Fixing the bow extension micro switch

I pulled the cylinder out and have tried to straighten the bracket on the microswitch but can't get it too function properly - I think its too bent.

Question - could this microswitch problem have caused the crazy behaviour of the top and can I buy the switch assembly without having to buy a cylinder, P/N or any other advise would be really appreciated - I am at my wits end with this thing - so please ....SOMEBODY HELP!!!!

Once you have a working micro switch in place, cycle the top manually a couple of times, then put your old pants on and try again...

If it doesn't work yet at that point, read codes and report to the forum.

I would recommend another go at fixing the micro switch, before replacing it. Be patient! You had best take the cylinder out again for this job, but you can leave the hydraulic lines on. Try to straighten out all the aluminum without hurting the plastic switch. Tighten the round metal clips holding the switch itself in place. It only matters that the black plastic lever releases from the switch when the cylinder retracts, and that the switch gets pushed when the cylinder rod is extended.

Bend the switch housing until this occurs -- see pictures below. The switch is 'normally closed', which means it is electrically open when pressed. You can check that with a multimeter.

I am parting out five SLs at this time, and have some switch assemblies left. I normally reserve these for my customers of rebuilds, but let me know if the final attempts at fixing the micro switch assembly fail. These switches cannot be purchased separately from the beloved dealers.

Hope this helps,

-Klaus

www.tophydraulicsinc.com

 

Klaus, Thank you so much for your reply, it really is appreciated at times of desperation such as this.:thumbsup:
I have removed the cylinder and then I removed the microswitch and have spent all evening trying to get the thing to work. Some how it has got graunched up, I can see marks on the metal bracket on the car where it has been catching which has caused it to deform.

The black plastic bit which contacts the microswitch is sticking out so the switch itself is not depressed at all. As I understand it, with the shaft extended on the cylinder the black plastic thingy keeps the microswitch depressed under spring pressure, when the rod retracts the golden block hits the lever and causes the black plastic thing to lift and release the microswitch so it opens.

I have tried and tried but the damn thing will not sit correctly to keep the m/s pressed in under spring pressure.

As such, the only way I can see out of this is to replace the m/s assembly. I would be eternaly grateful if you would consider selling me one of your microswitchs :bowdown: Please...Please...PLEASE
I've found a P/N on the switch - its written on the black plastic lever 1298205510. - I'm not sure if this number is for the black plastic lever or the complete Microswitch assembly.

Hope you can help me out.

Your pants comment gave me a laugh at this time of doom

Thanks again
PS I didnt know you also repaired the cylinders.

 

Good job, spotting the P/N on the black piece! I hadn't bothered to look it up before. Parts.com shows a price of $46.58 plus shipping for it, which is too much for a piece of plastic... EPC net calls it switch, and the picture looks like the whole assembly.

I'll place a bulk order for these right away, before they are not available any more. Let me know if you need me to send you one at cost...

 

Hi Klaus, I think its a damn good idea to order these in bulk, its seems this is not the first or the last time our members will have problems with this switch.

Yes please, it would be really appreciated if you could send me one. I just checked parts.com and they wont ship to Dubai.
I will PM you details etc. I am happy to pay for the part, plus any costs for your effort & time in sending to me and of course the shipping.

Thank you so much - I am amazed that a few hours ago I was almost in tears and fearing that I would never get round to enjoying my recent purchase and yet now there is light (or should that read lighthouse) at the end of the tunnel.
OH MY GOD...THIS FORUM ROCKS:thumbsup: YEE HAA....

 

Just for info, I damaged my switch when reinstalling the cylinder after repairing it.
It is easy to do if you install one side of the cylinder then move the cover to far forward when trying to line up the bottom holes!
After repairing my switch and reinstalling the assembly I then adjusted it by placing a tester across the contacts and moving the cover back the required distance to ensure that the contact makes and breaks at the correct point, hope this helps.

 

Hi guys, thought I'd post back and let you know how I got on with my soft top problem.
I received the LH bow extension micro switch from Klaus - Thanks Klaus:thumbsup:
Installed it back in the car very very carefully, paying attention to the hydraulic clips direction, moved the top manually to make sure all was good, then hit the red button. The top worked perfectly all was good - no bow banging up and down or dodge movement of the roll bar - just perfect
As you can imagine, I am ecstatic!! She's back on the road - yeehaa!!

Just wanted to thank you all for your advice & support - couldn’t have done it without you. Hope I can help someone in the same way in the future.

rpribilski, how did you get on with your soft top problem, is it sorted?

 

How not to damage the bow extension micro switch

Folks,

there have been several posts in the past few weeks with members having crushed their bow extension cylinder micro switches. I would like to suggest the 'Match Trick', as shown in my newly updated guide for removal and re-installation of the bow extension cylinder: http://tophydraulicsinc.com/R129 Bow Extension Cylinder Removal.pdf

The trick is illustrated in the last couple of pages of the pdf file. It's a 13-page guide for inspection, removal, and re-installation of the cylinders. In short, when re-installing the left side bow extension cylinder, line up the lower mounting hole of the cylinder with the mounting holes in the frame, and insert a 1-1/4" long piece of wire or wood (trim a match to this length...). From there, install the upper anchoring pin, move the soft top back into the storage compartment, and replace the match with the lower anchoring pin...

The two attached photos show how the switch can get crushed, and how to avoid that accident by first inserting a match on the bottom.

Hope this helps,

-Klaus

 

Folks,

there have been several posts in the past few weeks with members having crushed their bow extension cylinder micro switches. I would like to suggest the 'Match Trick', as shown in my newly updated guide for removal and re-installation of the bow extension cylinder: http://tophydraulicsinc.com/R129 Bow Extension Cylinder Removal.pdf

The trick is illustrated in the last couple of pages of the pdf file. It's a 13-page guide for inspection, removal, and re-installation of the cylinders. In short, when re-installing the left side bow extension cylinder, line up the lower mounting hole of the cylinder with the mounting holes in the frame, and insert a 1-1/4" long piece of wire or wood (trim a match to this length...). From there, install the upper anchoring pin, move the soft top back into the storage compartment, and replace the match with the lower anchoring pin...

The two attached photos show how the switch can get crushed, and how to avoid that accident by first inserting a match on the bottom.

Hope this helps,

-Klaus

Wonderful thread. My question is simple- what are the symptoms for this repair?
My top works perfect... except it doesn't. It doesn't line up with the front latches when it's closing. I can accept that but... when closing it the back part of the top will not go down. I can turn the car off and manually push it down. Then it will seat in the locked position after starting the car and finishing the process. The red actuator will stay lit sometimes and, of course, sound an alarm.

 

Soft Top Not Raising After Bow cylinders replaced.

The last 2 cylinders I replaced (bow) resulted in the following. The soft top was manually down and tonneau cover locked down with the special top wrench. I started the raise top sequence using the up button. Window and roll bar go down, tonneau cover unlocks and opens, bow folds up and the sequence stops with hydraulic pump still running. Suspect the micro switch not closing when bow folds up. Can't hear the micro switch click when moving bow by hand at the limit folding up. Take left rear inside panel cover off and disconnect micro switch cable connector behind door jam. Put ohm meter on the leads going to the switch and move bow back and forth never seeing the switch close contacts. Start looking at switch and don't have much access or sight even using a mirror to see the plunger or how the switch is being actuated. Pulled up slightly on the bottom of the plastic on the switch which has the small actuator under it for the switch and can hear it click so for some reason the hines joint on the cylinder is not actuating the micro switch although if I help it with my finger, it does work. So it sounds like a slight adjustment to me. Take long screwdriver and push slightly on the upper part of the switch that has a plastic piece sandwiched between two metal pieces as shown if this threads photos. Could hear switch click. Pressed harder on screwdriver obviously bending the metal guides a little, just enough for the micro switch to start working properly. Hooked the switch back up and finally the soft top is working perfectly up and down and no leaks with my new, rebuilt cylinders. This car is a present to my wife and I've been dealing with this problem for a couple of months so needless to say, my wife and I are extremely happy now. Thanks to Klaus for sticking with me to resolve this issue. As a sideline, if this switch doesn't operated when it is suppose to, it will affect both the opening and closing functions of the soft top and resulting in the chime and red button flashing when the top is down. If the top is manually put up and latched with the wrench, the bow would go down and latch with the button. I guess this works because the bow switch is "open" and so it will allow the rear bow to lock.

 

fixing the bow extension micro switch in place

Take long screwdriver and push slightly on the upper part of the switch that has a plastic piece sandwiched between two metal pieces as shown if this threads photos. Could hear switch click. Pressed harder on screwdriver obviously bending the metal guides a little, just enough for the micro switch to start working properly. Hooked the switch back up and finally the soft top is working perfectly up and down and no leaks with my new, rebuilt cylinders.

I did repair on car with flat screw driver I pushed upper section of aluminum housing little up just to get contact with micro switch and now top works again just fine

randyrking and Elvis81,

thank you very much for the feedback to the forum! I have heard similar reports from numerous customers. Elvis81, I have indeed referred you directly to this thread, and I appreciate you sharing your experience. Just to reiterate: the switch housing can often be bent back to operating condition when the switch and cylinder are still mounted in the car. Obviously, you have to be very careful in doing this.

When the switch assembly gets crushed only lightly, then it happens to the aluminum flange where it is crossing the top of the cylinder body, and that is what randyrking and Elvis81 have managed to bend back in place. Good job! :thumbsup:

FYI, Top Hydraulics now always puts a sticker on the package with the left bow extension cylinder that reminds people to avoid crushing the switch by using the "match trick" in http://www.tophydraulicsinc.com/R129 Bow Extension Cylinder Removal.pdf (pages 10-14), or by attaching the switch after the cylinder is fully installed.

Klaus

Top Hydraulics | Rebuilt and Upgraded Convertible Top Cylinders, Pumps, Hydraulic Lines - Top Hydraulics, Inc

 

1991 300sl

Hi guys, I had same problem with mine...I get car with leaking hydraulic cylinders and i find web site tophydraulics. I removed and send out all 12 cylinders to be reseal and in less than week I get them back in very nice package (professional work)
after installation on car I run to problem which drove me crazy for while, I send email to tophydraulics, gentlimen with name Klaus Witte responded back in short time and he told me to check this forum, after I did i find problem with that micro switch been damaged, I did repair on car with flat screw driver I pushed upper section of aluminum housing little up just to get contact with micro switch and now top works again just fine
I work on those cars for past teen years and some how i still give damage to switch-housing, but thanks to Klaus my problem is solved

 

Here is some additional illustration:

Klaus

Top Hydraulics | Rebuilt and Upgraded Convertible Top Cylinders, Pumps, Hydraulic Lines - Top Hydraulics, Inc

 

For further clarification, below is the photo of a switch that has not been bent before...

Klaus

www.tophydraulicsinc.com

 

I just wanted to extend my gratitude to the forum and particularly Klaus from Top Hydraulics for the posts on R129 soft top problems and solutions. I did the complete R&R of all the cylinders on my mother's 1998 SL500 and rebuilt each of them using the fine seals by Konstantin at MBSeals.com. Seems like Klaus cherished the opportunity to problem solve many varied situations like a chess master ponders a new match. And Konstantin was very helpful directly with excellent email support when I got stuck. We're lucky to have such great support.

I did want to share a few thoughts based on my experiences for the benefit of the community FWIW- especially if you are interested in rebuilding the cylinders yourself. Having the right tools on the ready was very important. Long needle nose pliers and an extendable magnetic bolt picker upper made all the difference. I went to Ace hardware and bought a few extra metric M5 E-clips for $0.17 each cuz you're gonna lose some. If I ever have to do it again I would pick up an E-clip Tool on Ebay for $17.

R&R'ing most of the cylinders was pretty straightforward utilizing the TopHydraulics info. Should you decide to do the actual rebuild yourself to save time and money the MBSeals.com write up describes the process of replacing the seals well but was incomplete IMHO. I found the bow cylinders the most difficult to not only replace but to disassemble. The other cylinders have C-clip retainers on them that once you know the tip described below then you can open them up in just a minute. In the end it is quite rewarding to save nearly $6000 by doing it yourself.

After struggling for quite some time to try to pry those C-clips out I finally realized that by putting the cylinders upright and securely held in a vice with support on the bottom that I could push down with significant force with a small screwdriver to easily pry out the clip. I used a quality flat head jewelers type screwdriver that had about 1/16" wide blade. That way you also avoid driving that blade into your hand while trying to hold the cylinder in between your knees or whatever. Protect the cylinder while in the vice with a rag and no need to crank the vice super tight. The important thing is to support the bottom.

And to take a bow ... plenty of write ups on these bow cylinders and smashing the switch. They are a real pain to get out at first but the key is putting the soft top in the correct position to get at the mounting bolts. Top hydraulics does a good write up on that. I'd recommend taking the drivers side with the switch out first to minimize damaging the switch and then replace it last. That way the passenger side bow stabilizes the top to a degree to help minimize the risk of crushing the switch as you manipulate the top into various positions. If you mess it up like I did its not the end of the world - you can bend them back into functional state fairly readily (assuming you didn't destroy it) once you play with it out of the vehicle and understand how it works. The write up and photos didn't really provide a clear picture on the process of R&R'ing these cylinders and protecting the switch IMHO. Despite all of the info out there many of us still mess up

Now replacing the seals in the bows is much more complicated which also for me wasn't very clear on MBSeals.com. These cylinders don't have a C-clip type retainer. They have a screw top that is locktited in. The reality is you need a blow torch and a good snap ring type plyers to get them open. You have to heat the top of the cylinder to break the locktite bond and then unscrew the cap with the pliers. Trust me I could not break that bond without heating it up. You'll destroy either the piston rod (scratching or bending it) or the cylinder itself. The heat worked great from my $15 walmart propane torch and it opened easily. Once open you still have to disassemble the piston rod from its end piece to R&R the seal. Take a 3" piece of fuel hose with about an 1/4" internal bore and slit it longitudinally. Place this around the rod to protect it and then put this business in a vice firmly after cleaning oil from the rod so it won't rotate. This will enable you to unscrew the top piece. That came off pretty easy so I don't think it was locktited. Sounds pretty involved but the second cylinder goes much faster.

One last piece of advice that saved a lot of time and headache when replacing the bow cylinders is forget about that "match trick". The concept is sound but instead of using a match stick just put the original bolt with the inner E-clip attached back in place as the first step. Then follow straight away with putting the top slowly into the correct position to place the upper bolt in completely (both E-clips). The lower bolt stayed in place for me and I didn't have to try to go aligning everything up again like you do with the match trick. Just proceed to putting the top in the correct position to put on the last outer E-clip on the lower bolt. And then you're done. The less you're moving the top around the less chance of messing up the switch. By the fourth time after figuring this out it took 15 minutes to put the cylinder in.

Thanks again to all, I hope this helps

 

Take the switch off of the cylinder before removal .... it only takes a minute .... with top down unscrew the plastic cable holder ..... with top up and rear up, remove the 3 screws holding the switch to the cylinder ..... disconnect the switch cable connection(lower door jam) and pull the switch out (rearward).....

*Placing a rag below the switch and allowing the screws to fall there and then retrieving them with a magnetic pick up could help .... also **Using a magnetized screwdriver tip helps re-install the screws.


Cheers,
Fast960

 

TH-K,

Thank you for taking the time to address this.
This '91 500SL has been well maintained but it is the newest of mine. The top was replaced prior to my purchase. The top worked fine except that it did act up a bit and the PO sprayed contact on a 4 pin connector located at the left tonneau cover cylinder lock.

Thinking of the subject a bit more- and being less distracted ATM (Bears can't finish a game!) I do noticed that top continues to apply pressure to the front throughout the closing process- meaning even after the front locks are engaged and "locked". However, I feel from what you are indicating if their azimuth is off too much then that would cause the top to not finish it's close as well as an alarm after it's closed. AKA the top still believes it's open.

I will investigate more fully tomorrow.

The only service performed since my ownership is the changing of hydraulic fluid to MB correct P/N. The reservoir fluid was black.

 

Klaus,

I inspected the front latching areas and used the allen wrench to gauge tightness and actuation. They seem to be very tight and rotate very slightly when engaging the actuator. (No more than a couple of degrees).
The roof line is (looking from the front of the car) off to the outside or right by a bit. Pics included.
The P/O sprayed contact cleaner on the shown contacts the day I bought it and it seem to resolve the issue for the moment. Well- that issue anyway.
From what I understand- if the alignment is off the system may believe that the front latches are not correctly engaged and will not perform other duties correctly, correct?