Broken K-frame Fix - PeachParts Mercedes-Benz Forum

BillGrissom · #1 09-20-2014, 05:42 PM

My 1984 300D right wheel started pointing 20 deg right with left wheel straight, while my son had it in San Diego. No photos that showed me the problem, so I had to take every tool I could think of. We were planning a Labor Day trip the next week anyway to swap the 1985 300D with him, but now drove our 2002 T&C van in case we had to tow-dolly it home (worst case). We tow-bar'ed the 1985 the 505 miles there (another post), saving fuel and easier for us, plus proved the method in case needed to recover the 1984.

I am sure most readers can imagine many things which could cause severe toe-out. Hint - when I bought the car years ago, the owner said the K-frame had "cracked again". First time was when it was stolen and crashed into a curb, then fixed by a shop. I found those weld repairs sound, but the left "LCA pocket" had cracked thru the hole, letting the LCA move outward, causing extreme camber & toe-out. After pulling back and tacking, I welded a metal strap across the bottom of the pocket. My son was sure the problem was that my weld had broken, but never sent photos of the left side, saying the problem was only on the right (makes sense?). 1st photo is my left LCA weld repair, still sound, though only 2nd time I had used my $90 Harbor Freight flux-wire welder.

I found the problem was on the right. The long-ago K-frame repair had separated (son swears he takes speed bumps lightly). The 2nd photo shows a large gap where it was welded to the spring tower, 3rd photo where it punched thru the bottom of the frame rail slightly. The car was in a parking garage. I strapped chains around the springs and used a come-along to pull the LCA back (as I did for prior right-side repair). I attached other chains (1300 lb rated, Ace Hardware) to the LCA's at their pivot and tightened (4th & 5th photo). The chain fit perfectly between the engine and K-frame, not touching the oil pan. I then adjust to 1/8" toe-in (used tape measure, required just slight tweak after pulling LCA tight) and drove 10 mi on I-5 to the motel, w/ just the chain holding the right LCA in position. The car drove like new, perfectly straight w/ hands off the wheel and steering wheel centered. Later, at the motel when I jacked the car by the frame, w/ wheels hanging, I found the chain loose so appears I didn't even need the come-along since the weight of the right wheel rotated the K-frame end into position.

We were going to tow-bar the 1984 home. Backup plan was to buy a tow-dolly (some for $400 on craigslist) or rent ($110 U-Haul). With a tow-bar, if something broke free the heavier van would still direct the car, so a bit safer. But, my wife wanted to attend a meeting in LA, so I ended up driving the 1984 home. No problems, or strange noises, and got 26 mpg even w/ crossing the mountains and stuck 2 hr in a jam (fatal accident in Lake Hughes). Many here wouldn't do that drive, and they should probably wear helmets while walking. I couldn't imagine the chains breaking.

At home, I made a permanent repair. I removed the turbo and engine mount, supported the car on the frame, then jacked the LCA pocket up tight against the K-frame and tacked in place, then removed the jack. The K-frame and LCA pocket is fairly thin sheet metal, not exactly the ruggedness people imagine of these cars (many also ask if I get 45 mpg, "no, that is VW diesels"). Previously I had fits trying to butt-weld a new floor (similar gage steel) in my 65 Dart, since kept getting burn-thrus. My HF welder has just min & max power settings. Max works well for 1/4" th steel, while min is a bit much for sheet metal. To try to reduce power further, I used a 100 ft, 16 awg AC extension cord (seemed to help). Welding was still tedious, w/ many passes of welding, wire-brushing, and grinding. I welded across some gaps by hammering re-bar tie wire into the gap.

To insure the top didn't pull away from the spring tower again, after solidly welding, I welded an L-brace over that (framing brace from Home Depot). Before covering bare sheet-metal you should protect both sides with "weld-thru primer". As others, I use the inexpensive "high zinc" primer shown. I also added a strap across the bottom to insure it couldn't punch thru the frame rail again. Probably over-kill, but don't want to revisit this repair. I would similarly improve the left side, but await a time when the hoses are out for other repairs. A tip, try to determine which side is thicker gage and start welding there, otherwise the new metal may stick to just the thinner side (appears what happened in the shop's job). In my case, the framing brace seemed thicker than the K-frame, and the lower strap seemed thinner than frame rail. Last photos (post 2) show the finished repair before paint.

BillGrissom · #2 09-20-2014, 05:44 PM

More photos.

leathermang · #3 09-20-2014, 06:02 PM

It is my opinion that you should have hired someone to fix that...or rented a more proper welder...
At the very least you need to grind down that slag and go over it to make sure you got a good hold... and to try to keep rust from attacking it...
I would never trust ' weld through ' primer...
your weld needs to start with clean metal ...

Tell your story and post those pictures here to get real feedback...

General Welding Questions

BillGrissom · #4 09-20-2014, 06:18 PM

I appreciate all feedback. So far, no weld I have made with my cheap welder (~6 yrs) has ever failed. There is no slag, all metal was shiny before I painted. Professional welders (whatever that means) use weld-thru primer (google it). Of course I sanded or ground away the primer where I welded, otherwise no spark. The primer protects the inside surfaces where you can't paint after welding, and only zinc survives the heat. No rust in CA anyway. I ground down the welds as best I could fit in the (fast) electric grinder and (slow) air die grinder. If you grind on sheet metal too much, you can go right thru. If the engine was out, one could make it real purty, but stupid to do that for this job. If I ever remove the engine I can clean it up. It actually looks clean in person, the camera shots are closeups. Most of the ugly welds are from the shop the prior owner hired (you did read the post?) and it was their welds that broke. You are welcome to always hire "professionals" and pay accordingly. I have several engineering degrees so don't require high-school educated "professionals" or even Wyotech grads.

leathermang · #5 09-20-2014, 07:12 PM

Having engineering degrees has no bearing on having a good ' hand ' at welding..
You admitted that you knew your power settings were not what they should have been... and that tried to compensate for that... filling a hole and having proper penetration are not necessarily the same thing...
And my input on this thread it not really for you... but for others who might come across some similar situation...
Welding upside down is very hard.... at the very least avoiding the sparks falling on you or rolling towards you once they hit the floor..
I suspect that what that really needed was TIG....
I would not spray anything which was going to be heated later with zinc...
I have seen ' cold zinc ' sprays intended to protect metal...
Proper zinc application to a metal of course involves electricity... ' galvanization '...

http://www.cdc.gov/niosh/docs/81-123/pdfs/0675.pdf

If you have a way to spray from the backside... I would recommend ' Fluid Film '
Fluid Film® | Corrosion Preventative, Lubricant and Rust Inhibitor

If you wire brushed that area....and brazed over it... it would also protect it from
moisture and rocks ....

AND.... you did not say you had not had any Automobile Suspension Welding fail in that six years... sometimes the ' Risk- Reward' judgement involves critical safety equipment ... and most of the time it does not...

BillGrissom · #6 09-20-2014, 07:35 PM

leathermang, it is obvious you have never welded, and still haven't googled "weld-thru primer". I wrote this mainly for people who want to try, and also to make people aware how fragile the thin K-frame and LCA pockets are. I imagine cars in salty areas have corrosion issues (despite the galvanized metal). For those who want to try weld repairs, buy long leather gloves (cheap at Harbor Freight), wear a long-sleeve cotton shirt (mine could have been thicker, a few ouches), and don't leave any place for a little hot ball to run down your clothes. I lie on cardboard (newspaper isn't wise), and turn it over regularly to keep clean.

TIG requires "elbow room". I doubt I could have gotten two hands in most places and still seen what I was doing. TIG is also a softer weld. Many use it for outer body panels since it doesn't heat as much and warp the sheet-metal, but I have read that the different weld material can cause differential thermal expansion that causes very slight waves in the body panel as ambient temperatures change, which bothers people with show cars. A TIG setup is ~$700. The main value for me would be to weld aluminum (challenging). The next step up over my cheap wire-fed flux welder is one with gas. The shield gas gives less popping and cleaner welds. However, flux-wire alone is fine for frame work like this and working in corners helps confine the out-gassing and keep oxygen away. My main fuss with the welder was the wire would often jam in the tip and stop feeding, especially after a long hot run. I think the copper tip melts slightly. It is removable and replaceable, but I just removed, cleaned the hole w/ another wire and shone the tip w/ sandpaper (for less radiant heating).

The hardest part of this type of welding is seeing what you are welding and trying to orient the wand in a cramped place. I am guessing the former shop did the repair w/ turbo in place, which must have been challenging, and perhaps why their welds apparently didn't penetrate well into the spring tower (no torn metal where it separated). I needed to also repair the turbo to intake manifold seal, so no extra effort for me.

Grinding is equally fun. Sometimes, the only way I could orient the electric grinder was with the debris coming at me. A full face shield is important then. The sparks are amazing, especially at night, but don't sting too bad (too hot here to bother w/ gloves). Just protect your eyes well, and always remember that the grinding wheel can shatter at any time, so consider the plane in which it has momentum and don't put your neck there.

leathermang · #7 09-20-2014, 07:55 PM

I have owned and used my Miller 240 amp Heliarc since 1970.... a pre WW2 model which came with a water cooled TIG torch which would weld 1 inch aluminum...never having seen one inch aluminum I immediately switched to argon gas cooled torch.. of course on a farm oxy acet is absolutely necessary.... and I have a Lincoln Weldanpower portable.. and just for fun I also have a plasma cutter....
I find my local welding shop has the softest leather gauntlet gloves....
I find some things are advertized to sell product.... and often following the basic rules works best... therefor I would not use zinc spray until after the welding was finished... if I used it... cotton shirts will allow sparks to burn you... I have a leather welding apron which has sleeves.... long enough to fit into the gauntlets of the gloves...
but you are correct that SEEING when upside down under a car is very hard.. when arc or tig welding...
but that might be a reason to oxy acet weld something... like they do the tail pipes... you can just use regular welding eye goggles in that case....

Diesel911 · #8 09-20-2014, 07:58 PM

Quote:

Originally Posted by leathermang

Having engineering degrees has no bearing on having a good ' hand ' at welding..
You admitted that you knew your power settings were not what they should have been... and that tried to compensate for that... filling a hole and having proper penetration are not necessarily the same thing...
And my input on this thread it not really for you... but for others who might come across some similar situation...
Welding upside down is very hard.... at the very least avoiding the sparks falling on you or rolling towards you once they hit the floor..
I suspect that what that really needed was TIG....
I would not spray anything which was going to be heated later with zinc...
I have seen ' cold zinc ' sprays intended to protect metal...
Proper zinc application to a metal of course involves electricity... ' galvanization '...

http://www.cdc.gov/niosh/docs/81-123/pdfs/0675.pdf

If you have a way to spray from the backside... I would recommend ' Fluid Film '
Fluid Film® | Corrosion Preventative, Lubricant and Rust Inhibitor

If you wire brushed that area....and brazed over it... it would also protect it from
moisture and rocks ....

AND.... you did not say you had not had any Automobile Suspension Welding fail in that six years... sometimes the ' Risk- Reward' judgement involves critical safety equipment ... and most of the time it does not...

I welded up a cracked rear cross member with a HF Flux Core Welder and it was somewhat as you said.

I had never used a Flux Core Welder before and I did not practice so I did a whole lot of grinding and re-welding and I set Myself on Fire x3 even though I was wearing a Cotton Military BDU Coat.
It is simply that if you are extremely close to what you are welding and a big enough blob comes off it can catch Cotton on fire.

It was extremely cramped and I finally took the time to raise the Vehicle as High as I could possibly get it with when I had available.

Being under the rear of the Car puts you in a dark area and it is extremely hard to see where you are going to weld until you start and it is too late.
There was places where a normal Drop Light was not enough. I think Something like a Flood Light would have done better.

Another thing is that I was told by nearly everyone that I should have scrapped the Car because it was a safety Issue. So I am wondering why everyones Flame Thrower is not on?

Having this type of problem in the Rear is not nearly the same as having it in the Front which has more weight on it to begin with and has to deal with the forward Weight shift when you brake.

Best Wishes to Bill on his repair.

leathermang · #9 09-20-2014, 08:05 PM

Diesel911,
AMEN.....

leathermang · #10 09-20-2014, 08:08 PM

Bill,
" Tig is a softer weld"... that depends on the filler rod you use...

leathermang · #11 09-20-2014, 08:22 PM

Quote:

Originally Posted by BillGrissom

......However, flux-wire alone is fine for frame work like this ......Grinding is equally fun.....

I have never used a fluxcore wire welder... as I have other options...
I am sure they could be just fine for your operation..

What I have a problem with is your admission that your only power settings were over and under what you thought you really needed...and had to try to compensate for that in technique.... on a safety related project.

As to the ' Wyotech' reference... I do not know what that is exactly.. but I promise you that a community college trained welder has had the opportunity to burn so much rod without regard to cost... that I highly recommend that type of training to anyone that might be interested... Stick welding is a ' hand eye coordination ' skill... ( after the decisions are made)... which benefits from PRACTICE.....

cooljjay · #12 09-20-2014, 08:34 PM

When I see people on here, with rotted out frames patching it up like a quilt....welding cracked frames...

I think to myself OMG what is wrong with you people....some times a car needs to be scrapped...

I don't care if you die in this car, but what happens if your doing 75mph on the freeway hit a pot hole, that LCA lets go completely, that spring pops out, the tire goes at an angle....you go into a min van with a family of 5 in there...

Do you just say, oh well I though my repair was good...

Man and driving that distance with it chained like that OMG!!!

Yeah stone me, flame me....what ever....but that stuff is just foolish to do...

Diesel911 · #13 09-20-2014, 10:01 PM

Quote:

Originally Posted by leathermang

I have never used a fluxcore wire welder... as I have other options...
I am sure they could be just fine for your operation..

What I have a problem with is your admission that your only power settings were over and under what you thought you really needed...and had to try to compensate for that in technique.... on a safety related project.

As to the ' Wyotech' reference... I do not know what that is exactly.. but I promise you that a community college trained welder has had the opportunity to burn so much rod without regard to cost... that I highly recommend that type of training to anyone that might be interested... Stick welding is a ' hand eye coordination ' skill... ( after the decisions are made)... which benefits from PRACTICE.....

Not true out here. You have to pay a Materials Fee and back a long time ago it was $150 a Semester. You also pay for your own Helment and Leather Apparel.
And, yes training is great; especially if you have it before you need it.

BillGrissom · #14 09-21-2014, 12:38 AM

Quote:

Originally Posted by cooljjay

... what happens if your doing 75mph on the freeway hit a pot hole, that LCA lets go completely, that spring pops out, the tire goes at an angle..
...
Man and driving that distance with it chained like that OMG!!!

Yeah stone me, flame me....what ever....but that stuff is just foolish to do...

I cast no stones. Wheels do come off sometimes and cars don't usually roll, except in the movies. Better in a car than a motorcycle. Control arms and tie rods break, but preferable to losing a wheel. I saw a fairly new car at my company's exit (speed bump) w/ one wheel pointing 90 deg away from the car. The local newspaper slowly test drove a then-new Hummer2 in the parking lot and something in the front suspension broke and pointed the wheel out. I suggest everyone look under your 300D and observe the pocket where the LCA pivots. Pretty thin metal isn't it? Same gage for the K-frame attachments to the frame rails.

I am sure the 1300 lb chain I used for the "get 'er home" fix more assuredly kept the LCA's together than the thin factory sheet-metal, even when it left the factory new in Germany. I would probably be safer driving like that all the time, but my L-bracket securing the top of the frame rail is tougher than the factory design, so I expect my car is now safer for that failure mode than anyone else's here. Of course, I haven't improved the left side yet.

There used to be state vehicle safety inspections when I lived in Florida. They were dropped in most states after repeated studies showed that defective cars weren't the cause of most accidents. It was invariably the defective biological control units, and now those controllers have Facebook in their lap.

whunter · #15 09-21-2014, 03:32 AM

Quote:

Originally Posted by BillGrissom

My 1984 300D right wheel started pointing 20 deg right with left wheel straight, while my son had it in San Diego. No photos that showed me the problem, so I had to take every tool I could think of. We were planning a Labor Day trip the next week anyway to swap the 1985 300D with him, but now drove our 2002 T&C van in case we had to tow-dolly it home (worst case). We tow-bar'ed the 1985 the 505 miles there (another post), saving fuel and easier for us, plus proved the method in case needed to recover the 1984.

I am sure most readers can imagine many things which could cause severe toe-out. Hint - when I bought the car years ago, the owner said the K-frame had "cracked again". First time was when it was stolen and crashed into a curb, then fixed by a shop. I found those weld repairs sound, but the left "LCA pocket" had cracked thru the hole, letting the LCA move outward, causing extreme camber & toe-out. After pulling back and tacking, I welded a metal strap across the bottom of the pocket. My son was sure the problem was that my weld had broken, but never sent photos of the left side, saying the problem was only on the right (makes sense?). 1st photo is my left LCA weld repair, still sound, though only 2nd time I had used my $90 Harbor Freight flux-wire welder.

I found the problem was on the right. The long-ago K-frame repair had separated (son swears he takes speed bumps lightly). The 2nd photo shows a large gap where it was welded to the spring tower, 3rd photo where it punched thru the bottom of the frame rail slightly. The car was in a parking garage. I strapped chains around the springs and used a come-along to pull the LCA back (as I did for prior right-side repair). I attached other chains (1300 lb rated, Ace Hardware) to the LCA's at their pivot and tightened (4th & 5th photo). The chain fit perfectly between the engine and K-frame, not touching the oil pan. I then adjust to 1/8" toe-in (used tape measure, required just slight tweak after pulling LCA tight) and drove 10 mi on I-5 to the motel, w/ just the chain holding the right LCA in position. The car drove like new, perfectly straight w/ hands off the wheel and steering wheel centered. Later, at the motel when I jacked the car by the frame, w/ wheels hanging, I found the chain loose so appears I didn't even need the come-along since the weight of the right wheel rotated the K-frame end into position.

We were going to tow-bar the 1984 home. Backup plan was to buy a tow-dolly (some for $400 on craigslist) or rent ($110 U-Haul). With a tow-bar, if something broke free the heavier van would still direct the car, so a bit safer. But, my wife wanted to attend a meeting in LA, so I ended up driving the 1984 home. No problems, or strange noises, and got 26 mpg even w/ crossing the mountains and stuck 2 hr in a jam (fatal accident in Lake Hughes). Many here wouldn't do that drive, and they should probably wear helmets while walking. I couldn't imagine the chains breaking.

At home, I made a permanent repair. I removed the turbo and engine mount, supported the car on the frame, then jacked the LCA pocket up tight against the K-frame and tacked in place, then removed the jack. The K-frame and LCA pocket is fairly thin sheet metal, not exactly the ruggedness people imagine of these cars (many also ask if I get 45 mpg, "no, that is VW diesels"). Previously I had fits trying to butt-weld a new floor (similar gage steel) in my 65 Dart, since kept getting burn-thrus. My HF welder has just min & max power settings. Max works well for 1/4" th steel, while min is a bit much for sheet metal. To try to reduce power further, I used a 100 ft, 16 awg AC extension cord (seemed to help). Welding was still tedious, w/ many passes of welding, wire-brushing, and grinding. I welded across some gaps by hammering re-bar tie wire into the gap.

To insure the top didn't pull away from the spring tower again, after solidly welding, I welded an L-brace over that (framing brace from Home Depot). Before covering bare sheet-metal you should protect both sides with "weld-thru primer". As others, I use the inexpensive "high zinc" primer shown. I also added a strap across the bottom to insure it couldn't punch thru the frame rail again. Probably over-kill, but don't want to revisit this repair. I would similarly improve the left side, but await a time when the hoses are out for other repairs. A tip, try to determine which side is thicker gage and start welding there, otherwise the new metal may stick to just the thinner side (appears what happened in the shop's job). In my case, the framing brace seemed thicker than the K-frame, and the lower strap seemed thinner than frame rail. Last photos (post 2) show the finished repair before paint.

Been there, done that, got the burns to prove it...
300D_why It Was For Sale Photos by whunter | Photobucket

Here is my emergency band-aid to get it home
300D_emergency Bandaid Body Steering Tube Repair Photos by whunter | Photobucket

Here is the correct repair, all done long ago.
300D_body Steering Repair Photos by whunter | Photobucket

This is now my Daughters car.

Your repair looks solid.

I agree it looks like you wrestled with excess power.

I strongly suggest getting a better welder.

Airco Mig Welder OBO

CRAFTSMAN MIG WELDER 110V IN VERY GOOD CONDITION

Lincoln Electric Mig Weld-Pac 100

millermatic 130 mig welder

.