Convertible Top Problem

[jporter]

I moved the relay circuit for the microswitch to a location behind the trunk liner in the front left corner of the trunk. This keeps it out of the weather and makes it accessible if there is a problem with the top.

[dogstarsix75]

Greetings it could be a broken pushrod that is rubbing against plastic. Its the plastic that is one of your side air intake plastics. This is what I am facing currently, my pushrod snapped and poked thru my drivers side air intake and seized that side top transmission. Could be expensive if not taken care of, at least in my case $700 or $350 from a dismanteler for the one transmission and all the other parts the pushrod broke. :unsure:

Good Luck,

Matthew

btw... anyone know how to get the center bolt off on a seized top transmission? it comes off on the other side by pushing the close top button in the car but this other one is STUCK!

[Alienz]

jporter, how did you fix the problem? Can you list the steps of what you did?

[jporter]

The following posts will be in reply to Alienz request for more details on the fix I’m using for the top issue referred to earlier in this thread. I will require 2 separate posts so that I can include the related images. The 2 posts will be on the microswitch, and the relay circuit and the related wiring. The following will focus on the microswitch.

The microswitch was used to provide additional control for the closing of the convertible-top compartment lid (CTCL). I believe the OEM approach of using an “after running time” once the lid switch is tripped is prone to variation due to age, wear, frictional changes and related torque required of the motor. I also believe, although I’m not sure, this was corrected in later models with the integration of a microswitch into the top drive transmission.

The microswitch provides a means to stop the CTCL when it is in the proper position. My first thought was to locate the switch so that it would be triggered by the CTCL, but I could not find a location to attach the switch so that the CTCL would contact it a the proper moment, be clear of the moving components and allow for adjustment. I also believe this would not allow for the addition motion of the transmission needed to close the CTCL tightly.

I ended up locating the switch at the top transmission because there is an area, indicated in the following image, that is free of moving parts and can be used to trigger the switch when the “V-lever” of the top transmission is in the proper location (CTCL properly closed).

The switch has an extension that makes it easier to locate it and was purchased at a local electronics store. The switch is attached to a piece of sheet metal with two small bolts. The piece of sheet metal was cut to a shape that allowed it to be attached to the frame for the CTCL support structure, pivot at the attachment point for adjustment and fit under the shield for the top transmission to hold it in place. The shape was developed by cutting pieces of cardboard until the size and shape worked. The shape is outlined in the following images.

The sheet metal is attached to the support frame with the single bolt indicated in the following images. If I were to do this again, I would use a significantly smaller bolt diameter. The bolt is ½ inch long. There are 3 washers with metal washers next to the nut and bolt head. The third washer is a rubber washer located between the piece of sheet metal and the support frame. When the bolt is loosely tightened, the piece of sheet metal can be rotated about the axis of the bolt. This allows you to adjust the location of the switch in relation to the “V-lever”. When the bolt is tightened (not too tight), the location of the switch is held in the proper position. The rubber washer adds additional friction to hold the switch in position.

The following is a discussion on adjusting the switch since this section covers the microswitch, but these steps occur after the relay is in place and properly wired.

The switch location is adjusted as follows. The top transmission must be timed prior to adjusting the switch since you are only using one side for the control. First unhook the top skirt and cables so that the back section of the top can be pivoted up – this will allow access to the switch when the CTCL is closed (see image below). You will also have to remove the shield on the side of the CTCL. With the back section up, close the top with the switch on the dash until the CTCL is tightly closed. If you go too far and hear the pop, you will have to retime the transmissions and start over. Loosen the bolt and rotate the switch until it is triggered by contact with the “V-lever”. The switch I used made an audible click when it was triggered. Tighten the bolt and partially open and then close the top to check the proper location of the switch. I was lucky enough to have the adjustment work the first time, but suspect you will have to adjust the position based on the trials.

The next post will cover the relay circuit and related wiring.

[Tool Pants]

Wow, very good. CTS, the company that makes the top, should hire you. You are correct that the new style transmission has a microswitch. I pulled one out and it is in my fingers. I guess that is why the lever/microswitch above the top motor was eliminated when the new style transmission went into production.

You do need the after running time, the second or so the motor continues to run, when the top is down. This pulls down on the black rods attached to the clamshell so that the clamshell is held tightly to the body. The underside of .clamshell, in turn, has those 5 round rubber discs which clamp down on the canvas. Otherwise you would have rattle city from the top and the clamshell.

I thought the run time was controlled by the top relay/control unit and that there is some type of timer in it that allows to motor to run that extra second. Your device stops the power to the motor sooner than normal. Is that what it does?

Did you ever try another relay and see if the problem went away?

[jporter]

This a reply to Tool Pants post. I have also included larger images for the previous post since they were difficult to read. I will also complete the second post covering the relay circuit and related wiring later today.

I spent some time analyzing the top relay and have traced most of the circuit related to the top motor control. I found several possible timing circuits (combination of capacitor and resistor) in this part of the relay. One of the most likely appeared to also control the window drop and I was concerned about the impact of changing this timing. I do believe that I would be able to come up with a way to control the “after running” time with the addition of a variable resistor that could be accessed from the outside of the relay. This will require much more effort/time to develop this solution.

You are correct that the current fix I’m using stops the power to the motor sooner than normal (before the “after running” time expires). This will be covered in more detail in the second post on the relay circuit I added to the car.

I also believe you are correct that a new relay could solve this problem as the “after running” time may be different. I have not been able to try this since I live in a state with more green and yellow vehicles that run like a deere than cars and more UFO sightings than Porsches. There is also only one Porsche dealer 180 miles away. I will pass on the results when I get a chance to try a new relay.

[jporter]

This is the second of 2 posts to describe the fix I’m using for the top issue described earlier. This post will focus on the relay circuit and wiring.

The relay circuit was developed to cut the power to the top motor long enough for the “after running” time to elapse and the top indicator light to turn off. At the end of the appropriate time, the power to the motor is restored so that the top can be operated. I used about 2 seconds for the time delay.

Although I bought the components at RadioShack, I found similar components at a local electronics store at competitive prices. The circuit is relatively simple with a relay that opens and closes the power line to the top motor, a capacitor stores a charge that is discharged through the coil of the relay at the appropriate time, a diode that prevents the capacitor from discharging back into the car’s system and a resistor to allow the capacitor to discharge when needed. The electrical components are as follows.

Relay 12 volts, 10 amps

Capcitor 2200 uF electrolytic

Resistor 1000 ohms, ¼ watt

Diode 50 piv, 6 amps

The circuit is shown in an earlier post. The circuit details are shown as an overlay in the following images. The circuit was developed using a breadboard so that the timing could be tested. Note that the capacitor used has polarity and must be oriented as shown. The orientation of the diode is also important.

The circuit was assembled/soldered on a circuit board and positioned in a kit box. I glued terminal blocks to the side of the kit box and slotted the sides of the box to allow the internal wires to be attached to the terminal blocks. I also attached a truss bolt to the inside of the box so that it could be attached to the car.

The following is a discussion on testing the circuit. The components used will have an impact on the actual delay time. As a result the circuit will have to be tested to determine the actual delay time. The relay makes an audible sound when it opens and closes. When the switch is triggered you should hear a click and then hear a second click about 2 second later. If the delay time is too short, you will need to increase the resistance of the resistor. If the delay time is too long, you will need to decrease the resistance of the resistor.

The relay is located in the front left side of the rear trunk as shown in an earlier post. The wires from the switch are tucked under the support frame and then run under the padding to a hole that gives access to the location of the relay. The wires from the top motor run with the top motors wires and are diverted to the relay at the hole referred to earlier. This can be seen in the images below.

The relay is inserted in the power line by cutting the green power line to the motor and then attaching the two lines from the relay to the free ends of the power line. This is shown in the image below. I made the cut near the top motor since I originally located the relay in the same area. I would move the cut to an area closer to the new location of the relay since the top motor wires run to an area much closer to the new relay location.

The attachment of the wires to the relay is shown in the close up of the relay in the new position. The power to charge the capacitor comes from a wire that is attached to the terminal 15 area of the fuse box in driver side area of the car. I had space available in row E spaces 8, 9 and 10. Although I ran the wire down the center console and under the padding to the hole referred to earlier, I would change this to running the wire through the channel next to the drive side floor board. There may also be a more convenient location for power where the relay is located in the rear trunk.

The following is a brief discussion of how the relay circuit and switch operate. When the ignition is on and the CTCL is open the power for the relay circuit flows through a circuit from the fuse box through the diode to capacitor to the Common (COM) terminal of the switch to the Normally Closed (NC) terminal of the switch to the ground of the car. The charging of the capacitor seems to happen almost immediately.

When the CTCL is closed (switch triggered) the stored power in the capacitor is discharged through a circuit that flows through the coil of the relay to the Normally Open (NO) terminal of the switch to the COM terminal of the switch and back to the capacitor. Some of the power is also discharged through the resistor.

The diode allows the power to flow from the fuse box to the capacitor and keeps the discharge from flowing back into the fuse box.

When the capacitor is discharging the power through the coil of the relay, the power is cut to the top motor. It takes about 2 seconds for the capacitor to discharge and as a result the power to the top motor is cut for about 2 seconds. When the capacitor is finished discharging, the power is returned to the top motor.

Edited June 27, 2004 by jporter

[Alienz]

THanks for the detailed reply. The only problem is that I don't have some of the components you have in the pictures you took. Maybe because mine is a 97? What about an easier solution, maybe replacing the relay?

[Alienz]

Now my top is so messed up! When I put the top down, the top transmissions won't een stop on the way down! This looks like a problem with the relay or something.

[Alienz]

http://cgi.ebay.com/ebaymotors/ws/eBayISAP...bayphotohosting

How about replacing the last 3 parts, will it fix the problem?

[Tool Pants]

Your top is haunted.

That is an interesting top fix kit on ebay. The relay is the one for your car but you can buy a new relay for a less than $80. The 2 switches in the kit do not cut power to the top motor when it is going down.

If you want to rule out the relay then find another 1997-1999 Boxster and swap. You will know immediately if that is the problem.

[jporter]

While doing some maintenance on my car recently, I found what I believe was the cause of the popping sound at the end of the closing cycle on the top. I removed the transmission from the side that made the popping sound prior to the fix covered in the earlier posts. The 4 screws indicated in the attached photo were very loose – significant gap between screws and black plastic piece that houses the driven gear. I believe this resulted in the driven gear partially backing out of the pilot hole on the other side of the transmission and allowing the gears to skip over a tooth under the added pressure at the end of the closing cycle.

I believe the loosening of the screws is the result of the plastic piece taking a permanent set (commonly called creep in plastics) due to the pressure of the screws. The permanent set would be increased due to the pressures cycles related to the thermal expansion of the plastic piece. The screws could become loose and slowly back out over time.

Although I plan to keep the fixed mentioned above for added control of the closing cycle, I believe tightening these screws could have solved my original problem and I thought it could help others in troubleshooting top problems.

PS: Apologies to Toolpants for using part of one of his photos so I could highlight the location of the screws.

[BoxsterPaul]

Guys,

Its been great to read about the convertible top issues.

My problem was that only driver side would raise and lower.

In reply to the four screws being loose, I found this also to be true. So I took the worm gear housing apart. Because I was not getting any spin from the main gear, yet I knew the motor was working.

Thanks to your guys input( and pictures) I found that my cable was short?? How could this be.. ?? What happened......

I noticed that the carriage (white plastic) that holds the worm gear in the tansmission housing, the far end from the cable, was broken from its backing, so that the worm gear could actually move a very little bit, in the housing thus shortening the cable.

So the question is do I need to buy a whole new housing or can I purchase particular parts ?

BTW its a 1998...which I read somewhere the dealers don't look at any more, or want to replace the whole thing ??

Thanks again

BoxsterPaul.

[jporter]

Although I plan to keep the fixed mentioned above for added control of the closing cycle, I believe tightening these screws could have solved my original problem and I thought it could help others in troubleshooting top problems.

I had some time to see if tightening the screws fixed the problem. I removed the microswitch and the top works perfectly. I'm now confident that the loose screws were the cause of the problem with the top.