Underseal and Trunk restoration

[Rick007]

Hello Guys ,

As i reported earlier it all started when i attended the Pagoda European Event last September , were i found out that that sqeeking noise from my rear axle was really
starting to anoy me , not to mention the swaying it did . With the advice of a few forum members i got the job don and an shyning almost new rear axle was looking at me to be installed . But having the axle out gave me a uportuninty to take a good look at my cars underside and started to scrape of the underseal ....And it was shocking to find out that this was not a moment too late . The trunk bottom-plate was completly gone . A previous owner thought it was good idea to just cover the rot wit sheetmetal an smeare a thick layer of black shi.... over it . This ment removing the trunk-bottom and weld a new one in . This is a precarius job because to do this without having to spray the car afterrwards means you have to have to go at it with great caution . But i did it and it worked out ok .
Now for my question : were are the holes for on the left side behinde the wheelarch ? foud them in my new sheetmetal that i installed and they seem like waterdrain-holes , and have 2 diameters . ( My car is a late 67 250 SL )

Well i will proceed with scraping the intire car and allready found my next metalwork . ( the 2 beams that run from the sills to the shockabsorber-cone ) this is a bit more difficult but not impossible ( already orderd the repair-sections from SLS ) .     

Thanks in advance for the help !

Rick007

[Larry & Norma]

Hi Rick,
Did you take photographs of your procedure, we would all benefit by seeing them.
The trunk floor welding without needing the fenders painted would be interesting to see.

[Naj ✝︎]

Hello Guys ,

Now for my question : were are the holes for on the left side behind the wheelarch ? found them in my new sheetmetal that i installed and they seem like waterdrain-holes , and have 2 diameters . ( My car is a late 67 250 SL )

  

Thanks in advance for the help !

Rick007

Hi, Rick,

The two holes in the panel are for late (70/71) US cars emissions control piping.

I guess there is now only one rationalised panel to suit all cars?

Another interesting change to these later cars is a small panel in the rear left wheel arch.
I guess it is there to avoid spraying the trunk panel with rain water and avoiding its deterioration.

How many people here with late cars have this panel?

Naj

[Rick007]

Thanks Naj , this makes sense because can't see any other reason for the holes . Think I'll plug them up with rubber caps , never know when i want to drain the trunk

And to answer your remark gnuface , i can tell you this : it is possible because the trunkfloor is not welded to the rear-panels ( allthough they were on mine , but was done with a piece of metal that was welded over the original remains of the floor ) like i sad it is doable and without damaging your panels . At the rear you need to trim the old floor at the seem and then fit the floor with a flush weld ( don't know the real English word for it ) but i mean don't overlap the panels or you'll end up with a double seem and to little material at the other end . The difficulty is getting the crossmember beam ( the one that holds your fuelpump ) free and tidy for the new floor . I used an air-chisel and spotweld-drill . Both the sidepanels are easier as the are straightforward , but leave the exhaust-clamps in place as the are attached to the beams that run from wheelarch to back .  I butwelded  most of the panels where possible , depending on the state of the underlying material , luckily my chassirails were still in good order . .....

Proceeding on to the front ...............

[Larry & Norma]

Thanks for the pictures, look forward to seeing the chassis rail ones.

[Rick007]

Progress so far ....

[Larry & Norma]

Looks like a tricky job. Are you a professional welder?

[tel76]

Hello Rick,
When i did my rails the rot carried forward to include the jack pickup point,i had to remove 22 inches of the sill to reach the point where the chassis rail /sill / crossmember meet in order to eliminate all the corrosion in that area,(this was done on both sides).
The repair sections did not carry forward enough and i had to make my own.
It is probable too late, but if not, open up the sill to ensure the corrosion has not gone too far forward.
To clarify, cut a section out at the sill end to inspect ,if everything is OK it is easy to weld in a new end section.
If the rot has carried forward you will have to remove a  section of sill ,the jacking point. Weld in new metal,repair the old jacking point and re weld it into position.
With the outer sill section i made a template and had a new piece made out of the same thickness of metal.

[114015]

Great work, Rick!

Keep on going!
I admired your car on the European Event; it is unbelievable how much sh... I mean shabbiness comes to the surface even with the nicer cars if we start to look close (very close).

How do you like the repair panels from SLS, the unpainted ones? I am thinking of getting a pair of these for my car but I don't know how good they are. As for the requested price I would like to get some recommendations in beforehand, e.g. you.
Do they fit well? Is it as thick as the original beam which was there before?

All the best & keep us updated

Achim


[One of the pics Naj showed looks so familar to me  ; don't remember where I saw that one before ... ]

[Rick007]

Thanks for the support guys , at this point I need it badly .
On the other hand it's very rewarding to do . When I looked inside the rails ( I have a keyhole camera ) I saw that the rails were gone because of overlaid sheet metal and the affect of water that went between the sheets .
I've don a lot of welding in the past on other cars and have seen worse situations . The repair sections from SLS do require fitting but this is in most repairs sections the case . My sills have already bin don by a professional car restorer ( have the invoice of that ) The former owner had that done , thank god . But I think he forgot to gave them the order to look at the backsection of the car .
But nevertheless the sills and bottom are renewed and I must say that it looks good and solid ( also on the inside ) .
One piece is in now but not welded up yet , because I need to repair the connection point of the axle as well , and this connects to the rail .  BTW I'm thinking of making the connection points for my seat belts in the rails now think it looks and fits better than in the bottom plate .

Will proceed on Monday evening again and will post the progress ....


Have a good weekend ! 

[Rick007]

Ok a small update on the progress so far ...

Got the welding on the back and rails finished . The repairsections from SLS were ok but really needed adjusting ,
and i can tell you  its always more then you bargain for , especially the reaction arm point and plate was a serious
job . But got all the rust out now and structural its original and sound again .  Have to give it a few more coats of anti rust and then i was planing on spraying repaintable anti stone chipping paint from 3M ....Anyone has experience with that ?
After that i would like to get the colour on because that black sh.... is never getting back on again .

[Dahlknudsen]

Another interesting change to these later cars is a small panel in the rear left wheel arch.
I guess it is there to avoid spraying the trunk panel with rain water and avoiding its deterioration.

How many people here with late cars have this panel?

Naj

hmm... mine had that panel, I just thought it was put there by some amateur bodyshop. I alwas wondered why! But they are original, sure dont look that like mercedes work to me, but its exactly the same as your picture Naj...

Thanks for clearing that up!

Jakob

[Larry & Norma]

Hi Rick
Looks like a great job, how do you protect the inside of the sections you just repaired? Do you think it would be
good to have a drain hole drilled at the lowest point?
I am planning to remove my rear axle shortly to renew the right wheel bearing and replace suspension rubber, I am
a little worried what I may find after seeing yours!
Larry

[Rick007]

Hi Larry ,

Well before i closed the boxsections i gave the inside a coat of 2 pack antirust primer . The panel that closed the rail was also coated on the inside with weld throu primer .
I don't rely on this alone for rustprevention do ,so i will drill some holes for the cavitywax , still have to decide on the exact locations .
I already suspected the back of the car was not so good ... but as you know once you start to dismantle the parts there's no end .

I also started with the axle , and it is true , once you decide to pull the axle then you better do it all ( on the axle i mean ) . So replace the bushings from the middle as well .
( Naj gave me some good advice in this forum ) Because if you don't have a ramp or carlift you don't want to do this again .... I think

Greetings ...

[wwheeler]

I have used both the 3M beige and the Wurth stone guard beige in a spray cans and the Wurth SKS stone guard used with a gun.   

The SKS is a courser finish more like the factory finish. It is water based but dries to a very tough coating and is black. You need to buy a "shutz gun" to use it. Wurth sells an expensive gun that works very well and a cheaper gun that I haven't used.

The Wurth spray stone guard is a solvent (VERY solvent) compound and is beige, black or clear. The beige is exactly the same color as the vintage MB coating. BUT... Wurth is discontinuing the beige color and they do have some left in stock if you buy now. This coating is not as tough or as rough as the factory and is somewhat elastic. A good coating nonetheless. It's best use is to touch up old coatings.

The 3M stone guard is maybe a little rougher than the Wurth but is more brittle. It's beige color is close to the original MB coating and is a good coating.

My conclusion is:

If coating a new metal surface, I would use the Wurth SKS to get the correct texture. You will have to paint it beige to match the correct color unless you are painting the entire underside body color. If going with a spray can, the wurth is better but beige is limited. The 3M is a good substitute.

[Rick007]

See what you mean , but don't know if i would want the underside in beige ... Its a silver coloured car ( 180 ) .
The stuff i scraped of was a bit ..offwhite ! Maybe not OEM but think i'll go for the grey 3m stuff ( applied with gun ) and then coverd with car colour .

 Thanks for the advise do..

[don p]

When I used the 3m shutz gun for my rocker covers you had to hold the gun upright or it would not work.
Is there a diffrent gun that allows you to paint straight up?