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Ran out of rear adjustment on sunroof lid

Started by ptashek, 26 June 2021, 11:33 AM

ptashek

I've been adjusting the sunroof lid today, as it was out of spec (*), and while I got the front edge aligned perfectly, I've ran out of adjustment on the rear edge.
After moving the side adjustment slides to the maximum lift position, the lid still sits 1 - 1.5mm below the roof edge. What could possibly be causing this?

The sunroof works perfect, runs parallel in the tracks and shuts nice and tight, so I don't think it's a case of mis-alignment.

(*) Factory spec is as follows:

- front edge: 0 to 1mm below roof edge
- rear edge: 0 to 1mm above roof edge

1993 "Pearl Blue" W124 280TE
1988 "Arctic White" W124 200T
1979 "Icon Gold" W116 450SE

UTn_boy

Is it possible that the cams that the lid slides up on at closing are worn, and is it possible that the shims are worn thin?  If not, then maybe try turning the emergency nut on the motor/transmission assembly until the rear of the lid is where it needs to be, cycle the sunroof open and close, and then check/re-adjust as necessary.  The only other thing I can think of is that the slip clutch is slipping too soon net being able to overcome the last bit of resistance when the lid is pushed all the way up.  Maybe tighten the slip clutch? 

If all of the aforementioned checks out, then don't be afraid to further shim the lid with additional shims.  No, it won't be "factory", but it'll work, and it won't be seen.  Sometimes the original set up just doesn't work. 
1966 250se coupe`,black/dark green leather
1970 600 midnight blue/parchment leather
1971 300sel 6.3,papyrus white/dark red leather
1975 450se, pine green metallic/green leather
1973 300sel 4.5,silver blue metallic/blue leather
1979 450sel 516 red/bamboo

ptashek

Quote from: UTn_boy on 26 June 2021, 12:12 PM
Is it possible that the cams that the lid slides up on at closing are worn, and is it possible that the shims are worn thin?

It's a possibility. They're still factory ones. I can't remember what it was, but I'm sure there was a reason they weren't renewed during the resto.
How would I check these?

QuoteIf not, then maybe try turning the emergency nut on the motor/transmission assembly until the rear of the lid is where it needs to be
Gave that a try. No change. As far as the motor/cable drive part is concerned I think everything works as expected. The motor runs for a brief moment (~1s) after the sunroof shuts and lifts, which would suggest the slip clutch is adjusted OK?


QuoteIf all of the aforementioned checks out, then don't be afraid to further shim the lid with additional shims.  No, it won't be "factory", but it'll work, and it won't be seen.  Sometimes the original set up just doesn't work.

You know me ;)
I'm not concerned with "factory" as much as I am with "working".

I think I will follow your advice with the extra shims.
I might try 3D printing the adjustment slides with a longer arc and more aggressive slope as well.
1993 "Pearl Blue" W124 280TE
1988 "Arctic White" W124 200T
1979 "Icon Gold" W116 450SE

UTn_boy

I think the motor continues to run after the movement of the the lid and cables ceases.  During this time is when the clutch is slipping like it should be.  I remember on Dad's 450sel having the same problem you are having.  I ended up having to tighten the slip clutch to where it slipped later at a higher torque, and I also had one of the side seals, or maybe the rear seal, impeding the lid from seating in the "home" position that last little bit. 

With the lid closed, can the lid be pushed up to the position it needs to be in?  (Try this with and without the cable connected).  If it goes that extra little by hand then we know the clutch is slipping too soon or that something is causing enough resistance that last little bit to cause it not to seat in the "home" position.  I'd try that first, and then add shims or make new thicker ones if all else checks out and/or fails. 
1966 250se coupe`,black/dark green leather
1970 600 midnight blue/parchment leather
1971 300sel 6.3,papyrus white/dark red leather
1975 450se, pine green metallic/green leather
1973 300sel 4.5,silver blue metallic/blue leather
1979 450sel 516 red/bamboo

ptashek

Good pointers on the seals.
The side ones sit correctly, but I have an odd feeling the rear seal may be involved. On close inspection, in the current lift position it fits as snug as it gets against the sealing edge. I'll double check by forcing the lid up when closed as you suggested.

It's not the end of the world if I can't adjust it fully. Sure, there will be a bit more wind noise, but my main concern was that it seals properly. There were no leaks, but the lid sat a good 3mm below the rear roof edge.
1993 "Pearl Blue" W124 280TE
1988 "Arctic White" W124 200T
1979 "Icon Gold" W116 450SE

ptashek

Mystery solved. Forced the lid forward and up by hand when closed, and it won't budge.
The (genuine) rear lid seal prevents the lid from raising any higher. Not much I can do about that.
1993 "Pearl Blue" W124 280TE
1988 "Arctic White" W124 200T
1979 "Icon Gold" W116 450SE

revilla

Good to know. So you can now pass to the next item in the list.
It's amazing how everything goes always to the most basic stuff. That's why we always start with the essentials, checking even the most obvious things first before launching complicated hypothesis.
The only thing that still catches my mind is why is a hand pushing capable to "adjust" things (i.e. seal) and not the mechanism?
It doesn't make too much sense to me.
Your sunroof was closing fine before I'm assuming, right? It's unlikely the seal moved, or dramatically changed shape enough to create the situation described (?).

ptashek

Quote from: revilla on 29 June 2021, 10:53 PM
The only thing that still catches my mind is why is a hand pushing capable to "adjust" things (i.e. seal) and not the mechanism?
It doesn't make too much sense to me.

As Aaron mentioned above, the sunroof motor has a clutch. As the lid shuts and starts resisting the motion of the cable, the clutch will start to slip and if not properly adjusted, it can slip too early. In my case the manual test was to make sure the motor is doing its job as expected, and the clutch is not slipping. Hence the push forward, and up to verify if there was any movement left in it.

Quote
Your sunroof was closing fine before I'm assuming, right? It's unlikely the seal moved, or dramatically changed shape enough to create the situation described (?).

Yes, it was always closing without any issues. Nice and smooth, fast motion.
But before the resto, with the old rock-hard factory seals it was closing nice and flush with the roof line.
1993 "Pearl Blue" W124 280TE
1988 "Arctic White" W124 200T
1979 "Icon Gold" W116 450SE

UTn_boy

I wonder if the newer Mercedes seals are made by a different company......with slightly different dimensions?   
1966 250se coupe`,black/dark green leather
1970 600 midnight blue/parchment leather
1971 300sel 6.3,papyrus white/dark red leather
1975 450se, pine green metallic/green leather
1973 300sel 4.5,silver blue metallic/blue leather
1979 450sel 516 red/bamboo

gavin116

Hi Lukas

What a frustration you've had with the sunroof! I remember trying to replace the seals myself. I managed well with the two side seals. The rear seal wasn't going to be easy to change in-situ as there was limited space. I realised this seal could only be changed by dropping the sunroof tray. Instead, I foolishly pulled the front seal and then found myself in a position where I could not seat the new front seal at all. I think in hindsight, the tray needs to be lowered to seat that and the rear seal. It kept on popping out of the channel. The result was that the sunroof didn't seal...

Not to worry as my other work over that weekend resulted in a dead fuel pump, l so I decided to let the 'garage ' fix it (it's the one named after W126 coupe models _ _ _shop.) Well, he did replace the old fuel pump with the new one I provided, but on the sunroof seal side of things, his solution was, well... :o  I know I'll just cut a notch in the seal where it's not seating!  >:(

The problem was solved when the car went into a different garage to have rust repairs to the sunroof tray. It all worked out well in the end, including all new seals. Actually, only two years down the line and it all got replaced for a second time when I did the bare-metal restoration.

The seals are quite variable you get from M-B: that front sunroof seal may have been a dud, I just don't know. But I can certainly say that the first front windscreen seal that was installed made the aluminium trim pop out, one piece of which was lost and the other bent... The second front windscreen seal has proved different. Both the replacements were slightly different in the way how the aluminium trim sits within them.

If it's not leaking, then leave it. However, if you're unsure, then I suspect the headlining needs to come out, and the tray lowered to see if the seal is correctly seated or not...

Good luck.

Keep on 116ing!  ;)
1979 450SE "Mrs White"
2022 Touareg-R 3.0TSi Hybrid
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ptashek

The seal certainly sits as it should. Nice and snug in its channel. But I hear you on the variability. I had the exact same windscreen seal saga, and wouldn't be at all surprised if it extends to other rubber parts.
1993 "Pearl Blue" W124 280TE
1988 "Arctic White" W124 200T
1979 "Icon Gold" W116 450SE

daantjie

Yet another reason for me to dislike a sunroof  :o  only cool when you have to blast baddies with your rocket launcher 8)
Daniel
1977 450 SEL 6.9 - Astralsilber