snap, crackle, pop...my top broke?

[rsfeller]

My car (1997) lives it's life in a garage or under a street at work, so little heat and sun. This weekend it sat in a parking lot in 90+ heat and when we went top the top down it made a horrible crack noise and the top never went down, I'm guessing plastic part failure. The clamshell opened fully but the roof never retracted. I didn't try to take it an further down but did manage to get the clamshell down w/o any concerns and drove the home a couple of hours home with the top up. I believe I stopped quickly before any major damage could have been done.

Best I can tell from other posts these arms in the photo below with the red plastic things broke off from the ball attachment on both sides and that is what I found once at home. I'm confused by all the discussion about cables and transmissions, do they cause failures in this part or is this just localized due to plastic part failure? I was able to put down the top manually w/o any concerns back home today.

I'm guessing it's just 10 year old plastic that failed in the hot summer heat. I also saw a note about a guy that made metal ends but I'm guessing the factory plastic design is for a reason (the failure point so other systems are not damaged) but would applicate any input on alternate solutions. Otherwise I'll order the arms with the white replacement linkage and move on!

bad ones:

good ones:

Just curious if I have bigger problems at work here or it's as simple as it seems!

Thanks.

Shawn

Ohio

Edited August 12, 2007 by rsfeller

[Chris_in_NH]

this should be posted in the Conv Top Forum.

while you're there, read the Conv Top R&R thread. the reason that the red ball joints break is because the cables are bad. check your cables for length and repair/replace if necessary. also replace the conv top push rod (the one with the red connector on the end). the ends are now white.

it's that simple.

[rsfeller]

Yea I couldn't figure out how to change the post entry location when editing it. I think I'm committed to the general area.

I'll re-read that post again as I found it before but failed to see how the cables interact with the push rods to shatter the ball end. If they changed them from red to white I figured they were the failure location.

I may have upgraded cables as they have the texture look as listed in the post you reference and have at least 3/4" of cable sticking out, but that is in my cool garage tonight. I doubt they shrunk that much in the sun this weekend!

Maybe mine is just weak plastic connectors on the rod unless you see another way the cable interact with the failure. Thanks!

Shawn

Edited August 13, 2007 by rsfeller

[1schoir]

Yea I couldn't figure out how to change the post entry location when editing it. I think I'm committed to the general area.

I'll re-read that post again as I found it before but failed to see how the cables interact with the push rods to shatter the ball end. If they changed them from red to white I figured they were the failure location.

I may have upgraded cables as they have the texture look as listed in the post you reference and have at least 3/4" of cable sticking out, but that is in my cool garage tonight. I doubt they shrunk that much in the sun this weekend!

Maybe mine is just weak plastic connectors on the rod unless you see another way the cable interact with the failure. Thanks!

Shawn

Shawn:

The older red plastic cups on the end of the rod arms become brittle with age and heat/cold cycles and the white ones apparently hold up better.

I think you are making a wise decision not to replace the connectors with the metal ones, for the specific reason that you listed.

If you do have 3/4" of metal cable sticking out on each end, make sure that everything has been "synchronized" before you press the button and that once the clamshell and then the top starts moving, that both sides (driver side and passenger side) are moving equally and that nothing looks lopsided as the top goes down and as the clamshell operates up and down to close.

Again, if you have 3/4" sticking out, there are two other possibilities, both of which have been covered on previous threads (one by Tool Pants and one by Jporter).

One possibility is that the inner metal cable may have come unwound or broken apart inside the black plastic sheathing (the cable actually consists of strands of wire twisted together, with a square end, like a speedometer cable).

The second possibility is that at the other end of the cable (i.e., not the electric motor end, but where the cable goes into the transmission) the worm gear plastic housing that holds the worm gear in its place so that it can transmit the spinning action of the cable to a turning action of the half-moon gear may have come loose or broken. I am attaching a photograph of the back of one of the transmissions. The red arrows show which screws you should be sure are tight. The yellow arrow points to where the worm gear resides. The white arrow shows it's a BMW part.

Either one of those possibilities would cause the motor, through the shielded cables, to exert uneven pressure on the left and right metal tension bow of the convertible top frame and break the plastic connectors.

Try to spin each of the metal inner cables by hand to see if they spin with no resistance at all, or even try to pull them out of their black plastic sheaths to see if they just pull out. If so, then it's probably the first possibility.

To determine whether it's the second possibility, you will have to remove the transmissions.

BE SURE TO TAKE A LOT OF PHOTOGRAPHS OF THE POSITIONS OF THE V-LEVERS BEFORE YOU TAKE ANYTHING APART, IF YOU HAVE TO GO THAT FAR.

Regards, 1schoir.

[rsfeller]

Good info, I'm re-read this a few times to absorb it.

A few questions comments I'd love you to comment on.

1. After taking off the broken arms I tested the transmission for even movement and measured the distance the connecting pin was on each side. They are currently identical on each side and they both turn nicely, but of course they are not under load. Do you think destroyed cable inside the sheath would only show "out of sync" under load? I do know they can fray as that is what my drivers window did!

2. Do you think there is a chance they everything is good and the plastic ends just lived their life? It seems Chris in NH is pretty opinionated that the cable has to be at fault which I respect...but I'm not seeing it yet! Additionally they broke together and I never noticed anything acting "out of sync" or twisted from uneven pressure.

3. Would you recommend a re-sync via the drill method and moving them to full forward motion I've seen posted or is there something better?

Shawn

[Tool Pants]

On the metal vs. plastic joint I can tell you what I know and then you decide.

6 plus years ago Scott Levy was trying to determine if there was an interest in metal joints. He is a 944 owner on the Pelican board, and now sells the joints. I talked to one of the mecahincs at my local dealer who had shown me how to fix tops about the metal joints. The plastic joint is designed to be a failure point in case something goes wrong with the top operation. That is why they are made of plastic.

I went back and forth with Scott. Does the plastic become brittle with age/heat and break, or does something cause the plastic to break. It is the chicken or the egg debate. I do note that back then there was only the red plastic joint. The white ones did not exist back then. The reinforced cables for the old style transmission had just become available back then. And for all I know, it could be a combination of factors.

I have worked on several cars over the years with broken red plastic joints. Each time something else in the top operation went wrong that caused the plastic to break. A few weeks ago someone on Renntech posted a picture of a bent pushrod with the metal joint. I think he is lucky that is all that got bent. You need to determine why the joints broke.

I have no problem with using the metal joints, if everything else is in perfect condition. Porsche did switch to white plastic around 2002, so maybe Scott was right all along. Maybe one of these days a local owner will want to try them.

[1schoir]

Good info, I'm re-read this a few times to absorb it.

A few questions comments I'd love you to comment on.

1. After taking off the broken arms I tested the transmission for even movement and measured the distance the connecting pin was on each side. They are currently identical on each side and they both turn nicely, but of course they are not under load. Do you think destroyed cable inside the sheath would only show "out of sync" under load? I do know they can fray as that is what my drivers window did!

2. Do you think there is a chance they everything is good and the plastic ends just lived their life? It seems Chris in NH is pretty opinionated that the cable has to be at fault which I respect...but I'm not seeing it yet! Additionally they broke together and I never noticed anything acting "out of sync" or twisted from uneven pressure.

3. Would you recommend a re-sync via the drill method and moving them to full forward motion I've seen posted or is there something better?

Shawn

Shawn:

I agree with Tool Pants when he says that the metal joints can be used if everything else is in perfect condition. To err on the side of caution, I would even go further and add "and if the newer style transmissions and related parts have been installed". Replacing the transmissions with Version "B" was a tacit acknowledgment by Porsche that the earlier transmissions (Version "A") and related hardware were too prone to malfunction, sometimes with catastrophic results.

With respect to your questions:

1. It depends on how far gone the inner cable(s) is/are. It's possible if one (or both) of the inner cables have just started to "unravel" that they could appear to function normally until they are placed under load, and then at that point react differently.

2. I think it would be too much of a coincidence for both red plastic joints to have reached the end of their service life at the exact same time. Are you sure that they let go at the precise same time (i.e., did you hear or feel only one big "pop") or is it possible that they broke in rapid succession. Let's assume that they both were brittle (10 years old, etc.) and that they were "weak". Now if one of them let go, the uneven tension could then cause to other ( already weakened one) to pop immediately thereafter. Did it possibly sound more like a pop-pop? That would also comport with Chris in NH's experience, where the second one would break because of the uneven pressure that would then be applied by the cable on the still-connected side.

3. I just recently successfully re-synched by using the "marking notches" on the outside face of the transmissions as a starting point. I am attaching a photo of the passenger side transmission with the "marking notches" and with a sketched-in V-Lever drawn onto it. To see the marking notches, you have to pull back the foam liner. You'll be interested to know that this method is the one reccommended in the factory manual for Version "A" (old style transmissions) and that for Version "B" they recommend a similar starting point AND measuring in a similar fashion to what you described. I used the marking notches method and after getting one lined up, I used a drill to operate the other cable so as to get the other V-lever in the same position relative to its marking notches and then measured the distances from the metal ball on the rearmost part of the V-lever to the bottom of the side section sealing channel (where the bottom of the clamshell arm slides back and forth).

One of the advantages to this method is that when the V-levers are between the marking notches, both the rod arms (with the plastic cups) and the black hydraulic pushrods are easy to reach and to attach to their respective ball sockets. If you spin the cables all the way to the forward position, it will be more difficult to reach from inside the car under the clamshell to attach those joints.

You should also first determine that your transmissions have not been replaced (I don't know if you have owned your Boxster since new). Also, it is possible to have only one side replaced with the new style transmission to work in conjunction with a Version "A" transmission. The switchover took place in either March or May 1999.

Regards, 1schoir.

[Chris_in_NH]

Good info, I'm re-read this a few times to absorb it.

A few questions comments I'd love you to comment on.

1. After taking off the broken arms I tested the transmission for even movement and measured the distance the connecting pin was on each side. They are currently identical on each side and they both turn nicely, but of course they are not under load. Do you think destroyed cable inside the sheath would only show "out of sync" under load? I do know they can fray as that is what my drivers window did!

2. Do you think there is a chance they everything is good and the plastic ends just lived their life? It seems Chris in NH is pretty opinionated that the cable has to be at fault which I respect...but I'm not seeing it yet! Additionally they broke together and I never noticed anything acting "out of sync" or twisted from uneven pressure.

3. Would you recommend a re-sync via the drill method and moving them to full forward motion I've seen posted or is there something better?

Shawn

1. CHECK YOUR CABLES.

2. CHECK YOUR CABLES.

3. you know what i'm going to say. ;)

seriously, checking the cables is the easiest part of diagnosis and takes 10 seconds. why haven't you done this yet? pull them out of the cable motor and let us know if they have 3/4" of drive cable sticking out of them.

*update* i didn't see that you checked your cables since you posted it in another thread. FYI, if you keep your issues to one thread then everyone can see the history, what you've done/tried, etc.

Edited August 13, 2007 by Chris_in_NH

[rsfeller]

Chris, thanks again for the comments. I might have missed with some private conversations that I have checked the cables and they are not 3/4" in length but appear to be upgrades as they have the textured sheath on them. Others have suggested they may have frayed inside like the side windows do...but I'm doubtful of that. I appricate you comments on staying organized but I have started 3 different threads for three different concerns with the top each needing it's own unique perspective. I tend to get caught up each night with updates for each topic.

Today I have determined a pin fell out of of the rear window pivot arm and did some damage. Thus I have two different top problems that are most likly related but may point away from cables and toward worn component failure. I am guessing this could have be the cause of uneven pressure and thus the dual failure of the worn red plastic knuckles.

I believe we are pulling the top frame tomorrow to get to the bent part as I cannot access the pivot pin with the top on. We will bend it back into shape and fix the offending part. Post that I'll resync the top and install the new white knuckles push rod as it should be here by Friday. I'll be documenting with photos the pulling of the top frame, repair of bent part and such in detail. I am still awaiting input from this board if the roll bar must be infact pulled before the top can come off. The Porsche Tech Manual says yes but my eyes say know. Experienced oppinions needed!

Thanks.

Shawn

Edited August 14, 2007 by rsfeller

[Chris_in_NH]

Chris, thanks again for the comments. I might have missed with some private conversations that I have checked the cables and they are not 3/4" in length but appear to be upgrades as they have the textured sheath on them. Others have suggested they may have frayed inside like the side windows do...but I'm doubtful of that. I appricate you comments on staying organized but I have started 3 different threads for three different concerns with the top each needing it's own unique perspective. I tend to get caught up each night with updates for each topic.

if that's the way you want to do it, i can't stop you. but i can tell you it's like the 3 blind men touching the elephant, each thinking it's a different animal. your top issues are all related (except for the roll bar question) and would be best kept to one thread. also, if you have conversations offline and don't update, it makes it more difficult to help you. i know you can't do anything about it now, but in the future it would really make things easier.

Today I have determined a pin fell out of of the rear window pivot arm and did some damage. Thus I have two different top problems that are most likly related but may point away from cables and toward worn component failure. I am guessing this could have be the cause of uneven pressure and thus the dual failure of the worn red plastic knuckles.

as for your cables, whether they are the new ones or the old ones, they NEED 3/4" sticking out the end. if there is not 3/4" sticking out the end, then there is your problem - as i said previously. i am guessing that your missing pin and all the other problems are also cable-related. how much cable is sticking out the end of each of the cable sheaths?

[rsfeller]

3/4" and they look in great shape, again others suggested they could be frayed inside but I'm not feeling it yet. At the moment a worn pin looks like the cause of my headaches. Everything measures and appears very synced but I will resync when the time comes to stall the new white knuckles.