Someone posted a thread about their rusted frame rails not too long ago. Mine are all dented up as it looks like someone used it to jack up the car. Are these frame rails really that weak? I mean, it is a frame. You'd think it'd be pretty beefy.

I'm kinda scared to pull back the undercoating to see how bad it looks. Might have the same rust problem as the previous poster.

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B
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1983 300SD

What happens is that someone puts jack stands under the frame rail without a block of wood. The jack stand puts a very high point load on the frame rail and does some localized damage. The frame rails are not structural steel..........they are simply stamped sheet metal.

So, a word to the wise. If you have the typical jackstand, make sure there is a piece of wood on top of it. The wood makes all kinds of cracking sounds but it evenly distributes the load onto the frame rail.

I've jacked the SD about 20 times using this method over the past five months
(two times today. )

Another word to the wise, be very wary if your frame looks like this too. My car was "rust free.'' I scraped back the undercoating to find some ugly cancer right in that area. ugh...

I'll post a pic soon.

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B
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1983 300SD

Welcome to the wonderful world of unibody

I've found that if your car has no rust, you can put a small piece of wood on top of your jack and jack on the rubber bumpers underneath the holes in which the tire jack would go.

Never had problems so far. I just can't conciously jack on unibody frame rails when there is a diesel engine hanging off the front of the car

So I use the little pads

Actually from my experience your front rails do not look that bad. Certainly probe them when checking them out. If pretty good I would spray a mixture of grease and oil into them. Generally after that they will not deteriate or at such a slow rate the rest of the car will disinegrate prior to any trouble from them. They of course gain their strength from the shape the metal is punch pressed into while not having particular great strength over a small load bearing area and as previously mentioned they bend and deform a little even if in good condition if load is not spread when car is jacked up at or resting on them.

Here's some shots of the rust... All the way through on the bottom where it looks like a single layer connects with a thicker (double?) layer.

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B
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1983 300SD

That's not good.

But, it's not too difficult to fix. You need a doubler plate on the underside and an additional plate on the outside. 1/8" plate should be plenty.

ooh. nice frame rails, wish mine were that nice. Soon though they will be. I've just welded the doors and quarters, the frame rails are next. - BTW, the metal on those rails is pretty thin, less than 1/16" everywhere I measured it - but overlapped at the front bottom corner.

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'82 300SD - 361K mi - "Blue"

"Good judgement comes from experience. Experience comes from bad judgement."

listen, look, .........and duck.

Quote:
Originally Posted by RUN-EM
Rust always wins Move south. TEXAS is a big state....sure we can find room fer ya !
Regards
Run-em
1983 300 S D -aka.- SPARKY THE DIESEL

I have lived down there.
Galveston, Texas = salt water RUST
Corpus Christi, Texas = salt water RUST
Don't forget the fire ants, killer bees, scorpions and random Hurricane to make life fun.