R129 resynching top mechnism - 1996 SL500 - Mercedes-Benz Forum

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post #1 of 13 (permalink) Old 04-25-2013, 08:48 PM Thread Starter
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R129 resynching top mechnism - 1996 SL500

My progress in renewing some of these parts seems to be not in a straight line, but I am getting there (see my post on installing the trunk latch)

Reading about Klaus' products I wanted to see if I could spot any leakng cylinders - so I stopped the soft top retraction half way (while the lid was up) to see what I could see. (the 4 visible cylinders looked fine).

But stopping the retraction half way was a BIG mistake. The red light on the switch stayed on (I know it has never happened to anyone else here) ;-)

Anyway, tried disconnecting the negative ground - reconnecting it - did not help.

Re-synct'ed the windows - windows are fine.

Called my friend Ernie who has a Mercedes shop - and he suggested something I have never found here (knowing the depth of stuff in the archives it may very well be here but I haven't found it).

Ernie said that sometimes all these micro switches will get out of sync (a perfect scenario since I stopped the thing in mid cycle)

So, what he suggested is to MANUALLY retract the top . Then restart it with the switch (when switches should be in sync).

This would have worked (at least the top was coming up and the switch was initially clear before use) - but apparently when I turned the allen bolts (releasing the front of the top) - they should apparently have been in another position because I heard a noise up in the pillar - and then the thing stopped.

The light continues to remain out but the top will not move (I retracted it manually back down).

1. Anyone know where these allen bolts are supposed to be set when you go back to powered operation (the owners manual does not seem to address this - just showing you how to pull the top up manually).

I will try a few things tomorrow in sequence before throwing in the towel and seeing Ernie - but wondered if anyone had gone down this path.

Man - these cars are temperamental but fun to drive - have gotten many compliments on it.

If I had had those allen bolts by the visors (perhaps since we see just a head I would call it an adjustor?) - if I had then set in the proper position I probably would have been fine.

But retracting the roof manually can help in some situations.

I will use Klaus as soon as I need some cylinder rebuilds.
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post #2 of 13 (permalink) Old 04-25-2013, 10:09 PM
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Hmm.. I did this exact thing to my car to view down to the rear actuators. I was retracting it and stopped half way. I used a flashlight to inspect the actuators, then continued with the retraction sequence. I didnt turn off the ignition switch. So I'm not sure what happened in your situation. There was another soft top issue posted today, I'd look there for some clues.

'95 SL320
'69 Jaguar E-Type

Last edited by jagboy69; 04-25-2013 at 10:20 PM.
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post #3 of 13 (permalink) Old 04-25-2013, 10:50 PM Thread Starter
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Jqgboy - in the 4 months I have had this car I have found if there is a way to mess it up I will find it. Had a 300E for 20 years - did most of the maintenance on it - not many problems. I seem to look at this SL wrong and it gets pissed off ;-)

But I am learning. I have learned (despite what the owner's manual says) to raise and lower the top manually - by myself.

Another thing - that top is original - the PO hardly used it - and it has shrunk to the point someone has to push down the back for the pins to catch (when the controller is working anyway).

BTW the Series 1 E-Type was/is one of my favorite cars. Lusted for one as a teenager to the point I would visit the dealer and on quite hours talk to the salesmen.
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post #4 of 13 (permalink) Old 04-26-2013, 04:14 AM
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On my 1996 had this once-

in resyncing- had to hold down each window button about 8 seconds after closing before I heard the click-

much longer than stated in the manual.
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post #5 of 13 (permalink) Old 04-26-2013, 08:17 AM
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have you checked the fuse for the controller? I think it's the third or fourth from the bottom in the trunk. There are several sections in the controller, and it can actually operate the windows (and you can synch them) while the 10A or 15A fuse is pulled. By the way, you can eventually find all ten rear cylinders when the tonneau cover is open - see attached location diagram.

If that wasn't it, let me start rambling a little:

I hope we are not getting too far into the land of anecdotes, but let me throw something out here that may or may not be correct - I haven't tried it on my car.

We work on over 20 brands of convertibles with high-pressure hydraulic tops, of which the R129 was the pioneer. Understandably, the computers in the R129 controllers are pretty antiquated. Newer controllers have a time-out feature where the top will not move automatically after it has been open for a long time with the ignition on. I had never considered that the R129 has that feature, but it's possible. What will it take to resume operation? Let me put out a few guesses:

1) Top must be fully up and locked or fully down and locked, just as is required for synchronizing the windows.
2) Obviously, windows must be synchronized for model years '95 and younger. Windows are synchronized if they drop a fraction of an inch upon opening the doors. There are various reports on how long the buttons need to be pushed for proper synch.

I have heard a few times that the controller sometimes needs to re-learn the switch positions. I think that could be the case only if there were various error messages before that put the controller on alert about something being illogical. That makes me wonder if there was a latent problem in wlb50's system already.

wlb50, has there been any odd soft top behavior before, including possible trouble after removing the hard top? Has the wiring to the micro switches on the various locks been disturbed at all?

Lastly, in response to your questions on the front locks and their Allen bolts: You should not be able to turn those unless the front prongs of the top are inside them. Both locks turn in opposite direction. If one of them got locked accidentally with the top open (which should be possible unless someone fiddled with it a lot), just insert the Allen wrench into both locks and gently turn them in either direction. If you can actually turn one of them some 90 degrees, then it was indeed accidentally locked before. Keep on turning until they are both open again, and all should be well.

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Last edited by TopHydraulics; 04-26-2013 at 08:19 AM. Reason: added info about seeing cylinders from the tonneau area
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post #6 of 13 (permalink) Old 04-26-2013, 08:59 AM Thread Starter
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Thanks Klaus for taking the time to thoroughly go over this - I am printing your reply and will check each thing. One problem with this car - while it was a 1 owner for the last 4 years or so a lot of things were ignored. And the top was rarely used - The PO gave me all of his receipts and I noticed after a jump start the dealer replaced the controller - as to any prior abnormalities I am not aware of any - the hard top came off easily - the soft top was working (with a neighbor having to push the back down because the material has shrunk from disuse) - this problem seems to have started when I wanted to pause it mid way and see what cylinders I could see.

Don't remember whether I kept ignition on or off but from reading posts it would appear that I had it off.

degegia - thank you too for your post - will try that too

Will let you all know the results
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post #7 of 13 (permalink) Old 04-26-2013, 10:42 AM Thread Starter
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All I had to do is turn the allen bolts 90 degrees counter clockwise of the windshield pillar.

Thanks you Klaus - and everyone - for your help.

Things I have learned fro this:

1. Keep the top operation going until completion
I think if I want to inspect all the hydraulic cylinders I will manually release the top

2. If it does get out of sync, manually put the top back into the boot (for lack of a better description) (the allen bolt position should not have to be changed since you have to turn them CCW to release the top - I had messed with them afterwards.

3. Look for a patron saint of R129s to pray to before starting any maintenance job? ;-)
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post #8 of 13 (permalink) Old 04-26-2013, 11:32 AM
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For my '98, I have no problem stopping the soft top operation halfway to inspect the hydraulic cylinders and then resume operation, but did not do it for more than a few minutes.
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post #9 of 13 (permalink) Old 04-26-2013, 01:17 PM
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My experiences have been that the soft top controller will tolerate being stopped midway if you then continue what you were doing, raising or lowering.

(I often stop it to place or remove a thin towel strip that keeps the rear plastic window from creasing sharply and cracking.)

BUT it doesn't like having the sequence being reversed, i.e. raising it after you have lowered it part way or vice versa. (That has caused it to freeze" on my car.)
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post #10 of 13 (permalink) Old 04-28-2013, 08:41 AM
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Having a new soft top installed

I'm getting a new top installed in the next week or so.

After reading this post I am wondering if I should instruct the installers to make sure they release the top manually before they start and not use the switch. It never occurred to me to ask them their procedure until I read this post and the problems others have stopping in mid cycle.

Trying to avoid any unessary problems.
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