Rear Sill Question and Quarter Panel Tips

[OKMike]

Howdy Guys:

I am replacing the rear quarter panels and rear sill on my 77. When I got the cruiser the rear of the tub and rear quarters were so rusted the sill was essentially gone. HOnestly I didn't even know the part existed until I started reseraching how to replace the quarter panels.

Bought the new sill from CCOT and replacement quarter panels from Real Steel. I see how the sill should line up. I know the “horns” on each end get spot welded to the insides of the new quarter panels and the top of the sill slides onto the tub. Two questions are: I see marks on top of the new sill (see pic) I assume these are for spot welds.? Do These get drilled out and the sill gets spot welded from the top? Also I see holes in the bottom of the sill that line up with factory holes in the bumper (second pic). I assume the sill attaches to the bumper there, question is how? When I removed the remnants of the old sill months ago I seem to recall there being bolts with some kind of rubber spacers between what used to be the sill and the bumper?

Second question is more of an "ask." I think I'm tracking on how to do the quarter panel replacement but if anyone has done it and has tips, advice, or lessons learned I would genuinely appreciate you chiming in. Thanks as always, Guys.

 

[Tancruiser]

 

[Tancruiser]

I just did mine on my 40 I butt welded versus lap welding.

 

[Vae Victus]

SILL SPOT WELDS:
You are right on - those are the locations for the spot welds. If you don't have a spot welder (who does?), then you can drill them out (larger hole on top - say 3/16", smaller hole on the bottom - say 1/16" - so that you get full penetration on both pieces of metal).

That is exactly how I did this earlier in the year.

SILL MOUNTING POINTS:
And yes, the holes that you are pointing to on the bottom of the sill are the places where the body mounts will go in between the bumper and the sill. If I can find my photos, I'll post.

QUARTER PANELS:
Regarding the quarter panels, if you are replacing the whole things like I did, make sure you brace the rear end of the truck across the bed so that the door frames in the back are square and level. I made a cross beam support from my front doors across the passenger area, and in the rear of the truck to make the top of the rear tub stay square with the bottom.

I butt welded as TanCruiser says. I did the entire thing though and had to carefully cut the whole panel out, then carefully fit the new panel so that I had gaps that were about 1/8" all the way down. I invested in and borrow more of the butt panel clamps that hold the panels together with a piece of steel in between creating a consistent gap. These really helped the butt welds stay level and clean.

You should also consider using Fitzee's method of panel welding that I discovered after I did my panels. Look him up on youtube - he's a very good car restore guy and shows a way to put a new panel over the old area and cut as you go so that your panel gaps are cut at the same time - old and new.

DO NOT cut out both the quarters all at once, you'll lose the integrity of the tub. Go slowly and cut out only one panel at a time after you have it all braced.

Again, photos in a few as I find them.

 

[Vae Victus]

This is my sill - the top cap had holes were already drilled (Thanks @Awl_TEQ - purchased 6 years ago when he still made them). I drilled the bottom holes because I like to weld all the way through.

You can see the upper cap turned upside down here with some weldable primer on it (copper), and the lower section with the small holes. By the way the blue pieces of tape show where the body mounts are lined up. I had to add/remove the whole thing so many times I got tired of feeling around for them.

Starting to "spot" weld here.....

And basically done with the spot welding.

Finished grinding down and priming. Note the first run on welding the rear lip of the top cap to the back of the tub.

 

[Vae Victus]

Here's a photo of the body mounts that go between the bumper and the sill. One piece of rubber goes on the sill, the other on the top of the bumper. The metal plates push against the rubber to make a solid but flexible mount.

You can also see the brace in the front of the truck that I made. It simply screws into the door hinge mount points with a piece of angle iron with some 3/4" square tubing made into a brace, cut and tacked in place. Measure everything across and make sure things are square and even. If not, force them to be and tack the brace pieces in place to hold it that way.

Finished rear sill, before doing the rear quarters.

Here is the rear brace. Nice and simple. Welded it in place. Screwed it into the rear door hinge locations to hold it.

 

[Vae Victus]

Then I started measuring the rear quarters so I could remember how they lined up. Photos always help me.

I used the piece of square tub on top to put the ruler up against and measure how far down the old quarters were supposed to go.

Then I clamped the new ones over the old ones, trying to line the bottom edges up so they did NOT overlap, but were in line (which made the panel stick out at the bottom while test fitting).

View above the rear sill. This would clearly be butted up against the sill once the old quarter panel was removed but it was helping me line it up and envision what would be welded to what when it was done.

Do the blinkers line up? Are there holes already cut? If not, mark them to be cut.

 

[Vae Victus]

Once you have the brace done, you can line up the quarter and mark it to be cut out. I replaced the whole thing from the front door pillar to the rear door pillar.

I marked the line where the inside panel overlaps with the quarter so that no matter what, I did not get near that line. Then I marked in thick blue-ing marker where the new quarter overlaps, and used a scribe to mark a precise line to be cut. It's hard to see under the thick blue line but it is there!

Before cutting out the quarter, you'll need to get a spot weld cutter and go through the joy of removing all those spot welds. I used the Blair Cutter set with 3 x 3/8" cutters in it. I ended up buying a couple of replacement cutter heads eventually, but YMMV, as they do break but are pretty beefy if you are careful.

You can see the spot welds cut out below, as well as the upper thin mark and the thick blue line for scribing. Don't forget to remove the gas door on the right side. Spot welds there too. Same for the door pillars - some spot welds to allow you to free that area.

Once you are ready to cut the old panel out, I used an Ingersol Rand air saw. I much prefer that tool vs a cutoff wheel, but hey, you do you. Even freehand, it is very precise, and doesn't shower you with a hail of sparks.

You can see the scribed line, and the very thin 1/32" cut the air saw makes. I drilled a hole to get it started.

Spots on the rear pillar.

There's some body filler between the front of the door pillar and the quarter. You can scrape that out (I again used the air saw like a sander to chew it out). The top and bottom of the quarter may be welded to the pillar. Depends on your situation. The bottom of the quarter by the door pillar was rotted away and I had to cut it out to get to the channel below to inspect it long before I cut the quarter panel off.

And viola! One off. Replacement begins.

 

[Vae Victus]

Fix the rot under the panel if it exists. For example, I had to fix this little area. Wasn't necessary, but it helps strengthen the quarter once you replace it.

I went ahead and installed the gas port while the panel was off the truck.

Eyeballing things....

 

[Vae Victus]

Next, starting fitting and grinding the two sections to get a good fit, and use the butt clamps if you have them to hold it in place. Note the floor jack holding it up on the rear end.

My gaps were not always great. I am a novice at this! Great thing is that you can fill it with metal using this cool stuff called welding!

The gaps at the curve were especially large. Not a great job cutting. I should have measured a couple more times. Fitting and scribing along the curve was tough.

Because I was using the butt welding clamps, I used a MIG technique. If I had used Fitzee's technique, the panel fit probably would have allowed using TIG, but you gotta be pretty good and have fairly perfect fit up to do that.

To keep the heat down, you must do a couple of spots, then move to a new location. If you do not, you will end up with a lot of warping in the panel. I also used a wet rag to cool down the welds as I went along (note the bucket under the truck). I would slowly remove the butt welding clamps as I went.

Note that the metal expands as it gets welded so the clamps can get stuck. Try to remove them before your welds get too close to the clamps. They like to bend your sheet metal when they get stuck as you try to wiggle them out.

You can see below a couple of interesting things. This is the back side of the weld, and the back of the butt clamps. They have a piece of rectangular steel that holds the clamp in place and makes the panels line up. Because my cut angled up as I got back toward the rear of the panel, and I got very close to that "no go" line where the upper portion of the rear lip that holds the top onto the tub overlaps with the quarter panel, the pieces of steel of the butt clamp that you see in this photo are at an angle (the top portion is thicker than the bottom portion). The big blue butt clamps are actually adjustable to account for different material thicknesses, hence the allen screw visible in the photo. This was very helpful to keep the panels lined up on the front side. If you can find the adjustable butt clamps, get a few of those to go along with 10 or so cheaper ones.

I hope all that made sense.

 

[Vae Victus]

Another tip - I used a VIM welding backer made of copper when doing each of the spot welds along the panel. Without this little backer, I would burn through the panels really often. (I'm also using an 0.30 wire on a pretty large MIG gun, so it made a lot of heat. I should have used a smaller diameter, but this one was fine with the backer). The backer also keeps the inside of the weld flat, and made clean up grinding much easier on the back side.

Yes, it takes forever to move the backer every time you had to move to a different spot, and sometimes I ended up doing 5-6 spots in one short stitch, which made a little bit of warping, but it is hardly noticeable and the body man is going to have to fill that in a bit.

This thing is about 4 inches long, and has a magnet on the end with the knob. the other end is copper. The knob allows you adjust the angle of approach so you can clamp on many different surfaces.

 

[Vae Victus]

When you get all your butt welding done, I went ahead and did the spot welds for the wheel well. Again, I like to cut two holes, a large one on the outside and a small one inside. I used the backer on these too. I checked the ones I could reach on the back side and filled them in if the small hole did not get filled from the front completely.

 

[Vae Victus]

The grinding is the next phase. I again use an air powered IR angle grinder with a 1" or 2" rolloc fitting. I have found that these grinding wheels work wonders on the weld edge (again, I don't use a big angle grinder, they are too hot and too imprecise when trying to do sheet metal, in one man's opinion): This is how they are listed on Amazon: "Cubitron - 51141277172 3M II Roloc Durable Edge Disc 984F - 80+ Grit Ceramic Metal Grinding and Blending Disc - For Disc Sanders - YF-Weight Backing - 2" "

These "Durable Edge Discs" are great when you get a fresh one for the blending of the weld bead onto the sheet metal. Use a fresh one when you get down to the blending phase. When you are just bombing down the main part of the welds, you can use an older one but when blending, you are using the very edge of the wheel, so a fresh one does wonders.

The Roloc system

New vs slightly used, but beyond being able to blend the final edge of the weld.

 

[Vae Victus]

Final product:

I slathered some primer on it to keep it from rusting futher. I did that on all new metal. Wasn't trying to be neat.

You can see a little wiggle in the metal, but not much. A thin coat of body filler, some primer, paint, and it'll all be great. I am not asking my painter to keep the spot welds visible as they did from the factory along the wheel well seam, since I hid them when I did the grinding. Some folks like to leave that factory look, so do so if you want.

Inside:

 

[OKMike]

View attachment 2489573

View attachment 2489577

View attachment 2489578

Great job, Brother. Hope mine look that good when I'm done.

 

[OKMike]

SILL SPOT WELDS:
You are right on - those are the locations for the spot welds. If you don't have a spot welder (who does?), then you can drill them out (larger hole on top - say 3/16", smaller hole on the bottom - say 1/16" - so that you get full penetration on both pieces of metal).

That is exactly how I did this earlier in the year.

SILL MOUNTING POINTS:
And yes, the holes that you are pointing to on the bottom of the sill are the places where the body mounts will go in between the bumper and the sill. If I can find my photos, I'll post.

QUARTER PANELS:
Regarding the quarter panels, if you are replacing the whole things like I did, make sure you brace the rear end of the truck across the bed so that the door frames in the back are square and level. I made a cross beam support from my front doors across the passenger area, and in the rear of the truck to make the top of the rear tub stay square with the bottom.

I butt welded as TanCruiser says. I did the entire thing though and had to carefully cut the whole panel out, then carefully fit the new panel so that I had gaps that were about 1/8" all the way down. I invested in and borrow more of the butt panel clamps that hold the panels together with a piece of steel in between creating a consistent gap. These really helped the butt welds stay level and clean.

You should also consider using Fitzee's method of panel welding that I discovered after I did my panels. Look him up on youtube - he's a very good car restore guy and shows a way to put a new panel over the old area and cut as you go so that your panel gaps are cut at the same time - old and new.

DO NOT cut out both the quarters all at once, you'll lose the integrity of the tub. Go slowly and cut out only one panel at a time after you have it all braced.

Again, photos in a few as I find them.

Thanks so much. That is all really helpful info. The CCOT site shows the rear brace technique you mentioned. I'm tracking on that now and from your explanation I have a better understanding of why its important to do it. I was able to order a body mount kit from SOR today. It comes with all the bolts and hardware. Figured in for a penny; in for a pound. Might as well replace all the body mounts while I'm at it with new mounts, new bolts, etc. FWIW I should probably be more precise with my welding terminology (I'm a welding noob) ...I when I say "spot welds" I am referring to plug welds.

Crazy that you mention Fitzee. Small worlds I guess. II stumbled on his videos when I started trying to learn how to weld a few months ago and I really find his tips helpful--so much so that I've been telling all my FJ 40 friends about his site. Its fun watching old craftsmen like him work. Have been using his angle cut technique from his butt welding video for a while now. It works great. He has a cool video on filling small holes. He uses a coat hanger to hold the sheet metal while he shapes it to fit. It cracks me up every time I watch it and hear him say "I loves me coat hangers."

 

[OKMike]

Thanks so much for the detailed info. I feel so much better about tackling this job now. Excellent write up. I owe you several beers!

 

[Ayuir]

Wow, nice detailed tutorial. Saved your post as I have to do much of that this summer. Thanks!

 

[plink01]

Final product:
View attachment 2489834

I slathered some primer on it to keep it from rusting futher. I did that on all new metal. Wasn't trying to be neat.

You can see a little wiggle in the metal, but not much. A thin coat of body filler, some primer, paint, and it'll all be great. I am not asking my painter to keep the spot welds visible as they did from the factory along the wheel well seam, since I hid them when I did the grinding. Some folks like to leave that factory look, so do so if you want.

View attachment 2489835

View attachment 2489849

View attachment 2489852

Inside:
View attachment 2489860

Awesome write up mate, that was super helpful. I've saved it for when I get around to doing my quarter panel one day.

 

[ratpin]

Saved