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Old 06-13-2017, 05:05 AM
berntd berntd is offline
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Default Frame rail is deformed. How can I bend it?

I have discovered that my 1973 450SL Mercedes unibody resto left front frame rail is deformed.

It has been repaired before but not nearly correct.

It is bent in by 16mm or 5/8"
That is at the 2 subframe mount points.
I need another subframe as well as this one matches the deformation.
Camber=NO WAY.

I have a Porto Power and wonder how I could try to bend this.

I can't push much against the other rail as that would surely bend then?

The rails are held together at the front by a nose piece.

Any ideas anyone?

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The pic seems rotated here on the forum.

It is a top view of the frame member.
The red line shows where the edge if the member should be. The masonite with the plumb bob is, is on the frame ourside.

Inner and outer guards removed.

Regards
Bernt
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Last edited by Steve Hamilton; 06-13-2017 at 12:25 PM.
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  #2  
Old 06-13-2017, 05:16 AM
berntd berntd is offline
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Side profile of said frame rail.

It needs most bending near the top bend.

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Bernt

Last edited by berntd; 06-13-2017 at 10:34 PM.
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  #3  
Old 06-13-2017, 09:13 AM
crystallographic crystallographic is offline
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Quote:
Originally Posted by berntd View Post
Side profile if said frame rail.

It needs most bending near the top bend.
Hi Bernt,
If I am understanding your descriptions correctly, it looks as if the car took impact from the front, onto that corner. It compressed the frame and wrinkled the firewall.
When I pull out damage like this I always try to mentally grasp the angle/direction of the impact, so I can accurately reverse it when I make my push/ pull.

I think - if I am seeing this correctly - that I would make a push between the sway bar mount and point B on your drawing. I might think about releasing the patch on the sidewall, as well, as that could be holding against the push ....
You might have to make up two perches to use your Porto to shove against, and then clean them off, afterwards.

It looks as if the frame arch went up with the impact, and also curved along the top view. The top curve can also be pushed/pulled at the same time.

To correct some heavy frame damage I have had three and four jacks, with chains holding the frame at one time, when I use my frame table bolted to the floor of my shop. I also use an old "Kansas jack" to pull out sections. Blackhawk made a pretty heavy one, a "Dozer" or a "Pull Dozer," and I use one of those, which might help you, here.
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Old 06-13-2017, 10:04 AM
John Buchtenkirch John Buchtenkirch is offline
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If you don’t have frame pulling equipment and experience an alternative might be to cut out & replace that uni-body rail. Or consider farming out that part of the job to a professional.

I always hated working on Mercedes, removing the rubberized undercoating was the absolute worst. Also many of the Mercedes didn’t have lips (pinch weld areas) at the bottom of the rocker panels to hold the cars and I was never really comfortable pulling them from the 4 jacking points. YIKES ……… very glad to be retired from heavy collision work. ~ John Buchtenkirch
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Old 06-13-2017, 06:16 PM
berntd berntd is offline
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Hi Kent and John

Thaks for the replies.

Yes, the damage must have been from the front left. That arm has a built in crumple zone at the point I show the wrinkles near poin A.
It had all been pulled and repaired an heated with Oxy before as I found heaps of telltales of it. Pity they decided to just keep it matched to the bent subframe. there are telltales on the subframe of heating and pushing as well.


Kent, I wish I had that equipment as my whole problem is holding the car and having useful anchor points outside the car to push and pull.

I can only push and pull to anchor points within and on the car itself.
I may have to give this up as I just see no way to do it.

I could buy or make a floor frame with sill clamps just for this but man, that is a lot of effort.

None of the professionals I contacted so far were interested in taking this on.
None are even prepared to look and want the car towed there, which is expensive, just to look see.

As John suggested, I may need to transplant that whole arm after all. That means buying a whole other car :-(

Regards
Bernt
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Old 06-13-2017, 09:17 PM
John Buchtenkirch John Buchtenkirch is offline
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I’m very familiar with the Mercedes sub-frames mounted on the 4 rubber mounts and it’s really very hard to pull those 4 mounting points into the correct position without a modern 3D measuring system like shown in the photos below. Just ask the mutt that attempted to repair the car previously . If the nose isn’t swayed, then swapping in a used uni-body rail isn’t too bad of a job, that is why I suggested it. ~ John Buchtenkirch
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Old 06-13-2017, 10:04 PM
berntd berntd is offline
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Hi John, group,

I have actually been able to accurately measure the points on right side of that car to it's proper centre line as per Mercedes frame drawing to within 2mm. I am seriously impressed thta I was able to do this and actaully find this problem. It all looks pretty straights to the eye and even measing with tabpe measure does not reveal the secrets. it took several attempts and ideas to get to the point where I can now repeatedly measure all this and get the same results every time.


I am thinking to swap the whole arm by making a jig from 2 flat bars with holes bored into them to go from the right arm mounting point to the left.

That must then give the right distance left to right for the subframe to fit.

Then maybe 2 pieces of tubing straight down to the floor for the correct height.

Any ideas on that are most welcome, bearing in mind that I can't use the current arm as a guide because it is off.

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I 'll be going to look see that donor car this afternoon.
Hopefully it is usable and does not have similar issues!

Here is a picture of the subframe. The straight edge (timber in this case :-) ) is supposed to lie flat across the 2 cups but there is quite a gap.

Regards
Bernt
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Last edited by Steve Hamilton; 06-13-2017 at 11:02 PM.
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  #8  
Old 06-14-2017, 05:50 AM
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neilb neilb is offline
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i work at mercedes bodyshop, the jig we have is celette bracket, merc don't recommend the car-o-liner universal jigs, mounting brackets do come up for sale from time to time. i have checked on our parts system for a replacement chassis rail, and although one is listed it comes up with no price or availability info. i do know that panels are still available for older models as i have ordered a panel for an old merc that was being repaired at the bmw shop i worked at before moving to where i am now. i will say i ordered the part from the merc dealers i worked for in sheffield uk and had it sent to Melbourne oz as people here told me they were un available.

i will try and upload a picture from web parts
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Old 06-14-2017, 07:28 AM
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just guessing on the vin number but that is what is listed in the parts diagram number 5 is shown as the wheelhouse with the chassis rail attached but seems that the closing panel is not, but it could just be the picture. stock is available at global logistic centre Germany but i would advise against ordering one going on the price listed lol
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Old 06-15-2017, 12:05 AM
berntd berntd is offline
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Ah yes, that is why I am staying away from the Mercedes forums. They always suggest to just get a new part. I am on a low budget fixer upper here :-(

Hey hey guys!!!
I went to see the donour car yesterday. 2 cars in fact!

I could not believe it but the chassis rails on the 1st one are different to mine!
Mine is a 1973 and that was a 1975.
Such a real pity as the rails reasonably nice. T

The cross section is almost triangle shaped instead of my rectangle. More room between motor and rail but I am not sure if that would just fit into my car without heaps of other mods?

The 2nd one is a 1974 107.043
That has the same rails as mine and they appear straight.

But boy is that rusty!! The first 4" of that rail is just not even present and I can see right through it.

Oh man

What to do next?

Regards
Bernt
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