W124 Cabriolet - Manual Top Bypass
 

This will show notes and pictures of simple work needed to "convert" a non-functioning convertible to manual operation. This may not work for every car, and it certainly involves risks for the owners and passengers.

Bought the 93 300CE Cabriolet (155,000 miles) from an owner who had purchased it as non-functional top, won't go down. He had sent top CPU to a shop, they said it was fried, replacement $800. He balked at that, and decided to take matters into his own hands. He removed the seats and the roll bar assembly, disconnected virtually every hydraulic line, and I bought it as a "basket case".

I took the roll bar assembly and removed the two large springs inside the square tubing. This allows the roll bar to be back in place, where it holds the rear seat back. It is non-functional, and always down. As the roll bar springs are relaxed when it is extended, the Torx bit removed the end mount screws without a large release of spring energy. This should only be done with the roll bar extended. When "cocked", there is a lot of spring tension.

Top stowage area is released by use of an 11mm wrench behind the seat back. The PO had removed the rear latch that holds the glass window section locked to the deck lid. That was operate hydraulicaly in the OEM version, I'm going to look at a manual release from the trunk, like an old choke cable.

I'm 6'3' 250+, and I can manage to get it up/down by myself. Would not be a good job for a small lady or young daughter. I may fashion a prop rod to hold up the tonneau cover, so I can use both hands on the top. Be sure to roll down windows before moving top.

Now at the moment, no roll bar. So rollover safety is the windshield frame, which is supposed to be strengthened to the point where the car can be lifted by that frame. Better than an old MG or Harley. I would like to get enough tech information to either repair the whole thing, which would involve connecting back every hydraulic line (PO did not label them); and getting the missing control unit. An alternative is figuring out the rollbar controller and reworking that to manual (hold switch for up/down) - let the rollbar stay up normally, and lower it only when operating the top.

Some owners would just drop it off at the shop and spend the dollars. Then there are others who get tired of a non-working top and sell their toy. This is somewhere inbetween, and perhaps just behind the owner who has the top down, roll bar up, and keeps it in a garage and carriers a car cover with him.

But a cabriolet makes anyone, including a shade tree mechanic 2nd class, look good.

When I had my top hydraulics out for replacement I was able to manually open/close the top but I only did it a few times so to not damage anything.

Your best bet and probably most expensive would be to repair the entire system, which can be expensive. I hope your main lift rams are still there, those things are $1200 each! (the other are around 6-800....last I checked)

But if there is some way to get the roll bar/head rests to work correctly I would just rock it as a manual top.

The hydraulic lines have numbers that correspond to the ports on the cylinders. If you have them they can be rebuilt for about $50 each, may be a bit more these days. However if the controller is "fried" that's an entire different matter.

The roll bar possibly could be deployed manually, then it is always up and no safety risk either.

If you do not have the factory service manual, it is available online at benzworld dot org, in the W124 Class section under Sticky 124 DIY thread. There is a Cabriolet owner's manual supplement there I think.

Good luck.

IIRC tophydraulicsinc.com charges around $55 each plus shipping.They rebuilt mine and I was very happy with the rebuild. I made the trunk and interior panel removal DIY and at the time used some threads from here and benzworld on removing the cylinders. Which could help you for checking connections and lines.

re: The roll bar possibly could be deployed manually, then it is always up and no safety risk either.

I found with roll bar up, you could not lower the top. As for the shop manual, I had been using the one at Mercedes Benz Model 124 - M104 Maintenance Manuals, but could not find hydraulics layout or elecrical for top system. Will try other manual, thanks.