SL/R129: Top action not smooth
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Member
Joined: Feb 2013
Posts: 144
Likes: 7
From: Seattle
1999 MB E430 1998 SL500
Top action not smooth
What are the characteristics of a bad electronic control module such as P/N
129 820 3226 and 3926? My top stops twice very briefly in its motion to come up to the windshield.
129 820 3226 and 3926? My top stops twice very briefly in its motion to come up to the windshield.
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Joined: Sep 2011
Posts: 475
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From: On the beautiful Oregon Coast
03 SL Kleemann, 97 SL320 pano top, 95 Lorinser E320 Cabrio, Ferrari 360, Tesla X
there are many ways in which a bad RST controller can exhibit problems. A bad controller will normally give a matching error code if checked through Star Diagnostic (SDS).
In your SL, there are two instances in which the top can show brief delays during movement without it being a fault at all. The first time would be when the top is at its highest point, and the second time would be when approaching the windshield header or locking thereto.
The explanation for the first speed bump at the highest spot is going to "differential operation". That is applying pressure to both sides of the main lift cylinders A129 800 02 72, which yields a slower effective cross section for the hydraulic pressure to move the piston upward, and thus results in the top moving slower. It is designed to keep the top from hitting the windshield too fast.
The explanation for the second speed bump is the magnetic sensor in the middle of the windshield recognizing the magnet in the front of the soft top and getting ready to latch with the top lock cylinders A129 800 16 72.
I know you had the front /top lock cylinder 1298001672 rebuilt/upgraded. Has the behavior of the top changed a lot after that, or may you just be more perceptive to the top movement's intricacies after dealing with the hydraulic system a little?
Klaus
www.tophydraulicsinc.com
R129 SL-Class roadster top hydraulic component locations
Thread Starter
Member
Joined: Feb 2013
Posts: 144
Likes: 7
From: Seattle
1999 MB E430 1998 SL500
Still needs attention
Hi Klaus:
Your parts (both top lock cylinders and center distribution box) are functioning perfectly with no leaks or other problems. The top problem became noticeable after these parts were replaced but the car left Convertibles Only with all systems working very smoothly. The plot thickens just a bit here by saying that late this last spring I got in one day and suspected that I smelled an electrical connection that had overheated and I still get this slight smell when the car is closed up. All I know is that when I bought the car the top ran very smoothly with only as you say a slight slow down when the top is nearing the windshield.
My next two steps are (1) to take it to an independent mechanic with Star Diagnostics capability to check for codes and (2) to cruise by Convertibles Only and get their advice. If nothing gets resolved then I will contact you offline for more possibilities.
Your parts (both top lock cylinders and center distribution box) are functioning perfectly with no leaks or other problems. The top problem became noticeable after these parts were replaced but the car left Convertibles Only with all systems working very smoothly. The plot thickens just a bit here by saying that late this last spring I got in one day and suspected that I smelled an electrical connection that had overheated and I still get this slight smell when the car is closed up. All I know is that when I bought the car the top ran very smoothly with only as you say a slight slow down when the top is nearing the windshield.
My next two steps are (1) to take it to an independent mechanic with Star Diagnostics capability to check for codes and (2) to cruise by Convertibles Only and get their advice. If nothing gets resolved then I will contact you offline for more possibilities.
