Priya's 79 chrome bumper conversion project
Melting Slicks
Joined: Jan 2012
Posts: 3,039
Likes: 504
From: myrtle beach sc
Army
Glad that you know about the difference, Priya. There are two larger holes in the bottom, to access the smaller upper holes, to put the radiator support holding bolts through.
I bought a new front crossmember from GM years ago and when I really looked at it later, I noticed that there was a 4 1/2" split in it from the GM part supplier! I brazed it shut and sprayed it inside. Really good quality control at that company!
That was the problem, if people are on piece work and stamping out parts, they didn't care if the part was crap. All they cared about was the number on their counter. Remember, I worked in an automotive parts plant for 34 years. Lou.
I bought a new front crossmember from GM years ago and when I really looked at it later, I noticed that there was a 4 1/2" split in it from the GM part supplier! I brazed it shut and sprayed it inside. Really good quality control at that company!
That was the problem, if people are on piece work and stamping out parts, they didn't care if the part was crap. All they cared about was the number on their counter. Remember, I worked in an automotive parts plant for 34 years. Lou.
Last edited by loup68; Mar 18, 2017 at 07:12 PM.
Team Owner
Joined: Sep 2006
Posts: 31,283
Likes: 4,374
From: Westminster Maryland
Hi P,
" as the lower quarter on the 79 is so much narrower than the 70-73 rear clip lower quarter I'll have to fabricate the entire lower quarter panel from the flare on the 79 back".
Would releasing the fender (quarter panel) from the inner fender/apron allow you to pull the bottom of the fender 'out' (to the side) just a bit to help make up some of the 'width' difference.
???
Regards,
Alan
" as the lower quarter on the 79 is so much narrower than the 70-73 rear clip lower quarter I'll have to fabricate the entire lower quarter panel from the flare on the 79 back".
Would releasing the fender (quarter panel) from the inner fender/apron allow you to pull the bottom of the fender 'out' (to the side) just a bit to help make up some of the 'width' difference.
???
Regards,
Alan
Thread Starter
Le Mans Master
Joined: Dec 2009
Posts: 6,397
Likes: 649
From: Saskatoon Saskatchewan
Glad that you know about the difference, Priya. There are two larger holes in the bottom, to access the smaller upper holes, to put the radiator support holding bolts through.
I bought a new front crossmember from GM years ago and when I really looked at it later, I noticed that there was a 4 1/2" split in it from the GM part supplier! I brazed it shut and sprayed it inside. Really good quality control at that company!
That was the problem, if people are on piece work and stamping out parts, they didn't care if the part was crap. All they cared about was the number on their counter. Remember, I worked in an automotive parts plant for 34 years. Lou.
I bought a new front crossmember from GM years ago and when I really looked at it later, I noticed that there was a 4 1/2" split in it from the GM part supplier! I brazed it shut and sprayed it inside. Really good quality control at that company!
That was the problem, if people are on piece work and stamping out parts, they didn't care if the part was crap. All they cared about was the number on their counter. Remember, I worked in an automotive parts plant for 34 years. Lou.
Thread Starter
Le Mans Master
Joined: Dec 2009
Posts: 6,397
Likes: 649
From: Saskatoon Saskatchewan
Hi P,
" as the lower quarter on the 79 is so much narrower than the 70-73 rear clip lower quarter I'll have to fabricate the entire lower quarter panel from the flare on the 79 back".
Would releasing the fender (quarter panel) from the inner fender/apron allow you to pull the bottom of the fender 'out' (to the side) just a bit to help make up some of the 'width' difference.
???
Regards,
Alan
" as the lower quarter on the 79 is so much narrower than the 70-73 rear clip lower quarter I'll have to fabricate the entire lower quarter panel from the flare on the 79 back".
Would releasing the fender (quarter panel) from the inner fender/apron allow you to pull the bottom of the fender 'out' (to the side) just a bit to help make up some of the 'width' difference.
???
Regards,
Alan
Pro
Joined: Nov 2007
Posts: 721
Likes: 105
From: hernando fl
The pictures of your "fit" look very familiar to me , the whole thing looks like a fools errand at this point in the process , but its not....... everything can be dealt with and overcome. first on the list is to forget matching dimensions across the top....these cars are all over the map , i have found as much as 3/8 difference between the tail sections of the 79s i have measured....i assume quality control was no better ( or worse) in the chrome years , so getting a match is a crap shoot at best. i think you will find that moving the ducktail forward ( closer to the chrome dimension) will improve the fit along the top greatly . get the ducktail located where you want it to be forever and find a way to remove the tail and get it relocated on the car consistently in the same location....i c clamped a rig to the rear frame and used the tail light holes for positive , repeatable locating ( up and down , side to side ...and angle with another rig on the frame) that is pretty important step. i don't want to write a book on the forum but will be happy to give you any additional thoughts privately. if i can do it a trained chimp can do it....don't get discouraged
Thread Starter
Le Mans Master
Joined: Dec 2009
Posts: 6,397
Likes: 649
From: Saskatoon Saskatchewan
I'm not sure whether you're referring to the 68-73 rear bumpers or the crash bar that was behind the rubber bumper of the 79. I will have the 68-73 rear bumpers. The entire rear factory crash bar in the 79 is too big to fit in once the 70-73 tail light section is bonded on but it consists of a number of pieces bolted together and I hope to retain at least part of it if I can fit it in.
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Le Mans Master
Joined: May 2008
Posts: 9,063
Likes: 2,736
2022 C3 of the Year Finalist - Modified
I was just curious. I did not think you could possibly fit that large steel bumper behind that early style fiberglass unless you move it way aft. I really like what you are doing. I would not think about changing my 77 now, after its done, but if I would have seen this type of conversion back when I was in the middle of it, I would consider it.
Thread Starter
Le Mans Master
Joined: Dec 2009
Posts: 6,397
Likes: 649
From: Saskatoon Saskatchewan
I'm told by people who have done this that the rubber bumper crash bar won't fit but I'm hoping that one of the various sections will fit, even if I have to trim it down some.
Race Director
Joined: Apr 2009
Posts: 19,294
Likes: 2,754
From: Charlotte NC
BUT..I do know your car should have had the impact shock absorbers that attached to the end of your frame rails...then the imapct bar attached it them.. And with those removed....and custom attachments used. I am having a hard time 'saying' that the factory impact bar could not be re-installed.
If that did work....then the FUN part would be getting the bumper brackets to attach to the impact bar and be able to be shimmed much like the rear bumper brackets for a 1963-1967 were done by GM.
AS for separating the rear quarter from the inner rear splash shield. I personally would not. This is where laminating the two pieces together is going to need to be done. I would NOT be at all concerned about how wide the gap between both of these panels. As you know...it can be filled in.
DUB
Thread Starter
Le Mans Master
Joined: Dec 2009
Posts: 6,397
Likes: 649
From: Saskatoon Saskatchewan
Yes, there were impact shock absorbers attached to the end of the frame rails
to get in that area to join and shape the two lower quarter panels together. I haven't tried to fit the impact bar yet, but it would seem to me that there is no room for the impact shock absorbers or with the 6" of rear deck to ducktail no room for any part of the factory impact bar.
I'll see once I get the 70-73 ACI rear clip mocked up into place more sturdily.
The inner splash shields are already removed. In retrospect it would have been better to leave them in place as long as possible although I will need to get behind the quarter panel where they glue on to join the two quarter panels and shape the join.
to get in that area to join and shape the two lower quarter panels together. I haven't tried to fit the impact bar yet, but it would seem to me that there is no room for the impact shock absorbers or with the 6" of rear deck to ducktail no room for any part of the factory impact bar.
I'll see once I get the 70-73 ACI rear clip mocked up into place more sturdily.
The inner splash shields are already removed. In retrospect it would have been better to leave them in place as long as possible although I will need to get behind the quarter panel where they glue on to join the two quarter panels and shape the join.
Race Director
Joined: Mar 2003
Posts: 11,608
Likes: 780
From: Eustis ( Area 51 Bat Cave ) Fl
I realize the inner structure was something you wanted to retain but seems that time already passed,
At this point i see more light than train at the tunnels end, but in my humble opinion as a person who has never built inside a box or with restraints,
I would suggest forgetting the inner structer for now get the outside looking as you desire, hit up don he has done this knows what is going on and then after the outside looks right get some inner structures you like to fit...but what gm had in a 79 isnt gonna fit in a 68-73 rear.
At this point i see more light than train at the tunnels end, but in my humble opinion as a person who has never built inside a box or with restraints,
I would suggest forgetting the inner structer for now get the outside looking as you desire, hit up don he has done this knows what is going on and then after the outside looks right get some inner structures you like to fit...but what gm had in a 79 isnt gonna fit in a 68-73 rear.
Melting Slicks
Joined: Jul 2010
Posts: 3,176
Likes: 633
From: perth western australia
Probably sound like captain obvious but maybe one thing about it , before you start the actual joining (bonding) ,IF you want/can use the hydraulic shock units you may have to put them in first while there's still room .
Don't be discouraged , its looking good from here
Don't be discouraged , its looking good from here
Thread Starter
Le Mans Master
Joined: Dec 2009
Posts: 6,397
Likes: 649
From: Saskatoon Saskatchewan
as always , this is just an opinion. i think you are going to have to do quite a bit of filling and fairing in the upper corner areas to get them looking right , the reason i say that is , if you get the tail section to fit with minimal filler in the top corners ( line up the measurements of the tail with the measurements on the body ) the rear of the car is going to look stretched out or way too long in the back. after a lot of fooling around i just went with the rear of the door opening measurement to get the duck tail in the right location. once that is located and looking right , everything else will be where it winds up being. again , in my opinion , get it looking like you want it to look from the side , the duck tail at the proper angle, the tail of the car proportional and let the seams fall where they may. fill and fair as needed
Last edited by Priya; Mar 20, 2017 at 01:47 AM.
Pro
Joined: Apr 2007
Posts: 528
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From: Grand Rapids Michigan
I have no technical skill to add here, but I want to say Priya, you're an inspiration to us all who have dreams of taking a plunge like this. It may seem like more hard work than fun right now, but a lot of people are pulling for you and genuinely interested in your project! Keep up your energy, and I look forward to seeing your result!