Roger D.]

Re: 1972 #4 Body Mount Reinforcement Replacement

IIRC... I was going to try doing the re-rivit thing... I soon realized that this would be near impossible.

I used round headed stainless allen screws, ground down the heads to match the rivet configuration and just installed them with the nuts on the inside.
I filled the allen head with epoxy and when it came time to lay down the light undercoat that area got a touch more.
I would defy anyone to tell the difference.

Pete:

Interesting idea. There was no undercoating on my reinforcements so the rivets are all visble (except the hidden one). Although I haven't tried it yet, seems like it should be possible to re-rivet. I will soon know if that is possible.

Anyone else reading this who have been able to re-rivet the reinforcements back in ?

Regards,
Roger

[David H.]

Re: 1972 #4 Body Mount Reinforcement Replacement

Pete:

Interesting idea. There was no undercoating on my reinforcements so the rivets are all visble (except the hidden one). Although I haven't tried it yet, seems like it should be possible to re-rivet. I will soon know if that is possible.

Anyone else reading this who have been able to re-rivet the reinforcements back in ?

Regards,
Roger

Roger,

These were not pop-rivets. Factory used a rivet set and bucking bar. Factory also had easy access to the mounts (picture) when installing reinforcements - hence SS screws (bolts) for me.

Dave

[Michael B.]

Re: 1972 #4 Body Mount Reinforcement Replacement

Roger,

I just completed the same repair on my 72 coupe last month. With the body removed from the frame access to the body mounts wasn't a problem. What did present a problem was figuring out how to set the two rivets facing into the wheel wells. There just wasn't enough room to maneuver a rivet gun or air hammer into position to properly set those two rivets.

I had recently stripped the paint from my car and had been repairing some damaged areas in the fiberglass so I figured "What's one more repair". I drilled a 5/8 inch hole in each rear quarter panel in order to use an air hammer fitted with an extra long rivet set. Once I had access to the rivets thru the quarter panel (and my limber wife was in position with the bucking bar), setting those rivets took about 3 seconds each. Repairing the holes in the quarters took several hours. Had I been concerned with preserving paint on my quarters I would have used bolts instead of rivets.

I also used that 5/8 bit to drill an access hole for the rear facing rivet. Once that rivet was set I repaired the hole with fiberglass, used some black paint to cover the repair, and it's not detectable.

Hope this helps.

Mike

[Roger D.]

Re: 1972 #4 Body Mount Reinforcement Replacement

Roger,

I just completed the same repair on my 72 coupe last month. With the body removed from the frame access to the body mounts wasn't a problem. What did present a problem was figuring out how to set the two rivets facing into the wheel wells. There just wasn't enough room to maneuver a rivet gun or air hammer into position to properly set those two rivets.

I had recently stripped the paint from my car and had been repairing some damaged areas in the fiberglass so I figured "What's one more repair". I drilled a 5/8 inch hole in each rear quarter panel in order to use an air hammer fitted with an extra long rivet set. Once I had access to the rivets thru the quarter panel (and my limber wife was in position with the bucking bar), setting those rivets took about 3 seconds each. Repairing the holes in the quarters took several hours. Had I been concerned with preserving paint on my quarters I would have used bolts instead of rivets.

I also used that 5/8 bit to drill an access hole for the rear facing rivet. Once that rivet was set I repaired the hole with fiberglass, used some black paint to cover the repair, and it's not detectable.

Hope this helps.

Mike

Thanks Mike. Interesting approach. Thanks for posting

Regards,
Roger