Author Topic: What is the proper procedure for trunk pan & qtr. replacement? (Read 11555 times)

6PKRTSE · « **on:** September 09, 2004 - 12:05:36 PM »

I have my 70' Challenger totally stripped on the rotisserie ready to be restored. It has actually been on their a couple of years now. I am now just getting back to it. I have removed all of what was left of the original trunk pan. I have purchased every repro sheet metal part available for the Challenger from Sherman. All of the sheet metal seems to be a pretty good fit with just a test fit. What is the best procedure to replace the trunk? Drill holes & try to duplicate the factory spot welds? I wanted to used as much of the original qtr. as poss. I was going to leave the factory door seam,side marker light holes & gas filler door hole & cur around them. Any suggestions or tips will be appreceiated. This is my first attempt to do something this involved, but I want the satisfaction to say I did all of the work myself.

camjam · « **Reply #1 on:** September 09, 2004 - 08:20:45 PM »

I have replaced the trunk pans in my charger and quarters on both the challenger and charger.

For the trunk pans I drilled out the spot welds on the old pans. After the pans could be removed I then placed the pans on the replacement pans and marked all the holes from the spot welds on the new pans and drilled them out. We were able to spot weld the pans into the same spots because there were fresh marks on the frame from the drilling. The pans went into the same spot with everything else tying in correctly.

The quarters are a different matter. Any reproduced quarter panels for the challenger do not match at the main body line. If you check you will find that the new ones are more rounded. What we had to do was replace the sheet metal below the body line so that we kept the correct line. If you have to replace any metal above the body line simply replace the bad areas but do not remove the body line. We also drilled out the spot welds on the areas being replaced on the quarters and again marked them out on the new metal so that an exact fit could be acheived.

Good luck.

6PKRTSE · « **Reply #2 on:** September 10, 2004 - 12:38:07 PM »

Is it best to drill thru the old trunk pan & thru the frame rail & just lay the new panel over it?Or is it easier to mark the new panel following the frame rails & then drill the trunk pans put & then weld to the frame rails?

HemiDog · « **Reply #3 on:** September 10, 2004 - 01:29:31 PM »

I don't know what the "proper" way is, but I decided to drill the spot welds on my old trunk pans and was careful not to go though the frame rail. Once the pan was out, I put my new ones in and marked where the frame rail was from below. Based on those marks I drilled holes in my new pans and reproduced the spot welds using the holes in the new pan. I chose that way because the frame rail is heavier gauge and made it easier for me to do the welding, plus help to not dull my bits so quickly. I was very happy with my results and there was minimal grinding I had to do to smooth the welds.

6PKRTSE · « **Reply #4 on:** September 10, 2004 - 02:06:33 PM »

Thanks, This is the way I was thinking of doing it also. I will get started this weekend.

miketyler · « **Reply #5 on:** September 23, 2004 - 09:11:28 PM »

Am interested in this topic, please let me know how this goes as I am in the same boat on my 72 Cuda. As I understand it, the preferred method is a butt joint, rather than a lap joint that might trap moisture. Of course you may not be able to do this everywhere and you may not have good metal around the edging either. Has anyone got pics of a Cuda being done or a finshed floor after installation?

HemiDog · « **Reply #6 on:** September 24, 2004 - 09:18:58 AM »

The cool thing about replacing the trunk, it that with the new floor pans being in two pieces, the only seam you have to worry about whether you butt weld or lap weld is where the pieces meet. That is if you drill all the spot welds out of the old one and are not doing patch work.

I did find that the seam in the middle was somewhat of a pain to get lined up correctly.

I just did mine recently, and will take a couple pictures this weekend, if I get the chance (busy weekend for me) otherwise I will get them next week.

Steve · « **Reply #7 on:** September 25, 2004 - 10:33:56 AM »

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miketyler · « **Reply #8 on:** September 25, 2004 - 10:10:40 PM »

great pics, it answers a lot of questions I had since my trunk has already been butched up and is far from original. I also have a pretty significant leak that a new seal has not fixed.

Any idea what a good shop might charge to do a trunk pan liek this on average?

Steve · « **Reply #9 on:** September 26, 2004 - 07:28:43 AM »

Leak? From where? Uh-oh. Check the seams along the length of your trunk gutters. This is where the quarter panel comes overtop and around the base of the trunk gutter. If any of that looks "swollen" , you've got rot and gaps that are likely letting water in. Is the car in question the one in your avatar?

Hmmmm...IF you "just" need the pans replaced, figure on what, 20 hours of labor to drop the tank, remove exhaust, replace the four panel sections (or just the 2 middle sections?), and put everything back together. IF you have the kind of rot that I had between the tail panel and the trunk floor area, the time required just jumped up exponentially (assuming you want to replace all of the bad metal). This is because of the amount of dissasembly required to get access to the pan at the tail panel area, not to mention the fabrication from scratch of the extension pieces.

Post some pics so we can see what's going on. IF the seam sealer is the orginal stuff on the original metal, it's probably cracked and letting water seep through. IF someone has "redone" the trunk gutters with fiberglass, the glass may be coming apart from the metal base and letting water in underneath. You should also check the rear section of the car to make sure that it is square. You might not be getting a good seal between the decklid and the trunk seal. To find out, you could put white shoe polish or a thin coat of white lithium grease on the trunk seal gasket and then close the decklid and see if you have gaps in where the polish/grease sticks to the decklid. My concern is that someone cut out significant portions of the trunk pan, the body twisted a little bit, and they welded in new sections without squaring the body first. Keeping things square on these unibody cars is a bear.

miketyler · « **Reply #10 on:** September 26, 2004 - 09:39:44 PM »

Hi Steve - yep, thats the one. It looks pretty good from the pic huh? Thats what I thought too until I became the owner and took delivery. Oh well, live and learn.

The pan was replaced with a home made panel. It prob didn't look too bad when it was first installed but since then it has rusted. I started removing it today. It was spliced in the middle and I now have the LH side out. I have discovered rust damage on the LH rear spring mount, and the aft most cross member. Looks like the guy before me opted not to do anything with it. Also about one ft of the inside upper flange on the LH frame rail was removed and not replaced. Wuttup with that?

Guess the guy was on a budget. the LH side of his panel was mostly screwed and riveted in and had no fasteners at all in the frame rail. I shouldnt complain, it made it easy to remove

Will try and get some pics of this and my recent booster attach point damage as well.

The fuel tank has a minor leak when it is filled up. I figured I would remove it and look it over to see if it can be fixed. Once I have it out, should be easy to wet the back end down, lay under it and watch where the leak shows up. It has had some bondo or FG in the forward radius' of the trunk lid jamb (badly finished at that) but all of it looks intact. Car has a new trunk seal installed as well. Good idea on the lithium�grease thing

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Steve · « **Reply #11 on:** September 27, 2004 - 11:54:24 AM »

Bummer.....

I guess if I were in your shoes, I would assess what I wanted to do with the car and how much time and money I am willing to sink in. I've done several restorations with different degrees of thoroughness. I've decided that the best route is the complete route. BUT, complete translates into $$$$, even when you're doing it yourself. If you just want a 10' driver (looks good from 10 feet away) for play, do as little as possible. If it isn't showing, don't fix it. Once you start digging in to this and that and the other, you'll just keep finding problems that you didn't know were there. For example, you probably have a substantial amount of rot in the tail panel and related pieces. A quick count in my head shows 4 sheet metal trunk pieces and brackets per side, a sheetmetall piece that attaches tail panel to the frame rails, and the licence plate recess area. All of that stuff will have some rot....it's just a matter of how much. You probably should repair those rails, though, as you'd hate to have a rear end break loose! Before goofing too much with the tank and trying to fix a leak, you might consider just replacing it, especially if you see lots of crud or surface rot on the inside! They run around $200.

See the pics of my trunk lid jamb. At least mine was obvious from the get go!

My approach is to fix all of the rot and fix it to last. I did do a car where the rot wasn't repaired properly and problems cropped up about a year after it was painted.

Just my 2 cents, which is worth less than that.

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Street_Challenged73 · « **Reply #12 on:** September 27, 2004 - 10:04:24 PM »

Steve, that's looking really good. It's amazing what can be done with some extra sheetmetal and a welder. Congrats on such a nice job thus far.

miketyler · « **Reply #13 on:** September 28, 2004 - 09:41:45 PM »

yes, nice work. Here are pics of my back end rails and the trunk area. The frame rails have been capped and most of the upper attach flanges were retained. You can see where they simply trimmed them away and didn't bother to splice in new angle. The inside corrosion is well hidden by the welded cap assemblies.

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miketyler · « **Reply #14 on:** September 28, 2004 - 09:47:47 PM »

here you can see the caps from the lower side; the caps overlay or straddle the hat-section frames and although they look good, they hide the corrosion within. I suppose I could bead blast and treat these before closing them out with the new trunk pan but am not sure it would be worth the trouble

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Author Topic: What is the proper procedure for trunk pan & qtr. replacement? (Read 11555 times)

6PKRTSE

What is the proper procedure for trunk pan & qtr. replacement?

camjam

Re: What is the proper procedure for trunk pan & qtr. replacement?

6PKRTSE

Re: What is the proper procedure for trunk pan & qtr. replacement?

HemiDog

Re: What is the proper procedure for trunk pan & qtr. replacement?

6PKRTSE

Re: What is the proper procedure for trunk pan & qtr. replacement?

miketyler

Re: What is the proper procedure for trunk pan & qtr. replacement?

HemiDog

Re: What is the proper procedure for trunk pan & qtr. replacement?

Steve

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miketyler

Re: What is the proper procedure for trunk pan & qtr. replacement?

Steve

Re: What is the proper procedure for trunk pan & qtr. replacement?

miketyler

Re: What is the proper procedure for trunk pan & qtr. replacement?

Steve

Re: What is the proper procedure for trunk pan & qtr. replacement?

Street_Challenged73

Re: What is the proper procedure for trunk pan & qtr. replacement?

miketyler

Re: What is the proper procedure for trunk pan & qtr. replacement?

miketyler

Re: What is the proper procedure for trunk pan & qtr. replacement?