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 6.9 #521 Restoration
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wbrian63

USA
900 Posts

Posted - 02/21/2015 :  22:04:40  Show Profile  Reply with Quote
My how time flies when you're grinding rust...

I've been working steadily, or as steadily as I can on the final stages of the "find rust, cut rust, replace with new" on #521.

Had a small setback when I managed to get a sliver of metal into my left eye, even around the safety glasses I was wearing.

20+ years of wearing contacts (gave them up about 5 years ago for bi-focals) have permanently desensitized my eyes to the point where I didn't even have any discomfort when the metal hit the eye. I remember an "impact", but there was nothing after that. That was a Thursday. That night, both my eyes were "achy", but I attributed that to a combination of allergies, and possibly a couple of inadvertent weld flashes. Cold compresses and some Tylenol got me to sleep. By the end of my Friday work day (3pm), I was in considerable discomfort. That night I finally located the source of the problem. A dark spec in the eye that most definitely did not belong. All attempts to wash it free were unsuccessful. A trip to the eye doctor on Saturday AM had me "de-metaled" and back on my way in less than 20 minutes.

A note for anyone that encounters the same problem - when the eye doctor says "we need to use a little brush to remove the rust that's fused into the outer layer of the eye" - it's not a "brush" - it's a small burr, and they abrade away the rusted tissue... No big deal - local numbing drops take care of any pain, but it's a bit shocking when the doctor tells you - "hold on - I need to get you a non-magnifying contact 'bandage' to cover the hole I just drilled in your eye"...

I now use a new set of safety glasses that touch my forehead above my eyes, and my cheeks below. They're not goggles - those fog up almost instantly - but they're working just fine. I've even outfitted them with a set of cling-on 1.5 diopter lenses to help with my presbyopia...

Back to our previous story: earlier posts show the amount of damage that was done as part of the hack-job repairs to the car from the rear-end collision it suffered at some point in the past.

Here is the passenger side inner rear fender adjacent to where the rear sway bar mounts:


Ended up expanding the hole to remove some dodgy metal:


And all nicely buttoned up:


It's been so long since I cut out the original metal while replacing the side braces and bottoms adjacent to the spare tire carrier, that I don't remember how the inner fender metal met up with the side brace. I think that a lot of that original metal was gone and all that was left was undercoat. If I recall, the inner fender basically stopped about where the mounting plate is for the rotisserie - I chose to go farther.

Anyway - the next step is to remove the edge of the inner fender where it meets the outer fender. When the repair shop added the new rear quarter panels, they did a real hatchet job (I seem to be using that phrase a lot) while separating the outer fender from the inner. I addition, they never bothered to seal up the join point between the two sections (and probably would have just used chewing gum if they did make the attempt, so it's most likely a good thing they didn't try).

There's no way to get my big head with welding helmet up into the fender to work on welding replacement pieces, so having a rotisserie, I rolled the car around about 110 degrees so I can work on the project looking down at the inner fender instead of up.

Before I started disconnecting the outer fender from the inner, I added a brace to connect the outer fender to the chassis so that nothing would move.


What follows is a series of narrow angle shots of what I was replacing. Remembering that everything shown here is effectively upside down, the first image is just to the right (rearward) of where the wheel well opening ends. Each image moves to the right (forward) finally ending at where the wheel well opening starts.










First I dealt with the half-dozen places where the inner fender was brazed to the outer. Then drawing a line parallel to the edge of the outer fender lip, I carefully ground through the inner fender along that line to cut the edge free. Here's a close-up view of what the inner fender looked like from the back side:


I did the replacement in small sections. Most of the pieces were simple L-shaped sections. Some needed to be curved to match the shape of the outer fender as it arches away from the car. Some needed to be curved to follow the outer fender as it arches from the forward edge around the tire to the back. Some needed curving in both directions. The shrinker/stretcher I showed in a previous post proved invaluable in this effort. Without it, I would have to resort to very small replacement sections. With it, I was able to do about 5 or 6 inches at a time.

The biggest challenge in the process was welding the pieces in at the very front and rear of the fender - I had to use a mirror to see where to weld. Same problem came when it was time to dress the tack welds down - grinder in one hand and mirror in the other, all the while trying to figure out where to place the lighting source so that I don't block it with my hand, the grinder, or the mirror itself. Quite a chore. I've pretty much ruined a good inspection mirror with weld splatter and flying sparks from the grinding effort - all for a good cause.

I also had problems with the edges of the fender creating shadows that blocked the sensors on my welding helmet, allowing me to get a few nice weld flashes.

All of the pieces are edge-matched to the original inner fender - there are no lapping sections. The meeting point between the inner fender lip and the outer fender lip was carefully shaped to eliminate gaps, and rosebud welds firmly fix the outer fender lip to the inner fender lip.

These next 6 images approximate the view of the previous 5 - I think things look quite a bit better, even if the first picture reveals a weld that I missed :(













And finally, here's the work done to cover the sway bar mount and join the inner fender to the horizontal brace that supports the spare tire carrier. The location of the beading on the horizontal brace on the driver's side is different than the passenger side, so I had to remove a section - but as I've had to remind myself on more than one occasion, none of this will be visible once the tires are installed - all that matters is that it should be structurally sound (and it is), and that no water may penetrate to the trunk or interior sections of the car (and hopefully it won't).



All tallied, I probably have about 35 hours in just the work on the driver's inner fender and covering up the holes cut around the sway bar mount. The passenger work shown at the start of this post was another 10-15 hours, as the angles involved in forming the replacement sections was a real test of my abilities.

What remains on this project is to deal with the rust-through to the left of the sway bar mount in the last picture. I'll be cutting that out and patching a new piece in place.

After that, the meeting of the passenger inner fender and outer fender are next. Then there's a couple of small areas in the front inner fenders that need attention.

Once that's done, it's time to clean the bottom of the car thoroughly in preparation for etching primer...

Oh my, did I say the "P" word (Paint)? Could it be so?

W. Brian Fogarty

'07 Lexus LS460L
'76 450SEL 6.9 Euro #521
'02 S55 AMG (W220) - sold
'92 300SE (W140) - sold
'76 450SEL 6.9 Euro #1164 - parted & gone

"Bond reflected that good Americans were fine people, and most of them seemed to come from Texas..." Casino Royale, Chapter VII
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arcijack

USA
476 Posts

Posted - 02/21/2015 :  22:47:49  Show Profile  Reply with Quote
speaking of your eyes, i had this happen to me twice 2 months apart same eye, 1st time metal stuck in the middle, 2nd time in the pupil, had goggle on , but was lying on my back grinding, vows it will never happen again, not a nice feeling, been waiting on your post, looking good, taking notes
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wbrian63

USA
900 Posts

Posted - 03/13/2015 :  23:30:35  Show Profile  Reply with Quote
In my last installment, nearly a month ago I used the phrase "what remains on this project", and proceeded to list a series of items to be accomplished.

I had finished the inglorious task of reconstructing the edge of the inner wheelhouse on the driver's rear side.

I moved forward, looking for things that needed attention. You know what they say - "go looking for trouble and trouble is what you'll find."

Same thing can be said of rust on a 39-year old car...

It's been so long, I don't remember what attaches to this point in the left side engine compartment, but there's obviously a problem with rust:


Below there, there's a place for something that bolts through the inner wheelhouse - lots of pitting here - that needs to go:


And so we begin the task of duplicating the removed section:


Gotta match the angle of the original piece:


I don't have the tools or skill necessary to form the second bend, so I'll have to section the part and weld it back together:


I formed this anvil out of a piece of 1/2" rod - works well for tweaking the metal in a tight space:


To create the dimples found in the original piece, I took a piece of hard maple and used the 3/8" carbide burr in my die grinder to form a divot.


A piece of 3/8" aluminum rod with a nice radius on the end forms the dimple die.


Jumped forward a bit to show the piece installed with the two divots.


The match is pretty good:


And all nicely welded and dressed into place:


The other patch was way easier:


And finished:


In the above picture, there's some pretty nasty rust in the lower right-hand corner of the image. This is what it looks like in full view. A small hole is visible near the center of the picture.


That rust is a result of a bad seal on the cover behind the headlamp. Water gets in and is held in place by the headlamp housing.

Out the rusty part comes - cut away section as viewed from the back:


And from the front. When the piece was removed, I discovered that the mating piece underneath needs help too, so it was removed along the red line:


Replacement pieces need to be formed in the reverse order of that they were taken out - what came out last goes back first.


The piece needs to be formed as an inside corner - no way to do this except to section the metal and weld it back together:


Getting close:


Weld it up:


A little work with a grinder:


And through the magic of the internet - et viola!


This is the section of the headlamp bucket that needs to be replaced. The thinned section near where I'm holding it is where I ground away the metal to separate this piece from that inside corner made in the previous steps.


You can see that there's a dip in the piece at the right edge. Need to form that on the replacement part - more sectioning and re-welding:


And the final result:


And welded back into place. The square hole is really sloppy - I cleaned this up later after getting a nice sharp double-cut triangular file.


Waaaay back on page 2 of this thread, we find this image from when I was stripping the undercoat:


And this statement:
"The rust below the fuse box looks worse than it is. The metal is still solid, although I expect the entirety of the metal behind the overlapping flange is rusty. I'll investigate from above how bad the problem is and may decide to drill the spot welds out, open the flange and do some abatement, then re-weld the assembly."

Hah!

I don't know if the rust got worse in the time since that picture was taken, but "do some abatement" wasn't going to cut it. A little poking around with my carbide scribe and I poked right through the "still solid" metal...


Drill the spot welds and cut the lower section out:


"Some abatement"...


Then cut out the body section. In order to find out how far back to cut, I had to drill the spot welds for the flange that forms part of the box rail that holds the front sway bar and fold it back. Didn't need to go up under the flange - the body section under there is just fine.


Spend HOURS forming the patch - it has dips and curves in more than one dimension:


Start tacking:


All dressed up:


Part of the problem with this rust is caused by how the body is assembled. Here we see the box frame flange folded back into place and re-welded. The edge identified with the red arrows faces up and was covered with seam sealer. Water runs down under the fuse box, works its way past the seam sealer placed to seal the inner fender where it meets the body and slides inside and under this tab.


Solution? Weld the top edge of the flange to the body:


Reconstruct the inner fender section and install it


Thanks for reading


W. Brian Fogarty

'07 Lexus LS460L
'76 450SEL 6.9 Euro #521
'02 S55 AMG (W220) - sold
'92 300SE (W140) - sold
'76 450SEL 6.9 Euro #1164 - parted & gone

"Bond reflected that good Americans were fine people, and most of them seemed to come from Texas..." Casino Royale, Chapter VII

Edited by - wbrian63 on 03/13/2015 23:49:57
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wbrian63

USA
900 Posts

Posted - 03/21/2015 :  22:13:57  Show Profile  Reply with Quote
One of the last sections of rust inside the driver's inner fender has been excised and replaced with nice good metal.

This is one of the areas after stripping the undercoating that I thought was solid. Since that time, I've improved my methods of checking, and indeed this section was soft.

The rust area right in the middle of the picture doesn't look like much, but the metal in that area is only about .035 thick, so any surface erosion results in a paper-thin cross-section.


Some (most) of this rust was caused because water worked its way in under the seam sealer starting at the gap in the flanges just to the left of the green arrow. I'm going to future-proof this area by cleaning out the remaining seam sealer, bead blasting it briefly and then closing up the upper edge of the vertical section of the flange with the welder.



Much of the metal to be removed is actually behind the box-section frame so a little detective work was required to figure out how much to remove. Once that was done, a sharp punch marked the center of the spot welds from inside the car, and careful surgery with a spot weld cutter was performed


Some careful cutting with a right-angle grinder and a cutoff wheel removed the panel


Here's the removed panel - rust was only really bad where the seam sealer and undercoat had allowed moisture to collect and stay. The rusty half-moon shaped section is what could be seen from inside the inner fender.


Some careful fitting and welding and the repair is complete.


I did the initial tacking from inside the car, the exposed section was welded from inside the fender well. After the outside welding was complete, I came back to the inside and filled in the blank areas.

I'll wait to dress these welds until I can get the car upright and the dash out. It was hard enough cutting the panel out which is not critical work - grinding the welds down needs to be done carefully and that will have to wait.


"As far as I know", there's one small rust repair inside the rear inner fender that I missed - that will be done next week. Then - honestly and truly, all the rust that needs to be repaired on the driver's side of the car has been repaired - as far as I know...

W. Brian Fogarty

'07 Lexus LS460L
'76 450SEL 6.9 Euro #521
'02 S55 AMG (W220) - sold
'92 300SE (W140) - sold
'76 450SEL 6.9 Euro #1164 - parted & gone

"Bond reflected that good Americans were fine people, and most of them seemed to come from Texas..." Casino Royale, Chapter VII
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daantjie

Canada
1056 Posts

Posted - 03/23/2015 :  10:59:01  Show Profile  Reply with Quote
Just goes to show how good these cars are at hiding rust!
Commendable effort, sir!

Daniel
1977 450 SEL 6.9
Vancouver, BC
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bigblockbenz

USA
379 Posts

Posted - 03/23/2015 :  11:56:19  Show Profile  Reply with Quote
Excellent Brian!

(aka 'the most determined 6punkt9 owner on the planet.)
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wbrian63

USA
900 Posts

Posted - 04/23/2015 :  23:19:39  Show Profile  Reply with Quote
Time has gotten in the way and I've made very little progress on #521.

I was contacted by a new member of this forum via another message board we frequent when he put 2 & 2 together and figured out that I'm the guy restoring a 6.9.

He wanted to purchase a 2.65:1 differential, and knows that the 6.9's are the only 116 chassis cars so equipped.

So today, I pulled the differential I've been lugging around from the long-since-gone #1164 and went about comparing that unit vs the one I pulled out of #521.

What I surprise I got. Outwardly, they appear identical. I did a quickie check of backlash on the ring gear and found about .0035 play in both units.

Checking for unusual wear on the ring gears revealed nothing.

Checking for wear on the spider gears in the #521 unit revealed - uh-oh:


I was surprised that I was able to freely rotate the spider gears to confirm that most of the teeth on the gears have the chipping seen in the photo. Figured that the limited-slip was worn out.

Then I went to check the spider gears in the unit from #1164 - and I could not rotate them at all.

Then I figured out why:


Comparing this carrier with the one from #521 - there are NO clutch packs in the #521 unit. It's not a limited-slip differential!

Checking ratios,#1164 takes about 2-1/2 + a bit of turns on the pinion to get one revolution on the ring gear.

#521 takes nearly 3 revolutions on the pinion to get one revolution on the ring gear.

That explains why the car tended to do a one-wheel-peel if pressed hard off the line, and why it was "just a bit" quicker that other 6.9's I'd driven.

So - the sale is off, and I'll be using the differential from #1164 when I get back to work on #521.

W. Brian Fogarty

'07 Lexus LS460L
'76 450SEL 6.9 Euro #521
'02 S55 AMG (W220) - sold
'92 300SE (W140) - sold
'76 450SEL 6.9 Euro #1164 - parted & gone

"Bond reflected that good Americans were fine people, and most of them seemed to come from Texas..." Casino Royale, Chapter VII
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wbrian63

USA
900 Posts

Posted - 05/27/2015 :  08:51:34  Show Profile  Reply with Quote
And yet another month has gone by with almost no progress on the car.

However, I am happy to report that I'm back at it again as of yesterday afternoon. Unfortunately, the work involves cutting out some work I'd done previously to re-do it again.

On the driver's side of the trunk floor, the panel that overlaps the spare tire carrier had some bodgy work done with the wreck, and I had to replace a 1-1/2" x 10" long piece on the overlapping edge.

This was done easily enough, but was during a time when I'd not completely polished my weld-dressing skills.

As I was buttoning up the work on the left-hand rear inner fender, I noticed that I'd not dressed the underneath of the area where I'd replaced this tab of metal.

Understand, that once the car is undercoated, with the exhaust system installed, this area will only be visible with the use of an inspection mirror, but an undressed weld is an undressed weld.

With much care, I began to work the area and some improvement was made. Not surprisingly, there were a few small pin-sized holes that were revealed.

No big deal - just a quick zap with the welder will seal the hole and on to better things.

Not so fast! Even set to a very low setting, some of these small holes were in a field of tin-foil-thick metal, thanks to over-aggressive finishing work on the trunk-side of things. "A quick zap" turned a tiny hole into a gaping maw... Trying to back-fill that mess led to an even larger mess, and the decision to excise the panel and start again.


And so I found myself yesterday afternoon removing a larger section of metal in search of clean edges to accept the replacement panel.

I've got the replacement formed and have to work the gaps out of the join line - it's a real bugger when you can't get your head directly in front of the cut line...

I've got the car rotated to about 80-degrees from horizontal with the left side down. I can sit in my mechanics roll-around chair and the work is at shoulder-height with this setup, it's just tucked a bit up under the trunk lid frame, so access isn't ideal.

Even more of a challenge is found in the need to do a bit of panel beating to deal with some of the kinks in the body panel that may have been caused by my ham-fisted attempt to close hole after blown-out hole. Can't get a body dolly on the underneath side because I'm working solo. Finally figured out I could slip a body hammer with a domed face through the hole and use that as a backup dolly for a little tweaking.

Anyway - progress is progress. I'll post some pictures of the carnage and resulting repair in the next installment.

Thanks for reading.

W. Brian Fogarty

'07 Lexus LS460L
'76 450SEL 6.9 Euro #521
'02 S55 AMG (W220) - sold
'92 300SE (W140) - sold
'76 450SEL 6.9 Euro #1164 - parted & gone

"Bond reflected that good Americans were fine people, and most of them seemed to come from Texas..." Casino Royale, Chapter VII
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wbrian63

USA
900 Posts

Posted - 05/29/2015 :  07:03:04  Show Profile  Reply with Quote
I feel like I'm going to confession, and I'm not even Catholic.

In my previous posting, I noted that my current effort involves fixing a problem I created on a section of the trunk floor that was removed and replaced with new metal, only to have me more-or-less destroy that work while trying to dress welds from the underside.

Well - here's the embarrassing evidence of my misdeeds.

I didn't take pictures before I removed the panel, but here it is in all its glory. This is the side visible from inside the trunk. The holes along the bottom edge are where I ground away the plug welds. The reason for the panel removal are the welds along the top.


Same piece as viewed from the bottom.

I have no idea what I was thinking.

Note to self: if you blow through a panel trying to patch a pin-hole in a weld, and it takes 50 more welds to close up the holes you blow trying to close up the previous hole, you should probably give up and cut the panel out...


And in profile, just to see how bad it is.


And repaired properly. The orientation is how the part is actually presented with the car at about 80-degrees from horizontal on the rotisserie.


This problem was caused by the way I was dressing welds when I did this repair. Grinding down the tiny welds used to edge-join panels must be done carefully to make sure you're not removing any of the panel material that surrounds the weld.

In these types of repairs, welds are typically harder than the metal they join, and using any sort of flexible grinding pad usually results in loss of panel thickness around the weld as the weld is ground away.

I switched to using a carbide burr in a die grinder, but this is a technique that is hard to master, in addition to the zillions of needle-sharp shards of metal it generates.

My current method involves a right-angle die grinder with a 3" diameter x 1/16" thick cutoff wheel. Used at a right-angle to the weld, the thin edge of the wheel is used to dress the weld down to just proud of the surface. The small diameter and narrow cross-section makes it easy to just grind the weld and nothing adjacent.

I purchase quality cutoff wheels from Lehigh Valley Abrasives. They're still cheap, at least when it comes to other purchases involved in restoring a Mercedes Benz - about 70cents each. The brand is Metabo, and they last a long time and don't produce the clouds of brown dust that cheaper wheels do.



Somewhat slower than the "hog it all down" methods used before, but far better results are obtained.

Today, it's time to attack the rust and rot along the inside of the passenger inner rear fender... oh boy, I can't wait!

W. Brian Fogarty

'07 Lexus LS460L
'76 450SEL 6.9 Euro #521
'02 S55 AMG (W220) - sold
'92 300SE (W140) - sold
'76 450SEL 6.9 Euro #1164 - parted & gone

"Bond reflected that good Americans were fine people, and most of them seemed to come from Texas..." Casino Royale, Chapter VII
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wbrian63

USA
900 Posts

Posted - 06/02/2015 :  09:27:22  Show Profile  Reply with Quote
Started cutting out the rotten edge of the passenger rear inner fender.

This is the view before:
This right edge of this image shows a bit of the work I'd already done on the rear section where it meets the well at the edge of the trunk.


And we work forwards around the arch towards the front of the car








The left side of this image shows some work already done where the inner fender intersects with the sill pocket behind the rear door. I ended up cutting this fix out to allow for a better overall result in this effort.


A little work with the cutoff disk in the right-angle die grinder, and we have two strips of high-iron swiss cheese:









I cleaned out all of the flaky rust left behind from the inner fender pieces - thankfully the outer fender seems unaffected. A quick shot of rust prep before I left last evening should make everything ready for some weld-thru primer and reinstallation of the replacement sections, just like on the driver's side.

W. Brian Fogarty

'07 Lexus LS460L
'76 450SEL 6.9 Euro #521
'02 S55 AMG (W220) - sold
'92 300SE (W140) - sold
'76 450SEL 6.9 Euro #1164 - parted & gone

"Bond reflected that good Americans were fine people, and most of them seemed to come from Texas..." Casino Royale, Chapter VII

Edited by - wbrian63 on 06/02/2015 23:26:51
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mirafioriman

United Kingdom
193 Posts

Posted - 06/02/2015 :  10:23:40  Show Profile  Visit mirafioriman's Homepage  Reply with Quote
Nice skills

Mercedes W116 450 SEL 6.9, W109 300 SEL 6.3, W126 420 SEL, Fiat 131 Supermirafiori, Fiat 131 Panorama, Fiat 130 saloon, Fiat 132 2000, Fiat Argenta and a Citroen Xantia 1.9D!
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benz_head

USA
452 Posts

Posted - 07/07/2015 :  13:06:07  Show Profile  Reply with Quote
Brian,

I continue to be amazed at your efforts. Keep up the good work!

benz_head
#1349
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wbrian63

USA
900 Posts

Posted - 07/07/2015 :  14:31:54  Show Profile  Reply with Quote
Thanks - progress continues, albeit very slowly.

I've had way too many distractions lately.

Hope to resume work later this week...

W. Brian Fogarty

'07 Lexus LS460L
'76 450SEL 6.9 Euro #521
'02 S55 AMG (W220) - sold
'92 300SE (W140) - sold
'76 450SEL 6.9 Euro #1164 - parted & gone

"Bond reflected that good Americans were fine people, and most of them seemed to come from Texas..." Casino Royale, Chapter VII
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wbrian63

USA
900 Posts

Posted - 08/05/2015 :  08:13:50  Show Profile  Reply with Quote
While I don't have supporting pictures for proof, as of 7pm last night I have finished ALL of the rust cut-and-replace efforts on #521!!!!

Sadly, it's not all of the rust but it is all of the rust that I've found on the main chassis. I know there are some small areas on the rear doors where the quarter glass was leaking and a couple of places where the door lock actuators mount.

What remains before I can start looking to priming the bottom of the car?

I've got a replacement front subframe rail section from Dave (mirafioriman) that needs to be installed, plus a few dents in the remaining frame rails to pound out (somehow).

I'm also going to pull all of the attached subassemblies from the chassis - the transmission support crossmember and the two attachment points for the parking brake equalizer. I've found too much rust hiding behind things to assume that nothing lurks beneath these parts.

I'll have to do a bit of butchery to these parts to get them free of the car. From the restoration photos in the library I can see that the pivot mount for the parking brake equalizer is edge-welded to the chassis, so I'll have to cut through the flange to remove it, then grind away the weld that remains on the body. I've gotten pretty good at rebuilding things, so it shouldn't be too much of a job to add back to the flange where I've had to cut away.

Once those areas are dealt with, I'll have to figure out what to paint behind them so that the rust won't return after I reinstall the parts.

I've seen some restorers that use a 2-part epoxy primer that they just paint on with a brush. I've also seen the popular POR (paint over rust) products in use.

My main concern will be getting something in place on the body and on the back side of the pieces that will hold up against the heat of welding...

Then - it's time to tackle the front cross member that runs under the engine. It's dented from years of jack abuse, and I'd like to fix that and add some bracing to allow for future use of a center-located jack without denting it again, plus I've got a lot of body seams up there to clean the remaining goo of oil and god-only-knows-what before I can think about primer.

Still - even without pictures to prove it - I'm glad to be at the end (at least what I think is the end) of the cut-it-out-put-it-back phase...

W. Brian Fogarty

'07 Lexus LS460L
'76 450SEL 6.9 Euro #521
'02 S55 AMG (W220) - sold
'92 300SE (W140) - sold
'76 450SEL 6.9 Euro #1164 - parted & gone

"Bond reflected that good Americans were fine people, and most of them seemed to come from Texas..." Casino Royale, Chapter VII
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wbrian63

USA
900 Posts

Posted - 08/16/2015 :  13:29:34  Show Profile  Reply with Quote
I'm an active member over at garagejournal.com (same user ID) and members there are fond of the phrase "pics or it didn't happen."

This is used in context when members report accomplishments without photos to prove the event.

Drum roll, please....


Standard pattern of work:
  • Cut a coupon of metal out of a sheet.
  • Bend it into an "L".
  • Add curves as required using the shrinker/bender.
  • Sculpt the mating edge to match the shape of the inner fender.
  • Mark and drill a few 1/4" (6mm) holes in the lip of the outer fender for plug welds.
  • Clean the inside edge of the outer fender for drill shavings.
  • Spray the inside of the outer fender with weld-through primer where any bare metal shows.
  • Spray the back side of the replacement piece as well.
  • Add a few welds to hold the piece in place.


I should note that the rust that appears in the previous photo was not there when I did the welding shown. I welded the piece in on a Friday, and the picture was taken on the following Monday. I'm guessing that it has something to do with the heat of welding combined with the shielding gas (Argon/CO2 blend) that causes this. There are acres of bare metal under the car that have nary a spot of rust, even after months of remaining bare after the under coat was removed. Touch one spot of that bare metal with a welder, and rust will form around the weld within 24 hours.



I don't attempt to match the edge that joins the outer fender at installation - it's left raw. Once I've got the opposing edge firmly attached to the inner fender, I clamp the replacement piece to the outer fender and add the plug welds at the holes I drilled in the earlier steps. Then I trim the edge of the patch to match the profile of the outer fender.

Continue with the pattern.
  • Add a weld along the seam between the new and the old.
  • Use a right-angle grinder with a thin cutoff wheel to dress the new welds down to almost flush.
  • Add more welds to connect the dots until the new is fully bonded to the old.
  • Clean everything up with another right-angle grinder equipped with an 80-grit 3" flexible sanding disc.



With a lot more of what is noted previously, one can attain a finished product. The following series of pictures show the fully repaired fender starting at the rear of the car and moving forward towards the front:












As noted in the previous update, I planned to remove all of the sub-assemblies inside the drive shaft tunnel to check for rust. I'm glad to report that work is fully underway, and the results have borne out that it was a good idea to make this effort. Rust was most definitely found - none of it critical, but time would have allowed the rust that was found to progress to where it would have eventually become critical, and that would have meant more work at a time and in a place where the process would be far less convenient.

The first stop on our journey was the flange where the parking brake equalizer bar pivots. You can see the stitch welds at the right and left-hand sides, plus the tell-tale bumps from spot welds at 4 places along the bottom edge.


The yellow lines show where I made my first cut to separate the bracket from the stitch welds:


And this is what I found when the part was removed - not critical, but given that this part was fully sealed at the bottom and sides from undercoat, and more-or-less open along the top edge, water and moisture definitely can find their way into the gap between the flange and the body and rust will be the result.


A word about removal/replacement of parts like this that need to go back where they came out. Simplest method is to drill a couple of small (3/32" - 2mm) locator holes before the part is removed. These are used to relocate the part at installation.


And here we see the rebuilt part back where it belongs. It's not welded in yet, but the original shape of the part has been restored and once the necessary painting has occurred on the body and on the back side of the flange, it will be reinstalled.


The next piece on the list is the transmission support. Before removing the part, I added a couple of cross braces to make sure that nothing would spread apart when the support was removed.


Same plan as before - cut inside the stitch weld and deal with any spot welds to remove the part. Rust was found - left-front corner:


Right-front corner:


The rear corners were clean and free of rust:




Not surprisingly, the back (upper when installed) side of the support was very dirty, with little or no undercoat.


Cleaned up to see the extent of the rust - fortunately it was all surface level.


I would love to form some patch panels and completely close up the sections of the mount that serve only to trap dirt, but bridging a gap the size of these would likely result in deforming the framework as the welds cool and shrink. I'll just make sure not to close up the drain holes when the undercoat goes on.

In a couple of places, I cut too deep and left a groove in the body. These welds fill the groove:




The work begins to replace what was cut away to remove the part. This work was slow and fiddly, but far easier than patching the body - this metal is far thicker - about .100 (2.5mm), and since I can see both sides of the piece, I don't have to worry about lurking rust waiting to spoil my welding. Same pattern of attack as with a body patch panel - tack it in place, fill in the gaps, but do this work on the face and back side of the part.


Next stop - parking brake cable frames. These are where the front side of the parking brake bowden cables attach. Beefy frames heavily spot welded into place. No access from the back, so I used my trusty spot weld broach to cut around the welds from the front. Only problem encountered was the frames are about the same thickness as the maximum depth capacity of the cutter. The broach lasts best when I use the waxy lubricant, but that traps shavings inside the broach, which reduces cutting depth. Just have to take the time to periodically clean out the recess.

Left-side mount from a couple of different angles - there's rust lurking in there somewhere...






Right-side mount:


Left-side removed - see, I told you there would be rust:


Right-side removed - as expected:


For these parts, I don't have much rebuilding to do, but I am going to use a different method to reattach the parts.

In most cases, I grind away the nub of the spot weld before I reinstall the part, and I use the hole created by the broach as my plug weld point. However, this really only works well when the mating pieces are the same thickness. In this case, the mounts are nearly 1/8" (3mm) thick, and the substrate is less than half that amount. Trying to get a good bond can result in burning through the underlying metal.

For these pieces, I'm going to leave the original nubs that are still securely attached to the body. There will be a nice gap around each nub, and I'll weld that gap closed to reattach the mounts.

For your consideration, next we have the mounting point for the parking brake equalizer bar. This has heavy rust pitting on the face, and it was actually the appearance of this piece that led me to decide to remove all of the other items featured here.


From the back - not much prettier:


The body shows some rust, but nothing that merits replacing metal.


This part had two stitch welds, plus 6 spot welds, but they were easy to find and remove.
Time to rebuild the part - a couple of pieces of 1/8" (3mm) flat bar should do the trick.


And yet more welding:


The final item is the drive shaft center support bearing mount.




Removing it was a good decision - there was definitely rust underneath:




Again, a combination of stitch welds and spot welds held the part in place. The spot welds proved particularly hard to find, so a couple of mistakes were made. The result is a mount that is going to need quite a bit of reconstructive surgery. Quite a few of the holes shown here were non-productive efforts. It looked like there was a spot weld, but when the cutter passed through the bracket, the puck fell away free - no weld there.






Weld a corner tab into place. I cut the piece longer than required and trim it back. It is very difficult to weld the end of a gap without burning away the two pieces. Having one longer than the other keeps that from happening.


It's too much trouble to try to patch all of the small 3/8" (9mm) holes made by the broach, so I just cut the edges away to form a tab, then scribe the replacement piece to match the edges.


All of the holes will be filled - 3/8" (9mm) is too big a hole to do a good plug weld - things get too hot and burn through. 1/4" (6mm) will be more than sufficient for the task, along with some good stitch welds along the edges where they were before.

W. Brian Fogarty

'07 Lexus LS460L
'76 450SEL 6.9 Euro #521
'02 S55 AMG (W220) - sold
'92 300SE (W140) - sold
'76 450SEL 6.9 Euro #1164 - parted & gone

"Bond reflected that good Americans were fine people, and most of them seemed to come from Texas..." Casino Royale, Chapter VII
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