Transforming a W111 Coupe into a Convertible? - PeachParts Mercedes-Benz Forum

GGR · #1 10-20-2009, 02:13 PM

I've seen several W111 Coupe transformed into convertibles for sale on EBay recently. There are two right now:

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=290359823434&viewitem=&sspagename=STRK%3AMEWAX%3AIT

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=290360263563&viewitem=&sspagename=STRK%3AMEWAX%3AIT

this third one has ended:

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=290358124397&viewitem=&sspagename=STRK%3AMEWAX%3AIT

all for sale by the same seller...

Adds usually claim that the transfoemation is made by using all original MB parts. Given the number of them, it looks to me there must be some shops out there who do it regularly. Would anybody know af any of them? What is involved it doing such a transformation properly? Is there a webpage somewhere where such a transformation is documented?

I may consider such a transformation myself after I've sorted out the mechanical side of my project. And as I also like the look of the Coupe very much, I would study the possibility of making a hard top out of the original roof, ala Pagoda: I would drive a Coupe in winter time, and a Convertible in summertime!

Pooka · #2 10-20-2009, 04:51 PM

Considering that the originals were done by hand I guess the parts would be available since Mercedes will sell you any part if you have the money to buy it and they have it to sell.

Originals like this go for around $150,000. I don't see how anyone could do the conversion and make a profit on the deal if all they could get for one is maybe $35,000, though. I am taking into account the cost of the rest of the restorations here.

As far as having it done I guess it would all come down to the skill of the converter.

Mark DiSilvestro · #3 10-20-2009, 04:56 PM

Aside from whatever effect a conversion might have on the car's value, factory-built convertibles generally have additional chassis/body bracing and reinforcement to make up for the lack of a steel roof to tie the structure together.
You need to consider whether a conversion shop will be able to properly and safely reinforce a coupe body for convertible service!

Happy Motoring, Mark

stimpy451 · #4 10-20-2009, 04:56 PM

I saw that first car on the PCH just a month or so ago. I followed it up into old Topanga canyon, driver looked like he was having fun.

Tomguy · #5 10-20-2009, 05:34 PM

A 111 convertible, being out of my budget, might be within reach if I were able to convert a coupe myself as well! It sounds great, but as Mark points out, work is REQUIRED to reinforce the chassis so the unibody is not permanently compromised by lopping the top off. And it must be done BEFORE the top is lopped off, otherwise the unibody will already start out warped!

GGR · #6 10-20-2009, 06:21 PM

I have looked on EPC and there are some reinforcement brackets in the back around the soft top pit. Most importantly, the reference of the inner sills is not the same. They must be thicker. One has to study this properly and see if it's better to replace the sills or to add vertical "holed" plate in between the inner and the outer sills. This is quite a good stiffening method used by Jaguar (MK II versus S Type). I've also seen it done recently on pictures a 6.3 restoration in the UK.

Regarding the value, my car already mechanically not original anymore... so a bit more or a bit less... It's mostly a question of doing it right.

Q45Denver · #7 10-21-2009, 12:19 AM

If the conversions are as cheap as the ones that were listed on Ebay, then why not just sell yours and buy one that has already been converted? Not like there is much premiun on the conversions anyways so you might be able to trade straight across. Be careful of rust and poorly done conversions. I remember quite awhile back when the conversion kits were being sold online for about $1000. Or better yet get a 300CE convertible.

t walgamuth · #8 10-21-2009, 06:17 AM

I don't know the specific values of the cars being discussed, but have done a lot of reading about collectible cars in general. The converts are generally worth about double the original coupes usually. A cut car is generally worth the same as the coupe it was cut from even assuming it is done correctly.

I think getting it done correctly would be tricky with the unit body benzes. OTOH, I would be interested in knowing if by "using factory parts" means all the structural reinforcing or just the top mechanism?

I drove a converted 123 once and it felt pretty loose. It was a shaggy dog and the seller wanted about double what I thought it was worth so I didn't bring it home.

Mark DiSilvestro · #9 10-21-2009, 09:46 AM

Quote:

Originally Posted by t walgamuth

I don't know the specific values of the cars being discussed, but have done a lot of reading about collectible cars in general. The converts are generally worth about double the original coupes usually. A cut car is generally worth the same as the coupe it was cut from even assuming it is done correctly.

I think getting it done correctly would be tricky with the unit body benzes. OTOH, I would be interested in knowing if by "using factory parts" means all the structural reinforcing or just the top mechanism?

I drove a converted 123 once and it felt pretty loose. It was a shaggy dog and the seller wanted about double what I thought it was worth so I didn't bring it home.

Even if the unibody had all the correct reinforcing added, I would be concerned with the quality of the welds, and if they were treated, coated or whatever needs to be done to preserve those areas. I've seen plenty of shoddy welds on simple jobs like rusted floors, where the repairs rusted faster and far worse than the original!

On one of my occasional trips to the local Mercedes dealer around 1980, I remember seeing one of those W123 convertibles in the showroom. This was when no domestic manufactureres were offering a factory-built 4-seat convertible, so a number of aftermarket companies popped up to do conversions of such popular cars as the Buick Riviera, Caddilac Eldorado and 300CD. I remember reading road-tests on some of these conversions that suggested the body stiffening wasn't quite up to par. And these were new cars, supposedly converted professionally, with all the required bracing. I don't think I would want to risk a chop-job on a vintage car.

Happy Motoring, Mark

alabbasi · #10 10-21-2009, 10:43 AM

I don't think I would have any issues buying one if it has been strengthened. I've cut a W109 up and can tell you that there is a lot of strength built into these cars. What exactly are we worried about? That it won't cope in an Accident? I think a Ford Focus would hold up in a front or side collision better then most 35-40 year old car.

GGR · #11 10-21-2009, 11:26 AM

Well, a nice original convertible is out of bound for nmy wallet: I see some advertised as high as $150.000. Not sure they sell though... I see more of them advertised in the $80.000 range, which is also out of bound.

Buying an already converted one while selling my Coupe can make sense financially, but there are three issues:
- the first one is the quality of the job that has been done.
- the second one is that my Coupe already went through quite some work mechanically (soon fitted with a Megasquirted Euro 5.0 engine with manual trans, internals of a 6.3 diff in a 4.5 one etc.) and I don't want transplant all that from one car to another.
- the third one is the pleasure of doing it as much as possible by myself, as a continuity of what I have started mechanically. In my case, the process is as much pleasure as the final result, it's my hobby.

It is a question of looking in detail into what is involved for a satisfactory result both in terms of stiffness and finish, establish a budget and see it it is in my range financially and capacity.

Q45Denver, could you tell me more about these $1000 kits that were available online? May be there is one left somwhere? It would nice to trace one to see what it is made of.

Tony H · #12 10-21-2009, 04:17 PM

The driveshaft tunnel is different on cabs also. I would be concerned about the long term integrity of a conversion. According to a MB restoration expert even factory cabs suffer from body distortion and need to be straightened out for a correct restoration. Doors not closing properly and uneven panel lines are a possibility. See if you can look at a conversion that was done a while ago.

Q45Denver · #13 10-21-2009, 04:21 PM

[QUOTE=GGR;2321032]Well, a nice original convertible is out of bound for nmy wallet: I see some advertised as high as $150.000. Not sure they sell though... I see more of them advertised in the $80.000 range, which is also out of bound.

Buying an already converted one while selling my Coupe can make sense financially, but there are three issues:
- the first one is the quality of the job that has been done.
- the second one is that my Coupe already went through quite some work mechanically (soon fitted with a Megasquirted Euro 5.0 engine with manual trans, internals of a 6.3 diff in a 4.5 one etc.) and I don't want transplant all that from one car to another.
- the third one is the pleasure of doing it as much as possible by myself, as a continuity of what I have started mechanically. In my case, the process is as much pleasure as the final result, it's my hobby.

It is a question of looking in detail into what is involved for a satisfactory result both in terms of stiffness and finish, establish a budget and see it it is in my range financially and capacity.

Q45Denver, could you tell me more about these $1000 kits that were available online? May be there is one left somwhere? It would nice to trace one to see what it is made of.[/QUOTE)

Haven't really checked prices lately but I would guess you can still get a nice original 220 or 250 convertible in the $30-50K range. A restored V-8 or 300SE might set you back $150K but these cars cost alot to retore. The 3.5 conversions on eBay might have cost several times their auction price to restore. The auction for the manual 3.5 which ends tomorrow would be quite the W111 to have.

I know the convertibles had some additional stiffing in the frame rails but that should not be too difficult to add. The top was built to a very high standard and driving in winter should not be a problem.

Don't remember too much about the kits other than they were closing them out as it was over ten years ago when I checked. You might call Bud's Benz or Silver Star restorations to see if they can help.

pch2021 · #14 10-21-2009, 07:50 PM

I'm currently working on a 3.5 cabrio conversion.

the car was done in the 80's.

my advice: A coupe is better. The cabrio was stiffened in numerous ways, all of which were very difficult to do to a coupe.

Buy a 220SE cabrio. Find one sold privately, needing some interior/rust repair, and maybe a few mechanical. They don't cost that much.