I noticed that it was time to lubricate the cabriolets side rails, when I raised the soft top yesterday. It’s time for maintenance.
This is a well known issue on the Smart Fortwo Cabriolet.
The soft top frame slide in the removable side rails, on plastic blocks.
If the plastic blocks had a Teflon lining, this wouldn’t be an issue, but without periodic lubrication, the friction rises until they get stuck in the rails.
If you are a seasoned fortwo cabrio owner you will recognise the sound of dry plastic in aluminium rails, while lowering the top. However the top will lower without any issues (please correct me in a comment if you have experienced otherwise).
It’s only when you raise it again, that you will can risk getting into trouble.
The cabriolets soft top is attached to a series of ribs. The plastic blocks are mounted on each end of these ribs.
If there is too much friction on one side compared to the other, the plastic blocks will get stuck in the rail. If a block gets stuck, stop operating the roof immediately. Trying to force it closed can cause the plastic to snap in two.
Run the roof back a bit, in order to create slack in the material, and carefully wiggle the block and rib, until it moves freely in the rails again.
Now you can keep an eye on the ribs while closing, to make sure they don’t get stuck again.
Lubricate the rails next time you lower it.
Lubrication is an easy task. Lower the soft top, and you can look directly down the side rails from the rear of the car.
The most difficult part is finding the best product to use.
Iv’e heard many different recommendations and tried three other solutions before I settled on the one I use now. The others didn’t last long enough, if at all.
When I lubricate the rails I use Lithium grease on a spray can.
My personal experience with lithium grease has been that if I use it in the spring, it lasts for the rest of the season. Yesterday was the first time the roof came down in the new season, and I could hear the “I need lubrication rattle“ while it was lowered.
The lithium grease Art. 36-4578 from Biltema has a practical straw, that makes it easier to deliver it to the exact location.
There are three grooves above, and three grooves below that need a little squirt each at the back of the side rails.
The plastic blocks will draw the grease forwards and leave a thin layer of lubricant.
It can be tempting to lubricate the whole length with grease, but while it will prevent the rails from getting stuck, it will also create a terrible mess, when the plastic blocks scrape all the excess grease out from the rails, and squeeze it out between the side rails and the window frame 🥹.
Do you use a different maintenance method? If so, please let us know in a comment below 👇
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