Need some bodywork advice. Trying to fix rear end damage on W123 - PeachParts Mercedes-Benz Forum

Mölyapina · #1 01-05-2016, 08:57 PM

Trying to fix some rear end damage on a 240D -- long story. The car was rear-ended by a garbage truck that was backing up.

Here is a picture of the car after the accident:

Here are pictures of the car with a new trunk lid fitted:

The problem is the trunk lid sill is pushed in 1/4" - 3/4", as shown in this picture:

Mölyapina · #2 01-05-2016, 09:00 PM

Here is my question: how should I go about bending back that part? A sledgehammer isn't going to work here, methinks. Here is the solution I am thinking of. I have a large bottle jack on an engine hoist. I can take that bottle jack, brace it on a bunch of 2x4s in the spare tire well (contact areas indicated by red circles), and place another 2x4 or 4x4 against the bent piece and use the jack to push the 2x4/4x4, and therefore the trunk sill, back into place.

How does this sound? I could brace the 2x4/4x4 with a piece of steel pipe or something to help it stay straight. I think it might have a shot of working because the trunk sill is supposed to be straight, as shown in the picure below. My main concern would be damaging the spare tire well. Do you guys think that would be an issue? Are there other ways of doing this than what I have proposed? What do you think?

Stretch · #3 01-05-2016, 09:31 PM

I think by pushing in those places with a bottle jack you will do more damage to the car rather than pushing the panel back out.

I would be looking at drilling out spot welds for that back panel and then knocking out the corners of the rear wings to get the shape there in the right place. Then plug weld the drilled out holes for the back panel once you've got that bit straightened out.

Mölyapina · #4 01-05-2016, 09:38 PM

Quote:

Originally Posted by Stretch

I think by pushing in those places with a bottle jack you will do more damage to the car rather than pushing the panel back out.

I would be looking at drilling out spot welds for that back panel and then knocking out the corners of the rear wings to get the shape there in the right place. Then plug weld the drilled out holes for the back panel once you've got that bit straightened out.

What is the back panel you refer to?

Stretch · #5 01-05-2016, 09:43 PM

Quote:

Originally Posted by Mölyapina

What is the back panel you refer to?

Bugger I knew I should have used pictures!

The whole "flat bit" where the lights fit is one panel. That is quite a flimsy thing when detached from the corners of the rear wings.

The rear wings give the rear end the shape and the stiffness. I reckon you will use less effort and make the least damage tackling each of those stiff corners with the connection to that flat panel removed. Drill out the spot welds - make the centre flat section floppy - bash out the corners as best you can...

...plug weld the back centre flat panel in place when done.

Mölyapina · #6 01-05-2016, 11:07 PM

Quote:

Originally Posted by Stretch

Bugger I knew I should have used pictures!

The whole "flat bit" where the lights fit is one panel. That is quite a flimsy thing when detached from the corners of the rear wings.

The rear wings give the rear end the shape and the stiffness. I reckon you will use less effort and make the least damage tackling each of those stiff corners with the connection to that flat panel removed. Drill out the spot welds - make the centre flat section floppy - bash out the corners as best you can...

...plug weld the back centre flat panel in place when done.

I'll try that if I can't just pull it out. Fingers crossed that I don't have to do that

Dan Stokes · #7 01-05-2016, 09:42 PM

I DO body work. The bottle jack will do the job or you can rent/beg/borrow/buy (HF has a serviceable one) a PortoPower (trade name for Blackhawk but widely used in the trade) and use the attachments to push the panel back. It'll take a little time as you'll have to over stretch it and determine how much it springs back. Also, when you have the lower back panel (that's what it's called) under pressure, tap lightly on the wrinkled areas to relieve the "memory" in the sheet metal. If you can get a template off a straight body (just trace the unbent one on cardboard and cut it out) it makes it a LOT easier to get it back to the right shape.

You can also carve out a block of wood to roughly fit that dent in the rear quarter and push that from inside the trunk to get that area back in shape - hardwood works best (old pallet skids are hardwood and free). A tip - drill a hole in your hardwood block for the jack's ram - it'll keep the block and ram in alignment.

EDIT: The areas you pointed out should work fine as push points. Any time you fold sheet metal it gets stronger so those 90* bends ought to be pretty stiff.

After that it's just finishing and painting. If you can't or don't want to handle that, MAACO can do a decent job if you do the prep.

Dan

97 SL320 · #8 01-05-2016, 10:07 PM

Is the front edge of the trunk lid in the proper place? If not you need to pull out / replace the hinges.

This can be straightened without drilling out welds. Any body shops near by? Pulling this back into shape is a few hour job with good tools so it might be worth subbing out.

t walgamuth · #9 01-05-2016, 10:40 PM

I have done some repairs like this. Always try to apply pressure and push out where it was pushed in. I like the hydraulic ram thingie. It comes with five or six different heads.

vstech · #10 01-05-2016, 10:42 PM

Ratchet straps holding vehicle still at the front, then pull out with additional straps.

ROLLGUY · #11 01-05-2016, 10:50 PM

Quote:

Originally Posted by vstech

Ratchet straps holding vehicle still at the front, then pull out with additional straps.

Agreed, with a 4x4 against the back panel, and straps on each end going through the tail light holes and over the top.

Mölyapina · #12 01-05-2016, 11:04 PM

Quote:

Originally Posted by Dan Stokes

I DO body work. The bottle jack will do the job or you can rent/beg/borrow/buy (HF has a serviceable one) a PortoPower (trade name for Blackhawk but widely used in the trade) and use the attachments to push the panel back. It'll take a little time as you'll have to over stretch it and determine how much it springs back. Also, when you have the lower back panel (that's what it's called) under pressure, tap lightly on the wrinkled areas to relieve the "memory" in the sheet metal. If you can get a template off a straight body (just trace the unbent one on cardboard and cut it out) it makes it a LOT easier to get it back to the right shape.

You can also carve out a block of wood to roughly fit that dent in the rear quarter and push that from inside the trunk to get that area back in shape - hardwood works best (old pallet skids are hardwood and free). A tip - drill a hole in your hardwood block for the jack's ram - it'll keep the block and ram in alignment.

EDIT: The areas you pointed out should work fine as push points. Any time you fold sheet metal it gets stronger so those 90* bends ought to be pretty stiff.

After that it's just finishing and painting. If you can't or don't want to handle that, MAACO can do a decent job if you do the prep.

Dan

Thanks for all the tips! I think I'll see if I can get away with using the bottle jack, since the porto-power kits are a bit more than I'd like to outlay and there aren't any used ones around.

Quote:

Originally Posted by 97 SL320

Is the front edge of the trunk lid in the proper place? If not you need to pull out / replace the hinges.

This can be straightened without drilling out welds. Any body shops near by? Pulling this back into shape is a few hour job with good tools so it might be worth subbing out.

Yes, the replacement lid fits perfectly at the front edge. I'll stop by a few shops and see what they say if I start thinking that I'm doing more harm than good.

Quote:

Originally Posted by t walgamuth

I have done some repairs like this. Always try to apply pressure and push out where it was pushed in. I like the hydraulic ram thingie. It comes with five or six different heads.

I think that's what Dan Stokes was talking about.

Quote:

Originally Posted by vstech

Ratchet straps holding vehicle still at the front, then pull out with additional straps.

Where would I hook the ratchet straps in the front?

Stretch · #13 01-06-2016, 03:14 AM

Bear in mind that the boot lid has a slight curve to it and that often when they have been stored their shape can be bent a bit out of whack - so don't put all of your trust in that shape.

I have no wish to start a heated debate over the best way to do this job - but for the record - the other ways described in this thread are more likely to need a lot more body filler once the main shape has been yanked back!

Oh yes - don't underestimate how rusty those spare wheel wells can get.

Skippy · #14 01-06-2016, 05:35 AM

That damage looks similar to what happened when my 300D got rearended a few years ago. I took it to a body shop that had a frame puller and let them take care of it. It wasn't exactly cheap, but the final result looks better than before it was hit.

Mölyapina · #15 01-06-2016, 08:16 AM

Quote:

Originally Posted by Skippy

That damage looks similar to what happened when my 300D got rearended a few years ago. I took it to a body shop that had a frame puller and let them take care of it. It wasn't exactly cheap, but the final result looks better than before it was hit.

How much did you pay, if you don't mind me asking?