W123 - Advice needed on jack point rust
 

bodywork experts,

I just got winter beater 85 300D, and I am getting it ready to go. I poked around at the one major rust area, the front jack point / rocker panel.

I discovered quite a bit of rust after stripping the chunks away.

Outside front driver's jack point area:
http://i414.photobucket.com/albums/p...08/mike012.jpg

Inside the driver's footwell:
http://i414.photobucket.com/albums/p...08/mike015.jpg

This car is not going to be a show car. I just want to make it last a while (5 years?) as a winter car. what's the best way to practically repair it? looks dont matter.

I have plenty of POR-15 and fiberglass cloth and bondo waiting. I don't have a welder, although I could access one. I am leaning towards coating in POR-15 and then using fiberglass cloth + bondo to fill the gaps since the area is not structural and full of complex curves that would be hard to fabricate.

Thanks,
dd

diesel,

i've done exactly this type of repair. the jack hole is part of the inner rocker panel support. if its rusted through, there's no way it can be reused. take a look at my blog in my sig, and read my Feb 14th, 18th and March 16th entries. if you want detailed advice, please email or PM me.

you sir, are a rust warrior...my goodness thats a lot of work and a labor of love. I hope the engine runs well :-)

The jack point itself is not ruster through, just the rocker panel around it.

I guess the main difference between us is that I need to get this car on the road in the next couple of weeks before they lay salt down on the roads ( so I can get my rust free car away from all salt :-) ).

Would you attempt this fix with fiberglass? I cant access the area as easily as your 124, there is a sheet metal flange in the way. All my welding (if I somehow acquired a MIG and learned to use it) would be inside the cabin, around the flammable foam. I can take some better pictures.

dd

Update - help....
 

Removed lots of the rust today. Its bad.

http://i414.photobucket.com/albums/p...8/lance001.jpg


http://i414.photobucket.com/albums/p...8/lance002.jpg


As I removed more, I found it had rusted a lot of the floor:

http://i414.photobucket.com/albums/p...8/lance007.jpg

http://i414.photobucket.com/albums/p...8/lance008.jpg

http://i414.photobucket.com/albums/p...8/lance009.jpg


I have driven this car less than 2 miles since I bought it. I was not expecting this at all. If I had known I wouldnt have gone poking.

What would you do? I need help...

If this is just a winter beater, I would treat the rust with POR-15 and then glue in sheet metal using pop rivets and JB Weld. Then coat that with POR-15 and top coat, then use rubberized undercoat under the car.

You could try welding in as much as possible and then finish it with the JB-Weld and pop rivets.

Chad, do you own stock in the JB Weld company?

You definitely need to weld in metal. This is a "unibody" car and the floor panels are the main lateral support.

No, but I probably should.:D

Thanks for the advice guys.

I have never welded before, so this may be the time to learn. I can't see completing everything by welding, I will probably need an eclectic mix of techniques for this.

How do I weld inside a car without it catching on fire?

and...

Anyone every use the POR-15 epoxy putty for this sort of thing?

dd

I used the putty in addition to the fiber sheets from the floorpan kit sold by POR-15. I repaired my rear floor and it is holding up very well.

The only way to keep the car from catching fire while welding is to remove the undercoating far enough from your welds and use a welding blanket to cover everything else. That's why I recommend using a combo of welds and JB-Weld or some other epoxy to glue some sheet metal in place with pop rivets.

I would go through the effort of stripping the car for full welding if you were expecting more from this car than being a winter beater.

Thanks Chas.

The cars purpose is as a winter beater and summer backup car for hopefully several winters. Ironically, there are no other major rust spots like this one. The undercarriage is fine.

Im happy to hear the POR-15 kit is working well for you. I have their fiberglass and epoxy putty waiting. I thought that would be all I would require.

Im really at a crossroads as to what to do.

Slap POR-15 everywhere, fix it with fiberglass cloth and epoxy putty and go. See how the car acts (i have only driven it 2 miles since buying it) for a year and re-assess.

OR

Buy a MIG welder and fashion in as many new pieces as I can using 16 gauge steel, filling gaps with cloth and epoxy putty.

Either way I wasn't expecting to put in this much effort before winter, so Im bummed.

Whats a good stripper for the undercoat?

dd

I can cut you a panel from a rust free car, that you could just weld in for $50 plus shipping

A heat gun and a chisel/scraper.

Quite a few new cars a being assembled with epoxies. I think you might get away with glueing in sheetmetal with Pop rivets for extra strength. I couldn't guarantee how it would hold up in an accident, but it would drive around fine. The repair I did on my floor board took a good whack with a 3 lb hammer and didn't crack or budge.

I wouldn't rely on the fiber sheets alone, but sheetmetal glued in and pop riveted and then coated with the fiber sheets will be VERY strong. I also use POR-15 paint with the fiber sheets, not resin.

Update
 

Well I took the plunge and got a MIG setup (Lincoln Electric Pro 140) to fix it right. I have some 16 and 22 gauge to weld in there.

(thanks for the offer to get a whole piece to weld in there, but I think it would not be easy to put in several surfaces like that.)

My questions -

1) should I work outside in, or inside out?

2.) for welding on the inside, as long as I back the insulation far away enough, do I need to take the dash out? or can i carefully cover the dash with welding blankets?

dd

dd,

btw, where are you in boston? spent 2 years at babson for grad school. somethings i miss about beantown, but not much ;)

have you gone through my blog? alot of the questions you asked are pretty well covered in there. I would reall take that person's offer for the rocker part for $50. you are getting a steal. not to mention, you will save yourself a TON OF HEADACHE.

as for catching things on fire, the most flammable stuff I found was this foamy black brittle material located at the front driver's side. i didnt find anything like that anywhere else. there's interior mastic which I took off by heating it w/ a mapp torch and a scraper. just wave it over a small 8 inch section at a time.

i know what youre worried about re catching things on fire. just make sure to spot weld from one end to the other with each spot weld being about 1" from each other. for example:

section youre going to weld:
-------------------------------------------

start a spot weld at each end:
X-----------------------------------------X

maybe put 2 to 3 in the middle:

X-------X-------X---------X--------------X

then work from one end to the other:

X----X-----X----X------X------X----X----X

the key is to allow the metal to cool.

also, be aware that galvanized steel is not good for you. i always powered a fan at speed setting 1 and held my breath when welding. and make 110% sure that you're welding bare metal. youll quickly realize that the ugly welds are usually caused by unclean metal.

email me for more tips and/or clarification re my blog entries. trust me after you read it, you'll have acquired a year's worth of hard earned knowledge!

bob

Bob -I have read through your blog. Thanks for documenting things so clearly. I wish I had the time to publicly document my work like that. All I have for now is thousands of pictures and greasy handwritten journal entries.

I took took joey dale up on his offer (as bob suggested). He is sending me the area thats rusted out cut out of a rust free florida car. After rethinking, that is definitely the way to go. It means my work will be fitting it into the car, not bending sheet metal into place like you did.

I got my welding setup complete. I actually ended up getting a Hobart Handler 140, it came with free shipping and a cart for $479 from Northern Tools.

Bob - what settings do you use on the Hobart for welding the MB steel?

An aside: For those looking in the future for which MIG/Flux core setup to buy, the Hobart machine is made by Miller and seems to get universally good reviews. The Lincoln Electric Pro-Mig series is made specifically for Lowes (which made me nervous about obtaining parts way down the road), and was slightly more expensive at $529+ tax. My research concluded the two units were really the same, and I could get the Hobart serviced at my local shop if needed. I got the argon tank and safety gear from my local welding shop. A respectable MIG setup after all the machine, gas, safety gear, wire, and other tools, cost me about $1000, but Ill have it forever and really I just wanted an excuse to get one.

Ill be back with pics and questions when all the components get here and I get get a good look at it all.

Im excited to do this right, even though its turning out to be a lot more than I bargained for.

dd

Good luck Dan. Congratulations on the new tool.:cool:

So what are you going to get to use as your winter beater now.:D

Maybe with any luck I can keep my 'no salt' car on the road until I finish this. No salt on the roads here yet. But if I get stuck Ill use my sister's 2001 Corolla that is dormant while she is at college (MAJOR downgrade in all respects from a W123). So no worries.

Trust me, once fixed, this car still qualifies for winter beater status :-)

Did your panel arrive in good shape?

Joey - Yes it did, thank you! It's great - I now have a piece I can weld in. I am jealous that a car that has zero rust could be in a junkyard FL. Unless it was an accident car, its still driving around somehow up here. I still do need a midnight blue front fender...:D

The only question now is how exactly to stitch it in, and where to cut. I will need to take some pictures of the piece alongside the car to get opinions. I could cut very high up the pillar in front of the door , but I dont know if that is a good idea.

This is the epitome of 'measure twice, cut once'.

dd

That piece is really off of half a car. Its easier to trim the new section than it is to trim the car. I would start by removing all of the rust, if its rustly, keep cutting. Then trim the new piece so that it is exactly the same size and shape as the hole. Then the fun starts. It would be a good idea to get some weld through primer, and use it on both the car and the patch. Make small (10mm) long welds at a time, if you weld to much in one area at a time, the heat will warp the car and panel, and it will no longer fit. Take your time and go slow, and it will all work out.

now i really really need help :-)
 

Okay, here are some pics. I dont really know where to cut and how much to replace. How should I deal with the rusty jack point - cut the whole thing out?

First a couple shots of the cleaned up rust:

http://i414.photobucket.com/albums/p...8/IMG_0491.jpg

http://i414.photobucket.com/albums/p...8/IMG_0492.jpg

Now some side by sides of the piece against the infected area:

http://i414.photobucket.com/albums/p...8/IMG_0493.jpg

http://i414.photobucket.com/albums/p...8/IMG_0494.jpg

Rear View
http://i414.photobucket.com/albums/p...8/IMG_0495.jpg

Top View
http://i414.photobucket.com/albums/p...8/IMG_0490.jpg

Any ideas on where to cut and how much? I feel like cutting into the vertical pillar would be a poor idea. My main question is how to deal with the jack point itself - the jack point is okay, the stuff around it is rusted.

dd

joey, thanks again for the piece. now that I see the heft and thickness of the metal, I cant imagine doing this with fiberglass or even 16 gauge.

I would cut out the jack point. The patch that I sent you has the whole thing. Also, I would try to use the patch as one piece, not a little here and there. If you feel up to it you should cut high up on the car, if you cut to low the jack point will be a major pain in the butt to weld in. OK, its past my bed time, so I am going to stop rambling now.

i'll respond to you tonight on where i'd cut with colored lines. i 'm at work right now

thanks bob - I look forward to it!

dd,

ok, lemme write first before i send modified pics. based on my experience and what joey advised, cut out as much rust as possible. the general rule of thumb seesm to be 1" past the edge of the rust. however, here is where I disagree with joey. joey mentioned to cut to shape, but I found better success with straight lines and the least # of lines as possible. the more lines and angles you cut, the less likely you are going to match them all perfectly once you start welding. furthermore, if you weld, the metal will ***contract*** so if you don't put a spot weld on one side and then move to another, the gap on the other side will get incrementally larger.

A-pillar advice: the rust is creeping up underneath the overlapped section. i saw it one too many times on my car and i know for 110% sure that is happening to yours. what you need to do is to (contrary to the rule of thumb above) is to cut away little slivers of the overlapped part until you dont see rust. guarantee waht you see underneath is rusted metal. but the good thing (at least from my experience and my car) is that mercedes puts that yellow anti-rust stuff underneath overlapping sections, presumably to stifle potential rust growth. so if you have an air die cutter or a dremel, cut away. there might be enough metal for you to then weld onto the lower panel if its not too rusted. and remember: always grind down to bare metal. this is where a dremel comes in handy b/c its a more precise tool. weld on a little rust, you will get horrible results. you will know by the sound and by the feel when you are welding on dirty metal vs clean.

jackpoint: its gone. dont even think about salvaging it. count your blessings that joey did such a good job cutting that nice piece for you. its the same feeling i get when my local sushi chef pulls out that big ass piece of fatty tuna from the back for me and the wife :D you may need to weld in a piece of metal in the area that extends inward...just eyeballing the pics you have.

weld thru primer: mixed feelings on that stuff. i didnt find it really good. but i always tried to use it on the interior side.

tools: do you have a grinder w/ cutting, grinding and flap discs? if no, go buy yourself a $60 dewalt from lowes and a bunch of cutting discs. a grinding disc goes a long way. 24 grit is good for sanding down your donor piece. but get a dremel w/ reinforced fiberglass discs if you dont ahve a compressor and an air tool cutter to do precision cuts

safety: WEAR EYE PROTECTION. wear hearing protection, even when welding. it'll make everything so much more tolerable. also, when you weld, galvanized steel fumes are not good for you. so what i did was i set a box fan a few feet away at speed setting 1. just enough to blow away fumes but not affect the gas coming out of the welder tip. practice and you'll discover what i'm talking about

i gotta do a little work on my car, so i'll post pics later and write a little more too.

dd: this is salvagable. dont fret, you'll do fine.

thanks bob - interested to see your drawings. i cant tell how much of the A pillar you are suggesting to cut into and where. it seems if I want to replace the jack point i have to cut high.

i have a dewalt angle grinder with cutting discs, a dremel with lots of 1.5" cut off wheels and assorted attachments, a full mig setup and a 10lb spool of mig wire, clamps, brushes etc......

Im just concentrating on the sense of accomplishment ill feel :-) seriously though, im having a lot of fun. too bad its now really cold out in the garage.

dd

bob,

Sorry - didnt see your drawings until now. they look great! I like that methodology.

o you are saying leave the jack point itself along, right? Just cut the sheet metal around it and re-weld in around it? I like that idea - leaving the structural stuff alone wherever possible.

I will take pics as I go through the whole thing. The A pillar is not bad, by the way. I wont have to cut much.

Thank you!
dd

Update
 

Spent the weekend going through and fitting in the piece I go from Joey. I had to split it into two pieces, I just couldn't get it to fit other wise.

Of course this post would be much more meaningful with pics, but I forgot my camera at home. Ill post later.

So here's my question for now:

So now with the pieces fit up, I do have some gaps between the two pieces I need to fill butt welding. Some up to 1/4". In some spots I can stitch in slivers of 16 gauge, but on most its pretty close. What's the best technique for gap filling? I have seen references to putting a backing piece of non-steel behind the gap to extend the weld pool (i.e. copper), but I dont know if this is valid here.

I practiced MIG welding with my new Hobart 140 last night for the first time. Cool! I can lay weld beads easily, and even do butt welds too. But I am having a hard time gap filling, hence my above question.

Pics later tonight..
dd

Turn the heat down, increase the speed and use .030" or smaller wire. Are you using gas or fluxcore? If you are using gas then dial the gas down as low as you can go.

Filling is a breeze once you get the settings right. You can fill a panel easy enough using a copper backing plate but I doubt you have access to the areas you are filling.

Small beads around the edges, let cool and then return. Get the edges close, build a "bridge" and fill the gap in a circular bead.

If you are using fluxcore then be sure to hit the bead after each pass with a wire brush to get a good solid weld.

Mike,

Thank you for the advice. I am using .030 wire, with standard 75/25 Ar/CO2 gas. Just curious, how does decreasing gas flow affect the weld? I will be able to access a good deal of the backside of the welding I am doing to put on a copper plate. See pics in next post...

dd

Update with pics
 

Okay, as promised here re a couple pics of the donor piece #1. There is a second portion of the donor piece not pictured here, Ill take some pics the next day I have in the garage.

http://i414.photobucket.com/albums/p...8/IMG_0510.jpg

http://i414.photobucket.com/albums/p...8/IMG_0511.jpg

I measured very carefully, it was just a big complex piece to get in there fit perfectly.

dd

Yup, you're gonna get good with filling after this one!:D

You can use a copper sheet for most of it from the looks of the pictures. That is structural so you need to get as much metal to metal contact as possible.

Turning the gas down will help you when you are doing the "fill" between the bridges. It lessens the weld's tendency to "balloon" when you are trying to do the circular part.

dan,

not bad cutting the piece to fit! so how'd it turn out? any pics?

take your time
 

JUst make sure that you take your time. After your done go over the whole area with por-15 and start fillin.....happy sanding

Update
 

Well its been awhile ... but the welding is done and now I am POR-15ing the area.

What I did was use 1/8" TIG rods as filler material where the gaps were over 1/8". Other than that I just went slow, tacked, ground and filled. Needless to say I got much better at welding as the task went on...

Some notes:
- I used a thick welding blanket on the inside of the car. I was paranoid and careful not to burn the inside of the car.
- I wore a respirator and earplugs 100% of the time. This made such a difference.
- If you are learning to weld, an auto-darkening helmet is absolutely necessary


Some pics of the highlights -

Example of tack-ing in the TIG rods:

http://i414.photobucket.com/albums/p...8/IMG_0522.jpg

Filled in area pictured above:

http://i414.photobucket.com/albums/p...8/IMG_0523.jpg

Front section ground down:

http://i414.photobucket.com/albums/p...8/IMG_0526.jpg

I am super happy with how it turned out. I am now sealing it up, undercoating, and getting ready to put the front fender back on. Its late now, but when the job is done Ill do a more complete post on techniques.

Thanks again to everyone here...
dd

Looks great Dan!! Nice work and keep the pics coming.:cool:

I also have w124's w126's and w107's that I will gladly cut up.

Nice work! My ears are ringing from the sound of your grinder from just looking at the pictures.

Lookin' good!

Why the earplugs when welding? While running a MIG I like to use the sound as a gauge for my speed/power rates.

Good question...

Two reasons:

1.) On this project I went back and forth between welding and grinding frquently. It was nice just to flip my mask up and grind (I wear safety glasses and a respirator under my welding helmet)

2.) I was in contorted positions under the car to weld the rocker. Sparks would go everywhere, and the earplugs made sure no live sparks went into my ears. :eek:

Normally, if I am welding I now don't wear earplugs. I didn't for my latest floor replacement project.

dd

you can still hear the 'sizzle' when wearing ear plugs. but like dan, i was doing alot of grinding and welding, so it became a necessity to have them in.